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This is to certify that the
thesis entitled

Assessing Recovery of Anthropogenically Disturbed Lakes
Using Reference Systems and Multi-elemental Techniques

presented by

Joel D. Fett

has been accepted towards fulﬁllment
of the requirements for the

MS. degree in Environmental Geosciences

 

 

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Assessing Recovery of Anthropogenically Disturbed Lakes
Using Reference Systems and Multi-elemental Techniques

By

Joel D. Fett

A THESIS

Submitted to
Michigan State University
In partial fulﬁllment of the requirements
For the degree of

MASTER OF SCIENCE

Department of Geological Sciences

2003

Abstract

Assessing Recovery of Anthropogenically Disturbed Lakes Using
Reference Systems and Multi-elemental Techniques

By
Joel D. Fett

Assessing recovery in anthropogenically disturbed lakes using sediment
core chronologies can be challenging. As is the case for Torch Lake, Houghton
County, Michigan, where approximately 200 million tons of heavy metal rich
mine tailings were dumped from 1868 to 1968. To deal with this issue, multi-
element data was collected and compared to a reference lake, Gratiot Lake, to
assess how the lake has responded to lessened anthropogenic burdens.
Sediment cores were collected from four depositional basins of the Torch Lake
and one from Gratiot Lake, metals extracted by a microwave-assisted HN03
digestion and the leachates analyzed for 21 metals via ICP-HEX-MS and AAS.
Sediment ages for Torch Lake were calculated using an “event dating” technique
that is based on historical and geochemical data. Copper concentrations in post
mine tailing dominated sediments still averaged 1,615 - 2,844 mg/kg, suggesting
the little recovery of the lake has occurred since direct inputs ceased. However,
other elements (e.g., Ti, Co) and elemental ratios (e.g., Co/Zn, KN) suggest
Torch Lake is responding to the cessation of mining activities and the sediments
are approaching levels reﬂective of Gratiot Lake. This study demonstrates the
importance of using reference systems and multi-element techniques when

assessing recovery of anthropogenically disturbed systems.

Acknowledgements

There are many people that I would like to thank for assisting me along
the way to completing this thesis. First, I would like to thank my committee
members, David Long, Lina Patino and Grahame Larson. Dave has been a
friend as well as an advisor. Without his support, I may never have made it out
of here. Lina was always willing to provide assistance with the lCP-HEX—MS
analysis, and her grammatical corrections to this thesis are appreciated.
Grahame was asked to be a committee member at the last minute and I
appreciate him for ﬁlling in for Nathaniel Ostrom who had to be away on a
sampling trip during my defense.

Also, I would like to thank some others that made my time in graduate
school a most enjoyable experience. There are too many to name them all, but
some of the most notable are Linker, Nick, Brian, Moss, Chris. We had a lot of
fun times together, whether it was just sitting at a bar, trying to catch some
steelhead or going to GSA. I guess we all just “lived and learned”. would also
like to thank Loretta, Cathy, Jackie, and the captain and crew (Polly) of the US
EPA R/V Mudpuppy. Last but certainly not least, I would like to thank my
parents for supporting me throughout my whole college experience to date,
without them, I don’t know if I could have done it. Well, Grahame Larson once
told me “the last one to leave turns out the lights”, so I guess I just hit the

switch. . ..

Table of Contents

List of Tables ....................................................................................... vi
List of Figures .................................................................................... ix
I. INTRODUCTION ................................................................................ 1
General Introduction ...................................................................... 1
Formation of Copper Deposits in Michigan ......................................... 4
Copper Mining in Michigan ............................................................. 6
History of Torch Lake .................................................................. 1O
Aqueous Geochemistry & Toxicity of Copper .................................... 15
Hypothesis ................................................................................ 16
Signiﬁcance .............................................................................. 16

ll. Methods and Materials .................................................................. 18
Study Area ................................................................................ 18
Sample Collection ....................................................................... 18
Sample Analysis ......................................................................... 23
Quality Assurance/Quality Control .................................................. 25
Reference Systems ..................................................................... 25

III. Results and Discussion ................................................................. 32
Nature of Sediments .................................................................... 32

210Pb and 1370s. ........................................................................... 35
Extractable Copper Concentrations ................................................ 44

Cu/Zn Ratios ............................................................................. 48
Multi-elemental Results ............................................................... 52
Elemental Ratios ........................................................................ 58
Co/Zn, Ti/Zn, K/V, Co/V, U/Zn and Ti/Ba ................................. 59

Controls on Copper in the Cap Sediments ....................................... 64

Grain Size ........................................................................ 64

Pore-water Diffusion ........................................................... 65

Microbial Processes ........................................................... 68

Event Dating ............................................................................. 69
Estimating Recovery Rates ........................................................... 74
Conclusions ............................................................................. 76
Future Work ............................................................................. 78
Appendices ....................................................................................... 80
Appendix A. Sediment-Core Descriptions ......................................... 80

Appendix B. Quality Assurance l Quality Control .............................. 88

Appendix C. .............................................................................. 97
Appendix D .............................................................................. 106
References ...................................................................................... 1 09

Table 1

Table 23

Table 2b

Table 20

Table 3

Table 4

Table 5

Table 6

Table 7

Table 83

Table 8b

Table 80

List of Tables

Percent water in the surﬁcial sediments from three sampling
Sites of Torch Lake: T1, T2 and T5, of Torch Lake. Site T3
sediments were not analyzed for porosity ............................... 21

Data from the 210Pb and 137Cs analysis for Torch Lake,
site T1 ............................................................................ 37

Data from the 210Pb and 13705 analysis for Torch Lake,
site T2 ............................................................................ 38

Data from the 21C’Pb analysis for Torch Lake, site T5 .................. 39

Copper concentrations in Torch Lake Sediments, Gratiot
Lake sediments, Lake Superior sediments and soils of the
Keweenaw Peninsula ......................................................... 48

Average ratios for Cu/Zn in the cap sediments and mining related
sediments of Torch Lake and several other sediments from within
and around the Keweenaw Peninsula of Michigan .................... 52

Concentrations (mg/kg) and trend shifts of U, Ti, K, Co, and Ca
from the cap sediments to the mining related sediments in
Torch Lake, MI .................................................................. 53

Average concentrations (mg/kg) and trend shifts of U, Ti, K, Co,
and Ca from basalts to sandstones. Averages based on data
from Reimann and Caritat, (1998) ......................................... 56

Selected elemental ratios in the sediments of Torch and
Gratiot Lakes .................................................................... 63

Data from the event dating method of age calculation for Torch
Lake, Site T1 ..................................................................... 70

Data from the event dating method of age calculation for Torch
Lake, Site T2 ..................................................................... 71

Data from the event dating method of age calculation for Torch
Lake, Site T1 ..................................................................... 71

vi

Table 9

Table 10

Table 11.

Table A-1

Table A-2

Table A-3

Table A-4

Table 8-1

Table 8-2

Table 8-3

Table 8-4

Table C-1

Table 0-2

Table C-3

Comparison of dates using the 210Pb and event dating
methods from site T1 .......................................................... 72

Number of years to reach ratios reﬂective of average Gratiot
Lake ratios for Co/Zn, Ti/Zn, K/V, CoN, U/Zn and Ti/Ba at
each sampling site ............................................................ 75

Recovery time in years for Torch Lake sediments to get to a
copper concentration of 61 mg/kg (Gratiot Lake average) based

on patterns of Cu concentrations in the cap sediments ............... 76
Sediment description from Torch Lake, Site T1 ........................ 80
Sediment description from Torch Lake, Site T2 ........................ 82
Sediment description from Torch Lake, Site T3 ........................ 84
Sediment description from Torch Lake, Site T5 ........................ 86
Data from the replicate sample analyses ................................. 89

lCP-HEX-MS and AAS results from blanks processed with each

digestion run ..................................................................... 92
Results from the lCP-HEX-MS and AAS analysis of SRM 2704
(Buffalo River Sediment) ................................................... 93

Detection and quantiﬁcation limits for selected elements
analyzed by lCP-HEX-MS and AAS ....................................... 96

Results from lCP-HEX-MS, AAS and event dating analysis

from Torch Lake, MI, Site T1 ............................................. 98
Results from lCP-HEX-MS, AAS and event dating analysis
from Torch Lake, MI, Site T2 ............................................. 100
Results from lCP-HEX-MS, AAS and event dating analysis
from Torch Lake, MI, Site T3 ............................................. 102

vii

Table 0-4 Results from lCP-HEX-MS, AAS and event dating analysis
from Torch Lake, MI, Site T5 ............................................. 104

Table D-1 Results from lCP-HEX-MS, AAS and 21"Pb dating of Gratiot
Lake, MI sediments ......................................................... 106

viii

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

List of Figures

Map showing the location of Torch Lake, Houghton County,
Michigan ............................................................................. 2

Generalized Stratagraphic column for the Keweenaw Peninsula of
Michigan ........................................................................... 5

Map showing the bedrock geology of the Upper Peninsula of
Michigan (modified from Milstein, 1987). Image is presented in
color .................................................................................. 7

Map of stamp mill locations in the Keweenaw Peninsula of
Michigan (modiﬁed from Wright et. al., 1973 and Kerfoot et. al.,
1999) ................................................................................. 9

Photos from the western shore of Torch Lake along M-26. Notice
the pink/purple colored stamp sands lining the shores. Image
is presented in color ............................................................ 12

Map showing the location of Portage Lake, Keweenaw Peninsula,
Michigan (modiﬁed from Wright et. al., 1973) ............................ 13

Map of sample sites within Torch Lake, Upper Peninsula,
Michigan. Image is presented in color .................................... 19

Photos of the Ocean Instruments MC—400 Lake/Shelf Multi-corer
on the deck of the R/V Mudpuppy. Image is presented in color ...22

Diagram of terms used in proﬁle descriptions ........................... 26

Map showing the location of Gratiot Lake, Portage Lake and Torch
Lake in the Keweenaw Peninsula of Michigan (modiﬁed from
Ellinger et. al., 1994) ......................................................... 28

Surﬁcial geology map of the Upper Peninsula of Michigan
(modiﬁed from Farrand, 1982). Image is presented in color.........29

Figure 12

Figure 13

Figure 14.

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Land cover/land use map for the Upper Peninsula of Michigan
(modified from http://u136.crs.msu.edu/db/maps/pdf/landuse/
landuse.pdf). Image is presented in color ............................... 30

Photo of a sediment core from Torch Lake, Site T1. Sediments
are labeled by depositional history and the dashed line represents
a depth of 10 cm. Image is presented in color ........................... 33

Proﬁle of excess 210Pb (Bq/g) vs. accumulated dry mass in Torch
Lake sediments. A) Site T1 and B) Site T2 .............................. 41

Proﬁle of excess 210Pb (Bq/g) vs. accumulated dry mass in Torch
Lake sediments, site T5 ....................................................... 42

Proﬁle of excess 210Pb (Bq/g) vs. depth and 137Cs (Bq/g) vs.
depth in Torch Lake sediments. A) Site T1 and B) Site T2 ..........43

Vertical Proﬁles of copper concentrations in Torch Lake
sediments. A) Site T1, B) Site T2 .......................................... 45

Vertical Proﬁles of copper concentrations in Torch Lake
sediments. A) Site T3 and B) Site T5 .................................... 46

Cu/Zn vs. depth proﬁles in Torch Lake sediments ...................... 50

Cu/Zn vs. copper concentration proﬁle for selected sediments
in and around the Keweenaw Peninsula of Michigan, including
Torch Lake ........................................................................ 51

Normalized concentrations of uranium, calcium, potassium,
cobalt and titanium in Torch Lake sediments. A) Site T1
and B) Site T2 ................................................................... 54

Normalized concentrations of uranium, calcium, potassium,
cobalt and titanium in Torch Lake sediments. A) Site T3
and B) Site T5 ................................................................... 55

Concentration vs. depth proﬁles from Torch Lake sediments.
A) arsenic and B) lead ........................................................ 57

A) Log Co/Zn vs. log cobalt concentration and B) Log Ti/Zn vs.
log titanium concentration for the cap sediments and mining
related sediments of Torch Lake and Gratiot Lake Sediments......60

Figure 25

Figure 26

Figure 27

Figure 28

Figure 29

A) Log KN vs. log potassium concentration and B) Log CoN
vs. log cobalt concentration for the cap sediments and mining
related sediments of Torch Lake and Gratiot Lake Sediments......61

A) Log U/Zn vs. uranium concentration and B) Log Ti/Ba vs.
log titanium concentration for the cap sediments and mining
related sediments of Torch Lake and Gratiot Lake Sediments......62

Normalized iron, manganese and copper concentrations vs.
depth. A) Site T1, B) Site T2, C) Site T3 and D) Site T5 ............ 66

Normalized iron, manganese and copper concentrations vs.
depth. A) Site T1, B) Site T2, C) Site T3 and D) Site T5 ............ 67

Copper concentrations in the sediments of Torch Lake, site
T1, as a function of: A) the 210Pb dating method, B) the event
dating method and C) depth .................................................. 73

xi

Assessing Recovery of Anthropogenically Disturbed Lakes
Using Reference Systems and Multi-elemental Techniques

I. Introduction

 

General Introduction

One of the greatest concerns presently confronting the Keweenaw
Peninsula of Michigan is the persistence of Cu contaminated sediments that are
the result of mining practices of the past. The predominant source of Cu
contamination was the direct input of heavy metal rich mining tailings into rivers,
lakes and their surrounding ecosystems. Through bioaccumulation, heavy metal
contaminated sediments can negatively impact the surrounding wildlife and
humans, and represent a continual source of contamination in aquatic
environments (Song and Breslin, 1999 and Catallo et al., 1995). As a result,
several studies have focused on Cu (i.e., concentration, mobility, distribution or
toxilogical effects) in numerous environments within and around the Keweenaw
Peninsula, such as: Lake Superior (Smith and Moore, 1972; Kemp et al., 1978;
Kerfoot et al., 1999a and Kolak et al., 1999), Portage Lake (Kerfoot and Lauster,
1994 and Kerfoot and Robbins, 1999b) and Torch Lake (Wright et al., 1973;
Lopez and Lee, 1977; Charters and Derveer, 1991; EPA, 1992; Ellenberger et
al., 1994; Cusack and Mihelcic, 1999; Jeong et al., 1999 and Lytle, 1999).

This study will focus on Torch Lake, a US. EPA Superfund site located in

Houghton County, Michigan (Figure 1). Wasteful mining practices led to the

Houghton County

p

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Figure 1. Map showing the location of Torch Lake, Houghton County, Michigan.

 

 

 

 

 

 

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deposition of 200 million tons of heavy metal rich mine tailings into the Torch
Lake basin and around its shores. Direct inputs of tailings have ceased,
allowing for a more dominant natural sediment input, but millions of tons of
tailings still line the shores of Torch Lake and are potentially available for erosion
and re-deposition into the lake. Currently, the US. EPA is in the process of soil
covering and revegetating the exposed tailing deposits in an attempt to control
further erosional inputs, but the success of this effort is unclear.

Previous studies of Torch Lake sediments have been restricted “largely to
bulk chemical analyses on sediment samples retrieved using grab samplers”
(Cusack and Mihelcic, 1999), and little work has been done to determine the
spatial and temporal trends of heavy metals. However, lake sediments can act
as recorders of historical as well as modern inputs (Edgington and Robbins,
1976; Erten, 1997; Wakeham et al., 1979 and Mueller et al., 1989), when
properly collected and analyzed (VonGunten et al., 1997). So, the main purpose
of this research is assessing the recovery of Torch Lake by evaluating the
spatial and temporal changes of Cu and other heavy metals (i.e., the multi-
elemental approach) in the sediments of the lake. With a multi-elemental
approach, the focus is not only the contaminant of interest (i.e., the target
speciﬁc approach), such as Cu, but also several other non-toxic elements. This
approach allows for the understanding of diagenesis and inﬂuences from
terrestrial inputs from the surrounding watershed, and differentiating terrestrial

inputs from anthropogenic inputs (Yohn et al., 2002).

When attempting to assess recovery of anthropogenically disturbed lake
sediments, several questions should be answered such as: 1) what was the past
state of the system; 2) what is the current state of the system; and 3) what is the
future state of the system. These questions will be addressed in an attempt to
assess the recovery of Torch Lake from past disturbances. It is hypothesized
that the source for Cu and other heavy metals to Torch Lake was once
dominated by anthropogenic local inputs of stamp sands and clays, but today is

dominated by a more regional, watershed input.

Formation of Copper Deposits in Michigan

A “hot spot” beneath the current Lake Superior region led to doming and
creation of a rift zone approximately 1.10 to 1.0 billion years ago (LaBerge,
1994). Basaltic ﬂows spread out of the rift zone and the region was covered with
lava deposits over hundreds of kilometers wide and 4 to 24 km thick (Kerfoot
and Nriagu, 1999). The Cu in Michigan is thought to have been deposited by
hot, briny ﬂuids that rose up through these basaltic ﬂows (Kerfoot and Nriagu,
1999). As the brines approached the surface, the Cu in the underlying Portage
Lake Volcanic series was re-dissolved and deposited in the form of native Cu on
the upper sections of these basalt ﬂows or inter-bedded within the conglomerate
and shale sequences of the Oronto Group (Kerfoot and Nriagu, 1999) (Figure 2).
The two main Cu bearing rock types of the Keweenaw Peninsula of Michigan
are: 1) amygdules, which contain Cu and other minerals within vesicles and

fragmented surface materials, and 2) sedimentary rocks, such as conglomerate

Jacobsville -Bayfleld
Up to 1600m

Freda Sandstone
Up to 4250m

PreCambrlan

Oronto Group

Nonesuch Fm.
40-200m

Copper Harbor
Conglomerate
11.92.280.11. _

Portage Lake Volcanlce
3000-4000m

South Range Volcanice

PreCambrlan

Barron
Quartzltee

Basement

 

Figure 2. Generalized stratagraphic column for Keweenaw Peninsula of Michigan.

and shale, which have Cu ﬁlling pore openings or surrounding pebbles and
grains of sand (Dorr and Eschman, 1977). Copper deposits of the Keweenaw
consist mainly of native copper and copper sulﬁdes (mainly chalcocite) (Kerfoot
and Nriagu, 1999). Recent studies have suggested that the Cu in Michigan was
formed between 1.06 and 1.05 billion years ago, which is about 20 million years

after the period of volcanism in the region (Kerfoot and Nriagu, 1999).

Copper Mining in Michigan

Small-scale Cu mining in the Lake Superior region began with the Native
Americans approximately 7,000 years ago, and these practices lasted for about
4,000 years. Then much later, 1844, mining of Michigan’s native copper began
again on an industrial scale, and between 1850 and 1929, the Keweenaw
Peninsula of Michigan was the second largest producer of Cu in the world
(Kerfoot and Nriagu, 1999). Productive copper-mines were mainly localized to
rock formations of Precambrian age, which run the entire length of the
Keweenaw and stretch from the northern tip, along the western shore, then
down the center of the peninsula (Figure 3). The Portage Lake Volcanic series,
Copper Harbor Conglomerate and the Nonesuch Shale, were host to the largest
deposits of native copper in the world. Ninety-six percent of the native copper
harvested came from a 28-mile stretch that extended southwest from the town of
Pinedale to just east of Mohawk (Kerfoot and Lauster, 1994) (Figure 3).

