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TECHNICAL REPORTS

Vadose Zone Processes and Chemical Transport

Sorption and Transport of 17ß-Estradiol and Testosterone in Undisturbed Soil Columns

Dep. of Crop and Soil Sciences, 3111 Plant Sciences Bldg., Univ. of Georgia, Athens, GA 30602-7272

^* Corresponding author (dradclif{at}uga.edu)

Received for publication October 18, 2005. Land-applied domestic animal wastes contain appreciable amounts of 17ß-estradiol (henceforth, estradiol) and testosterone. These sex hormones may be transported through soil to groundwater and streams, where they may adversely affect the environment. Previous column transport studies with these hormones used repacked soil and did not consider preferential flow. We, therefore, determined the sorption and transport characteristics of estradiol and testosterone in undisturbed soil columns (15-cm i.d. by 32-cm height). In the sorption experiment, isotherms for estradiol and testosterone were nonlinear with Freundlich exponents (n) less than one. Sorption of both hormones decreased with soil depth, and estradiol sorbed more strongly than testosterone. Average estradiol Freundlich sorption coefficients (K_f) values were 36.9 µg^{1 – n} mLⁿ g^–1 for the 0- to 10-cm soil depth and 25.7 µg^{1 – n} mLⁿ g^–1 for the 20- to 30-cm soil depth. Average testosterone K_f values were 26.7 µg^{1 – n} mLⁿ g^–1 for the 0- to 10-cm soil depth and 14.0 µg^{1 – n} mLⁿ g^–1 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, breakthrough concentrations of estradiol, testosterone, and a chloride tracer peaked simultaneously. Simultaneous breakthrough and HYDRUS-1D transport parameters indicated both chemical and physical nonequilibrium processes affected hormone transport. This suggests hormones placed on soil surfaces may contaminate groundwater under conditions of preferential flow.

Abbreviations: CDE, convection dispersion equation • LSC, liquid scintillation counting • PVC, polyvinyl chloride • TOC, total organic carbon