Environmental Health - Toxic Substances Hydrology Program

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Chemicals from Land-Applied Biosolids Persist in Soil

A soil sampler in an farm field
Soil sampling in Eastern Colorado indicated that some chemicals introduced to nonirrigated farmland through biosolids application persisted through 468 days, and some chemicals were sufficiently mobile to be detected in soil as deep as 126 centimeters below land surface. Photo credit: Tracy Yager, USGS.

A study by scientists from the U.S. Geological Survey (USGS) and Colorado State University-Pueblo shows that some chemicals in biosolids that are applied to nonirrigated farmland are sufficiently persistent and mobile to move into the soil beneath farm fields. Biosolids are the treated solid-waste component of wastewater treatment plant effluent; about 50 percent of the biosolids produced in the United States are applied to land as a fertilizer.

The field-scale study was initiated in 2007 in a semi-arid environment in eastern Colorado on land with no previous history of biosolid application. Typical agronomic practices were employed in the study. The biosolids, soil, and crop were monitored for a year and a half, which enabled the evaluation of the persistence and movement of contaminants from biosolids into the soil column after biosolid application.

Measurements indicate that nonylphenols (commonly used in detergents and other manufacturing), benzo[a]pyrene (a polycyclic aromatic hydrocarbon and byproduct of incomplete combustion of organic matter), diethyl phthalate (commonly used in plastics), d-limonene (a solvent obtained from citrus fruits), HHCB (galaxolide, a polycyclic organic musk used in fragrances), and triclosan (an antimicrobial) had migrated downward through the soil by 468 days after application. The study also showed indications that uptake by mature wheat plants was minimal. Soil and biosolid samples that were collected before and after biosolids application and incorporation in the soil were analyzed for 57 chemicals of potential environmental concern. During harvest, wheat samples were collected from control fields and from fields on which biosolids had been applied.

This study was supported by the USGS Toxic Substances Hydrology Program.


Yager, T.J.B., Furlong, E.T., Kolpin, D.W., Kinney, C.A., Zaugg, S.D., and Burkhardt, M.R., 2014, Dissipation of contaminants of emerging concern in biosolids applied to nonirrigated farmland in eastern Colorado: JAWRA Journal of the American Water Resources Association, v. 50, no. 2, p. 343-357, doi:10.1111/jawr.12163.

More Information

This article was featured as an article in the USGS GeoHealth Newsletter, Vol. 11, No. 1, 2014

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