Estradiol and testosterone sorption and transport in soil with and without poultry litter
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The estrogenic hormones 17-β estradiol and testosterone are naturally occurring steroids found in poultry litter. The effects of litter on transport of these hormones are not known. Adsorption isotherms and breakthrough curves with packed soil columns were developed for 14C-labeled testosterone and 3H-labeled estradiol in a Cecil soil with and without poultry litter addition. The effect of applying the hormones alone or together (as they occur when litter is the source) was also investigated. Linear sorption coefficients (Kd) decreased significantly (p<0.05) from 19.7 to15.9 mL g-1 for testosterone and significantly (p<0.05) increased from 18.6 to 24.3 mL g-1 for estradiol in the presence of litter. In column experiments, estradiol peak concentrations occurred immediately after chloride (a conservative, slightly sorbed tracer) and the breakthrough curves were highly skewed. Testosterone peak concentrations occurred almost 12 pore volumes after chloride and the breakthrough curves were more symmetrical. Litter had no effect on the percentage of testosterone leaching from the columns (on average 18.0%) but estradiol leaching significantly decreased from 28.2 to 25.4% with litter. Applying the hormones together increased the mobility of estradiol and decreased the mobility of testosterone. Although the sorption coefficients of both hormones were high, appreciable amounts of estradiol moved through soil quickly due to chemical non-equilibrium. Litter may facilitate the movement of testosterone due to co-transport by fine particulate organic matter.