Transport of steroid hormones in the vadose zone after land application of beef cattle manure

Few studies have been conducted to investigate the potential contamination of groundwater from manureborne steroid hormones. The objective of this study was to monitor leaching of steroid hormones at the bottom of 2.4 m deep percolation lysimeters installed in plots treated with beef cattle manure. Soil samples were also collected from surrounding field plots. Treatments consisted of application of manure from two treatment methods (stockpiling and composting) or no manure application. Laboratory analyses of manure, soil, and leachate samples used liquid chromatography and tandem mass spectrometry to identify 17 steroid hormones and metabolites. Progesterone, estrone, β-zearalenol, and 4-androstenedione were detected at varying concentrations in both composted (1.6 to 8.4 ng g^-1 dry weight) and stockpiled (3.7 to 11.4 ng g ^-1 dry weight) cattle manure. Steroid hormones were detected in only 5% of the leachate samples, with the greatest detected being progesterone (20 ng L^-1) from a lysimeter in a plot treated with stockpiled cattle manure. Steroid hormones or metabolites were detected in 10% of the soil samples. The majority of detections (74%) were for soils sampled within the top 1.2 m. The steroid detected most frequently in the soil samples (4%) was 17β-estradiol, with a maximum concentration of 4.3 ng g^-1 in a plot treated with composted cattle manure. No synthetic steroids were detected in any soil or leachate samples. The low detection of steroid hormones in the soil and leachate samples suggests that while some hormones may move through silt loam soil, most are readily degraded or adsorbed after manure application.