Sorption of Estrogen to Three Agricultural Soils from Virginia, USA

摘要

Land-applied manures and grazing livestock are sources of estrogens to the environment. Natural steroid estrogens such as 17 � -estradiol (E2) in low concentrations (ng L -1 ) can adversely affect the reproductive health of aquatic organisms. The goal of this research was to quantify the sorption of E2 to three agricultural soils from different physiographic regions in Virginia, a critical step in predicting transport of estrogens in runoff from agricultural fields. Batch equilibrium experiments were conducted with a range of E2 concentrations (50 to 2000 � g L -1 ) in a background solution of 5 mM calcium chloride and 100 mg L -1 sodium azide added to samples of Groseclose loam, Myatt sandy loam, and Cecil loam soils collected from the plow layer (0 to 15 cm) in addition to a Cecil soil sample from the Bt horizon. The concentration of E2 in the liquid phase was measured by gas chromatography/mass spectrometry (GC-MS) and was used to develop sorption isotherms for each soil. The time required to reach apparent equilibrium for all soils was less than 24 h. In general, the linear isotherm provided a good fit to model the sorption of E2 to agricultural soils from the plow layer (R 2 > 0.9). The sorption of E2 to agricultural soil was correlated to the organic carbon content of each soil (Pearson coefficient, 0.79) with log K oc values ranging from 2.90 to 3.99.