Sorption and Desorption of Testosterone to Agricultural Soils: Inhibition Effects and Competitive Sorption

Previous studies indicated that transport of steroid hormones was limited in the soil/water system. Strong sorption and rapid degradation are believed to be the main reasons for dissipation of steroid hormones in soils. However, evidences of hormones leaching to groundwater have been reported frequently. In this study, batch sorption and desorption experiments were conducted to evaluate the fate and transport of testosterone in agricultural soils. Sorption isotherms were found to be generally linear and were fitted well by the Freundlich model. Correlation of sorption with soil properties indicated that the sand content, clay content and soil organic matter were of utmost importance in determining sorption. Desorption of testosterone from agricultural soils is significant in this study. After 3 desorption cycles, 16.33–44.34 % and 34.29–102.35 % of sorbed testosterone desorbed from the HAL and NP soils, respectively. Comparisons between detections with liquid scintillation counter (LSC) and high performance liquid chromatography/mass spectrometry (HPLC/MS) and between the tests with and without biotransformation inhibition provide a quality control confirmation of widely used radio-labeled chemicals/LSC detection for sorption tests. Adding NaN3 is believed to be effective in biotransformation inhibition. Competitive sorption effects of testosterone were observed. Estradiol and 4-androstendione were found effective in inhibiting testosterone sorption.