Fate of Hormone Conjugates in Soils.

In the United States the majority of the more than 2 billion farm animals are raised in confined animal feeding operations (CAFOs), resulting in concentrations of large quantities of animal waste in small land areas. In fact more than 500 million tons of animal waste is generated annually in the 238,000 CAFOs in the United States and typically this waste is stored on site for an extended period before being applied on land as fertilizer. Hormones associated with manure from concentrated animal feed operations (CAFOs) are of concern for both surface and groundwater quality, driving the need to monitor their occurrence, input, and subsequent fate in the environment. Our previous investigation has shown significantly higher levels of hormone conjugates compared to that of hormones in animal waste. Although the environmental fate of hormones is well understood, little information is available on the fate of their conjugates in animal waste and animal waste-applied soil. The aim of this study was to investigate the transformation of hormone glucuronide and sulfate conjugates in three soils with different physic-chemical properties. Appropriate levels of 17β-estradiol-3-sulphate and 17β-estradiol-3- glucuronide were spiked separately and together to sterilized and non-sterilized soils at an initial concentration of approximately 5 mg/kg soil. The spiked soils were incubated aerobically in darkness at 5, 15, and 30^oC for up to 100 days. Periodically sub-samples were obtained to analyze the transformation kinetic of target conjugates and to identify their metabolite formation. Faster transformation of 17β-estradiol-3-sulphate and 17β-estradiol-3- glucuronide back to their parent compound 17β-estradiol was observed in non-sterilized soil compared to the sterilized soil. However, this transformation was affected by temperature.