Developing a quantitative framework to track the fate and transport of estrogens on a watershed scale

Abstract

• The first study to develop an HSPF modeling framework to simulate three estrogens with interconversion. • The modeling framework can be used to characterize the temporal and spatial variation of estrogens in streams. • The modeling framework can help to investigate the factors leading to high estrogen levels, evaluate the potential health risks to aquatic animals, and determine the best management practices for estrogens. The risks associated with estrogens in detectable concentrations in the aquatic environment underscore the need to best manage the release of estrogenic compounds. Modeling work can effectively help to understand the variation of estrogens in the natural water bodies at low costs. This study developed a modeling framework based on the Hydrological Simulation Program – FORTRAN (HSPF) code to simulate the fate and transport of three dominant estrogens, estrone (E1), 17β-estradiol (E2β), and 17α -estradiol (E2α) in surface water by integrating their excretion, transport, interconversion, and attenuation processes. This work focused on estrogens from sewage systems, failing septic systems, grazing animals, and manure land application. The developed modeling framework was applied to the Redwood River Watershed in Minnesota to model the in-stream estradiol equivalents (EEQs). The modeled EEQs were comparable to the values measured at three sampling sites along the Redwood River in 2007. The modeling results indicate that wastewater treatment plant discharges elevate estrogen levels on dry days, and surface runoff caused by storms or snow melting after the manure land application and/or cattle grazing can drastically spike EEQs levels, suggesting the application of buffer stripes and manure storage/composting for estrogen control. The case study shows that the modeling framework can be used to characterize the temporal and spatial variation of estrogens in streams, evaluate their risk to aquatic animals, and determine the best management practices for estrogen control.