Sorption and dissipation of testosterone, estrogens, and their primary transformation products in soils and sediment

Concern over the potential negative ecological effects of steroid hormones from human- and animal-derived wastes has resulted in an increased interest regarding the mobility and persistence of these compounds in the environment. Batch experiments were conducted to examine the simultaneous sorption and dissipation of three reproductive hormones (testosterone, 17beta-estradiol, and 17alpha-ethynyl estradiol) in four midwestern U.S. soils and one freshwater sediment. Sorption isotherms were generated by measuring aqueous concentrations and by extracting the sorbed parent chemical or transformation products (e.g., estrone, androstenedione). Apparent sorption equilibrium is reached within a few hours. Measured sorption isotherms for the three parent chemicals and their principal transformation products were generally linear. Average organic carbon normalized sorption coefficients (K(oc)) resulted in standard deviations of less than 0.2 log units and were consistent with reported aqueous solubilites and octanol-water partition coefficients, indicating hydrophobic partitioning as the dominant sorption mechanism. Large log K(oc) values (approximately 3-4) suggest that leaching from soils will be limited, runoff of soil- and land-applied biosolids are the most likely inputs into surface waters, and that a significant fraction of these compounds will be associated with sediments. Half-lives for hormone dissipation in the aerobic soil and sediment slurries estimated assuming pseudo first-order processes ranged from a few hours to a few days with testosterone having the shortest half-life.