In the early stages of Cu mining, the focus was on the easily extractable

forms of Cu such as: ﬂoat copper (i.e., native copper that has been relocated by

 

Pinesdale

 

miles E

0 50
kilometers E
0 100
Key

 

O

Bedrock Geology of Western Upper Peninsula

ﬂ Jacobsville Sandstone
E Freda Sandstone

- Nonesuch Formation
u Copper Harbor Cong.
- Oak Bluff Formation
ﬂ Portage Lake Volcanice
- Siemens Creek Formation
- Intrusive

E] Quinnesec Formation
D Paint River Formation
- Riverton Iron Formation
- Bijiki Iron Formation
- Negaunee Iron Formation
- Ironwood Iron Formation

I Dunn Creek Formation
I Badwater Greenstone
- Michigamme Fomiation
- Goodrich Quartzite
ﬂ Hemlock Formation

n Menominee 8r Chocolay Groups
E] Emperor Vulcanic Formation
- Siamo State & Ajibik Quartzite

[j Palms Formation

I. Chocolay Group

E] Randville Dolomite

- Archean Ultramaflc
Archean Granite & Gneissic
ﬂ Archean Vol. & Sedimentary

Figure 3. Map showing the bedrock geology of the Upper
Peninsula of Michigan (modiﬁed from Milstein, 1987). Image is

presented in color.

  

Gratiot Lake

 

     
  

,- Key
Bedrock Geology of Eastern Upper Peninsula

Mackinac Berccia
- Bois Blank Formation
- Garden Island Formation
a Bass Island Group
D Saline Group
E: St. Ignace Dolomite
E] Point Aux Chenes Shale
- Engadine Group
- Manistique Group
I Burnt Bluff Group
I Cabot Head Shale
- Manitoulin Dolomite
- Queenston Shale
a Big Hill Dolomite
- Stonington Formation
I: Utica Shale Member
D Collingwood Shale

Trenton Group
a Black River Group
H Prairie Du Chien Group
E Trempealeau Formation
D Trempealeau Formation

natural processes such as erosion or glaciation), vein copper, and mass copper
(large masses of pure copper) (Kerfoot and Nriagu, 1999). When the easily
extractable lodes began to be depleted, focus turned to less Cu rich ores. The
concentration of Cu within these ores ranged between 0.5 and 6.1% (Kerfoot
and Lauster, 1994). As part of the Cu extraction process, the ore was stamped
or crushed into smaller fractions. Stamp mills were generally located in small
clusters and dotted the landscape throughout the Keweenaw Peninsula. One
such cluster was located on the western shore of Torch Lake, where ﬁve stamp
mills operated within a 6-mile stretch (Figure 4). The Shores of lakes were the
preferred location of the many stamp mill operations because of the need for
water to create steam for power generation and the easy disposal of mine
tailings into the natural lake basins.

At the peak of the industry, there were over 140 operational Cu mines
and 40 stamp mills to process the Cu rich ores (Kerfoot and Lauster, 1994).
From approximately 1850 to 1960, there was an estimated 4.8 million tons of Cu
harvested, with the maximum Cu production in one year being 122,000 tons.
Since the percent Cu was relatively low in the ores, huge amounts of rock were
extracted and stamped to yield enough Cu to be economically proﬁtable. As a
result, over 500 million tons of solid waste was also generated (Kerfoot and
Lauster, 1994). There were two main types of solid waste: stamp sands and
slime clays (Kolak et al., 1999). As the name suggests, stamp sands were sand
sized particles generated by crushing the host rock (e.g., large pieces of crushed

basalt and conglomerate). Stamp sands have elemental compositions that

 

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Figure 4. Map of stamp mill locations in the Keweenaw Peninsula of Michigan (modiﬁed
from Wright et. al., 1973 and Kerfoot et. al., 1999).

resembled local bedrock, but also contained high concentrations of Cu and other
metals such as titanium and calcium, since these elements were major
constituents of the parent rock (Kerfoot et al., 19993). Compared to natural lake
sediments, stamp sands are distinctive in color, elemental composition, and
have different physical characters (Kerfoot and Lauster, 1994).

Slime clays were reprocessed stamp sands that were ﬁner grained and
more mobile (Kolak et al., 1999). Copper concentrations in Slimes range from
1,000 — 2,000 mg/kg (Wright et al., 1973) and are still elevated compared to the
local geology. Their small size, which excluded them from gravity separation
techniques, created a large surface area to volume ratio for the absorption of
dissolved Cu to the sediments (Kerfoot and Lauster, 1994). Slime clays and
stamp sands had three potential depositional fates: 1) upon introduction to a
waterway, the particles separated out by size and the ﬁne clay particles
dispersed away from the point of injection, 2) when sluiced into plies, the grains
separated naturally by density and formed layers of ﬁne clays within the stamp
sand piles, and 3) wave-action eroding and carrying the ﬁne particles off-shore

and re-deposited in the lake basin (Kerfoot and Lauster, 1994).

History of Torch Lake

Wright et al., (1973) has stated that the history of Torch Lake is one of
abuse and degradation, and this can be attributed to the heavy impact from
mining activities around the lake. From 1868 to 1968, Torch Lake was

inundated with 200 million tons of stamp sands and slime clays (about half of the

10

total stamp sands produced in the Keweenaw Peninsula) (Kerfoot and Lauster,
1994). These materials were deposited directly into and around the shores of
the lake, and sill are visible today (Figure 5). Assuming that the concentration of
Cu in the stamp sands ranges from 0.4 to 1.7% (Kolak et al., 1999), the
sediment burden of Cu to the lake during direct anthropogenic inputs (assuming
200 million tons) was on the order of 1.8 x 101° to 7.7 x 101° kg.

The burden of stamp sands and slime clays deposited into Lake Superior
was only 1/3 of what was received by Torch Lake; and Portage Lake, a lake
hydrologically connected to Torch Lake (Figure 6), had only about 1/9 the inputs
of mining waste inputs. According to Wright et al., (1973), approximately 20% of
the original Torch Lake basin had been ﬁlled with stamp sands between 1946
and 1968. This translates to a decrease in the depth of 7-9 meters in some
locations. The total amount of lake volume ﬁlled prior to 1946 is not known
(Wright et al., 1973).

New technologies after WWII allowed for the reclaiming of previously
deposited stamp sands and extraction of the Cu by chemical leaching. Stamp
sands were re-collected from the Shores and within the lake with the use of
mechanical dredges that were capable of extracting the sediments up to depths
of 33.5 m (Kerfoot and Lauster, 1994). The previously discarded tailings were
reclaimed using an ammonia leach, involving cupric ammonia carbonate. When
the Cu was extracted from these tailings, they were once again discharged back

into Torch Lake.

11

 

 

 

Figure 5. Photos from the western shore of Torch Lake along M-26. Notice the pink/purple
colored stamp sands lining the shores. Image is presented in color.

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After most mining activities ceased in the Keweenaw Peninsula and
around Torch Lake, there were spills of stored cupric ammonium carbonate into
the lake during the late fall (October) 1971 and again in early summer (June)
1972 (Wright et al., 1973). These discharges released approximately 27,000
gallons of used leaching solution directly into the waters of Torch Lake (Wright et
al., 1973). The cupric ammonium carbonate contained Cu in the concentration
range of 007-78 g/L (parts per thousand) (Wright et al., 1973). Dissolved Cu
concentrations of Torch Lake in 1972 ranged from 40 pg/Lat the surface to 100
pg/L with depth in the water column, and were almost nine times higher near the
spill location, with concentrations as high as 910 ug/L (Wright et al., 1973).

Also in 1972, it was discovered that some ﬁsh species of Torch Lake (i.e.,
Sauger) were beginning to develop liver tumors and ﬁsh populations were
decreasing. Although not proven at the time, the higher concentrations of Cu
were thought to be the cause of the tumors. The US. Environmental Protection
Agency (EPA) classiﬁed Torch Lake as an Area of Concern in 1983 and a Super
Fund site in 1984. Remediation strategies are being implemented that are
attempting to control the amount of Cu rich shore tailings from entering the lake.
The main action done by the US. EPA since 1999 was covering the stamp
sands and re-vegetate the exposed piles in an attempt to control further stamp
sand erosion. The success of this strategy as well as the current state of natural

recovery is unclear, and remediation efforts are currently on going.

14

Aqueous Geochemistry & Toxicity of Copper

Copper is a chalcophile, and Cu II is the normal oxidation state for soluble
Cu complexes (Nriagu, 1979). With further oxidation Cu compounds may be in
the +3 oxidation state, or by reduction Cu+ or Cu0 can be formed, especially
when sulﬁde is present in the system (Ellis, 1999). Available Cu in a natural
system is dependent on absorption and desorption processes and precipitation
of certain Cu compounds (Stumm and Morgan, 1996). The concentrations of Cu
in the environment, as well as the presence of other metals may led to a
competition of the adsorption sites and led to higher dissolved values, and Cu
toxicity in aqueous systems depends on the amount of free Cu ion in the system
and not total Cu (ManSiIIa-Rivera and Nriagu, 1999).

Living organisms need speciﬁc levels of naturally occurring elements
such as Cu for sustaining biochemical processes (ATSDR, 1990). However, in
high concentrations, Cu can then potentially become toxic in aquatic ecosystems
(Hodson et al., 1979). Thus, Cu is a cause for concern when levels in the
environment (e.g., lake sediments) greatly exceed levels sustainable for proper
cell function. The toxicity of Cu to biological systems may be attributed to free
ions of Cu binding to the cytoplasmic membrane of cells and halting proper cell
division (Charters and Derveer, 1991 ). Dissolved organic matter may
signiﬁcantly bind to heavy metals, such as Cu. Copper is bound more strongly
than any other divalent metal (McBride, 1994), and when complexed with

organic matter, the Cu available in the water column is reduced, thus reducing

15

Cu toxicity in the system (Sprague, 1968; Lytle, 1999 and Cusack and Mihelcic,
1999).

Hypothesis

The main purpose of this research is to determine extent of recovery that
Torch Lake has undergone since the cessation of mining activities around its
shores. It is hypothesized that the source for Cu and other heavy metals to
Torch Lake was once dominated by anthropogenic local inputs of stamp sands
and clays, but today is dominated by a more regional, watershed input. If this
hypothesis is true, then concentrations of heavy metals in the sediments will
change from being reﬂective of stamp sands and slime clays to being reﬂective
of watershed inputs controlled by the local geology. Copper concentrations
should also be lower in the recent sediments compared to the mining related

sediments.

Signiﬁcance

Mining wastes, such as stamp sands and Slime clays, represent historical
and potentially continual source of Cu to the aquatic systems of the Keweenaw
Peninsula, and the controls on Cu and Cu concentrations in different I
environments (i.e., near-shore to off-Shore, lake to lake and stamp sands
deposits) vary throughout the Keweenaw Peninsula (Kerfoot et al., 19993; Kolak
et al., 1999; Kerfoot and Lauster, 1994; Kerfoot and Robbins, 1999b; Wright et

al., 1973; Lopez and Lee, 1977; Ellenberger et al., 1994; Cusack and Mihelcic,

16

1999; Jeong et al., 1999 and Lytle, 1999). This means that areas in the Cu
mining region of Michigan have been affected differently, and no one ecosystem
can be considered fully representative of another or the peninsula as a whole.
Therefore, ecosystems in the Keweenaw must be examined as separate entities
to better assess recovery of the Keweenaw area from Cu mining activities on a
local scale. If the aforementioned questions about Torch Lake can be
answered, than the information can be used to better determine what further

remediation procedures, if any, Should be undertaken.

17

ll. Methods and Materials

 

Study Area

Torch Lake is an oligotrophic lacustrine system located on the eastern
Side of the Keweenaw Peninsula in Houghton County, Michigan. The lake has a
surface area of 20.5 km2 (approximately 2.2 km wide and 9.3 km long), with a
maximum depth of 36 m and average depth of 17 m (Ellenberger et al., 1994).
The southern extent of the lake is about 8 km WNW of Houghton and its
northern extent is adjacent to the town of Lake Linden (Figure 6). There are two
distinct basins within Torch Lake, a north and south basin (Cusack and Mihelcic,
1999). Discharge from Torch Lake ﬂows south into Portage Lake, eventually
reaching Lake Superior via the Keweenaw waterway. Residence time of the

water is approximately 1 year (Cusack and Mihelcic, 1999).

Sample collection

Sediment cores were collected from four sites within Torch Lake in late
July 1999. The locations of each sample site are Shown in Figure 7. Sample
sites were located in both the north and south basins. It must be noted that
initially more sites were chosen for sampling, however after several uses of the
multi-corer, the fine-grained nature of the sediments caused the multi-corer to

malfunction, and only four sites were collected. Sites were chosen based on

18

.660 c. 3203:. a. come. amazes. 632.com Loan: .93.. :20... 2.5.3 8.6 anmm .o no.2 K 9:9“.

 

no.5 ucom aegw

 

 

 

 

9.3 ommton. o: 265:0

 

O =¢nn=I
are.
N o
a..- [ll cease:
_. 0

C065...— 0xu4 "Fill-run” 3:8
l e

19

depth, and assumed to be depositional areas of the lake based on the
classiﬁcation scheme of Hakason (1977). This classiﬁcation scheme uses the
percent water content of surﬁcial sediments (0-1 cm) to predict sedimentation
zones (erosional, transitional or depositional) by assuming that there is a
relationship between grain size and percent water in lake sediments. For
example, if the percent water in the surﬁcial sediments is greater than 75%, the
sediments will be composed of silts and clays, and represent a depositional area
of the lake (Hakason, 1977). Percent water in the surﬁcial sediments (0-5 cm) of
sites T1, T2 and T5 was greater than 75% (Table 1), so these sites were
considered to be depositional zones of the lake. Site T3 sediments were not
analyzed for porosity, however site T3 is assumed to be a depositional zone of
the lake based on depth, which is similar to sites T1 and T2.

Cores were taken using an Ocean Instruments MC-400 Lake/Shelf Multi-
corer. The multi-corer is based on the principle of the box corer, but slightly
different from a box-corer, the multi-corer retrieves four individual core samples
at one time, and sub-coring of the sample is not necessary (Figure 8). The
multi-corer was deployed from the US Environmental Protection Agency R/V
Mudpuppy. Core tubes measure 64 cm in length and 10 cm in diameter, but the
actual sediment lengths collected were between 30 and 40 cm.

After retrieval, the sediment cores were inspected on the boat to insure
good quality cores were taken. A core was considered good quality and

undisturbed if: 1) the water above the sediment column was clear and free of

20

Table 1. Percent water in the surﬁcial sediments from three sampling sites of Torch Lake: T1,
T2 and T5. Site T3 sediments were not analyzed for porosity

cm

io'roio'cnbilh'siim'co'o)

A

7
.9
.8
.3
.3
.0
.7
.7
.2
.4

N

—L
iob'co'cnbki'coiew'cn

O1

 

21

3.8 c. Ecomoa w. ommE. x3393. >\m 05 .o x0e... 9.... co .98....35. 2299.3 0910.2 ﬂcoEaﬁs cacao o5 .o 8.9:. .w 939“.

 

22

sediment, and 2) the sediment at the sediment/water interface was horizontal. If
the cores were considered not to be good quality, the sediment was discarded
and new samples were immediately taken. Good quality core were transported
to Shore for the extrusion process.

Sediments were extruded on-site, using a manual extruder (i.e., no
electrical or hydrologic power is needed) that allowed for precise sampling of the
sediment/water interface (Yohn et al., 2002). Extrusion intervals were 0.5 cm for
the top 2.5 cm, in an attempt to get a higher resolution record of recent loading
histories, and 1 cm below the 2.5 cm depth. At depths greater than 20 cm,
intermittent sample intervals were skipped and discarded. To prevent
contamination from smearing along the walls of the core-tubes, sediment that
was in contact with the sides of the core tube (outer rind sediments) were
scrapped away using a Teﬂon coated spatula (Kolak et al., 1998). Sectioned
slices were also described on-site in terms of color, texture, and evidence of
zoobenthos disturbances. Sample descriptions for each slice are summarized in
Appendix A. Extruded sample intervals were placed into acid washed plastic
sample containers, stored in ice packed coolers and transported back to

Michigan State University for metal analysis.

Sample Analysis
Upon returning to Michigan State University, sediment samples from
Torch Lake were stored, frozen and then freeze-dried in preparation for metals

extraction. For the metals extraction, 10 ml of concentrated, trace metal grade

23

nitric acid was added to ~0.5g of sediment, sealed in Teﬂon vessels and
digested by microwave assistance in a CEM-MDS-81 D microwave (Hewitt and
Reynolds, 1990). The concentrated leachates were diluted to 100mL with
distilled-deionized water (DDW) and ﬁltered through acid washed; DDW rinsed,
Nucleopore® 0.40 pm polycarbonate ﬁlters. The samples were then separated
into a total extractable metal fraction and a Hg sample by ﬁltering the solutions
into separate 60mL, HCI acid, washed Nalgene® bottles. The 40 mL of digest
solution for Hg analysis was preserved by adding 200 DL of a 100 pg/mL gold
chloride (AuCl) solution (EPA, 1998). The Hg samples were not analyzed as
part of this study.

The prepared digested ﬂuids were then analyzed using a Micromass
Platform inductively coupled plasma mass-spectrometer with hexapole
technology (lCP-HEX-MS) at a 1:10 or 1:100 dilution, depending on the
concentration of the element. All standards were Spiked with 30 pg/mL Ca in an
attempt to match the matrix of the samples. Bismuth and In were used as
internal standards. Sediments were analyzed for a suite of metals and
metalloids including Mg, Al, K, Ti, V, Cu, lVln, Se, Co, Ni, Sc, Zn, As, Cd, Ba, Pb
and U. Between the analyses of each sample, there was a three minute rinse
period of 2.5% HNO3 + 2.5% HCI + 10 pg/mL AuCl to minimize memory effects
of the previous sample before the next is analyzed. Due to high concentrations
within the digestive ﬂuids, Fe and Ca were analyzed on Perkin-Elmer Zeeman
5100 PC Atomic Absorption Spectrometer (AAS) at dilutions of 1:3 to 1:20

depending on the concentration in the sample.

24

210Pb and 137Cs analyses were performed on a sub-core from sites T1
and T2 and 210Pb only was measured for site T5 to determine accumulation
rates, sedimentation rates, and sediment ages. Samples were sent to The
Freshwater Institute in Winnipeg, Manitoba, Canada for radionuclide analyses.
Porosity measurements were also done at the Freshwater Institute for sites T1,

T2 and T5.

Quality Assurance/Quality Control

See Appendix B.

