Commonly Used Chemicals Transported to Agricultural Field through Municipal Biosolids Application

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Commonly used chemicals (including fragrances, detergents, fire retardants, plasticizers, and antibacterials) transferred to wastewater treatment plants were detected in municipal wastewater biosolids applied to agricultural field plots and subsequently detected in the runoff transported from the plots during precipitation events.

Biosolids (the solid residue from treatment of sewage at wastewater treatment plants) are recognized as a useful soil amendment. Biosolids are applied in agricultural landscapes to improve soil nutrient and characteristics. In the United States, the U.S. Environmental Protection Agency estimates that 8 million tons of biosolids are produced per year, of which about one-half are land applied.

Scientists collecting samples of runoff from a test plot during a simulated rainfall event

Scientists collecting samples of runoff from a test plot during a simulated rainfall event. The field received an application of biosolids, and the runoff samples were analyzed for organic chemicals that are commonly used in our everyday lives.  Photo Credit: Tracy Yager, US Geological Survey.

Wastewater treatment is effective at removing a portion of the chemicals from incoming wastes; however, some chemicals are not removed but instead are sorbed to biosolid materials. When biosolids are land applied as fertilizers, the potential exists for these chemicals to run off the land surface into local surface waters.

Previous research indicated that biosolid-derived steroid hormones were present in runoff from test plots amended with biosolids following a simulated rainfall event. This current report expands on the previous research and assesses the potential for rainfall-induced runoff for 17 organic chemicals that are commonly used in our everyday lives, such as fragrances, detergents, fire retardants, plasticizers, and antibacterials that were collected simultaneously with steroid hormone samples from the previous study.

This field-plot based study shows that chemicals that we commonly use are transferred from our homes to wastewater treatment plants and subsequently transported in biosolids to agricultural fields as soil amendments.

The scientists confirmed that rainfall mobilized chemicals from municipal biosolids-amended agricultural fields directly to runoff. Most (14 of 17) of the chemicals examined were present in edge-of-the-field runoff and not depleted in concentration even after three simulated 100-year rainfall events. It is likely that these chemicals are resistant to any further degradation, having already been subjected to biological wastewater treatment within the wastewater treatment plant. Understanding organism exposure and effects, if any, represents important next steps for study.

The U.S. Geological Survey (USGS) Environmental Health Mission Area continues to support ongoing science related to the identification and quantification of the environmental sources, presence, magnitude, and transport of contaminants in the environment in order to understand the actual as compared to the perceived health risks to humans and other organisms.

The USGS Toxic Substances Hydrology Program funded this study, as well as the Colorado Water Institute (CWI) and a National Science Foundation (NSF) CAREER Award (EAR 0847683).

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