Long-Term Temporal Trends of Polychlorinated Biphenyls and Their Controlling Sources in China

Abstract

Polychlorinated biphenyls (PCBs) are industrial organic contaminants identified as persistent, bioaccumulative, toxic (PBT) and subject to long-range transport (LRT) with global scale significance. This study focuses on a reconstruction and prediction for China of long-term emission trends of intentionally and unintentionally produced (UP) Σ7PCBs (UP-PCBs, from the manufacture of steel, cement and sinter iron) and their re-emissions from secondary sources (e.g., soils and vegetation), using a dynamic fate model (BETR-Global). Contemporary emission estimates combined with predictions from the multimedia fate model suggest that primary sources still dominate, although unintentional sources are predicted to become a main contributor from 2035 for PCB-28. Imported e-waste is predicted to play an increasing role until 2020-2030 on a national scale due to the decline of IP emissions. Hypothetical emission scenarios suggest that China could become a potential source to neighbouring regions with a net output of ~0.4 t year-1 in the case of 7 PCBs around 2050. However, future emission scenarios and hence model results will be dictated by the efficiency of control measures.