Reference Systems

Torch Lake offered additional challenges not encountered in most other
relatively disturbed or undisturbed lake systems. Direct anthropogenic inputs
buried the older, natural sediments with up to 9 meters of stamp sands and
slime clays (Wright et al., 1973). Due to these inputs, the 30 - 40 cm sediment
cores from Torch Lake didn’t penetrate deep enough to reach non-mining
deposited/impacted sediments. So, for lake systems that have been severally
anthropogenically disturbed, reference systems provide the data for comparing
impacted and non-impacted sediments in a lake. The baseline or
anthropogenically undisturbed concentration value from the reference system
will be known as a “background concentration”. In order to better understand

chemical concentration versus depth proﬁles, some terms will be deﬁned.

25

.ocoﬁtomoo oan 5 new: onto. .0 E930 .m 9:9“.

 

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Egon. ucaoaxomm

uidad

 

 

 

xmmm

  
 

    

.. i
_. .
..N. 1: .. .1
it. a}
4. ,..a..mw...r.

 

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. .3. L1: 5.
3.... av .
w 1).? a... .r ... .
.. ..l 4.. . 1...!“ “lie . i
.. a . , a. . . .
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.. Wow... ..., tn... .x Tam. .. a . ur . ...... x .
v. I . . . . . ., ...... . KYLIE... ..JA... 2‘ a . .
an: .w "ans. x ... 159%.? .93... ...? ...ts. ... :m‘ r. aw‘ i... .

3.

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26

Figure 9 is a generalized sediment core proﬁle of an element concentration
versus depth. Background concentrations at a given site are calculated by
averaging the concentrations below a certain background depth, and this is the
depth in the core at which the element concentration reaches a steady-state
(Kolak et al., 1999). Peak concentrations are the highest concentrations in the
core.

The system chosen to represent background heavy metal concentrations
(i.e., sediments unaffected by mining inputs) in Torch Lake is Gratiot Lake.
Gratiot Lake is located on the eastern side of the Keweenaw Peninsula (Figure
10), and has a maximum depth of 24 m and area of 5.82 kmz. The factors for
choosing this lake as a reference lake in this study were its similarities to Torch
Lake in terms of: 1) bedrock geology (e.g., Jacobsville Sandstone) (Figure 3)
(Milstein, 1987), 2) surﬁcial geology (e.g., coarse textured glacial till) (Figure 11)
(Farrand, 1982), and 3) land cover (e.g., deciduous forest) (Figure 12). Other
reasons for choosing Gratiot Lake were that no mining or processing activities
have occurred in the immediate vicinity (i.e., not in the watershed) of the lake
(Ellenberger et al., 1994), and Gratiot Lake has a low anthropogenic inventory of
contaminants despite being in close proximity to the Cu deposits and mining
activities (Kerfoot et al., 1999a). Gratiot Lake has also been used as a reference
system for Torch Lake in a ﬁsh reproduction assessment done by Ellenberger et
al. (1994). The sample collection (depth of 24 m), sample preparation and

chemical analysis of Gratiot Lake were performed using the same methods as

27

 

Lake Superior

 

    
  
   

Gratiot Lake

Torch Lake

Portage Lake

Keweenaw Bay

 

 

 

miles E
0 10

kilometers E
0 25

 

 

Lb

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

l

l

l

 

l

 

 

Z

 

 

 

J

 

Figure 10. Map showing the location of Gratiot Lake, Portage Lake and Torch Lake in the
Keweenaw Peninsula of Michigan (modiﬁed from Ellinger et. al., 1994).

28

 

Dunc-nalunmnnaana

 

Artiﬁcial till miles E

Coarse-textured glacial till 0 50
”um and kilometers E
End moraines of ﬁne textured till 0 100

End moraines of medium textured till

End moraines of coarse textured til

Exposed bedrock surfaces

Fine textured glacial till

Glacial outwash sand and graveVpost-glacial alluvium
Ice-contact outwash sand and gravel
Lacustrine clay and silt

Lacustn'ne sand and gravel

Lakes

Medium-textured till

Peat and muck

Post-glacial alluvium

Thin to discontinuous glacial till over bedrock

Figure 11. Surﬁcial geology map of the Upper Peninsula of Michigan (modiﬁed from
Fanand, 1982). Image iS presented in color.

29

N
t

    
 
  

miles E
0 50

kilometers E
0 100

I
i

~54

Agriculture
Barren

4V 1

IDIﬂElﬂi

 

Forest
Open ﬁeld
Urban
Water
Wetland

 

 

 

Figure 12. Land cover/land use map for the Upper Peninsula of Michigan (modiﬁed from
Center for Remote Sensing & Geographic Information Science, Michigan State University).
Image is presenmd in color.

30

discussed earlier. Studies on Portage Lake have documented different
sediment types coming into the lake since the cessation of mining activities.
Portage Lake is hydrologically connected to Torch Lake (Figure 4) with the same
bedrock geology, surﬁcial geology and current land use. Portage Lake had 3
Similar history to Torch Lake, but stamping operations ceased around 1920 and
the lake has had more time to potentially recover from past disturbances. Data
from several studies of Portage Lake sediments (Kerfoot 3nd Lauster, 1994;
Kerfoot et al., 19993 and Kerfoot and Robbins, 1999b) will also serve as a

reference for Torch Lake

31

III. Results and Discussion

 

Nature of Sediments

Sediment cores from Torch Lake could be separated into two distinct
layers based on color. The top 8-10 cm of sediment from each sample location
was either 3 light brown or brownish/red color, and the remaining length of
sediment (23-39 cm depending on the site) was a pink/purple color (Figure 13).
On-Site descriptions are summarized in Appendix A. Sediment analyses done
by Kerfoot 3nd Lauster (1994) on Portage Lake documented 3 similar difference
in sediment color, and these results will be used to help interpret the Shift in
color of sediments documented in the Torch Lake cores. On average, the top
15-22 cm of sediment from Portage Lake was reported to consist of 3
brown/light brown color, then there was 3 middle region that was a
pinkish/purple color, and the remaining length of the sediment core was a red to
purple color with thin, regular bands (Kerfoot and Lauster, 1994). These
observations were related to three different depositional histories: 1) sediments
deposited after mining had ceased, which have a higher organic content, 2)
stamp sands and Slime clays which were the dominant input of sediment to the
lake after 1900 until about 1920, 3) sediments deposited when early (pre-1900)
mining activities were ongoing.

In Torch Lake, organic rich sediments near the sediment/water interface

are watery, then grade to thicker clay like sediments with depth until the

32

 

Figure 13. Photo of a sediment core from Torch Lake, Site T1. Sediments are labeled by
depositional history and the dashed line represents a depth of 10 cm. Image is presented
in color.

33

pink/purple sediments are reached. This organic rich layer will be referred to as
the “cap layer”. Cap layer sediments are as thick as 10 cm and varied in color
from light brown to brownish-red (Figure 13). These sediments were deposited
in the years after the cessation of mining activities around the lake. Although
organic content analyses was not performed in this study, Jeong et. al., (1999)
found organic matter content in top 5 cm of Torch Lake, near MSU site T3
(Figure 7), to be 7.7%. A study by the US. EPA in 1992 also found a similar
dark brown layer overlying the mining sediments that varied in thickness and
between 1.0 and 2.5 cm, these samples were also collected near MSU site T3
(Figure 7).

Below the cap layer, mining related inputs dominate the sediment make-
up. The pinkish-purple color of these sediments is attributed to tailings from the
Allouez Conglomerate, a main rock processed after 1920 in stamp mills along
the Shores of Torch Lake (Kerfoot 3nd Lauster, 1994). These sediments are ﬁne
grained, with watery layers inter-bedded with Slightly ﬁrmer layers. Pink/purple
sediments extended from the bottom of the cap layer through the remaining
length of each core. Due to the massive Inputs of stamp sands and slime clays
to the lake, it was observed that the coring device didn’t penetrate deep enough
to encounter background sediments in Torch Lake or 3 third (pre-1900) layer as

documented in Portage Lake by Kerfoot and Lauster (1994).

34

me and 1370s

In an attempt to document temporal changes, sediments from Torch Lake
were dated using 210Pb and 137Cs. Age dating of lake sediments via the
radionuclide 210Pb has been a successful method used in numerous studies
(Robbins and Edgington, 1975; Edgington and Robbins, 1976; Hilton et al.,
1986; McKee et al., 1989; Appleby and Oldﬁeld, 1983 and Golden et al., 1993).
In soils, 226Rn decays to 222Rn, which eventually decays to 210Pb. This 21oPb is
known as “supported 21oPb”. During decay, some of the 222Rn gas escapes to
the atmosphere, where it eventually decays to 210Pb and gets re-deposited onto
the earth’s surface (e.g., depositional basins of lakes) (Wetzel, 2001 ). This
210Pb is known as “unsupported 21oPb”. Sediment ages are calculated by
subtracting the supported 210Pb (210Pb resulting from the presence of 226Rn in
the sediment) from the total 210Pb, yielding the unsupported 210Pb (Wetzel,
2001). Knowing the half-life of 210Pb (~22.3 years) and activity of unsupported
21oPb relative to the surface, age calculations are made based on the decay
constant of 210Pb and the slope of the regression line of excess 21oPb (Bq/g) vs.
accumulated dry mass (g/cmz).

Interpretations of sediment ages via 210Pb are strengthened with the use
of fallout horizons (nuclear testing, pollen, etc.), which are recorded in the lakes
sediments (Robbins, 1978). The fallout horizon chosen for this study was the
radionuclide 137Cs. This isotope is produced during nuclear reactions (i.e.,
power generation, nuclear bombs, etc.). The concept of using 137CS for an age

marker is that the ﬁrst appearance of 137CS can be traced to the early 1950’s,

35

and the peak fallout occurred during the span of 1963-1964, when nuclear bomb
testing was at its peak (Robbins and Edgington, 1975; Mueller et al., 1989 and
Walling and Qingping, 1992). Assuming that the 137Cs peak recorded in the
lake sediments is 1963-1964 and dates calculated via 210Pb are similar, than the
calculated sediment ages will be considered valid. Lead-210 analysis was
performed on three cores, T1, T2 and T5, and 137Cs analysis was performed on
two cores, T1 and T2.

The results from the 210Pb and 137Cs analyses are summarized in Tables
23, 2b 8 2c. The 210Pb ages for Site T1 were determined using a constant ﬂux,
constant sedimentation rate model (CF:CS). The CF:CS method assumes that
there is 3 constant ﬂux of 210Pb with a constant sediment input into the lake over
a given time (Robbins, 1978 and Golden et al., 1993). The equation for the

CF:CS model is:

Afz) = As eXP ((‘k z) / “0
Where:
Am: the unsupported 210Pb activity at mass depth 2
As: unsupported 210Pb activi at the sediment-water interface
W= sedimentation rate (g/cm /yr)
2: mass depth (g/cmz)
k= decay constant 0.0311/yr
A modiﬁcation to the CF:CS model was proposed by Heyvaert et al.
(2000) where the slope of 210Pb vs. accumulated dry mass was segmented into

different sedimentation rates. This method is known as SCF:CS. The equation

for the SCF:CS method is the same as the CF:CS method with the exception of

36

Table 23. Data from the 210Pb and 137CS analysis of Torch Lake sediments, site T1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Depth Acc. Dry wt. Excess me 1"70s Age
Sample (cm) (glcm’) Porosity (Bqlg) (Bqlg) Date
T1 -1 0.25 0.091 1 0.97 7.26E-01 1999
T1 -2 0.75 0.0632 0.96 8.07E-01 1996
T1 -3 1.25 0.0564 0.94 8.39E-01 1994
T1 -4 1 .75 0.0663 0.94 7.25E-01 1992
T1 -5 2.25 0.0804 0.93 5.70E-01 3.47E-02 1990
T1 -6 3 0.1985 0.93 5.125-01 4.00E-02 1985
T1 -7 4 0.2061 0.92 4.54E-01 5.60E-02 1978
T1 -8 5 0.2179 0.92 3.92E-01 6.82E-02 1972
T1 -9 6 0.2292 0.91 3.10E-01 6.80E-02 1964
T1 -10 7 0.1762 0.92 2.52E-01 5.51 E-02 1958
T1 -11 8 0.5334 0.82 1.14E-01 4.82E-02 1946
T1 -1 2 9 0.6921 0.76 3.83E-02 1 945-02 1926
T1 -13 10 0.6220 0.79 2 .65E-02 1905
T1 -14 11 0.6454 0.78 2.25E-02 1884
T1 -15 12 0.5884 0.80 1.17E-02 1864
T1 -16 13 0.4317 0.85 7.82E-03 1847
T1 -17 14 0.6031 0.79 3555-03 1830
T1 -18 1 5 0.5883 0.80 1 .28E-02
T1 -19 16 0.5403 0.81 4.50E-03
T1 -20 17 0.6153 0.79 1.58E-02
T1 -21 18 0.6766 0.77 1.45502
T1 -22 19 0.5802 0.80 1 .02E-02
T1 '23 20 0.4874 0.83
T1 -24 21 0.5011 0.83
T1 -25 22 0.4991 0.83
T1 -26 23 0.6020 0.79
T1 -27 24 0.6164 0.79
T1 -28 25 0.5458 0.81
T1 -29 26 0.4091 0.86
T1 -30 27 0.4513 0.84
T1 -31 28 0.5245 0.82
T1 -32 29 0.5251 0.82
T1 -33 30 0.5399 0.81
T1 -34 31 0.6105 0.79

 

37

 

Table 2b. Data from the 210Pb and 13705 analysis of Torch Lake sediments, Site T2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Depth Acc. Dry Excess me 137Cs Age
Sample (cm) wt. (glcm’) Porosity (Bqlg) (Bqlg) Date
T2-1 0.25 0.0336 0.97 1 .06E+00 1999
T2-2 0.75 0.0690 0.96 1 .1 1 E+00 1997
T2-3 1.25 0.1045 0.97 1.12E+00 1996
T2-4 1.75 0.1532 0.96 1.14E+00 1993
T2-5 2 .25 0.2022 0.96 9.93E-01 1.84E-02 1991
T2-6 3 0.3561 0.94 7.65E-01 2.72E-02 1986
T2-7 4 0.5288 0.93 5.90E-01 3.73E-02 1979
T2-8 5 0.7326 0.93 5.01 E-01 4.80E-02 1972
T2-9 6 0.9237 0.93 4265-01 5.08E-02 1965
T2-10 7 1.1409 0.90 3.08E-01 4.63E-02 1958
T2-11 8 1.9682 0.71 6.04E-02 1.60E-02 1928
T2-12 9 2.7852 0.72 2.61 E-02
T2-13 10 3.6257 0.71 1905-02
T2-14 1 1 4.3676 0.74 1.67E-02
T2-15 12 5.1547 0.73 1.64E-02
T2-16 13 5.8128 0.77 1.495-02
T2-17 14 6.4973 0.76 1.12E-02
T2-1 8 15 7.0862 0.80 9.32E-03
T2-19 16 7.6106 0.82 8.44E-03
T2-20 17 8.1048 0.83 9.28E-03
T2-21 18 8.6566 0.81 3.36E-03
T2-22 19 9.0672 0.86 5.29E-03
T2-23 20 9.6217 0.81
T2-24 21 10.3541 0.75
T2-25 22 1 1.5824 0.58
T2-26 23 12.5748 0.66
T2-27 24 13.1077 0.82
T2-28 25 13.6902 0.80
T2-29 26 14.2351 0.81
T2-3o 27 14.7679 0.82
T2-31 28 15.3023 0.82
T2-32 29 15.8402 0.81
T2-33 30 16.3961 0.81
T2-34 31 16.9636 0.80

 

38

 

Table 20. Data from the 210Pb analysis of Torch Lake sediments, site T1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Depth Acc. Dry wt. Excess 21oPb Age
Sample (cm) (glcm’) Porosity (Bqlg) Date
T5-1 0.25 0.0420 0.98 1 .1QE+00 1998
T5-2 0.75 0.0312 0.97 1.18E+00 1995
T5-3 1.25 0.0550 0.95 1 .17E+00 1993
T5-4 1.75 0.0566 0.95 1.23E+00 1991
T5-5 2.25 0.0772 0.94 8945-01 1989
T5-6 3 0.0849 0.94 7.34E-01 1988
T5-7 4 0.1061 0.93 5.70E-01 1985
T5-8 5 0.1034 0.91 4.94E-01 1983
T5-9 6 0.1213 0.90 3.80E-01 1983
T5-10 7 0.2592 0.91 2.80E-01 1979
T5-11 8 0.4592 0.84 1.30E-01 1964
T5-12 9 0.7238 0.75 1.16E-02 1937
T5-13 10 0.6152 0.79 4.41E-03 1912
T5-14 1 1 0.5989 0.79 1 .97E-03 1907
T5-15 12 0.5166 0.82
T5-16 13 0.5566 0.81
T5-1 7 14 0.5738 0.80
T5-18 15 0.5573 0.81
T5-19 16 0.6184 0.79
T-20 17 0.6828 0.76
T5-21 18 0.6902 0.76
T5-22 19 0.6282 0.78
T5-23 20 0.5776 0.80
T5-24 21 0.6528 0.77
T5-25 22 0.5678 0.80
T5-26 23 0.6908 0.76
T5-27 24 0.5808 0.80
T5-28 25 0.6355 0.78
T5-29 26 0.5810 0.80
T5-30 27 0.5962 0.79
T5-31 28 0.6436 0.78
T5-32 29 0.6886 0.76
T5-33 30 0.6248 0.78
T5-34 31 0.6743 0.77
T5-35 32 0.7200 0.75

 

39

 

varying sedimentation rates for different segments of the core. The SCF:CS
method was used in cores T2 and T5. Plots of excess 21oPb vs. accumulated
dry weight are shown in Figures 14 and 15.

One assumption when using 210Pb for dating sediments is that there has
been very little or no re-suspension of sediments or migration of the 210Pb. This
assumption is usually valid for depositional basins, however the aforementioned
dredging of previously deposited stamp sands seriously disturbed the historical
record in the sediments (Kerfoot and Lauster, 1994). Large mechanical
dredges were capable of extracting the sediments up to depths of 33.5 m in
Torch Lake, so even the deep basin of the lake (32 m) could have been affected.
Also, below the cap layer, the excess 21oPb rapidly approach supported levels of
210Pb, due to the substantial contribution of 210Pb deﬁcient stamp sands entering
the lake with the 21oPb from the atmosphere and naturai sediments. These
factors caused 210Pb dates to approach the 1800’s at depths below 10 cm
(Tables 23, 2b & 20). Based on historic data oﬂake basin ﬁll, 7-9 m, these dates
could not be valid. So, dates in the cap sediments (<10 cm) might be
considered valid, but below the cap sediments, age dates were not considered
valid.

However, the 210Pb dates in the cap sediments were also considered to
be not valid, even though peaks in 137Cs activity corresponded to a 210Pb date of
1964 and 1965 for Sites T1 and T2 respectively (Figure 16). Peak activities of
137Cs are at the 6 cm depth for both Sites T1 and T2, and based on sediment

composition, sediments at the 6 cm depth are still within the cap sediments

40

1 .OE-03

1 .OE-02

Excess me (Bqlg)
1 .OE-01

1 05-00

1.0E+01

 

Accumulated Dry Mass (ngcm’)

 

 

 

1 .OE-02

Excess me (Bqlg)
1.05-01

4

1 .0E+00

1.0E+01

 

Accumulated Dry Mass (gmlcm’)
U’I

 

10

 

 

B'l

 

Figure 14. Proﬁle of excess 21°Pb (Bqlg) vs. accumulated dry mass in Torch Lake sediments. A)

Site T1 and B) Site T2.

