Distribution of Polybrominated Diphenyl Ethers in Benthic Organisms from West Lake, Hanoi: Levels, Congener Profiles, and Seasonal Trends

Abstract

This study determined the concentrations of seven polybrominated diphenyl ether (PBDE) congeners — BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, and BDE-209 — in snail samples as representative benthic organisms from West Lake (Ho Tay), Hanoi, Vietnam. Samples were collected across four biannual monitoring campaigns in May 2022, November 2022, May 2023, and November 2023. Total PBDE concentrations (ΣPBDE) ranged from 2.50 to 3.27 µg/kg wet weight, with a cumulative increasing trend of 13.7% over 18 months of monitoring. BDE-209 was the dominant congener (~57% of ΣPBDE), followed by BDE-99 and BDE-47 (~11% each), reflecting inputs from commercial deca-BDE mixtures. Dry-season (November) PBDE concentrations were consistently 3–5% higher than wet-season (May) values, attributed to reduced dilution effects and extended sediment contact time during the dry period. Compared to regional studies, contamination levels at West Lake were relatively low; however, the persistent increasing trend warrants long-term monitoring. These findings provide the first time-series baseline dataset on PBDEs in benthic organisms from West Lake, supporting ecological risk assessment and environmental quality management of urban lakes..