Research Of Heavy Metal Pollution In Intertidal Flat Of The Changjiang Estuary And Their Source Identification

Being the transiting zone between the land and ocean sea, estuarine wetland is a valuable system. influenced both by natural factors and strong human activity, and therefore a vulnerable environment. The intertidal flat of Changjiang River Estuary has been strongly influenced by Shanghai city and Jiangsu Provience, the fast economic developing area in China. Heavy metal pollution of various degree has been found on some parts of the intertidal flat ,but information related to the source of metal input is scarce. Therefore a survey of heavy metal levels and their provenance discrimination could contribute to wetland protection and sustainable use. The aim of this thesis is to investigate and value the degree of heavy metal pollution in intertidal flat of Shanghai and three specific purposes are: (l)the spatial status of pollution, (2)the variation of heavy metal pollution with time and, (3)heavy metal source identification using stable carbon isotope and stable lead isotope analysis.The samples in this study cover the following places, the southern bank Changjiang Estuary ,estuarine isolands (Chongming,Changxing,Hengsha and Jiuduansha), and some parts of the coastal area in Jiangsu Province. The mainly sampling period were Oct,2004 and Apr/Aug,2005. The total samples analysed include 59 surface sediments, 2 short core sediments(about 25cm in length) and selected samples from a drill hole. All samples were determined for heavy metals(Fe,Mn,Al,Zn,Cr,V,Cu,Ti,Pb,Cd and Ni), nutrition elements(C,N and P), Stable Carbon Isotope, Stable Lead Isotope, particle size and mineral magnetism.The main conclusions are summarized a following:(l)Compared with background values of soil in China, the concentration of elements including Fe,Mn,Zn,Cr,V,Cu,Ti,Pb,Cd and Ni in intertidal flat sediments of Changjiang Estuary are relatively higher. Significant pollution of Zn,Cr,Cu,Ti,Cd is observed in some part of the coastal area ..(2)Based on calculation of enrichment coefficient, it is found that the states of Fe,V,Ni and Pb are primary of natural origin, Mn and Cr slightly pollution in a few sites, Zn and Zn,Ti and Cu polluted in a number of sites and Cd polluted in almost all the sites.(3) The concentration of TOC and ratio of C/N in surface sediments are close to the values of suspended particles in the Changjiang River, indicating that the organic material in surface sediments are primary derived from the suspended particles of the Changjiang River.