41

Excess me (Bqlg)
1.0E-03 1.05-02 1.05-01 1.0E+00 1.0E+01

 

Accumulated Dry Mass (gm/cmz)

 

 

 

Figure 15. Proﬁle of excess 21"Pb (Bqlg) vs. accumulated dry mass in Torch Lake sediments,
site T5.

42

 

 

 

 

Depth
8
l
I
l
l
I
l
l
I
l

 

 

 

 

 

 

 

 

 

- __j -e— Excess 21on (Bqlg) j_ __

l —o— 137C: (Bqlg)

l
-l

 

 

 

 

10 .- _ - -

Depth

12- ~~~

14 4»

16 »

18 _-_ __,

 

 

 

 

 

1 +137c: (Bqlg)

_ i—n—Exooee 21on (eqrglj

 

 

 

20

Figure 16. Proﬁle of excess 210Pb (Bqlg) vs. depth and 137Cs (Bqlg) vs. depth in Torch Lake

sediments. A) Site T1 and B) Site T2.

43

(Appendix A). If stamp sand inputs ceased the final time in 1968, than the 137Cs
was most likely not captured in the cap sediments. Dating of Torch Lake

sediments is further explored in the “event dating” section.

Extractable Copper Concentrations

Copper concentrations were anticipated to be lower in the cap sediments,
because of the cessation of direct inputs of mine tailings, however this was not
observed. The vertical proﬁles of Cu concentrations versus depth are shown in
Figures 17 and 18. At sites T1, T2, T3 and T5, the average concentration of Cu
in the cap sediments was 2,752, 2,044, 2,262 and 1,551 mg/kg respectively.
Below the cap sediments (total depth varied with sample site), average Cu
concentrations were slightly lower at 1,746, 1,063, 1,120 and 1,442 for sites T1,
T2, T3 and T5 respectively. Copper concentrations in the north basin peak in
the cap sediments, with site T1 had the largest peak concentration at 5,472
mg/kg, correlating to 3 depth of 9.0 cm. This peak is most likely attributed to the
Spill of stored cupric ammonium carbonate solution that occurred from October
1971 to June 1972. Average Cu concentrations within both the cap sediments
and mining related sediments of Site T1 were the highest of the four sites
sampled. In the south basin of the lake, Site T5, the highest concentration of Cu
(2,132 mg/kg) was measured in the mining related sediments, at a depth of 39
cm. Both basins Show an overall increase in Cu concentrations from the bottom

of the cap layer to the sediment/water interface.

44

Cu Concentration (mg/kg)

 

 

 

 

Depth

 

 

 

 

 

 

 

Cu Concentration (mg/kg)
0 500 1000 1500 2000 2500 3000

 

 

103

 

15—

Depth

 

20 ~

 

 

30

 

 

 

 

 

35

Figure 17. Vertical proﬁles of copper concentrations in Torch Lake sediments. A) Site T1
and B) Site T2.

45

Cu Concentration (mg/kg)
0 500 1000 1500 2000 2500 3000
o t 1 L i _. J'.

 

 

 

 

 

 

 

 

 

Depth

 

 

 

 

 

 

Cu Concentration (mg/kg)
0 500 1000 1500 2000 2500

 

0

 

5 _

 

 

 

10 -~

 

 

15--— -

 

 

 

20%

Depth

25 ..

 

304k

 

 

35 l"

40 1*

 

45

 

 

 

 

50

 

Figure 18. Vertical proﬁles of copper concentrations in Torch Lake sediments. A) Site T3
and B) Site T5.

46

The average Cu concentration from all four basins in the cap sediments
was 2,197 mg/kg and in the average in the mining related sediments was 1,232
mg/kg. These results are consistent with previous studies (Jeong et al., 1999;
Cusack and Mihelcic, 1999 and EPA, 1992), and still remain high compared to
other sediments in the Keweenaw Peninsula that are relatively anthropogenically
undisturbed (Table 3). For example, in deep basins of Lake Superior Cu
concentrations have been reported at 57 mg/kg (Kolak et al., 1998) and 60
mg/kg (Kemp et al., 1978), dry weight. Background Cu concentrations in
sediments of Gratiot Lake averaged 61 mg/kg (this study). Cu in sediments of
the Keweenaw Peninsula, not adjacent to any Cu mining activities, averaged 70
mg/kg (Jeong et al., 1999). Cu concentrations in unaffected sediments of the
Keweenaw Peninsula region are approximately 38 times lower than Cu
concentrations in the cap sediments and 21 times lower than the mining related
sediments of Torch Lake. The average sediment-copper concentrations for
Torch Lake and other selected sediments and soils within and around the

Keweenaw Peninsula are summarized in Table 3.

47

Table 3. Copper concentrations in Torch Lake sediments, Gratiot Lake sediments, Lake
Superior sediments and soils around the Keweenaw Peninsula.

 

 

 

 

 

 

 

 

 

 

 

 

 

Average Std.
Location (mSLKQ) Dev.
Torch Lake - Cap sediments (this study) 2,197 518
Torch Lake - Mining related sediments (this study) 1,232 197
Torch Lake — Tailings (EPA, 1992) 2,330-18,500 ND
Torch Lake - Organic L3yer(EPA, 1992) 10,100-24,100 ND
Torch Lake - S. Basin(Cusack and Mihelcic, 1999) 976 365
Torch Lake — N. Basin(Jeong et al., 1999) 4,200 200
Gratiot Lake (this study) 61 8
Lake Superior (Kolak et al., 1999) 57 ND
Lake Superior (Kemp et al., 1978) 60 ND
Keweenaw Peninsula soils (Jeong et al., 1999) 70 ND

 

 

 

 

CuIZn Ratios

Copper ores mined the Keweenaw Peninsula have a unique signal of Zn
depletion relative to Cu, and this depletion is preserved in lake sediments that
have been affected by mining inputs (Kerfoot and Lauster, 1994; Kerfoot and
Robbins, 1999b; Kerfoot et al., 19993 and Kolak et al., 1999). Copper is
normally less abundant in lake sediments due to geology, greater solubility of Zn
and higher concentrations of Zn in living matter (Kerfoot et al., 1999a).
Therefore, Cu/Zn ratios can be used to correlate total Cu within the sediments to
a source such as stamp sands (Kerfoot et al., 19993; Kerfoot and Lauster, 1994
and Kolak et al., 1999). For example, Cu/Zn ratios in some Lake Superior
sediments are <1 and fairly constant when concentrations of Cu are below 100
mg/kg, which is near background concentrations for the region (57-61 mg/kg).
However, once the Cu/Zn ratio is > 1, Cu concentrations often exceed

background, implying that the sediment-copper concentrations are dominated by

48

inputs from stamp sands and slime clays (Kolak et al., 1999). At all sample
depths from each of the four sites, the Cu/Zn ratio is greater than 1. Site T1 had
the highest Cu/Zn ratio with a value 16.5 at 9 cm depth, and site T5 had the
highest Cu/Zn ratio in the mining related sediments at a value of 12.3. Site T1
had the highest average Cu/Zn ration in the cap sediments at 10.9, and site T5
had the highest Cu/Zn ratio for mining sediments at 7.9. Ratios of Cu/Zn versus
depth for all four sediment cores of Torch Lake are shown in Figure 19. Overall,
the Cu/Zn ratio in the cap sediments (<10 cm) averaged 9.4 and the mining
related sediments (>10 cm) averaged 5.8 for all four sites. The Cu/Zn ratios
from Torch Lake and other sediments and soils around the Keweenaw
Peninsula are summarized in Table 4.

When the Cu/Zn ratios from the mining related sediments and cap
sediments are plotted with Lake Superior, Gratiot Lake and stamp sands, Torch
Lake sediments plot in the same cluster as stamp sands for the region (Figure
20). These data suggest that the Cu/Zn ratios measured in this study are the
most reﬂective of stamp sand ratios, especially in the cap sediments. This
suggests that there is a continual, dominant input of stamp sands from the

shoreline erosion of tailing deposits.

49

.EcoEﬁom 9.3 :20... c. «.6an 58... .m> cNBO .3 9:9...

 

III-IL

 

 

 

 

8A8

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

om

-mw

ov

mm

on

2.3

,, om

as

; -2

 

 

 

 

we

or

E

o .. m
0.31 :N30

m

o

(on llidao

50

9.9. no.0... 9.3.0:.

68.5.5. eo gassed 26:833. 2.. 959m new 5 355.8» 698.8 .0. 852a coagcoocoo ..oaaoo .m> cNBo .om 9:9“.

 

36:.»
25. 9.3 6.5.5 I
.62» 8.5.
Eu 2 v. 9.3 58a
. Seas 8.5.
.5 2-9 9.3 5.8 e
.89
...m ..o 3.98.. E:
tv 8:8 seam x
.89 .._o ..o 3.88..
E: V 8:8 95% ®

.82 .._o ..o .98..
.5338 5:88 ..

 

  

9

 

 

   

.

 

 

»
1 4 ..1 A N 4. , . q a 4 a

89 8..
Bios: 2032:5030 Lonnoo

 

o

a
o

. n
U

r u
a
B
"J

E

a 8.

o..

51

Table 4. Average ratios for Cu/Zn in the cap sediments and mining related sediments of Torch
Lake and several other sediments from within and around the Keweenaw Peninsula, Michigan.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CuIZn Ratio
Location (study) Average Std. Dev.
Stamp Sands (Kerfoot and Nriagu, 1999) 23.4 15.83
Torch Lake (Kerfoot and Nriagu, 1999) 9.97 2.53
Torch Lake (Cap Sediments) (This Study) 9.4 1.2
Portage Lake (Kerfoot and Nriagu, 1999) 9.00 5.33
Torch Lake (Bottom Sediments) (This Study) 5.8 1.4
Keweenaw Waterway (Kerfoot and Nriagu, 1999) 5.49 4.06
S. Lake Superior (Kerfoot and Nriagu, 1999) 1.95 1.66
S. Lake Superior (Kerfoot and Nriagu, 1999) 1.64 1.45
N. Lake Superior (Kerfoot and Nriagu, 1999) 1.06 0.76
N. Lake Superior (Kerfoot and Nriagu, 1999) 0.92 0.58
Inland Lakes (Kerfoot 3nd Nriagu, 1999) 0.79 0.71
Gratiot Lake - Average (This Study) 0.76 0.12
South Portage Lake (Kerfoot and Nriagu, 1999) 0.37 0.07

 

 

 

Multi-elemental Results

Results from the Cu analysis and Cu/Zn ratios suggest that even though
direct anthropogenic sediment inputs have ceased, Cu concentrations still
remain high throughout the core, perhaps due to the continual input of stamp
sands eroding from Shoreline deposits (Kerfoot and Lauster, 1994). However,
there is a visible shift in color of the sediments when mining activities ceased.
To further examine the nature of these observations, the trends of 20 other
elements were examined as part of the multi-elemental approach. For several
elements (e.g., Ba, Ca, Co, K, Mg, Ti, U) there is a shift in concentration at the
same depth as the change in color of sediment. These elements have
concentration trends that both increase (e.g., U and K), and decrease (e.g., Ti,
Co and Ca) in the cap sediments towards the sediment/water interface. To

better visualize the trend in concentration Shifts for Ba, Ca, Co, K, Mg, Ti and U,

52

the concentrations determined at each increment were normalized to the highest
concentration in a particular core. These results are plotted in Figure 21 and 22.
Since elemental concentrations both decrease and increase in the cap
sediments, dilution of materials via intra-lake production of organic matter (that is
visible in the cap sediments) cannot account for the differences in elemental
concentrations from mining related sediments to cap sediments.

Average mining related and cap sediment concentrations of U, K, Ti, Co
and Ca and their trends from mining related sediments to cap sediments are
summarized in Table 5. The overall trends of U, K, Ti, Co and Ca
concentrations versus depth are consistent with an overall shift from basaltic
rocks (e.g., Portage lake Volcanics) to sandstones (e.g., the Jacobsville
Sandstone) based on world averages from Reimann and Caritat (1998) (Table
6). These trends are also consistent with a change in dominant sediment input
from mine tailings to more natural, watershed inputs dominated by the local

bedrock geology of Torch Lake.

Table 5. Concentrations (mg/kg) and trend shifts of U, Ti, K, Co, and Ca from the cap sediments
to the mining related sediments in Torch Lake, MI.

 

 

 

 

 

 

Mining ~ Trend from Mining Related
Element Related Cap sediments to Cap
(mgikg) Sediments Sediments Sediments
U 0.65 2.14 Increase
Ti 6,425 3,259 Decrease
K 289 1 ,019 Increase
Co 60.41 34.81 Decrease
Ca 40,085 22,639 Decrease

 

 

 

 

 

 

53

Normalized Concentration
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

 

 

 

 

 

 

 

 

0 TH: L ‘r ...‘. ‘ i ‘ .. —=—:-.
«‘I
5 -A—Ca .i‘ )P'
A +K ". ‘ ,hl
10 il-O-Tl . ' . “ \ - \
j.7 a
I . ____‘
I «‘7"
15 - I ‘5‘:
E I 1”.
3 20 ,-'- ‘ﬁ‘. .
a: II A’
'5 25 . ‘5'» ﬁ.‘
0 #- ‘Tk‘ﬁ-ﬁ-
D I .7"?
3o - I... , ‘
qr
35 './ \
4‘“ . \
A. . . - t
45 --——-~-"-—---—-- —

Normalized Concentration
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

 

 

   

l

 

Depth (cm)
A D

30- ". ' $4

35

 

 

Figure 21. Normalized concentrations of uranium, calcium, potassium, cobalt and titanium
in Torch Lake sediments. A) Site T1and B) Site T2.

Normalized Concentration

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
o 1 1 1- " _~ _ 1 1 1 . ‘_ . 1
D U “I?“ ‘1- ‘ . I—— I
5 - +601 i I ‘1
K V‘ ‘26-._ $.
10 - ' “ .: z- ‘
15 - ti
’<-—.g-—__z
A”. .

A «d;
E 20 A '1'»
8 ...”
g 25 4" u
‘5. w
8 30] v i.

35 t‘ ‘

40 ~ ! ¥ ‘

45 " w—I— ’ : ‘

50

Normalized Concentration
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
0 1 1 1 ..-:8‘If‘; '4 1 L 1 1 .1
5 - V‘ n ' I
- ‘ . ‘ =5—
10 l I. I .l‘
:' “a:
15 l . ' ‘5

N
0

(ID
0

1

Depth (cm)
32

40~

45

50

 

 

 

- {... “
I +ca A
- +K .
. +00 .1/
.I +11 . .

 

 

 

 

Figure 22. Normalized concentrations of uranium, wlcium. potassium, cobalt and titanium
in Torch Lake sediments. A) Site T3 and B) Site T5.

55

Table 6. Average concentrations (mg/kg) and trend shifts of U, Ti, K, Co, and Ca from basalts to
sandstones. Averages based on data from Reimann and Caritat, (1998).

 

 

 

 

 

 

 

 

 

 

Element Trend from Basalt to
(mﬂgg) Basalt Sandstone Sandstone
U 0.5 1.3 Increase
Ti 10,000 1 ,500 Decrease
K 8,000 1 1 ,000 Increase
Co 45 0.3 Decrease
Ca 74,000 1 3,000 Decrease

 

 

 

Even with the overall change in dominant sediment input, there are still
local heavy metal inputs. Lead concentrations in the sediments near MSU sites
T2 and T3 were reported as high as 18,400 mg/kg and As concentrations were
as high as 494 mg/kg (Charters and Derveer, 1991). Slag piles on the grounds
of the Peninsula Cu Industry (PCI), the former Calumet and Hecla Smelter
facility have been identiﬁed by the US. EPA as the potential source for heavy
metal contamination (EPA, 1992). The PCI building is located on-shore of sites
T2 and T3. Arsenic and Pb concentrations in the cap sediments from the
northern basin were elevated with respect to the southern basin (Figure 23).
Arsenic also has two distinct peaks, one at 7 cm for sites T1, T2 and T3 and 5
cm at site T5 and another at the surface (Figure 23). The surface peak is
related to early diagenesis (i.e., redox) processes, but the lower peak represents
an anthropogenic input of arsenic. This conclusion is further supported by the
fact that both As and Pb peak at the 7 cm depth, because Pb is not inﬂuenced
by redox processes. At site T5 (south basin), the As and Pb concentrations

versus depth proﬁles are similar to those from sites T1, T2 and T3 (north basin),

56

As Concentration (mg/kg)
0 10 20 30 40 50 60

 

Depth
02 B

 

 

 

 

 

 

 

 

 

8848238

Pb Concentration (mg/kg)
0 50 100 150 200 250 300

O

 

 

 

 

Figure 23. Concentration vs. depth proﬁles in Torch Lake sediments. A) arsenic
and 8) lead.

57

but the absolute concentrations for these elements in the south basin are lower
by 2.8 and 3.0 times for As and Pb, respectively. Site T5 may not have been as
anthropogenically inﬂuenced by inputs from the PCI. From these data, it is clear
that the two basins of Torch Lake have been affected differently by past, local

anthropogenic inputs.

Elemental ratios

To better determine the source for the cap sediments, elemental ratios
were examined and compared to Gratiot Lake. Ratios are used and not
absolute concentrations, because there are two main sources of sediment input
into a lake: watershed (terrestrial) inputs and intra-lake production (i.e., organic
matter or carbonate production), and these factors can vary greatly from lake to
lake (Yohn et al., 2002). This makes absolute concentrations vary from lake to
lake, and direct comparisons of two different lake systems is not often possible.
However, by using ratios of one element to another or to organic matter, and not
absolute values, comparisons between lakes can be made. For example, it is
believed that geochemically similar terrestrial inputs are entering both Gratiot
and Torch Lakes, but organic material produced in the eutrophic Gratiot Lake
has “diluted” the elemental signatures within the sediments. Ratios to organic
matter in the samples could correct for this anomaly, however sediment samples
were not analyzed for organic content. So, elemental ratios (e.g., Cu/Zn, Ti/Zn,
Co/Zn) in the sediments of Torch Lake were compared to ratios in sediments

from Gratiot Lake. Assuming that pre-mining related sediments in Torch Lake

58

are geochemically similar to Gratiot Lake (based on their geologies), and the
current sediments entering Torch Lake have similar ratios as Gratiot Lake, it will
be assumed that the sediments currently entering Torch Lake are reﬂective of

watershed-dominated inputs.

