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Sediment-water distribution of contaminants of emerging concern in a mixed use watershed

David J. Fairbairn, M. Ekrem Karpuzcu, William A. Arnold, Brian L. Barber, Elizabeth F. Kaufenberg, William C. Koskinen, Paige J. Novak, Pamela J. Rice, Deborah L. Swackhamer
Science of the total environment 2015 v.505 pp. 896-904
agricultural land, drug residues, ecosystems, exposure assessment, hydrophobicity, land use, personal care products, pesticide residues, pesticides, plant estrogens, population density, prediction, risk, rivers, sediments, streams, subwatersheds, surface water, water distribution, water pollution, Minnesota
This study evaluated the occurrence and distribution of 15 contaminants of emerging concern (CEC) in stream water and sediments in the Zumbro River watershed in Minnesota and compared these with sub-watershed land uses. Sixty pairs of sediment and water samples were collected across all seasons from four stream sites over two years and analyzed for selected pesticides, veterinary and human medications, personal care products, and phytoestrogens. Spatial and temporal analyses indicate that pharmaceuticals and personal care products (urban/residential CECs) are significantly elevated in water and/or sediment at sites with greater population density (>100 people/km2) and percentage of developed land use (>8% of sub-watershed area) than those with less population density and land area under development. Significant spatial variations of agricultural pesticides in water and sediment were detectable, even though all sites had a high percentage of agricultural land use. Seasonality in CEC concentration was observed in water but not in sediment, although sediment concentrations of three CECs did vary between years. Average measured non-equilibrium distribution coefficients exceeded equilibrium hydrophobic partitioning-based predictions for 5 of the 7 detected CECs by at least an order of magnitude. Agreement of measured and predicted distribution coefficients improved with increasing hydrophobicity and in-stream persistence. The more polar and degradable CECs showed greater variability in measured distributions across different sampling events. Our results confirm that CECs are present in urban and agricultural stream sediments, including those CECs that would typically be thought of as non-sorptive based on their log Kow values. These results and the observed patterns of sediment and water distribution can augment existing information to improve prediction of CEC fate and transport, leading to more accurate assessments of exposure and risk to surface water ecosystems.