Sorption of male hormones by soils and sediments

Abstract

This paper reports the sorption of two male hormones, testosterone and androstenedione, by four soil and sediment samples at both equilibrium and rate-limiting conditions. Unlike prior studies, androstenedione was studied independently of testosterone. Apparent sorption equilibrium is achieved in one to two weeks when the initial aqueous hormone concentrations (C0) at 10,000 microg/L (approximately 30% of their solubility limits [S(w)]) and two to three weeks when the C(0) is 300 microg/L (less than 1% of S(w)). The Freundlich model parameter n ranged from 0.698 to 0.899 for all soil-solute systems indicating nonlinear sorption isotherms. Isotherm nonlinearity leads to an inverse correlation between single-point organic carbon-normalized sorption distribution coefficients (K(oc)) and equilibrium androgen concentration (C(e)). When C(e)S(w) = 0.012, the log K(oc) values for testosterone and androstenedione on the various sorbents ranged from 6.18 to 6.75 and 6.83 to 6.04, respectively, compared to 6.30 to 6.80 and 6.16 to 6.92 when C(e)/S(w) = 0.004. This study suggests that male hormones may exhibit slow rates of sorption over 14 d or longer and that soils and sediments may have greater sorption distribution coefficients when concentrations fall into the ng/L range.