The study, published in the journal Environmental Science & Technology, found that estrogens, which are naturally occurring hormones found in manure, can bind to dissolved organic matter (DOM) in wastewater and persist for long periods of time. This is because DOM can protect estrogens from degradation by bacteria and other microorganisms.
"This is the first study to show that estrogens can persist in dairy wastewater for long periods of time by binding to DOM," said Heather Dalton, a postdoctoral researcher in the Department of Civil and Environmental Engineering at UC Davis and lead author of the study. "This finding is important because it highlights a potential ecological risk that had been overlooked until now."
Estrogens are known to have a variety of negative effects on aquatic organisms, including fish and amphibians. For example, estrogens can disrupt the reproductive systems of these organisms and can lead to population declines.
The researchers conducted a series of experiments to investigate how estrogens persist in dairy wastewater. They found that estrogens bound to DOM in wastewater were more persistent than estrogens that were not bound to DOM. The researchers also found that the persistence of estrogens in wastewater was affected by the type of DOM present.
"Our findings suggest that the persistence of estrogens in dairy wastewater is a complex process that is influenced by a number of factors, including the type of DOM present and the environmental conditions," said Dalton. "Further research is needed to better understand these factors and to develop strategies to mitigate the ecological risks associated with estrogens in dairy wastewater."
The study was funded by the California Dairy Research Foundation and the UC Davis Center for Water Resources.
