Heavy metals and polychlorinated biphenyls (PCBs) sedimentation in the Lianhua Mountain Reservoir, Pearl River Delta, China.

The Pearl River Delta is one of the biggest electronics manufacturing regions in the world. Due to the presence of abandoned industrial sites and the proliferation of large-scale electronics companies in the past four decades, it is therefore imperative to investigate the extent of heavy metals and polychlorinated biphenyls (PCBs) contamination in the region. Spatial and temporal distribution of heavy metals (Cr, Cu, Ni, Pb, and Zn) and PCBs (PCB28, PCB52, PCB101, PCB118, PCB138, PCB153, and PCB180) in the Lianhua Mountain reservoir in the Pearl River Delta, Dongguan City, China were examined based on a sedimentary profile analysis. Higher concentrations of the heavy metals detected were recorded in bottom sediments whereas 70% of the detected PCBs recorded maximum concentrations in top sediments. The geo-accumulation indices (Igeo) indicate that the study area is uncontaminated to moderately contaminated. Also, the integrated pollution indices (IPI) were above 1, except Pb, which shows that the study area is contaminated with heavy metals from anthropogenic sources. The concentrations of individual heavy metals and PCBs over a period of 60 years were also analyzed in order to establish a historical trend of pollution in the study area. This study provides baseline information on the level and historical trend of heavy metals and PCBs pollution in the study area.