Chemicals of emerging concern (CECs), such as pharmaceuticals and per- and polyfluoroalkyl substances (PFAS), have been frequently detected in agricultural systems, resulting from crop irrigation with contaminated water and land application of biosolids and animal manures. Crops can take up CECs from soil and water, leading to their accumulation in human and animal foodstuffs. The long-term consumption of contaminated foodstuffs and the resulting potential human and animal health impacts is of particular concern. Currently, the mechanism(s) controlling the uptake and accumulation of CECs in crops is not well understood. Additionally, agricultural lands contaminated by CECs can serve as a source that spread pollutants to the surrounding environment. The first study of this dissertation examined the accumulation and distribution of a commonly prescribed pharmaceutical (cephalexin) in lettuce, celery, and radish. Cephalexin did not accumulate in the shoots of all three vegetables but accumulated in the roots in the order of lettuce > celery > radish. Sorption of cephalexin to vegetable roots ranked in the order of lettuce > celery > radish, and the transformation of cephalexin by root enzyme extracts in the order of lettuce < radish < celery. Therefore, the sorption of cephalexin to plant roots and its transformation by plant enzymes could collectively determine the uptake and accumulation of cephalexin in vegetables. The second study examined the mechanisms controlling the transport of PFAS, from roots to shoots, using Arabidopsis thaliana Columbia-0 (wild type) and a mutant of this ecotype with a compromised Casparian strip (a potential barrier root-to-shoot transport). A. thaliana wild type and mutant plants were exposed to a mixture of PFAS and the pharmaceutical carbamazepine. Biomasses at harvest, amount of water transpired, carbamazepine concentration in shoots, and PFAS and carbamazepine concentration in roots were not significantly different between wild type and mutant plants. Significantly higher concentrations of PFAS were observed in the shoots of the mutant plants than in the wild type plant shoots suggesting that the Casparian strip plays a role in reducing the translocation of PFAS from roots to shoots. Translocation factors for PFAS with a molecular weight 450 g/mol were 3.4 times and 1.5 times higher in mutant plants than in wild type plants, respectively. This suggests that the translocation of PFAS with molecular weight < 450 g/mol could be more impacted by the Casparian strip. The final study investigated the concentrations and compositional profiles of PFAS in surface water and sediment samples collected near an agricultural field which received biosolids likely containing PFAS in the early 1980's. The total PFAS concentrations downstream of the biosolids-applied field ranged from 596 ng/L to 12,530 ng/L in surface water samples, with the highest concentration occurring immediately downstream of the biosolids-applied field. The total PFAS concentrations decreased with increasing distance away from the biosolids-applied field. The total PFAS concentrations in surface water samples upstream of the biosolids-applied field ranged from 40 to 173 ng/L. The highest concentration of total PFAS in the sediment samples (15,220 ng/kg) was found at an intermediate distance downstream of the biosolids-applied field, suggesting the transport of PFAS-contaminated sediments. These results indicate that the application of PFAS-containing biosolids to agricultural lands could have a long-term impact on the downstream environments.
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