Co/Zn, Ti/Zn, K/V, Co/V, U/Zn and Ti/Ba

Changes in the Cu/Zn ratios with depth do not indicate a change from
stamp sand dominated inputs to natural inputs, but the physical nature (e.g.,
color, texture) of the cap sediments compared to the bottom sediments, as well
as the total elemental concentrations, indicate that a change in dominant
sediment input to Torch Lake has occurred. To determine if this is any indication
that the Torch Lake system is beginning to again come into equilibrium with its
watershed, several other elemental ratios of Torch Lake sediments were
compared to Gratiot Lake sediments. When the Co/Zn, Ti/Zn, KN, CoN, U/Zn
and Ti/Ba ratios are plotted, there is a trend from mining related sediments to
cap sediments that are more reﬂective of Gratiot Lake. Sediments from the cap
layer of Torch Lake plot between the lower sediments of Torch Lake and
sediments of Gratiot Lake, which implies that the cap sediments of Torch lake
are being inﬂuence by a different sediment input than the mining related
sediments (Figures 24, 25 and 26). These data may suggest that sediments
currently entering Torch Lake are more representative of a terrestrial,
watershed dominated input as opposed to an input dominated by erosion of

stamp sands surrounding the lake, which is consistent with visual interpretations

59

Log Co Concentration (mg/kg)

 

       

 
    

 

    

   

 

 

 

 

 

 

1 10 100
1.0 >
O Torch Lake (0—10 cm)
ATorch lake (<10 cm)
lGratiot Lake
% A i
n: A o
c O
u .4" 35:3
00.1*7*477#7#i *7 4
O
O)
o '- "
_l
A.
0.0 *ﬁ~ ———~—¥~———
Log Ti Concentration (mg/kg)
1 10 100 1000 10000
100 . ... 4 ..
’ oTorch Lake (0—10 cm)
A Torch lake (<10 cm)
lGratiot Lake
9
+0
N
0C
C
N 10 7 *‘hi
E .0
L .I .3-
0) J
O
_l
B.

 

 

 

1 ...

Figure 24. A) Log Co/Zn vs. log cobalt concentration and B) Log Ti/Zn vs.|og titanium
concentration for the cap sediments and mining related sediments of Torch Lake and
Gratiot Lake.

60

Log K Concentration (mg/kg)

 

 

 

 

 

 

 

Log CoN Ratio
l
l
l

 

 

1 10 100 1000 10000
100 . . . . . .. ..+ 1 . f
t oTorch Lake (0-10 cm)
C ATorch lake (<10 cm)
IGratiot Lake
.9
Ti 10 ****************** ———'ﬂ
0: :
§ .
O)
O
_l
1+ 7e4777—;W———_— -_—s
A.
0.1
Log Co Concentration (mg/kg)
1 10 100
1.0 . . . 4
* OTorch Lake (0-10 cm)
ATorch lake (<10 cm)
lGratiot Lake

 

 

 

0.0

Figure 25. A) Log KN vs. log potassium concentration and B) Log CoN vs. log cobalt
concentration for the cap sediments and mining related sediments of Torch Lake and

Gratiot Lake.

61

U Concentration (mg/kg)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

0.00 0.50 1.00 1.50 2.00 2.50 3.00
0.03....1....;-..,.L,.+,,,,+,,,,
O Torch Lake (010 cm)
ATorch lake (<10 cm)
lGratiotLake
90.02 4 I.
.... I
62 - -.
C
N I
\ . .
3 . O 0
$
0.01 7* ‘vm—n. 4 -_*._____, g I; .
3 O .0 ’g 0*
A . 0
.0
A.
0
Log Ti Concentration (mg/kg)
1 10 100 1000 10000
1000, . '~ .
oTorch Lake (0—10cm)
-* ATorch lake (<10cm)
r IGratiotLeke
2100+- ++ -- e
...:
(u _
a:
m
m
h
l-
8’.
_l 10
O
B.
1

 

 

Figure 26. A) Log UlZn vs. uranium concentration and B) Log Ti/Ba vs. log titanium
concentration for the cap sediments and mining related sediments of Torch Lake and

Gratiot Lake.

62

of changes in dominant sediment input (Figure 13). These data are summarized

in Table 7.

Table 7. Selected elemental ratios in the sediments of Torch and Gratiot Lakes.

 

 

 

 

 

 

 

Ratio Torch Lake (<10 cm) Torch Lake (0-10 cm) Gratiot Lake
Co/Zn 0.29 0.15 0.091
Ti/Zn 31.6 14.1 5.40

KN 2.1 9.8 18.2
CoN 0.42 0.29 0.09
U/Zn 0.0032 0.0093 0.0131
Ti/Ba 122.7 21.1 7.1

 

 

 

 

 

 

Based on elemental ratios, there seems to be a shift in sediment input
since the cessation of mining activities around Torch Lake. At depth, <10 cm,
the dominant control on sediment chemistry was the direct inputs of stamp
sands and slime clays, based on historical records and distinct elemental ratios.
In the cap sediments, there seems to be a switch in the dominant sediment input
from stamp sands to inputs that are reﬂective of a watershed signature (i.e.,
sediments more geochemically similar to those from Gratiot Lake). These
conclusions would not have been made if only Cu concentrations were studied
(i.e., the target speciﬁc approach), demonstrating the need for multi-elemental

data when assessing recovery of anthropogenically disturbed systems.

63

Controls on Copper in the Cap Sediments

Results from the copper and Cu/Zn data from Torch Lake suggest
continual inputs of stamp sands dominating the recent sediment geochemistry.
However, multi-elemental data suggests that recent sediments entering Torch
Lake are beginning to reﬂect watershed dominated sediments (e.g., Gratiot
Lake). With several elements and elemental ratios showing a new, dominant
watershed source for recent Torch Lake sediments, several possibilities are
explored to explain the anomalous copper and Cu/Zn trends in the cap

sediments.

Grain Size

Kerfoot and Robbins (1994) found that Cu concentrations in stamp sands
increase with decreasing grain size. For example, the authors found that tailings
from the Point Mills stamp mill (located on Portage Lake) had more Cu
associated with the clay fraction than the sand or silt sized fraction. Particles
<53 pm contained 0.46% (4,600 mg/kg) Cu and particles >53 um contained
0.32% (3,200 mg/kg) Cu (Kerfoot and lauster, 1994). Prior to the cessation of
direct anthropogenic inputs, the bottom sediments of Torch Lake primarily
consisted of tailings (Lopez and Lee, 1977). If the ﬁner, more Cu enriched
particles are now accumulating in the deep depositional basins of Torch Lake,
the increase in copper may be a shift of grain sizes from larger, stamp sands

and silts to smaller, wave-eroded clays size materials.

64

Pore-water Diffusion

Enrichments of trace metals such as Cu have been attributed to near-
surface oxic precipitation of Fe and Mn metals that are mobilized under reducing
conditions (Kerfoot et al., 1999a). Below the redox horizon in lake sediments,
iron and manganese oxides dissolve and release Fe and Mn into the pore-
waters, which then can diffuse upward towards oxic waters (Bemer, 1980). In
Torch Lake there is a sharp redox horizon in the top 2 cm, and this process is
capable of concentrating trace elements (e.g., AS, Cu, Ba) at the redox
boundary (Belzile and Tessier, 1990). Iron and Mn appear to be signiﬁcantly
affected by redox, but Cu did not appear to be signiﬁcantly affected by the redox
characteristics of Torch Lake (Figures 27 and 28). The proﬁles of Fe and Mn
are much sharper then the Cu proﬁle that is gradually increasing from the 10 cm
depth towards the surface. These results are consistent with other studies that
have shown that Cu is relatively unaffected by changes in redox conditions
(Kolak et al., 1998 and Shaw et al., 1990).

However, Cu in the sediments of Torch Lake may be migrating up the
core via sediment pore-water and being sequestered in the organic rich cap
sediments. in a study by Cusack (1995), pore-water samples were retrieved
from Portage Lake that contained both an organic rich top layer (>10% organic
matter) and mining related sediments. Pore-water Cu concentrations in the
organic rich top sediments were reported at 0.077 mg/L and when the organic
matter decreased in the mining related sediments, the pore-water Cu

concentrations increased to 0.20 mg/L (Cusack, 1995). These results suggest

65

Normalized Concentration
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0 1 1 A 1 1 1 1 1 1
1 m’ c _

 

 

 

OI

 

 

Depth (cm)
(a) c» N N —¥ -8
0| 0 01 O 01 O

h
C

 

 

 

.5
U!

Normalized Concentration
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

O 1 1 1 1 1 1 1 4
5 - —

A
_ .—

 

 

..\
o
C

0 +Fe +Mn -O-Cu

Depth (cm)
8 a:

N
0|

0)
O

 

 

 

 

35’

Figure 27. Normalized iron, manganese and copper concentrations vs. depth. A) Site
T1 and B) Site T2.

66

Normalized Concentration

 

    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
0 1 L 4 1 1 l 1 :e=—————.__.
5 a
10 -
15 -
A o F u c
E 20 — z. + e + n -O- u
5 25 - °. ,
e . -
o 30 -
35 ~ , '
40 ~ - '
45 — ' ,o
A.
50 —-———
Normalized Concentration
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
0 1 1 :- 1 l 1 - 1- 1 (é; b 1 I
5* i
10 , -
ﬂ : +Fe +Mn -o-Cu
15 -
A 0' :3
E 20 «If :3
3 ‘0‘»
5 25 4 .(T . I. .
o. " .
8 30~ .~ '
35 - , '
40 >
45 «
50 B.

 

 

 

Figure 28. Normalized iron, manganese and copper concentrations with depth. A) Site T3
and B) Site T5.

67

that Cu is being scavenged out of the pore-water by complexing with the solid
organic matter. Similar results were also documented in Torch Lake by Cusack
and Mihelcic (1999). Samples from Torch Lake with higher organic matter had
lower aqueous Cu concentrations (Cusack and Mihelcic, 1999). In the
Keweenaw Watenivay, at least 50% of the dissolved Cu is bound to the organic
fraction (Kerfoot et. al., 1999c). If Cu were available in the pore-waters in high
enough concentrations, then complexes formed by the interactions with organic
matter might account for the observed copper enrichment in the cap sediments

of Torch Lake.

Microbial Processes

Konstantinidis et. al. (2003), examined the microbial resistance to Cu and
other heavy metals (Ni, Zn and Cd) in the sediments of Torch Lake. In
particular, two isolates harvested from sediments of sites T1 and T2, Ralslonia
and Arthrobacter were resistant to elevated levels of Cu, at least to 200 mg/L
CuSO4. Scanning electron microscopy showed changes in the outer envelope
of cells when they were grown in the presence of Cu (Konstantinidis et al.,
2003). The microbe Ralslonia was resistant up to 1,200 mg/L CuSO4 and
produced green colonies when grown in the presence of CuSO4. A green
“coating” on the microbe Ralslonia suggests that Cu sequestration is a
mechanism of resistance (Konstantinidis et al., 2003). Sequestering of CuSO4
from the pore-water in Torch Lake may also be a mechanism of Cu enrichment

in the cap sediments.

68

Event Dating

Since the 210Pb and 137Cs data from torch Lake are unreliable due to past
disturbances, a different approach was taken to date the sediment cores. This
approach, called “event dating” is based on historical and geochemical data from
Torch Lake. There is a well documented history of mining activity around the
lake, and having a good history of anthropogenic activities for disturbed lakes
can be used to deduce a history when their radionuclide records are questioned
(Kerfoot and Lauster, 1994). In an attempt to event date the sediments, the
transition of pink, mining related inputs to brown, watershed inputs (a depth of
~10 cm) was set to be 1968, the year of the cessation of mining inputs. This
shift also corresponded to shifts in elemental concentrations of Ba, Ca, Co, K,
Mg, Ti and in particular U.

To calculate an age, a sedimentation rate has to be established at each
sample location. By assuming that the sedimentation rate since the cessation of
mining activities has been constant, sedimentation rates were calculated based
on the total accumulated dry mass (g/cmz) and number of years of accumulation

(31 years, 1968-1999). The method for calculating the sedimentation rate was:

VV= {A (nu/ﬂ

Where:

W= sedimentation rate (gm/cmzlyr)

A(m)= accumulated dry mass at depth 2 (g/cmz)

n= number of years from depth 2 to the sediment/water interface (31 yrs)

69

The method for age calculation was based on the previously calculated

sedimentation rate and was as follows:

X: ‘00- cm- W2

Where:

X= date of sectioned slice
Y(s)= year sample was taken (1999)

C(y)= cumulative years to depth 2 (acc. dry mass to z / sedimentation rate)

y/2= years per section / 2

Results of event dating are summarized in Tables 8a, 8b and 80.

Table 83. Data from the event dating method of age calculation for site T1 .

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Acc. Dry
Mass Depth Cumulative

ngcmz) (cm) Years/Slice years Years/2 Date
0.091 1 .25 0.8736 0.874 0.437 1999
0.0632 .75 0.6057 1 .479 0.303 1998
0.0564 1 .25 0.5406 2.020 0.270 1997
0.0663 1.75 0.6355 2.655 0.318 1997
0.0804 2.25 0.7710 3.426 0.385 1996
0.1985 3 1.9037 5.330 0.952 1995
0.2061 4 1.9769 7.307 0.988 1993
0.2179 5 2.0893 9.396 1.045 1991
0.2292 6 2.1977 1 1 .594 1.099 1989
0.1762 7 1.6896 13.284 0.845 1987
0.5334 8 5.1151 18.399 2.558 1983
0.6921 9 6.6368 25.035 3.318 1977
0.6220 10 5.9644 31.000 2.982 1971

 

Sedimentation Rate = 0.1043 g/cmzlyr

70

 

Table 8b. Data from the event dating method of age calculation for site T2.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Acc. Dry
Mass Depth Cumulative
_(glcm2) (cm) Years/Slice years Years/2 Date

0.0336 .25 0.2873 0.287 0.144 1999
0.0354 .75 0.3028 0.590 0.151 1999
0.0356 1.25 0.3040 0.894 0.152 1998
0.0487 1.75 0.4162 1.310 0.208 1998
0.0490 2.25 0.4186 1 .729 0.209 1997
0.1539 3 1.3161 3.045 0.658 1997
0.1727 4 1.4765 4.521 0.738 1995
0.2039 5 1.7431 6.264 0.872 1994
0.1910 6 1.6333 7.898 0.817 1992
0.2173 7 1.8577 9.755 0.929 1990
0.8272 8 7.0730 16.828 3.537 1986
0.8171 9 6.9860 23.814 3.493 1979
0.8404 10 7.1857 31.000 3.593 1972

 

Sedimentation Rate = 0.1170 g/cmzlyr

Table 80. Data from the event dating method of age calculation for site T5.

 

 

 

 

 

 

 

 

 

 

 

 

 

Acc. Dry
Mass Depth Cumulative
__(glcm2) (cm) Years/Slice years Years/2 Date

0.0420 .25 0.4760 0.476 0.238 1999
0.0732 .75 0.3534 0.829 0.177 1998
0.1282 1.25 0.6236 1.453 0.312 1998
0.1848 1.75 0.6412 2.094 0.321 1997
0.2620 2.25 0.8746 2.969 0.437 1996
0.3469 3 0.9626 3.931 0.481 1996
0.4530 4 1.2024 5.134 0.601 1994
0.5564 5 1.1721 6.306 0.586 1993
0.6778 6 1.3751 7.681 0.688 1992
0.9369 7 2.9373 10.618 1.469 1990
1.3962 8 5.2047 15.823 2.602 1986
2.1200 9 8.2038 24.027 4.102 1979
2.7352 10 6.9726 31 .000 3.486 1971

 

 

 

 

 

 

 

 

Sedimentation Rate = .0882 glcmZ/yr

71

 

 

Using the dates calculated via event dating, the spike in the Cu concentration at
site T1 corresponded to an age date of 1971-1977. A spill of cupric ammonium
carbonate occurred in Torch Lake during the span of 1971-1972, and a date of
1977 calculated by event dating techniques is much more accurate, based on
historical data, than the date calculated via 210Pb, which was 1926 (Figure 29).
There is a gap in time of six years from the known data to the calculated date of
the spill because of the 1 cm sampling interval. The results from the two dating

techniques, 210Pb and event dating are summarized in Table 9.

Table 9. Comparison of dates using the 21oPb event dating methods from site T1.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Depth (cm) me Dates Event DatlnL
.25 1 999 1999
.75 1 996 1998

1 .25 1 994 1997
1 .75 1 992 1997
2.25 1 990 1996
3 1 985 1995
4 1979 1993
5 1 972 1 991
*6 1 964 1989
7 1958 1987
8 1946 1 983
9 1926 1 977
10 1905 1 971

 

*peak in 137Cs.

 

Lead-210 and 137Cs analyses are proven methods to date lakes that have
not been disturbed (Kemp et al., 1978; Kada and Heit, 1992; Robbins and
Edgington, 1975; Golden et al., 1993 and Yohn et al., 2002), however in

systems such as Torch Lake with a disturbed history, the data must be carefully

72

 

1980~

 

 

 

 

 

1920

 

 

 

 

1900

21 OPb

 

1880*
1860-

 

 

 

 

 

 

1840*
1820

 

 

 

 

2000 ...,cc

 

 

 

 

 

1990 w“ \\
1985 ____, A hp, ,, ,,,, -__c_ -_ ___L._.- -. , . ..

1980 E

 

Event Dating

1975 ~— ~ —

1970 ~—

 

 

1965

 

 

 

 

 

 

 

 

 

 

 

 

 

Depth (cm)

 

 

 

 

 

 

 

 

45

Copper Concentration (mg/kg)

0 $00 2000 3000 4000 5000

6000

Figure 29. Copper concentrations in Torch Lake sediments from site T1, as a function

of. A) the 21oPb dating method, 3) the event dating method and C) depth.

73

examined to assess the accuracy of the data. Age dating of sediment cores
based on historical in geochemical records has proven to be useful in

anthropogenically disturbed systems.

Estimating Recovery Rates

In order to manage a changing system such as Torch Lake, it is
necessary to calculate its rate of change. Using the age dates calculated by
event dating, it might be possible to predict recovery rates for the sediments of
Torch Lake. Recovery will be deﬁned as changing element ratios in the
sediments of Torch Lake to ratios reﬂective of Gratiot Lake. A recovery rate per

year was calculated as follows:

Recovery rate = Am — Am / n

Where:

Am: element ratio at depth 2
A5): ratio at sediment/water interface
n = number of years from depth 2 to the sediment/water interface

From that data, an estimate of recovery in years was calculated. The
equation for calculating recovery is as follows:

Recovery in Years = (G — TS) / Rr

Where:

G = Gratiot Lake average
T8 = elemental ratio for the top sample of cap sediments in Torch Lake
RR = recovery rate / yr

74

Results from the recovery analysis are summarized in Table 10.
Although recovery time varies depending on the elements chosen, sediments of
the north basin show very similar average estimates of recovery, ~10-12 years.
In the south basin, site T5 is slightly longer than the others at ~23 years. This is

possibly due to the slower sedimentation rate in the south basin.

