Effect of Pb2+, Cd2+, Cu2+ and dissolved organic carbon (DOC) on the distribution and partition of decabromodiphenyl ether (BDE-209) in a water–sediment system

Abstract

The combined pollution of polybrominated diphenyl ethers (PBDEs) and heavy metals in electronic waste dismantling areas has received increasing concern in recent years. The distribution and partition of decabromodiphenyl ether (BDE209, a major constituent in the PBDE family) in a water–sediment system in the presence of Pb²⁺, Cd²⁺ and Cu²⁺ at different concentrations were systematically investigated in this study, with the goal of revealing the adsorption behavior of BDE209 co-existent with heavy metals in sediment. The experimental results revealed that all the metals increased the sorption capacity of BDE209 of the sediment (p < 0.05) in the order of Pb²⁺ > Cd²⁺ > Cu²⁺, and the concentration effects of Pb²⁺ and Cd²⁺ were obvious compared with Cu²⁺. A linear equation fitted well with the adsorption process, and the partition coefficient K_d increased with increasing concentrations of the heavy metals in the range of 0–10 mg L⁻¹. Dissolved organic carbon (DOC) played a vital role in BDE209 sorption. When co-existent with heavy metals, DOC, particularly larger-sized DOC molecules in liquid phase decreased significantly and tended to migrate to the sediment. This modification led to a significant increase in the capacity of BDE209 sorption by the sediment. In addition, heavy metals decreased the stability of the water–sediment system, and the stability of the system decreased gradually with the increase of heavy metal concentration, as a result of combination with DOC. These combined to increase the BDE209 sorption by the sediment.