Atmospheric deposition of heavy metals in the Pearl River Delta, China

Rapid urban and industrial development in China in the last few decades has provoked some serious environmental concerns. As one of the regions with the fastest economic development in China, the Pearl River Delta (PRD) is particularly susceptible to environmental degradation. Atmospheric emissions represent a major pathway of anthropogenic inputs of heavy metals into the surface environment. Samples of atmospheric deposits were collected at urban, suburban and rural locations in the PRD (including Hong Kong) using bulk deposition samplers in the summer and winter seasons of 2001-2002. The samples were analyzed for heavy metal concentrations and Pb isotopic compositions. According to the analytical results, atmospheric deposition of Cr, Cu, Pb and Zn in the PRD (6.43±3.19, 18.6±7.88, 12.7±6.72 and 104±36.4mg/m2/yr, respectively) was significantly elevated compared with other regions, e.g. the Great Lakes region in North America and the North Sea in Europe. It was also found that atmospheric deposition of Cu, Cr and Zn was generally higher in the summer than that in the winter, which could be caused by the washout effect of the rainy season in the subtropical region. The Pb isotopic composition of the air deposits (206Pb/207Pb 1.161-1.177) indicated that atmospheric inputs of Pb derived mainly from anthropogenic sources, e.g. vehicular exhaust and Pb ore in the PRD. However, the distribution of206Pb/207Pb and208Pb/207Pb ratios of some atmospheric deposits in the summer season suggested that atmospheric Pb at some locations of the PRD could be attributed to other anthropogenic source(s).