Tracking the fate and transport of estrogens following rainfall events

Surface runoff following rainfall events can transport estrogens from agricultural land to water systems, causing potential risks to aquatic biota. This study adopted two simple models, the wash-off and empirical models, to quantify the pathway of three prevalent manure-borne estrogens, estrone (E1), 17β-estradiol (E2β) and 17α-estradiol (E2α), from agricultural land to the receiving water following rainfall events. The complex interconversion of the three estrogens during attenuation was considered in the models. These two models were calibrated and validated using the data obtained from three artificial rainfall events from the literature. The data from the first two rainfall events were used to quantify key model parameters and the data from the third rainfall event were used to validate the models. The performances of the models were then evaluated through a statistical analysis. Results show that both models can closely reproduce the mass loads of estrogens during rainfall events and that the wash-off model shows a better overall performance than the empirical model for the data used in this study.