Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2006
Publication Date: 11/1/2006
Citation: Sangsupan, H.A., Radcliffe, D.E., Hartel, P.G., Jenkins, M., Vencill, W.K., Cabrera, M.L. 2006. Sorption and transport of 17b-estradiol and testosterone in undisturbed soil columns. Journal of Environmental Quality. 35:2261-2272.
Interpretive Summary: The potent sex hormones estradiol and testosterone have been detected in surface waters throughout the developed world. Both hormones have been shown to adversely affect aquatic life, and have the potential of being a serious public health concern. Sources of hormone contamination include both human and domestic animal waste. The poultry industry generates millions of tons of poultry litter annually, much of which is applied to pastures and cropped fields as fertilizer. Both estradiol and testosterone are natural components of poultry litter. Scientists, policy-makers, and the poultry industry require information to determine if these components pose an environmental risk when litter is appropriately applied. Scientists at the USDA-ARS J. Phil Campbell Sr. Natural Resource Conservation Center in Watkinsville, GA, in collaboration with scientists at the University of Georgia initiated a study to determine if and how these hormones leach through soil to groundwater and streams after a litter application. Intact soil columns were removed from an experimental field site at the J. Phil Campbell Sr. Natural Resource Conservation Center and taken to a laboratory at the University of Georgia. In the laboratory radioactively labeled estradiol and testosterone (along with the non-reactive tracer, chloride) were applied to the surface of the soil columns in concentrations comparable to those contained in litter; several liters of water were applied and the water that leached out of the column was collected and analyzed for the hormones and the chloride tracer. Results of these soil column experiments indicated that 27% of the estradiol and 42% of the testosterone leached through the soil columns with the chloride. Approximately 50% of the remaining soil-bound hormones were detected in the upper 10 cm of soil. These data indicated that these two sex hormones can move through worm holes, large interconnected pores, and cracks in the soil column, a phenomenon referred to as preferential flow. Under conditions of preferential flow, these hormones contained in litter that is applied to agricultural fields may contaminate groundwater. This information can be used by the poultry industry and environmental agencies to ensure safe application of the millions of tons of poultry litter generated annually in the USA.
Technical Abstract: Land-applied domestic animal wastes, such as poultry litter, contain appreciable amounts of the sex hormones 17'-estradiol (henceforth, estradiol) and testosterone. These hormones may be transported through soil to groundwater and streams, where they pose a potential health threat to humans and wildlife. Previous column transport studies with these hormones used sieved soil and did not consider preferential flow. Therefore, we determined the sorption and transport of estradiol and testosterone in large (15 cm i.d. by 35 cm height) intact soil columns, and compared this transport to a chloride tracer. In the sorption expermient, isotherms for estradiol and testosterone were nonlinear with Freudlich exponents (n) less than one. Sorption of both hormones increased with soil depth, and estradiol sorbed more strongly than testosterone. Average estradiol Freudlich sorption coefficient (Kd) values were 36.9 cm3 g-1 µg1-n for the 0- to 10- cm soil depth and 25.7 cm3 g-1 µg1-n for the 20- to 30- cm soil depth; average testosterone Kd values were 26.7 cm3 g-1 µg1-n for the 0- to 10- cm soil depth and 14.0 cm3 g-1 µg1-n for the 20- to 30- cm soil depth. In the transport experiment 27% of the estradiol and 42% of the testosterone leached through the soil columns. Approximately 50% of the remaining soil-bound hormones were sorbed in the top 10 cm of soil. In almost all instances, concentrations of estradiol, testosterone, and chloride peaked simultaneously. Modeling the data with HYDRUS-1D suggested that both chemical and physical non-equilibrium processes affected hormone transport. Hormones placed on the soil surface may contaminate groundwater under conditions of preferential flow.