Occurrence and risk assessment of polybrominated diphenyl ethers in surficial water and sediment from Buffalo River estuary, South Africa

This study assessed PBDE congeners in surface water and sediment from the Buffalo River estuary, East London, South Africa. Samples were collected across three seasons in 2020 and analyzed using GC–MS and GC-μECD to respectively identify and quantify analytes. The concentration of ∑6PBDEs in the surface water and sediment ranged from n.d. to 0.947 μg/L and from 1.87 to 2554 ng/g (dw), respectively. We found the relative abundance of the congeners in water and sediment to be in this order: BDE-66 (36 %) > BDE-100 (25 %) > BDE-17 (21 %) > BDE-183 (9 %) > BDE-153 (6 %) > BDE-47 (3 %) and BDE-66 (26 %) > BDE-100 (23 %) > BDE-17 (18 %) > BDE-47 (15 %) > BDE-153 (10 %) > BDE-183 (9 %) respectively. The ecological risk assessment reveals that the risk quotient, RQs, of BDE-100 (85.1), BDE-47 (2.1) and BDE-183 (1.1) for surface water and BDE-47 (229606), BDE-153 (1192) and BDE-100 (141) for surface sediment were all significantly higher than one, indicating high ecological hazards for both water and sediment-dwelling organisms. The point sources of PBDE pollution were the First and the Second Creek, which regularly carry residential and industrial effluents into the estuary. Sediment under the Pontoon Bridge is the most polluted due to non-point sources. Regular dredging of the estuary is highly recommended to reduce the levels of PBDEs in the sediment. [Display omitted] •The surface water and surface sediment from BRE are moderately polluted.•BDE-66 is the dominant congener in both water and sediment.•Both pelagic and benthic organisms are at high ecological risk levels of BDE-47 and BDE100.•The First and Second Creeks as well as the overhead Pontoon bridge are the primary sources of PBDEs pollution.