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Title: Persistence of polybrominated diphenyl ethers in agicultural soils after biosolids applications

Author
item ANDRADE, NATASHA - University Of Maryland
item McConnell, Laura
item TORRENTS, ALBA - University Of Maryland
item RAMIREZ, MARK - District Of Columbia Water & Sewer Authority (DCWASA)

Submitted to: Journal of Agriculture and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2010
Publication Date: 2/12/2010
Citation: Andrade, N.A., Mcconnell, L.L., Torrents, A., Ramirez, M. 2009. Persistence of polybrominated diphenyl ethers in agicultural soils after biosolids applications. Journal of Agriculture and Food Chemistry. 58:3077-3084.

Interpretive Summary: Many consumer products are required to meet flame resistant requirements, for example, mattresses, furniture and fabrics. Chemicals known as flame retardants are added to the materials in these products to decrease their flammability. Residues of the flame retardant chemicals are released over time to the environment and into wastewater streams. Low concentrations of these flame retardant chemicals have been detected in solids produced from the wastewater treatment process. These organic carbon- and nutrient-rich solids, called biosolids, are often recycled as soil conditioners in agricultural and remediation settings. Concerns over the environmental fate of flame retardant chemicals present in these solids prompted a survey of soils from farms that received zero, one or multiple biosolids applications to examine the concentration and persistence of these residues. These polybrominated diphenyl ethers or PBDEs were detected in some fields that had received zero applications, but levels were higher in single and still higher in fields receiving multiple applications. Results showed that biosolids applications do increase the concentration of PBDEs in soil, the persistence of PBDEs in soil is enhanced under high organic carbon soil conditions, and soil concentrations of PBDEs can be predicted using a fairly simple modeling approach.

Technical Abstract: Polybrominated diphenyl ethers (PBDEs) are used as additives in consumer products for their fire-retardant properties. While scientists observe PBDEs in various environmental media, little is known of their fate in soils. This study examines the potential fate of PBDEs in agricultural soils treated with biosolids. Surface soil samples were collected from farms in the Mid-Atlantic region of the U.S. Biosolids samples from the source wastewater treatment plant were collected to evaluate PBDE levels and trends. The mean concentration of PBDEs (sum of BDE-47, BDE-99, and BDE-209) in biosolids from this plant was 1250 +/- 134 ug/kg d.w. with no statistically significant change in concentration over 32 months. PBDE congener patterns in biosolids were mirrored in soils receiving biosolids applications. Mean concentration in soil from fields that received no biosolids was 5.01 ug/kg d.w.; fields that received a single application within 3.5 years averaged 15.2 ug/kg d.w.; and fields that received multiple applications over 5 to 10 years averaged 53.0 ug/kg d.w. The cumulative application rate and soil organic carbon content appear to influence the persistence of PBDEs in soil, especially BDE-209. A simple prediction model assuming a soil half-life of 10 years achieved results within a factor of two as compared with observed values.