Table 10. Number of years to reach ratios reﬂective of average Gratiot Lake ratios for
Co/Zn, Ti/Zn, KN, CoN, U/Zn and Ti/Ba at each sampling site.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ratio T1 T2 T3 T5
Co/Zn 13 5 5 21
Ti/Zn 10 9 5 12
K/V 6 27 22 51
CoN 31 23 23 51
U/Zn 2 8 9 0
Ti/Ba 0 1 0 2
Average time to
Gratiot Lake ratios 10.3 12.1 10.6 22.8

 

The recent temporal trends indicate some decline in recent Cu loadings
Cu concentrations, but the trends are quite noisy. There is enough data
however to estimate the possible rates of decline of Cu loadings to compare to
the other geochemical indicators of recovery (Table 10). Therefore, estimated
time to recovery was also calculated using absolute Cu concentrations (Table
11). Recovery rates were calculated based on a segment of decreasing trends
in the cap sediments. The decreasing trend was determined from these
intervals: Site T1, sample 2 to 8; site T2, sample 2 to 9; site T3, sample 2 to 9
and site T5, sample 2 to 11 (Figures 17 and 18). The target Cu concentrations

representing recovery was estimated to be 61 mg/kg of Gratiot Lake which is

75

similar to average Great Lakes sediments (Kolak et al., 1999). Even though
there is possibly signiﬁcant error in the calculations, estimated time for Cu
loadings to return to inferred watershed values are similar for all four basins
around 50 years. Because of the potential for error, the value of 50 years should
not be used for any lake management decisions, and further monitoring to better
deﬁne the trend is needed. However, the values are longer than what is
predicted from some elemental ratio analysis, which further supports the
observation that recent Cu loadings in Torch Lake are not related to watershed

processes.

Table 11. Recovery time in years for Torch Lake sediments to get to a concentration of 61
mg/kg (Gratiot Lake average) based on patterns of Cu concentrations in the cap sediments.

Site T1 T2 T3 T5
49 56 > 49 47

 

 

 

 

 

 

 

 

 

Conclusions

Sediment cores were collected from Torch Lake, Upper Peninsula,
Michigan to assess the recovery of the lake from past anthropogenic
disturbances related to the copper mining industry. This was done by
determining the spatial and temporal trends of heavy metals in the sediments
and comparing these data to a reference lake and the local geology. A multi-
element approach of assessing recovery in Torch Lake was undertaken, where

several other elements, many non-toxic, were measured as well as the chemical

76

of interest (i.e., Cu). Sediment ages were calculated based on historical and
geochemical data by a process known as event dating.

It was hypothesized that Cu concentrations in recent sediments would be
lower compared to the mining related stamp sands and slime clays, however this
trend was not observed. Copper concentrations in the top 10 cm of sediments in
Torch Lake still remain elevated at an average of 2,197 mg/kg. This suggested
that Torch Lake is not responding to the cessation of mining operations, possibly
due to continued to inputs of tailings eroding from shoreline deposits and post-
depositional processes (e.g., porewater diffusion and microbial processes).
However, results from other elements (Ti, Co, K, etc.) and elemental ratios
(Ti/Zn, Co/Zn, KN, etc.) suggest the lake is responding to the cessation of
mining activities and the sediments are approaching levels reﬂective of a
reference system (i.e., Gratiot Lake) and expected levels based on the local
geology of the region. If the re-vegetation of the shoreline controls new inputs,
there is little re-mobilization of previously deposited stamp sands and local
inputs cease, Torch Lake may continue to recover from the heavy anthropogenic
disturbances of the past. Torch Lake sediments will have elemental ratios in the
surface sediments similar to ratios in Gratiot Lake sediments in: from 10 to 12
years in the north basin and ~23 years for the south basin. However, the
estimates for copper recovery are longer than what is predicted from some
elemental ratios at ~50 years, which further supports the observation that recent
Cu loadings in Torch Lake are not related to watershed processes. This study

not only demonstrates the importance of using reference systems and multi-

77

element techniques when assessing environmental remediation, but also of

event based sediment chronologies.

Future Work

I would propose that the lake be sampled in ~10 years at approximately
the same location as this study, using the same equipment and methods. It
seems that there is natural attenuation processes at work in Torch Lake and
new samples could document further change from a geochemical signature
dominated by mining inputs to one the is dominated by a more watershed input
consistent with ratios similar to Gratiot Lake. Also, to better characterize Torch
Lake sediments and possible sources of copper enrichment in the cap
sediments, pore-water samples should be collected and analyzed for the same
suite of metals as the sediments and organic carbon analyses should also be

done.

78

Appendices

79

Appendix A. Sediment-Core Descriptions

Table A-1. Sediment description from Torch Lake, site T1.

Torch Lake - T1

Sample Date: 7/26/1999
Water Depth: 28 m (89 ft)
Location/Description: Latitude: 47°10.989' N Longitude: 88°24.528' W

Core description: ~ 44 cm long, sediment color changes from brown to
purple, many copepods in surface water

 

Sample # Thickness (cm) Depth (cm) Description

1 0.5 .25 Red/light brown

2 0.5 .75 Red/light brown

3 0.5 1.25 Brown and dark grains

4 0.5 1.75 Brown, dark speck, rust
specks

5 0.5 2.25 Brown in color

6 1.0 3.0 Brown in color

7 1.0 4.0 Brown in color

8 1 .0 5.0 Brown/red

9 1.0 6.0 Darker red/brown

10 1.0 7.0 Darker red/brown

11 1.0 8.0 Darker red/brown

12 1.0 9.0 Dark red at the top and
pink/purple at bottom

13 1.0 10.0 Solid pink with dark
streaks

14 1.0 11.0 Becoming more watery

15 1 .0 12.0 Watery

16 1.0 13.0 Watery

17 1.0 14.0 Watery

18 1 .0 15.0 Watery

19 1.0 16.0 Very watery

20 1.0 17.0 More ﬁrm

21 1.0 18.0 Pinkish in color

22 1.0 19.0 Pinkish in color

23 1.0 20.0 Watery

24 1.0 21.0 Watery

25 1.0 22.0 Less watery

26 1.0 23.0 Evidence of sand

27 1.0 24.0 Evidence of sand

80

28
29
30
31
32
33
34

Skip
35
Skip
36
Skip
37
Skip
38
Skip
39
40
41

1.0
1.0
1.0
1.0
1.0
1.0
1.0

1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0

25.0
26.0
27.0
28.0
29.0
30.0
31.0

32.0
33.0
34.0
35.0
36.0
37.0
38.0
39.0
40.0
41.0
42.0
43.0

81

Evidence of sand
More watery
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color,
piece of leaf stem
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Hit extruder piston

Table A-2. Sediment description from Torch Lake, site T2.

Torch Lake - T2

Sample Date: 7/26/1999
Water Depth: 33 m (105 ft)

Location/Description: Latitude: 47°10.285' N Longitude: 88°24.826' W

Core description: ~41 cm, at 10 cm the brown sediment changes to
purple; ~ 24 cm down, a darker (black) layer present

 

Sample # Thickness Depth (cm) Description
(cm)

1 0.5 .25 Light brown, very watery, top
very crooked

2 0.5 .75 Light brown, very watery, dark
brown mixed in

3 0.5 1.25 Light brown, watery, dark
brown mixed in, slightly
thicker

4 0.5 1.75 Light brown, thicker

5 0.5 2.25 Light brown, thicker

6 1.0 3.0 Thick brown sediment

7 1.0 4.0 Dark reddish brown, thicker

8 1.0 5.0 Dark reddish brown, thicker

9 1.0 6.0 Dark brown, thick

10 1.0 7.0 Dark brown, some purple,
very thick, clayey

11 1.0 8.0 Dark brown, some purple,
very thick, clayey

12 1.0 9.0 Brown -> purple, very thick ->
wetter

13 1.0 10.0 Purple, pudding like

14 1.0 11.0 Purple, thick

15 1.0 12.0 Purple, thick

16 1.0 13.0 Purple, less thick

17 1.0 14.0 Purple, watery, thinner

18 1 .0 15.0 Watery, moving into thicker

19 1.0 16.0 Purple, still watery

20 1.0 17.0 Purple, more watery

21 1.0 18.0 Purple, even more watery

22 1.0 19.0 Purple, very watery

23 1.0 20.0 Purple, very watery

24 1.0 21.0 Purple, very watery

25 1.0 22.0 Purple, watery, bottom
suddenly very thick

82

26 1.0 23.0 Purple, very thick top 0.5 cm,
bottom more watery

27 1.0 24.0 Purple, still thick, some gray
streaking
28 1.0 25.0 Purple, more watery, little
gray streaking
29 1.0 26.0 Purple, watery
30 1.0 27.0 Purple, watery
31 1.0 28.0 Purple, watery
32 1.0 29.0 Purple, watery
33 1.0 30.0 Purple, watery
34 1 .0 31.0 Purple, gooey
Skip 1.0 32.0 Purple, gooey
35 1.0 33.0 Purple, gooey
Skip 1.0 34.0 Purple, gooey
36 1.0 35.0 Purple, gooey
Skip 1.0 36.0 Purple, gooey
37 1.0 37.0 Purple, gooey
Skip 1.0 38.0 Purple, gooey
38 1.0 39.0 Purple, gooey

83

Table A-3. Sediment description from Torch Lake, site T3.

Torch Lake - T3

Sample Date: 7/27/1999
Water Depth: 32 m (100 ft)
Location/Description: Latitude: 47°10.436 'N Longitude: 88°24.024' W

Core description: ~51 cm long. 4.5 cm light brown; 5.5 cm dark brown
changing to purple

 

Sample # Thickness (cm) Depth (cm) Description

1 0.5 .25 Lt brown, v. ﬂuffy, sediment
probably suspended in water
removed

2 0.5 .75 Light brown, black, gray, and
lighter brown specks

3 0.5 1.25 Light brown, black, gray, and
lighter brown specks, thicker

4 0.5 1.75 Light brown, black, gray, and
lighter brown specks

5 0.5 2.25 Light brown, black, gray, and
lighter brown specks

6 1.0 3.0 Darker brown, still mixed with
gray, black and lighter brown

7 1.0 4.0 Dark brown, mixed w/ a little
back, much thicker

8 1.0 5.0 Dark brown, thick

9 1.0 6.0 Brown/purple, gray streaks, thick

10 1 .0 7.0 Brown/purple, gray streaks, thick,
bottom very thick and clayey

1 1 1.0 8.0 Brown/purple, very thick, clayey

12 1.0 9.0 Thin layer of brown and gray in
purple

13 1.0 10.0 Purple, thick, stick

14 1.0 11.0 Thin line of brown and gray

15 1.0 12.0 Purple, thin brown line

16 1.0 13.0 Thick on top of watery, gray layer

17 1 .0 14.0 Purple, somewhat watery,
swirled with lighter purple

18 1.0 15.0 Above on much more watery
layer, gray brown streaking

19 1.0 16.0 Purple w/ gray, watery

20 1.0 17.0 Purple w/ gray, watery, thicker

21 1.0 18.0 Purple w/ gray, watery

22 1.0 19.0 Purple w/ gray, watery

23 1.0 20.0 Purple w/ gray, watery

24
25
26
27
28
29
30
31
32
33
34
35
Skip

36
Skip
37
Skip
38
Skip
39
Skip
40
Skip
41
Skip
42
43

1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0

1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
2.0
1.0
2.0
1.0
1.0

21.0
22.0
23.0
24.0
25.0
26.0
27.0
28.0
29.0
30.0
31.0
32.0
33.0

34.0
35.0
36.0
37.0
38.0
39.0
40.0
41.0
42.0
44.0
45.0
47.0
48.0
49.0

85

Purple w/ gray, watery
Purple w/ gray, watery
Purple, gray line

Purple w/ gray, little thicker
Purple w/ gray, thicker
Purple, gray layering
Purple, gray layering
Purple w/ gray, thinner
Purple w/ gray

Purple w/ gray, gray layer
Purple w/ gray, thicker
Purple w/ gray, thicker

Purple w/ gray, thick on more
watery
Purple, thick layer on thinner

Medium thickness

Medium thickness

Medium thickness

Purple, med thick

Purple, thinner

Purple

Purple

Gray streaking

Thick brown/ gray layer, ~ 1 mm
Purple, some gray

Purple w/ some gray

Purple w/ some gray

Purple into a thick clayey brown

Table A—4. Sediment description from Torch Lake, site T5.

Torch Lake - T5

Sample Date: 7/27/1999
Water Depth: 21 m (66 ft)
Location/Description: Latitude: 47°08.823‘ N Longitude: 88°26.944' W

Core description: ~ 42 cm total; top ~8 cm brown; 0.5 cm pink below; some

 

mottling
Sample # Thickness (cm) Depth (cm) Description

1 0.5 .25 Brown/red

2 0.5 .75 Brown/red

3 0.5 1.25 Brown/red

4 0.5 1.75 Brown/red

5 0.5 2.25 Brown/red

6 0.5 3.0 Brown/red

7 0.5 4.0 Brown

8 0.5 5.0 Brown

9 0.5 6.0 Brown

10 1.0 7.0 Brown w/ layers of black
coal?

1 1 1.0 8.0 Brown/red

12 1.0 9.0 Brown/red, transition to
pink/purple

13 1.0 10.0 Pink/purple in color Very
wet

14 1.0 11.0 Pink/purple in color

15 1.0 12.0 Pink/purple in color

16 1.0 13.0 Pink/purple in color

17 1.0 14.0 Pink/purple in color

18 1.0 15.0 Pink/purple in color

19 1.0 16.0 Pink/purple in color

20 1.0 17.0 Pink/purple in color

21 1.0 18.0 Pink/purple in color

22 1.0 19.0 Pink/purple in color

23 1.0 20.0 Pink/purple in color

24 1.0 21.0 Pink/purple in color

25 1.0 22.0 Pink/purple in color

26 1.0 23.0 Pink/purple in color

27 1.0 24.0 Pink/purple in color

28 1.0 25.0 Pink/purple in color

29 1.0 26.0 Pink/purple in color

30 1.0 27.0 Pink/purple in color

86

31
32
33

35
Skip
36
Skip
37
38
Skip
39
Skip
40
Skip
41
Skip
42
Skip
43
Skip
44

1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0

28.0
29.0
30.0
31.0
32.0
33.0
34.0
35.0
36.0
37.0
38.0
39.0
40.0
41.0
42.0
43.0
44.0
45.0
46.0
47.0
48.0
49.0

87

Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Pink/purple in color
Hit piston

Appendix B. Quality Assurance / Quality Control

Solids digestion

The method of digestion via microwave-nitric acid has been shown to be
effective for sediment chemical extractions (Hewitt and Reynolds, 1990). This
method is not a total extraction (i.e. aluminosilicates are not digested), but is a
method used to extract metals that are potentially available to natural leaching
and biological processes (eg. copper, mercury, lead, etc) (Hewitt and Reynolds,
1990). A total digestion is not the goal of this research, since the majority of
anthropogenic metals in soils and sediments are associated with the organic
matter or absorbed onto clay particles.

After each use, the Teﬂon® digestion vessels were rinsed with DDW,
subjected to a 10% HCL bath for 24-hours, soaked in DDW for 24-hours and set
to air dry in a class 100 hood. Digestions in duplicate and triplicate were
performed on at least one sample per core. A procedural blank and a standard
reference material (SRM #2704, Buffalo River Sediment, New York) were also

processed with each set of ten samples.
Duplicates & Tn'plicates of samples

Results from the ICP-HEX-MS and AAS analysis of sediments are

summarized in Table B-2.

88

Table B-1. Data from the replicate sample analyses

Sample
T3-6
T3-6R2
T3-6R3
Mean
Std. Dev
% RSD

T3-36
T3-36R2
T3-36R3

Mean
Std. Dev

“/5 RSD

T2M—14
T2M-14R2
T2M—14R3

Mean
Std. Dev
% RSD

T1 T-22
T1 T-22a
Mean
Std. Dev
°/e RSD

T1 T-31
T1 T-31 a
Mean
Std. Dev
% RSD

T5-20
T5-20a
Mean
Std. Dev

°/o RSD

Sample Replicate Results

 

 

 

 

 

 

 

89

Units (Mg/kg)
Sc Ti V Cr Co Ni Cu As Mo Cd Pb
6.45 2,440 121 58.72 35.19 71.81 2,168 20.87 0.51 0.71 140
6.88 2,643 125 62.70 35.16 73.49 2,239 21.13 0.60 0.77 133
7.05 2,637 127 64.05 36.40 74.62 2,191 21.69 0.61 0.81 134
6.79 2,573 124 61.83 35.58 73.31 2,200 21.23 0.57 0.76 136
0.31 115 2.73 2.77 0.70 1.42 35.79 0.42 0.06 0.05 3.53
4.5% 4.5% 2.2% 4.5% 2.0% 1.9% 1.6% 2.0% 10.1% 6.9% 2.6%
7.04 5,762 146 84.43 67.61 132 1,450 4.14 0.44 0.20 61.39
6.76 6,029 150 83.03 67.18 131 1,433 3.94 0.48 0.21 60.51
6.96 6,367 151 85.23 68.74 133 1,481 4.36 0.57 0.23 61.38
6.92 6,053 149 84.23 67.84 132 1,455 4.15 0.50 0.22 61.09
0.15 303 2.54 1.11 0.81 0.92 24.53 0.21 0.07 0.02 0.51
2.1% 5.0% 1.7% 1.3% 1.2% 0.7'%' '_1.7% 5.1% 13.5% 7.9% 0.8%
4.91 6,293 133 82.41 64.06 143 1,653 5.59 0.29 0.38 78.67
4.70 6,424 135 83.01 65.07 145 1,681 6.06 0.27 0.37 78.85
4.53 6,719 135 80.80 63.52 142 1,680 6.25 0.32 0.42 77.81
4.71 6,479 134 82.07 64.22 143 1,671 5.97 0.29 0.39 78.44
0.19 218 1.29 1.14 0.79 1.06 16.12 0.34 0.02 0.03 0.55
4.1% 3.4% 1.0% 1.4% 1.2% 0.7% 1.0% 5.7% 8.3% 70% 0.7%
6.90 7,219 146 86.80 70.12 139 1,590 3.51 0.51 0.16 102
7.07 7,078 144 84.14 69.33 134 1,612 3.43 0.40 0.12 100
6.98 7,149 145 85.47 69.72 137 1,601 3.47 0.45 0.14 101
E2 100 1.39 1.88 0.56 3.01 15.32 0.06 0.08 0.03 0.94
1.7% 1.4% 1.0% 2.2% 0.8% 2.2% 1.0% 1.7% 18.2% 22.7% 0.9%
7.27 8,158 160 86.43 72.05 129 931 3.43 0.30 0.22 32.77
7.48 8,242 160 89.38 72.26 134 933 3.84 0.44 0.20 32.34
7.37 8,200 160 87.90 72.15 131 932 3.64 0.37 0.21 32.56
0.15 59.57 0.17 2.09 0.15 3.52 1.33 0.29 0.10 0.01 0.30
2.0% 0.7% 0.1% 2.4% 0.2% 2.7% 0.1% 7.9% 26.5% 7.0% 0.9%
7.21 5,851 139 64.57 43.41 92.75 1,575 2.26 0.28 0.12 9.15
6.99 5,835 138 63.66 42.90 82.99 1,573 2.03 0.30 0.20 7.58
7.10 5,843 139 64.12 43.15 87.87 1,574 2.14 0.29 0.16 8.37
0.15 11.25 1.30 0.65 0.36 6.90 1.34 0.16 0.01 0.06 1.11
2.2% 0.2% 0.9% 1.0% 0.8% 7.9% 0.1% 7.6% 5.0% 37.5% 13.2%

