Forms Of Reduced Inorganic Sulfur (RIS) And Heavy Mentals In Sediments Of Jiangsu Coastal Area

With the rapid development of urban economy, a large number of heavy metal pollutants enter waters through surface runoff, and a large number of pollutants containing sulfur enter waters through acid rain, which aggravates the urban estuary and river pollution. As the origin and sink of inorganic sulfur、organic sulfur and heavy metals, the sediments of estuary area not only is the important accumulation base and pollution source, but also is the important reaction place of aquatic heavy metals. The pollutants transportation in the Jiangsu coastal area makes great contribution to the sea, and the aquatic environment of this area have great significance to the development of the surrounding cities.The study shows the research of reduced inorganic sulfur species and heavy metals in the Jiangsu coastal area. The aim is to know the contents of inorganic sulfur species, and further find out the biology toxicity of heavy metals and pollution status to provide theoretical basis for the aquatic treatment of the Jiangsu coastal area.The result shows that, contents of acid-volatile sulfide(AVS) in surface sediments of Jiangsu coastal area range from0.13to3.32μmol/g, chromium(Ⅱ)-reducible sulfide(CRS) from0.89to11.96μmol/g, elemental sulfur(ES) from0.38to0.83μmol/g. CRS (FeS2-S) is the main reduced inorganic sulfur species in surface sediments, which occupies80%. The content sequence of reduced inorganic sulfur (RIS) in most sample points is CRS>AVS>ES. The content sequence of active iron in surface sediments of Jiangsu coastal area range from13.00to81.37umol/g.The contect of Cu、Cr、Pb、Zn、Cd、Ni range in19.56～42.79mg/kg,37.06～84.30mg/kg,41.37～144.78mg/kg,12.01～36.82mg/kg,<0.02～0.22mg/kg,16.62～44.62mg/kg individually. The order of average content is Zn>Cr>Ni>Pb>Cu>Cd. Compared with other typical coastal areas in the world, the content of Cu、Cr、Pb、Zn、Cd、Ni is relatively low. The distribution of six heavy metals is complicated and has many peak areas. It is influenced by many environmental factors, especially human activities. Every two elements of Cu、Cr、Pb、 Ni、Be、As and Sb in sediments are close related to each other, which proved that these elements have similar pollution sources and environmental geochemistry features.The results of BCR sequential extraction for heavy metals show that Cu, Cr, Pb, Zn and Ni are mainly associated with residue fraction, Cr, Zn and Ni are mainly associated with exchangeable and carbonate fraction; Except for residue fraction, Cu and Pb are mainly associated with Fe/Mn oxide fractions. The order of non-residue fraction percent is Pb>Ni>Cu>Zn>Cr, which is also the potential bioavailability order.The results of pollution assessment by Index of Geoaccumulation and the Potential Ecological Risk Index were similar. The order of polluting degree is Cd>Pb>Zn>Ni>Cu>Cr. For most of the sampling areas, the pollution of Cd, Pb and Zn is at middle level, Ni and Cu is at low level, Cr is at clean level. The assessment result of ecological risk revealed this area belongs to low potential ecological risk. However, the ecological risk of Cd is relatively high and belongs to the middle or higher potential ecological risk degree. The order of ecological risk is as follow: Cd>Pb>Ni>Cu>Cr>Zn.The contents of SEM in the surface sediments on different sampling points of Jiangsu coastal area don’t vary too much. The SEM/AVS of most sample points are all over1expect Guanhe, Sheyang and Dafeng, which shows the middle heavy metals toxicity to biology in the surface sediments of Jiangsu coastal area.