W6 PM Environmental Changes in Response to China's Economic Expansion
Wednesday, 16 November 2005: 1:50 PM - 5:30 PM in 324-326

(AAA-1117-867552) Trace metal distribution, chemical partitioning and Pb isotopic compositions in sediments of the Pearl River Estuary, South China.

Ip, Carman¹, Li, Xiangdong¹, Zhang, Gan², Wai, Onyx¹, Li, Yok-sheung¹, ¹ Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, Hong Kong² State Key Laboratory of Organic Geochemistry, Guangzhou Intitute of Geochmistry, CAS, Guangzhou 510640, China, China

ABSTRACT- The rapid economic development in the Pearl River Delta (PRD) region, south China in the last three decades has had significant impacts on the local environment. In the present study, surface sediments and sediment cores were collected in the Pearl River Estuary (PRE) and its surrounding coastal area. The samples were analysed for total metal concentrations, chemical partitioning and Pb isotopic compositions. There has been a significant increase in inputs of Cu, Pb and Zn in the Pearl River Estuary (PRE) since the 1970s. The distribution of Cu, Pb and Zn in sediments demonstrated typical diffusion patterns from the land to sea direction. Two hotspots of trace metal contamination in sediments were located at the mixing zone between freshwater and marine waters of the PRE. The metal enrichment in the sediments could be attributed to the deposition of the dissolved and particulate trace metals in the water column in the estuarine area, mainly derived from industrial operations and urban activities of the PRD region. The similar Pb isotopic signatures of the sediments at the PRE and its surrounding coastal area offered strong evidence that the PRE was a major source of trace metals to the adjacent coastal area. The slightly lower 206Pb/207Pb ratios in the coastal sediments may indicate other inputs of Pb in addition to the PRE sources, including the inputs from Hong Kong and other parts of the region.

Key words: trace metals, sediments, Pb isotopes, Pearl River Estuary China