Table B-1 Continued

Sample
T3—6
T3-6R2
T3-6R3
Mean
Std. Dev
% RSD

T3-36
T3-36R2
T3-36R3

Mean
Std. Dev

% RSD

T2M—14
T2M-14R2
T2M-14R3

Mean
Std. Dev
% RSD

T1T-22
T1T-22a
Mean
Std. Dev
% RSD

T1T—31
T1 T-31 a
Mean
Std. Dev

°/o RSD

T5-20
T5-20a
Mean
Std. Dev
% RSD

Sample Replicate Results

 

 

 

 

 

 

Units (Mglkg)
Al Zn Sr Mg K Mn Ba Fe "‘ Ca“ u
13,269 263 30.77 12,551 875 1,511 217 18,621 31,846 2.35
13,458 265 34.90 12,729 1,001 1,566 223 19,859 32,944 2.44
13,335 269 36.50 12,614 1,023 1,573 226 19,695 33,483 2.44
13,354 266 34.06 12,631 966 1,550 222 19,391 32,757 2.41
95.91 3.24 2.95 90.60 79.83 33.92 4.41 672 834 0.05
0.7% 1.2% 8.7% 0.7% 8.3% 2.2% 2.0% 3.5% 2.5% 2.1%
13,762 227 38.79 12,833 275 1,008 50.26 37,042 36,821 0.62
14,445 232 37.03 13,470 284 1,008 50.51 36,547 36,463 0.61
14,616 233 35.21 13,630 268 1,025 51.09 37,277 35,809 0.64
14,274 230 37.01 13,311 276 1,014 50.62 36,955 36,364 0.62
452 3.16 1.79 422 7.81 9.79 0.42 372 513 0.01
3.2% 1.4% 4.8% 3.2% 2.8% 1.0% 0.8% 1.0% 1.4% 2.2%
12,703 219 38.40 12,111 392 984 100 37,273 35,162 0.85
14,451 222 40.25 13,777 407 1,002 100 38,625 35,588 0.87
14,630 219 35.14 13,947 391 990 100 37,493 35,137 0.86
13,928 220 37.93 13,278 397 992 100 37,797 35,295 0.86
1,064 1.95 2.59 1,015 8.67 9.07 0.08 725 253 0.01
7.6% 0.9% 6.8% 7.6% 2.2% 0.9% 0.1% 1 .9% 0.7% 1 .3%
9,158 255 35.93 9,231 340 1,170 57.82 33,796 41,889 0.55
8,884 258 37.80 8,955 356 1,185 57.64 38,357 41,149 0.55
9,021 257 36.87 9,093 348 1,178 57.73 36,077 41,519 0.55
194 2.26 1.32 195 11.05 10.01 0.13 3,225 524 0.00
2.1% 0.9% 3.6% 2.1% 3.2% 0.9% 0.2% 8.9% 1.3% 0.0%
10,059 218 39.42 9,995 248 1,086 68.92 46,860 40,663 0.48
9,984 218 37.62 9,921 241 1,091 69.48 45,020 41,120 0.50
10,021 218 38.52 9,958 245 1,089 69.20 45,940 40,891 0.49
52.68 0.13 1.27 52.31 4.75 3.50 0.40 1,301 323 0.01
0.5% 0.1% 3.3% 0.5% 1 .9% 0.3% 0.6% 2.8% 0.8% 2.6%
10,919 139 23.03 10,722 228 812 51.52 37,816 30,614 0.46
10,295 133 21.21 10,109 192 813 33.92 41,861 29,294 0.45
10,607 136 22.12 10,415 210 813 42.72 39,839 29,954 0.45
441 4.42 1.29 433 25.12 0.16 12.45 2,861 934 0.01
4.2% 3.3% 5.8% 4.2% 12.0% 0.0% 29.1% 7.2% 3.1% 1.5%

* Analyzed by AAS

90

Procedural Blanks
Results from the lCP-HEX-MS and AAS analysis of the blanks are

summarized in Table B-2.

Standard Reference Material Accuracy & Reproducibility

The certiﬁed elemental concentrations of the SRM were determined by
the NIST via Instrumental Neutron Activation and Direct-Current Plasma
Emission Spectrometry. The extracted values of several elements from this
study were in some cases much lower than the certiﬁed values, due to the use
of partial digestions. Recoveries of elements from the SRM ranged from 1% to
109% for titanium and copper, respectively. Although the digestion method
chosen was not a total digestion of the sediment, the SRM could still be used to
evaluate the precision of digestion method via microwave assistance.
Reproducibility of the standard reference material was better than 15% relative
standard deviation for all elements except for selenium. Results are

summarized in Table B-3.

91

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94

Detection and Quantiﬁcation Limits

Detection limits (DLs) are the concentration or response that is
considered the lowest reliably detectible level for a particular instrument.
Detection limits (DLs) for the lCP-HEX-MS were determined by calculating the
standard deviation of the count response of each element from ten replicates of
a Nanopure® blank. Detection limits for the lCP-HEX—MS were determined by

this equation:

conc. of known standard X
* 3 standard deviations of 10

 

counts for standard X readings of the blank count forX

Quantiﬁcation limits (QLs) of an instrument differ from the detection limits
in that QLs are based on the concentration and accuracy of the prepared
standards. Therefore, the concentration of a sample may be higher than the
detection limits of the machine, but may not be quantiﬁable based on the QL.
The quantification limits for each element were calculated using a method from

Miller and Miller (1993). Results are summarized in Table 34.

95

Table B-4. Detection limit and the quantiﬁcation limit of the Torch Lake sample analyzed via

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

lCP-MS and AAS.
Element DeterLtIgo/rlt L'm't Quantiﬁcation Limit pg/L

As .0650 2.73

Al NA 87.52
Ba .0014 4.22
Ca* NA 3.9 (mg/l)
Cd .0170 .109
Co .0150 4.70
Cr NA 5.31
Cu .0690 77.35
Fe“ NA 3.8 (ﬁg/l)
Hg .1300 ND

K .2000 1 10
Mg NA 177
Mn .0036 25.99
Mo NA 0.092
Ni .4600 10.88
Pb .0012 4.50
Sc .0130 3.97
Se .07902 0.82
Sr NA 6.86

Ti NA 66.12

U .0003 .10

V .0077 4.29
Zn .0560 5.84

 

 

 

 

* Elements analyzed via AAS.

96

 

Appendix C.

Results from lCP-HEX-MS and AAS analysis

The Results from the lCP-HEX-MS, AAS and event dating technique are
summarized in tables C-1 through C4. The values shaded in gray are lower
than the quantiﬁcation limit and grater than the detection limit. Even though
some of the concentration values are higher than the QL in the table, the QL is
based on the concentration of the digested leachate and not the representative
sediment concentrations. The reported sediment concentrations are calculated

by this equation:

00‘) * D(f) * S(v) / W

Where:

C(f) = cone. of ﬂuid (pg/L)

D(t) = dilution factor

S(v) = volume of initial sample (0.1L)

W = weight of sediment digested

97

Table C-1. Results of lCP-HEX-MS and AAS analysis and event dating, site T1.

Units (mg/kg)

 

[:1 Below QL above DL

98

Table C-1. Continued

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Units (mg/kg)
Sample Date Depth (cm) Al Zn Se Sr Mg K Mn Ba Ca‘ Fo‘ U
TM 1999 0.25 21,382 211 2.13 43 16,032 1,591 7,864 309 35,347 50,120 2.65
T1-2 1998 0.75 22,643 199 0.00 43 16,719 1,506 4,384 308 16,647 49,146 2.22
T13 1997 1.25 24,175 230 0.00 37 19,174 1,290 2,050 244 16,423 40,648 2.69
T14 1997 1.75 25,612 231 0.00 39 20,196 1,331 1,660 273 17,105 37,530 2.65
T15 1996 2.25 25,340 218 0.06 42 21,283 1,174 1,879 321 17,450 44,274 2.23
T1-6 1995 3 24,806 237 0.00 37 20,002 1,298 1,441 224 17,546 31,664 2.40
T1-7 1993 4 26,199 232 0.08 38 21,246 1,270 1,208 172 16,995 27,395 2.26
T1-8 1991 5 26,758 242 0.06 40 22,200 1,248 1,212 163 18,103 26,134 2.11
T1-9 1989 6 28,319 291 0.08 45 24,150 1,182 1,205 174 18,679 27,683 2.34
T1-10 1987 7 28,162 306 0.12 45 25,728 996 1,133 156 20,976 29,391 2.00
T1-11 1983 8 30,991 306 0.00 65 31,931 1,167 1,089 172 22,436 31,181 1.99
T142 1977 9 35,598 332 0.00 45 39,706 679 1,020 87 24,409 36,485 1.13
T143 1971 10 37,128 272 0.00 39 44,520 432 1,044 71 30,404 37,585 0.70
T1-14 11 36,967 269 0.00 48 46,560 454 1,040 66 31,198 39,438 0.84
T1-15 12 38,785 290 0.00 43 51,471 391 1,128 67 31,867 42,956 0.71
T1-16 13 38,165 279 0.00 45 52,386 385 1,114 64 33,452 42,982 0.67
71-17 14 34,572 218 0.00 53 45,372 294 942 53 45,436 37,381 0.66
T1-18 15 37,370 247 0.00 47 48,881 356 1,017 64 40,989 39,673 0.65
71-19 16 35,326 216 0.00 50 46,582 298 934 50 35,041 37,727 0.73
T1-20 17 34,723 248 0.00 50 44,652 381 938 57 43,103 36,318 0.76
T1-21 18 36,845 242 0.00 41 46,910 379 1,019 55 35,634 37,476 0.65
T1-22 19 41,514 255 0.00 36 53,993 340 1,170 58 33,796 41,889 0.55
T1-23 20 43,796 250 0.00 36 59,445 353 1,265 52 38,218 46,070 0.53
T1-24 21 40,102 224 0.00 37 53,319 280 1,118 52 45,700 43,984 0.48
T1-25 22 41,592 219 0.00 35 55,445 259 1,158 57 47,171 43,072 0.48
T1-26 23 37,494 201 0.00 34 47,421 236 1,004 50 45,141 38,162 0.51
71-27 24 39,329 212 0.00 43 49,510 267 1,031 48 46,848 39,391 0.57
T1-28 25 43,223 240 0.00 37 54,319 340 1,205 63 45,206 43,450 0.62
T1-29 26 41,968 240 0.00 42 56,207 234 1,131 54 38,577 42,292 0.51
T1-30 27 45,529 240 0.17 47 58,983 259 1,189 70 46,364 44,766 0.71
T1-31 28 39,796 218 0.00 39 52,316 248 1,074 69 46,860 40,663 0.48
T1-32 29 43,677 232 0.00 44 54,716 287 1,149 78 44,440 44,484 0.54
T1-33 30 44,874 252 0.00 39 55,950 285 1,181 71 45,040 45,898 0.55
T1-34 31 37,277 223 0.00 42 45,526 479 974 74 39,429 36,456 0.84
T136 35 41,280 236 0.00 51 52,244 289 1,107 76 39,185 41,397 0.59
T139 41 45,145 255 0.00 37 58,256 310 1,215 83 47,308 45,453 0.51
T1-40 42 42,650 247 0,00 36 54,880 272 1,140 79 41,132 44,268 0.55

 

 

 

 

 

[3 Below QL above DL
* Analyzed by AAS

99

Table C-2. Results of lCP-HEX-MS and AAS analysis and event dating, site T2.

Units (mg/kg)

57 32 74 192 40 1.41 1 154

 

[:1 Below QL above DL

100

Table C-2. Continued

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Units (mglkg)
Sample A499 Depth AI Zn 88 Sr ML K Mn Ba Ca* Fe“ U
T2-1 1999 0.25 25,184 259 3.38 43 20,347 1,218 11,457 278 18,712 35,231 2.88
12.2 1999 0.75 24,350 2130.74 49 17,848 1,336 20,787 502 18,787 53,594 2.25
12.3 1998 1.25 21,840 189 0.12 58 15,848 976 8,887 530 18,721 88,717 1.98
12.4 1998 1.75 26,456 219 0.14 48 20,335 1,154 2,748 401 17,980 49,755 2.12
125 1997 2.25 29,045 212 0.67 44 23,858 979 1,585 228 20,805 31,329 1.86
T2-6 1997 3 29,311 2010.50 47 24,788 1,071 1,340 192 21,845 31,207 1.87
12.7 1995 4 29,247 258 0.24 40 25,203 1,113 1,297 197 22,044 28,115 2.28
T2-8 1994 5 30,128 283 0.70 42 28,310 983 1,298 173 23,538 27,585 2.38
12.9 1992 8 28,578 297 0.89 44 25,486 970 1,242 187 23,790 26,865 2.22
T210 1990 7 25,908 217 0.40 84 25,471 1,074 929 175 30,848 24,980 2.13
12.11 1986 8 28,180 194 0.18 57 32,232 833 905 134 43,820 27,551 1.86
12.12 1979 9 34,341 2210.00 31 39,848 516 1,007 78 38,394 33,482 1.11
12.14 1972 10 38,703 219 0.00 38 42,095 392 1,002 100 37,273 35,182 0.85
12.15 11 37,384 2200.00 32 45,459 313 1,012 77 38,947 35,824 0.87
T2-16 12 38,412 222 0.00 39 44,078 339 999 73 38,058 38,382 0.79
72.17 13 35,484 218 0.00 43 43,803 400 982 77 37,054 34,319 0.88
T248 14 33,108 198 0.00 37 41,789 285 907 82 41,770 33,885 0.80
72-19 15 37,089 237 0.00 48 47,811 385 1,017 81 38,289 37,553 0.91
72.20 18 35,881 239 0.00 59 48,271 388 983 77 43,388 37,211 1.01
T2-21 17 38,015 258 0.00 58 49,215 385 1,009 74 41,825 38,852 0.91
12.22 18 35,187 241 0.00 52 45,855 322 935 71 42,998 38,812 0.93
12-23 19 38,453 2380.00 49 48,194 341 984 79 44,423 38,239 0.83
12.24 20 29,942 182 0.00 44 38,753 252 791 83 43,484 30,879 0.78
72.25 21 27,885 188 0.00 38 33,805 211 720 50 44,820 28,059 0.78
T2-26 22 19,591 92 0.00 27 18,884 139 458 31 42,753 17,893 0.70
T2-27 23 33,822 223 0.00 40 40,158 292 891 89 39,982 33,387 0.94
T2-28 24 37,521 270 0.00 41 49,081 313 1,002 79 39,148 38,482 0.77
12.29 25 31,505 214 0.00 43 42,173 328 838 74 37,594 32,349 0.72
T2-30 28 32,844 217 0.00 49 43,241 304 888 87 44,808 34,232 0.83
12.31 27 31,510 213 0.1145 41,989 277 851 87 42,798 32,887 0.91
72.32 28 31,747 222 0.00 42 42,854 288 858 88 40,408 33,584 0.73
72-33 29 30,480 212 0.00 42 42,299 230 857 84 39,156 32,040 0.77
72.34 30 32,283 2130.00 47 43,325 284 881 88 42,058 33,909 0.77
72.35 32 30,159 189 0.00 37 40,242 196 781 57 37,820 31,371 0.89
T2-36 33 29,407 180 0.00 47 37,235 201 728 58 38,881 30,337 0.75
Below QL above DL

* Analyzed by AAS

101

 

Table C-3. Results of ICP-HEX—MS and AAS analysis and event dating, site T3. Event dates
from site T2 are reported as site T3 due to their close proximity to each other.

Units (mg/kg)

 

E Below QL above DL

102

Table C-3. Continued

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Units (mg/kg)
Sample Ag: Depth Al Zn Se Sr Mi K Mn Ba Ca* Fo‘ U
T3-1 1999 0.25 25,844 272 2.13 51 19,215 1,317 14,242 407 17,951 52,515 2.64
T3-2 1999 0.75 24,023 2460.74 52 18,208 1,076 10,374 419 22,447 66,303 2.31
T3-3 1998 1.25 25,615 2220.24 36 20,253 912 5,346 354 17,016 53,004 2.04
T34 1998 1.75 27,241 2921.17 40 21,645 1,034 3,088 316 17,778 42,424 2.61
T3-5 1997 2.25 29,139 2641.30 32 25,276 907 2,163 259 18,455 36,606 2.42
T3-6 1997 3 28,877 263 0.59 31 25,953 875 1,575 217 18,621 31,846 2.35
T3-7 1995 4 29,633 292 0.60 36 25,311 1,047 1,408 218 19,066 29,087 2.39
T3-8 1994 5 31,014 321 0.91 48 26,533 1,159 1,413 195 22,123 30,635 2.40
T3-9 1992 6 29,267 311 0.82 44 24,534 1,018 1,446 183 21,363 29,840 2.34
T3-10 1990 7 29,071 3110.84 50 27,580 906 1,240 176 21,989 29,944 2.06
T3-11 1986 8 25,262 214 0.10 70 26,673 1,000 883 184 28,948 25,992 2.20
T3-12 1979 9 30,072 210 0.00 48 33,747 714 935 103 32,690 30,819 1.48
T343 1972 10 34,469 240 0.00 33 39,475 440 984 84 32,382 35,688 1.01
T3-14 11 37,688 243 0.00 35 43,974 345 1,023 84 32,760 37,320 0.74
T3-15 12 38,135 278 0.00 41 45,938 367 1,044 83 30,272 36,534 0.89
T346 13 36,921 245 0.00 53 46,138 400 1,001 74 33,041 37,271 0.90
T3-17 14 37,784 289 0.00 48 48,469 467 1,077 76 31,799 39,729 0.95
T3-18 15 36,408 259 0.00 54 47,095 350 1,001 66 34,560 38,242 0.93
T3-19 16 31,199 204 0.00 51 37,563 313 850 56 41,773 33,588 0.80
T3-20 17 38,097 3070.00 45 48,851 443 1,098 91 33,004 41,376 0.74
T3-21 18 34,262 257 0.00 44 45,356 340 952 74 34,517 36,227 0.74
T3-22 19 33,378 232 0.00 57 44,414 394 942 65 40,059 35,198 0.79
T3-23 20 33,133 248 0.00 45 46,026 326 959 66 37,678 35,580 0.77
T3-24 21 33,999 254 0.00 40 46,024 256 952 62 37,258 37,830 0.75
T3-25 22 32,858 223 0.00 46 43,004 307 893 59 38,802 33,576 0.73
T3-26 23 34,109 230 0.10 46 45,521 308 914 61 38,235 34,235 0.90
T3-27 24 31,228 195 0.00 38 40,325 242 818 51 37,679 31,839 0.73
T3-28 25 31,669 191 0.00 46 40,391 233 817 50 39,293 31,198 0.77
T3-29 26 34,405 251 0.00 42 42,794 281 868 56 37,238 33,306 0.77
T3-30 27 37,648 250 0.00 48 49,008 317 998 76 33,292 37,743 0.72
T3-31 28 35,012 216 0.00 51 45,923 246 888 57 38,740 35,573 0.69
T3-32 29 34,122 201 0.00 57 44,656 239 851 51 41,688 34,750 0.71
T3-33 30 31,936 180 0.00 49 40,477 214 787 46 41,923 31,712 0.69
T3-34 31 35,244 1960.00 56 43,564 240 851 48 43,476 33,573 0.82
T3-35 32 33,352 215 0.00 38 44,166 239 849 49 36,914 33,601 0.74
T3-36 34 38,094 227 0.00 39 46,975 275 979 50 37,042 36,821 0.62
T3-37 36 37,535 189 0.00 40 46,806 241 1,023 43 42,722 36,389 0.54
T3-38 38 38,142 191 0.00 39 48,682 223 1,042 43 44,549 37,107 0.59
T3-39 40 34,923 174 0.00 31 43,373 212 930 37 42,667 34,457 0.51
T340 42 35,957 175 0.00 30 45,155 1119-4872. 962 38 44,369 35,135 0.54
T341 44 34,602 170 0.00 39 42,350 1193 909 37 44,297 33,707 0.61
T342 45 35,089 175 0.00 29 44,236 f:'_7;-;-11._7,.8.3 926 39 42,979 33,766 0.53
T343 46 33,411 155 0.0.0 29 39,986 731.8852 828 36 42,966 30,297 0.57

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1:] Below QL above DL
* Analyzed by AAS

103

Table C-4. Results of lCP-HEX-MS and AAS analysis and event dating, site T5.

