Hormone transport in a tile drained agroecosystem receiving animal waste applications

Manure is increasingly being viewed as a threat to aquatic ecosystems due to the introduction of natural and synthetic hormones from land-application to agricultural fields. Of particular environmental concern are the natural hormones 17α and 17β -estradiol (E2), estrone (E1), estriol (E3), testosterone (TST), and androstenedione (AND) and the synthetic hormones 17β - and 17α-trenbolone (TB) and trendione (TND). These compounds are known to cause endocrine disruption in sensitive aquatic organisms (e.g., fish, turtles) at ng/L concentrations. Despite the known negative effects of hormones on fish and other aquatic organisms, the fate and transport of hormones in agroecosystems remains poorly understood. Therefore, this dissertation assessed hormones released to receiving ditches from tile drained Midwestern fields under various manure applications practices. The study was conducted at Purdue University\u27s Animal Science Research and Education Center (ASREC), an EPA-designated concentrated animal feeding operation consisting of 600 ha of tile drained cropland in North Central Indiana. Animal wastes were stored on-site in lagoons and then land-applied through lagoon effluent pivot irrigation, solids broadcasting, and subsurface injection. Seven monitoring stations were installed to monitor flow and collect samples from four tile drain and three receiving ditch locations. The hydro-chemo dynamics of hormones associated with various manure application practices were assessed, and hormone transport to tile drains was found to be rapid, likely due to the presence of preferential flow pathways. The chemograph dynamics observed during storm events showed concentrations generally following hydrograph trends, suggesting that high flow events contribute to the majority of hormone loads. Hormones also were found to persist over the winter with increased concentrations coinciding with early thaws and snow melt. The highest concentrations of hormones in the receiving ditches were observed in June, potentially posing a threat to fish during a sensitive time in their sexual development. These concentrations were associated with dairy effluent irrigation; however, the frequency of detection of hormones was higher for fields that had received higher applications of dairy solids. Therefore, it is likely that dairy effluent irrigation may cause short-lived high concentrations whereas the application of solid wastes may cause more chronic exposure to aquatic organisms. The estrogen loads exported by the receiving ditches were estimated to be \u3c 3% of the masses applied with the majority of loads (60-92%) exported by the 80th percentile flow rates. Fields that received primarily poultry and swine lagoon effluent exported the highest estrogen loads, whereas fields receiving primarily dairy wastes (solid and liquid) exported the largest natural androgen loads. Additionally, the hormone loads were compared to nutrient loads, and phosphate\u27s export from the agroecosystem was found to be most similar to that of E1. Furthermore, 17α- and 17β-estradiol (E2) were exported early compared to other constituents, resulting in minimal export despite additional applications during the rest of the year. Differences in the export of the constituents were likely due to differences in the magnitudes and mechanisms of the biogeochemical processes impacting their respective fate and transport within and from the agroecosystem. This study significantly adds to the understanding of hormone release from tile drained agroecosystems and has important environmental implications regarding best management practices that can be implemented to reduce hormone loads exported to downstream locations