Distribution of Polybrominated Diphenyl Ethers in Sediments of the Pearl River Delta and Adjacent South China Sea

TLDR

PBDEs in the Pearl River Delta likely originate from waste discharges in Guangzhou, Dongguan, and Shenzhen, the region's fastest‑growing cities. The study mapped spatial and temporal PBDE distributions in Pearl River Delta and adjacent South China Sea sediments. Sixty‑six surface sediment samples were collected and analyzed for ten PBDE congeners. BDE‑209 dominated the PBDE mix (73–100 %) with concentrations up to 7340 ng g⁻¹, while total PBDEs were generally <50 ng g⁻¹; spatial patterns mirrored those of nearby rivers, and core analyses revealed a sharp rise in BDE‑209 near the surface linked to expanding electronics manufacturing.

Abstract

Spatial and temporal distributions of polybrominated diphenyl ethers (PBDEs) in sediments of the Pearl River Delta (PRD) and adjacent South China Sea (SCS) of southern China were examined. A total of 66 surface sediment samples were collected and analyzed to determine the concentrations of 10 PBDE congeners (BDE-28, -47, -66, -100, -99, -154, -153, -138, -183, and -209). The concentrations of BDE-209 and ∑PBDEs (defined as the sum of all targeted PBDE congeners except for BDE-209) ranged from 0.4 to 7340 and from 0.04 to 94.7 ng/g, respectively. The ∑PBDEs concentrations were mostly <50 ng/g, within the range for riverine and coastal sediments around the world, whereas the BDE-209 concentrations at the most contaminated sites were at the high end of the worldwide figures. Congener compositions were dominated by BDE-209 (72.6−99.7%), with minor contributions from penta- and octa-BDEs. Slightly different PBDE compositions were observed among samples collected from different locations, attributable to possible decomposition of highly brominated congeners and/or redistribution between particles of various sizes during atmospheric or fluvial transportation. The PBDE patterns in the SCS and Pearl River Estuary sediments were similar to those in sediments of the Zhujiang and Dongjiang Rivers, reflecting the widespread influence from local inputs. Analyses of two short sediment cores collected from the Pearl River Estuary showed that concentrations of BDE-209 rapidly increased in the upper layers of both cores, coincident with the growth of the electronics manufacturing capacities in the PRD region. The major sources of PBDEs were probably waste discharges from the cities of Guangzhou, Dongguan, and Shenzhen, the three fastest growing urban centers in the PRD.