Spatial Risk Assessment And Integrated Source Apportionment Of Heavy Metals In Sediment From The Dongting Lake Based On GIS And Multivariate Models

The urban rivers accepted large amounts of anthropegenic contamination from the city.Among the various contamination, heavy metals are particular concerd duo to their environmental persistence and cycle and ecological risk. The sediment is not only the exchange of heavy metals, but also a potential source of secondary pollution. To carry out the heavy metals pollution assessment in sediment help to understand the the potential risk of human human and different organisms exposure in the aquatic environment and the environmental quality of the space, the source apportionment an help people fundamentally effective control reduce emissions of pollution sources.In this paper, the sediments in Dongting Lake was selected as research object and10representative sampling point were set.By use Ekman-Birge device for sampling, heavy metal contents in every samples were measured by Inductively coupled plasma mass spectrometry (ICP-AES) and Atomic Fluorescence spectrometry (AFS), derived by analyzing:the average content of seven kinds of heavy metals were higher than sediment background values of Dongting Lake; The average content of seven kinds of heavy metal are in the following order:Zn>Cr>Pb>Cu>As>Cd>Hg.Inverse distance weighted interpolation results show tha:in addition to Hg and Cr, Pb, Cd, As, Zn and Cu have similar spatial distribution, the high values of heavy metals are mainly concentrated in the middle and lower reaches of Dongting Lake.The geo-accumulation index, potential ecological risk index and GIS spatial visualization technology were used to assess the pollution level of heavy metals in sediments of Dongting Lake.The result is that Cd, Hg, Cr and As are serious contamination elements, and the serious contaminated monitoring sections are Dongting Lake exports and its nearby area, river estuary.Taking into account the uncertainty of the model, correlation analysis, principal component analysis(PCA), positive matrix factorization and Fourier spectral analysis were used to apportion sources of heavy metals in sediment of Dongting Lake. Through qualitative analysis by the four methods, the pollution sources are divided into three major types, the first principal components included Pb, Cd, As, Zn and Cu, which were considered to come fron mining and heavy industry.The second principal componet included Hg, which is probably from natural weathering.The thirdly principal componets include Cr, which were probably from agricultural contamination and sewage. In case of insufficient amount of data, the analytical results of principal component analysis(PCA) combined with Fourier spectral analysis will be more accurate and reliable.