Units (mg/kg)

 

[:1 Below QL above DL

104

Table C-4. Continued

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Units (mg/kg)

Sample Age Depth Al Zn Se Sr M; K Mn Ba Ca“ Fe" U
T5-1 1999 0.25 26,670 181 1.11 33 18,218 924 6,991 227 44,058 22,500 2.50
T5-2 1998 0.75 24,259 157 0.00 37 15,328 837 3,038 260 22,641 68,957 2.15
T5-3 1998 1.25 28,222 169 0.00 41 16,958 1,172 1,869 270 19,857 60,972 2.25
T5-4 1997 1.75 31,527 2020.00 35 21,427 1,111 1,192 156 22,551 35,061 2.51
T5-5 1996 2.25 34,491 192 0.00 36 22,226 1,974 1,014 153 25,408 33,926 2.25
T5-6 1996 3 31,261 1920.02 26 23,720 676 1,005 144 24,397 34,620 1.75
T5-7 1994 4 32,157 221 0.00 27 25,447 628 997 121 26,509 32,409 2.17
T5-8 1993 5 32,672 217 0.06 26 26,282 593 962 105 28,239 32,638 1.92
T5-9 1992 6 30,615 209 0.00 23 25,496 523 888 93 29,305 33,038 1.75
T5-10 1990 7 33,344 209 0.00 28 25,642 657 947 101 29,537 33,467 1.72
T5-11 1986 8 32,555 198 0.00 29 30,686 466 930 74 30,741 32,824 1.08
T5-12 1979 9 25,986 152 0.00 31 30,575 350 740 45 29,745 27,287 0.69
T5-13 1971 10 30,529 153 0.00 29 34,400 306 821 42 27,782 30,823 0.56
T5-14 11 29,483 141 0.00 26 30,803 264 729 38 33,153 28,337 0.55
T5-15 12 32,120 151 0.00 24 33,353 215 782 40 35,988 30,762 0.50
T5-16 13 29,695 129 0.00 37 29,046 212 703 38 39,158 28,558 0.46
T5-17 14 30,073 128 0.00 32 28,229 197 713 37 38,904 29,383 0.46
T5-18 15 28,420 143 0.00 36 29,531 230 660 38 41,098 27,602 0.61
T549 16 28,309 145 0.00 29 30,583 216 667 35 38,689 26,633 0.50
T5-20 17 29,942 139 0.00 23 28,020 228 758 52 37,816 30,614 0.46
T5-21 18 32,201 144 0.00 18 29,738 194 827 36 40,818 31,709 0.41
T5-22 19 37,946 178 0.00 24 35,083 291 1,061 43 40,334 39,846 0.54
T5-23 20 31,770 198 0.00 28 35,843 304 833 42 45,423 32,016 0.49
1'5-24 21 35,120 185 0.00 24 33,948 253 926 42 38,065 36,395 0.46
T5-25 22 32,520 202 0.00 24 36,356 290 857 41 42,751 33,508 0.46
T5-26 23 39,242 177 0.00 26 35,965 259 1,133 42 38,327 42,465 0.46
T5-27 24 42,818 189 0.00 26 39,004 285 1,252 46 45,150 46,521 0.46
'l'5-28 25 37,882 151 0.00 26 32,894 242 968 37 44,875 37,247 0.39
T5-29 26 33,407 152 0.00 30 34,394 221 795 32 44,738 30,516 0.48
T5-30 27 38,368 155 0.00 27 37,080 219 998 34 41,151 38,205 0.43
T5-31 28 41,102 181 0.00 27 35,761 252 1,097 34 45,444 41,934 0.50
T5-32 29 45,113 152 0.00 21 37,221 224 1,272 37 48,762 47,010 0.42
T5-33 30 45,447 175 0.00 24 41,829 251 1,232 42 52,800 45,709 0.43
T5-34 31 39,306 1800.00 29 38,037 253 1,009 37 46,319 37,955 0.43
T5-35 32 39,390 179 0.00 29 37,134 245 1,046 37 44,465 40,694 0.56
T5-36 34 39,251 173 0.00 23 42,159 g 217 1,014 35 44,940 38,994 0.40
T5-37 36 39,926 195 0.00 34 43,745 271 1,095 40 39,300 41,434 0.52
T5-38 37 38,764 222 0.00 32 44,099 295 1,070 42 41,893 42,811 0.55
T5-39 39 43,081 209 0.00 27 42,702 272 1,266 49 35,105 47,542 0.43
T540 42 44,706 2180.00 27 46,673 289 1,298 44 44,672 49,529 0.43
T541 44 34,015 179 0.00 31 35,474 224 898 37 43,992 39,572 0.43
T542 46 27,400 248 0.00 31 35,816 321 773 43 41,599 41,793 0.47
T543 48 38,136 212 0.00 28 45,366 268 1,045 34 37,680 40,166 0.55
T5-44 49 37,123 204 0.9.0, 29 43,169 294 1,016 42 36,740 38,015 0.53

 

Below QL above DL

* Analyzed by AAS

105

 

Appendix D.

Table D-1. Results of lCP-HEX-MS, AAS analysis and 21°Pb dating of Gratiot Lake sediments.

Units ((mngg)

 

 

Sample Age Depth (cm) Sc Ti V Cr Co Ni Cu As Mo Cd Pb
Gratiot-1 1599 0.5 5.57 325 68.1 20.9 5.98 20.55 68.21 7.19 0.40 0.79 43.2

 

 

Gratiot-2 1998 1.0 4.81 268 62.0 14.6 4.69 13.4 55.5 5.89 0.44 0.75 34.8

 

Gratiot-3 1998 1.5 5.06 284 61.6 18.7 5.54 17.2 59.1 6.83 0.48 0.93 40.5

 

Gratiot-4 1997 2.0 5.26 312 64.6 20.2 6.26 19.7 62.6 6.41 0.48 0.93 47.9

 

Gratiot-5 1997 2.5 3.98 250 49.5 15.3 4.43 14.1 47.2 5.73 0.38 0.72 37.1

 

Gratiot-6 1996 3.0 5.41 377 64.3 20.6 6.52 20.3 62.5 6.56 0.44 0.89 48.7

 

Gratiot-7 1995 3.5 5.87 397 70.3 22.9 6.98 21.3 68.0 7.57 0.51 1.02 55.8

 

Gratiot-8 1994 4.0 5.72 389 66.1 23.7 7.08 22.3 66.5 6.97 0.46 1.00 53.9

 

Gratiot-9 1993 4.5 5.27 323 61.6 22.0 6.41 19.7 63.5 6.37 0.45 0.92 50.2

 

Gratiot-10 1992 5.0 5.62 354 64.1 29.3 6.35 20.1 64.7 6.43 0.44 0.94 51.1

 

Gratiot-11 1990 6.0 5.59 331 61.5 22.0 6.68 20.6 63.6 5.69 0.42 0.91 47.5

 

Gratiot-12 1987 7.0 5.45 360 62.1 19.9 6.53 20.1 61.3 6.04 0.43 1.00 48.1

 

Gratiot-13 1985 8.0 6.06 401 66.7 23.2 7.22 22.9 67.3 7.99 0.46 1.09 60.4

 

Gratiot-14 1982 9.0 5.87 420 69.6 21.2 7.27 23.1 67.4 8.54 0.45 1.07 67.4

 

Gratiot-15 1979 10.0 5.63 435 67.3 43.4 6.95 22.2 65.1 8.56 0.48 1.04 67.7

 

Gratiot-16 1975 11.0 5.87 417 69.0 26.3 7.34 23.3 68.5 9.49 0.49 1.06 71.5

 

Gratiot-17 1972 12.0 5.69 426 67.5 30.6 7.03 22.8 67.5 9.59 0.53 1.10 71.4

 

Gratiot-18 1968 13.0 5.89 470 70.9 22.5 7.29 22.8 69.1 10.06 0.51 1.10 72.1

 

Gratiot-19 1965 14.0 5.70 412 69.8 27.5 7.05 23.1 69.1 9.86 0.52 1.08 70.8

 

Gratiot-20 1961 15.0 6.55 426 71.2 23.2 7.86 26.4 74.1 11.93 0.51 1.27 70.5

 

Gratiot-21 1957 16.0 6.08 456 70.6 22.0 7.20 23.4 72.9 10.27 0.54 1.11 62.9

 

Gratiot-22 1954 17.0 5.87 443 67.4 23.2 6.95 22.8 67.4 9.64 0.52 1.12 58.5

 

Gratiot-23 1950 18.0 6.20 447 71.7 22.6 7.46 24.2 71.7 9.88 0.52 1.19 60.1

 

Gratiot-24 1946 19.0 5.79 418 68.3 20.5 6.78 22.5 67.0 9.84 0.51 1.09 53.6

 

Gratiot-25 1943 20.0 6.34 463 73.0 22.0 7.33 24.2 69.5 10.43 0.56 1.16 52.5

 

Gratiot-26 1939 21.0 5.72 429 67.0 21.6 6.70 22.2 63.3 8.95 0.47 1.09 47.8

 

Gratiot-27 1935 22.0 6.06 433 68.4 21.6 7.12 23.8 65.3 8.92 0.45 1.20 48.2

 

Gratiot-28 1932 23.0 7.16 497 74.8 29.1 8.04 25.8 66.9 9.19 0.48 1.21 46.8

 

Gratiot-29 1928 24.0 6.22 485 74.3 22.7 7.74 24.1 63.1 8.77 0.44 1.13 40.8

 

Gratiot-30 1924 25.0 6.15 498 74.2 29.3 7.63 24.4 62.4 8.72 0.47 1.15 38.2

 

Gratiot-31 1920 26.0 6.44 489 75.5 23.6 7.95 25.5 64.3 8.98 0.44 1.23 38.8

 

Gratiot-32 1916 27.0 6.11 468 73.8 22.8 7.03 22.9 60.3 7.88 0.42 1.09 35.3

 

Gratiot-33 1912 28.0 6.16 440 76.7 28.9 7.36 22.9 60.1 7.80 0.44 1.17 33.7

 

Gratiot-34 1909 29.0 6.37 452 79.5 21.0 7.25 22.9 55.5 7.60 0.49 1.05 29.4

 

Gratiot-35 1905 30.0 6.56 440 82.8 23.9 7.08 23.1 55.7 6.04 0.50 0.88 25.2

 

Gratiot-36 1901 31.0 6.76 413 82.1 28.0 6.92 23.8 51.0 3.89 0.48 0.66 16.6

 

Gratiot-37 1896 32.0 7.07 429 83.9 24.4 7.07 22.9 50.7 3.18 0.47 0.61 15.4

 

Gratiot-38 1892 33.0 7.08 446 83.2 23.3 7.06 22.9 49.8 2.63 0.46 0.60 11.9

 

Gratiot-39 1888 34.0 7.23 459 83.9 23.6 7.25 23.5 51.3 2.54 0.50 0.55 10.3

 

Gratiot-40 1883 35.0 6.79 345 84.1 22.1 6.98 23.2 49.1 2.37 0.43 0.56 9.91

 

Gratiot-41 1879 36.0 7.10 442 81.2 26.1 7.99 23.4 51.1 2.39 0.45 0.44 8.01

 

Gratiot-42 1873 37.0 6.86 526 75.7 23.5 8.09 24.0 49.0 2.03 0.38 0.57 6.46

 

Gratiot-43 1867 38.0 6.50 531 70.1 22.2 7.69 22.8 45.3 1.98 0.37 0.56 5.44

 

Gratiot-44 1854 40.0 7.45 509 75.6 26.3 8.25 26.2 52.2 2.14 0.39 0.55 6.65

 

Gratiot-45 1839 42.0 7.22 506 78.5 25.8 8.47 26.9 55.2 2.23 0.40 0.56 3.10

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Gratiot-46 1823 44.0 7.93 477 97.3 27.1 9.07 29.1 66.9 2.79 0.48 0.64 3.09

 

 

106

Table D-1 Continued

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Units (mg/kg)
Sample Age Depth (cm) Al Zn Se Sr Mg K Mn Ba Ca* Fe* U
Gratiot-1 1E9 0.5 12,555 91.7 40715.8 4,408 1,332 718 78.4 2,845 19,476 0.86
Gratiot-2 1998 1.0 11,505 74.01.85130 3,606 2,110 772 75.4 2,280 19,087 0.75
Gratiot-3 1998 1.5 12,290 81.8 24812.8 4,078 2,090 617 77.5 2,236 17,520 0.83
Gratiot-4 1997 2.0 13,009 84.1 3.15128 4,548 1,774 822 77.7 2,352 17,043 0.89
Gratiot-5 1997 2.5 10,589 84.41.88100 3,445 1,735 478 57.4 1,921 13,459 0.74
Gratiot-6 1996 3.0 13,715 85.0 24513.3 4,874 1,818 526 68.4 2,449 17,022 0.93
Gratiot-7 1995 3.5 14,838 92.2 2.27143 4,928 1,543 518 70.2 2,598 17,880 0.99
Gratiot-8 1994 4.0 14,032 91.5 24514.5 5,008 1,499 484 88.8 2,557 17,454 0.96
Gratiot-9 1993 4.5 13,381 83.3 3.31 13.7 4,714 1,549 483 82.2 2,657 16,588 0.90
Gratiot-10 1992 5.0 15,145 85.1 2.11 14.2 4,701 1,887 472 84.4 2,627 17,229 0.94
Gratiot-11 1990 6.0 14,128 84.8 28414.3 4,820 1,983 470 87.8 2,830 16,137 0.93
Gratiot-12 1987 7.0 14,388 79.8 2.02138 4,599 1,966 429 59.7 2,828 16,000 0.94
Gratiot-13 1985 8.0 15,050 99.0 23015.7 5,208 1,709 440 88.4 2,628 17,219 1.03
Gratiot-14 1982 9.0 15,059 102 21915.4 5,126 1,377 397 83.5 2,727 17,874 0.99
Gratiot-15 1979 10.0 15,240 98.01.88155 5,005 1,324 388 60.7 2,625 17,255 1.00
Gratiot-16 1975 11.0 15,115 104 2.17161 5,140 1,238 388 81.3 2,887 17,988 1.05
Gratiot-17 1972 12.0 14,782 101 1.89155 5.039 1,181 348 58.5 2,707 18,071 1.02
Gratiot-18 1968 13.0 15,320 103 1.77187 5,121 1,257 343 59.8 2,870 17,998 1.04
Gratiot-19 1965 14.0 15,343 108 1.85159 5,130 1,134 338 58.8 2,701 17,972 1.02
Gratiot-20 1981 15.0 15,088 113 29818.2 5,291 1,098 334 80.1 2,710 18,318 1.05
Gratiot-21 1957 18.0 15,296 101 21018.4 5,387 1,219 330 59.2 2,678 17,485 1.03
Gratiot-22 1954 17.0 14,910 98.21.84158 5,226 1,154 309 58.8 2,619 18,774 1.00
Gratiot-23 1950 18.0 15,183 117 2.12185 5,579 1,147 327 59.9 2,813 17,505 1.06
Gratiot-24 1948 19.0 14,075 94.81.81 15.8 5,091 1,105 298 55.6 2,671 18,489 1.01
Gratiot-25 1943 20.0 15,429 997190171 5.444 1,188 312 58.8 2,793 17,845 1.07
Gratiot-26 1939 21.0 14,419 909188158 5.004 1,079 280 53.8 2,570 16,367 1.00
Gratiot-27 1935 22.0 14,470 95.01.88188 5,277 1,047 291 55.7 2,702 15,882 1.03
Gratiot-28 1932 23.0 15,207 105 22217.8 5,735 1,129 304 58.8 2,810 16,976 1.09
Gratiot-29 1928 24.0 15,011 928174173 5,819 1,040 293 58.2 2,889 16,707 1.07
Gratiot-30 1924 25.0 14,709 90.71.84175 5,497 1,082 285 58.1 2,901 18,518 1.05
Gratiot-31 1920 26.0 14,472 94.01.7418.1 5,608 1,047 289 58.7 2.920 18,782 1.09
Gratiot-32 1918 27.0 14,482 885188178 5,269 1,103 272 55.4 2,737 18,282 1.05
Gratiot-33 1912 28.0 14,332 84.31.5517.4 5,363 994 278 54.6 2,807 15,975 1.07
Gratiot-34 1909 29.0 14,377 75.51.99173 5,149 902 270 52.8 2,889 15,963 1.13
Gratiot-35 1905 30.0 14,255 89.5 2.00183 5,164 921 277 54.6 2,954 14,900 1.18
Gratiot-36 1901 31.0 14,295 56.6 208181 4,955 935 287 54.0 2,842 14,181 1.10
Gratiot-37 1898 32.0 14,912 554183193 5,133 948 275 56.7 2,921 13,831 1.10
Gratiot-38 1892 33.0 15,295 53.31.69196 5,148 1,007 287 58.9 2,852 13,519 1.10
Gratiot-39 1888 34.0 15,230 55.1 1.83 20.1 5,231 1,003 271 57.4 2,891 13,786 1.11
Gratiot-40 1883 35.0 13,639 50.71.87188 4,980 758 256 54.5 2,800 12,295 1.04
Gratiot-41 1879 38.0 14,335 61.2 2.12 20.9 5,404 835 253 54.8 2,920 13,182 1.08
Gratiot-42 1873 37.0 14,885 53.71.29198 5,761 860 257 55.2 3,011 14,216 1.02
Gratiot-43 1887 38.0 14,604 556137195 5,485 837 244 52.7 2,913 13,904 0.98
Gratiot-44 1854 40.0 18,180 54.91.95198 6,094 852 257 59.6 2,959 15,010 1.09
Gratiot-45 1839 42.0 15,908 52.61.89195 8,077 855 247 58.8 2,877 15,229 1.11
Gratiot-46 1823 44.0 18,018 54.9 2.13 21.3 8,132 918 244 52.0 3,081 14,333 1.37

 

* Analyzed by AAS

107

 

 

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