Polybrominated diphenyl ethers: Residence time in soils receiving biosolids application.

Area of Science:

• Environmental Chemistry
• Soil Science
• Ecotoxicology

Background:

• Polybrominated diphenyl ethers (PBDEs) can accumulate in biosolids, posing environmental risks upon application to agricultural lands.
• Limited data exists on PBDE dissipation in agricultural soils following biosolids application.

Purpose of the Study:

• To investigate the fate and dissipation of PBDEs in agricultural soils after biosolids application.
• To determine dissipation half-lives and residence times for specific PBDE congeners (BDE-47+BDE-99 and BDE-209).

Main Methods:

• A 3-year field study on a small-scale continuously cropped plot with a single biosolids application.
• A large-scale survey of 26 pasture fields across 10 farms with detailed biosolids application history.
• Analysis of PBDE concentrations (BDE-47+BDE-99, BDE-209) in soil samples over time.

Main Results:

• Maximum PBDE concentrations were observed one year post-application in the small-scale study.
• After 3 years, BDE-47+BDE-99 levels returned to pre-application levels, while BDE-209 remained elevated.
• Estimated residence times varied, with longer estimates from the large-scale study (704 days for BDE-47+BDE-99, 1440 days for BDE-209).

Conclusions:

• PBDE dissipation in agricultural soils primarily occurs within the first two years after biosolids application.
• Residues remaining after two years are less available for degradation, suggesting long-term soil contamination.
• The study provides crucial data for assessing the environmental persistence of PBDEs from biosolids application.