Spatial-temporal accumulation, microbial response, and integrated risk assessment of organochlorine pesticides in urban bioretention facilities.

OCP accumulation in bioretention facilities is highest in the uppermost layer after the rainy season, with longer operation and higher runoff increasing risks.

• Why it matters: Understanding how persistent organochlorine pesticides accumulate and impact microbial communities in urban stormwater systems is crucial for managing long-term environmental and health risks.
• What they did: The study examined eight field-scale bioretention facilities with different ages and runoff ratios, analyzing spatial distribution, microbial shifts, and risk levels related to OCPs.
• The result: Findings indicate that prolonged operation and intensive runoff loading enhance OCP buildup and ecological risks, suggesting that periodic maintenance of the top 5-10 cm media layer can mitigate contaminant accumulation.