By

Writer, Jeff HÌý1Ìý;ÌýBarber, LarryÌý2Ìý;ÌýStephanie, KeefeÌý3Ìý;ÌýBrown, GregÌý4Ìý;James, GrayÌý5Ìý;ÌýSchoenfuss, HeikoÌý6Ìý;ÌýJahns, NathanÌý7Ìý;ÌýFerrey, MarkÌý8

1ÌýUniversity of Colorado/USGS, Â鶹¹ÙÍø, CO
2ÌýUSGS, Â鶹¹ÙÍø, CO
3ÌýUSGS, Â鶹¹ÙÍø, CO
4ÌýUSGS, Â鶹¹ÙÍø, CO
5ÌýUSGS, Denver, CO
6ÌýSt. Cloud State University, MN
7ÌýSt. Cloud State University, MN
8ÌýMinnesota Pollution Control Agency

Select endocrine disrupting compounds were measured in four rivers in southwestern Minnesota. Additionally, caged and wild fish populations were assessed for indication of endocrine disruption using plasma vittelogenin, morphological data, and histopathology. To determine fate of these compounds, a tracer study was performed on one of the rivers (Redwood River) using Lagrangian sampling coupled with hydrologic modeling incorporating transient storage. Mass exchange (transient storage, sorption) and degradation were approximated as pseudo first order processes, and in-stream removal rates were then computed by comparing conservative tracer concentrations to organic compound concentrations. The distance required for 17β-estradiol and nonyl phenol to undergo a 50% reduction in concentration was >2 km and >10 km, respectively, indicating that endocrine disrupting compounds are transported several kilometers downstream from sources and therefore have the potential of adversely impacting the lotic ecosystem. Water quality results indicated the widespread distribution of low level concentrations (<100 ng/L) of endocrine disrupting compounds. Elevated plasma vitellogenin in caged and wild fish populations indicated that endocrine disruption was occurring.