Fate and Transport of 17beta-estradiol Beneath Animal Waste Holding Ponds

Steroidal hormones, such as 17beta-estradiol (E2) and its primary metabolite, estrone (E1), are prevalent in animal waste and are a common subject of study due to potential soil, stream, and groundwater contamination. These particular hormones are labeled as Endocrine Disrupting Chemicals (EDCs) because of their developmental effects in reptiles and amphibians. Dairy waste at concentrated animal feeding operations (CAFOs) is typically stored in a waste pond. Even though these waste ponds are regulated to include a soil liner with a minimal hydraulic conductivity to limit leaching, previous studies have traced stream and groundwater contamination from waste ponds. This research included field and laboratory studies to examine E2 transport and included a potential engineering solution to limit hormone transport—applying biochar to new pond liners to act as a retardant. Soil cores were collected beneath a mature waste pond and analyzed for moisture content and hormone concentrations. In the laboratory study, columns with sand, clay, and cores from the waste ponds were packed and were subjected to infiltration by dairy waste using a head of 2.3 m. A subset of the laboratory columns were amended with powdered biochar to test its ability in retarding E2 and E1. The column of dairy waste was maintained on the soil columns for three months, leachate was analyzed for hormone concentrations, and at the conclusion of the study, the columns were dissected for moisture content and E2 and E1 concentration profiles. The biochar-amended laboratory columns considerably improved the retardation of E2. A batch sorption experiment found that the retardation factor of E2 by biochar was approximately 607, while clay had a retardation factor of approximately 159 at low concentrations. Because E2 concentrations of 4-250 ng/g were found beneath the waste pond, these findings suggests that a biochar amendment to a clay pond-liner would further limit hormone transport to the surrounding environment.