Laboratory results for anthropogenic bioactive chemicals in the Illinois Waterway upstream and downstream of the bigheaded carp population front (2015)

Two nonnative bigheaded carp species have invaded the Illinois River system and are a potential threat to the Great Lakes ecosystem. Discharges from industry, wastewater treatment plants, and urban and agricultural runoff, may be a factor contributing to the stalling of the upstream movement of the bigheaded carp population front near Illinois Waterway mile 278. In 2015, the U.S. Geological Survey collected 4 sets of water samples under a range of seasonal and hydrologic conditions from 3 locations upstream and 4 locations downstream from river mile 278 using a Lagrangian-style sampling strategy. Water samples were analyzed for over 639 constituents of which 280 were detected at least once, including many anthropogenic bioactive chemicals (ABCs) such as pesticides, pharmaceuticals, hormones, and volatile organic compounds (VOCs). Many ABCs were detected upstream of river mile 278, and some persisted or were introduced downstream. For example, in June 2015, at river mile 286, sampling detected 43 of 105 pharmaceuticals (total concentration and total load of 9,251 nanograms per liter (ng/L) and 66.2 kilograms per day (kg/d), respectively); 46 of 251 pesticides (total concentration and load of 5,956 ng/L and 84.5 kg/d); 9 of 55 wastewater indicator chemicals (total concentration and load of 4,092 ng/L and 58.0 kg/d); and 10 of 116 VOCs (total concentration and load of 9,626 ng/L and 137 kg/d). By the time that water moved downstream to river mile 243, sampling detected 13 pharmaceuticals (total concentration and load of 417 ng/L and 27.8 kg/d); 51 pesticides (total concentration and load of 11,207 ng/L and 1,687 kg/d); 5 wastewater indicator chemicals (total concentration and load of 309 ng/L and 46.5 kg/d); and 2 VOCs (total concentration and load of 340 ng/L and 51 kg/d). Differences between the two sites are a function of dilution, downstream inputs (i.e. pesticides), degradation, sorption, uptake, and other geochemical processes.