Linking water–sediment respiration to micropollutant biodegradation across aquatic environments

Abstract

Biodegradation makes major contributions to the removal of micropollutants from contaminated environments, but the factors that influence the removal rate in specific environments remain unclear. This study examined environmental biochemical oxygen demand (BOD) as a potential indicator of site-specific attenuation rate constants for 47 micropollutants. A modified BOD protocol for water-sediment systems was developed and applied in parallel with a modified OECD 309 biodegradation test on samples collected from 10 sites along an urban wastewater-impacted river. The biodegradation test provided attenuation rate constants for 34 compounds that met quality criteria for at least three sites. After normalizing by sediment dry weight, 23 compounds showed a significant positive correlation (p < 0.05) between BOD and attenuation rate constant, with an average linear regression R² of 0.71. Normalization by BOD significantly (p < 0.05) decreased the observed variability in attenuation rates. If biodegradation mainly occurs through co-metabolism, BOD may act as an integrative indicator of microbial metabolic activity relevant to micropollutant transformation. Our results suggest that a water–sediment BOD test may provide a practical indicator of relative biodegradation rate across sites for a subset of compounds.