ABSTRACT
Previous research has documented the ubiquity of human and veterinary pharmaceuticals and personal care products (PPCPs) in freshwater, though their persistence and transport is relatively unknown. The objective of this study was to quantify the abundance and transport of human and veterinary PPCPs in a rural, central Indiana stream influenced by confined animal feeding operations (CAFOs). Research objectives also aimed to identify mechanisms controlling abundance and transport. PPCP concentrations and stream physicochemical characteristics were measured monthly over one year at multiple sites along a 60 km reach. Overall, human PPCPs were more abundant and measured at higher concentrations than veterinary pharmaceuticals. Veterinary pharmaceutical concentrations (lincomycin, sulfamethazine) were greatest in stream reaches adjacent to CAFOs. No distinct spatial variation was observed for human PPCPs. However, caffeine and paraxanthine had significant temporal variation with higher concentrations in winter. In contrast, DEET had higher concentrations in summer. Pharmaceutical load (µg/s) ranged from<0.005 to 1808 µg/s across sites, sampling events and pharmaceutical compounds with human PPCPs having higher loads relative to veterinary pharmaceuticals. Reach input ranged from net retention (sulfamethazine in August) to 1667 µg/m/d paraxanthine in March. Triclosan had the highest measured mean input into the reach (661 µg/m/d) and sulfamethazine had the lowest mean input (32 µg/m/d). Across measured compounds, input of PPCPs into the reach was two orders of magnitude lower than nitrate-N input (57,000 µg/m/d). Transport metrics indicated acetaminophen and caffeine are transported farther than triclosan though had lower loss velocities (loss relative to abundance). Loss rate of PPCPs was an order of magnitude lower than nitrate-N loss rate. Human PPCPs were more abundant than veterinary pharmaceuticals in this rural watershed influenced by CAFOs. Further, concentrations had significant temporal and spatial variation highlighting differential sources and fates. Thus, mechanisms driving PPCP retention and transport need to be identified to aid management of these emerging contaminants.
