Heavy Metals Pollution Associated With Magnetic Character Study On Sediments Of Chongming Island

The tidal flat at the Yangtze estuary is a complex ecosystem influenced both by natural factors and strong human activities. Heavy metal pollution in sediment of chongming island where there exit typical tidal flats were studied, Magnetic inspection methods, as a fast and economical measurement technology, have been successfully applied in environmental pollution research. This study aims to discuss of the relationship between the magnetic parameters and the content of heavy metal in the sediments whith different environmental conditions. Eight sample sites, around chongming in shanghai , have been surveyed. The surface sediment sample and the columnar sample were collected. We examined the particle size distribution, heavy metals content such as Cu,Zn,Pb,Cr, Ni, Cd and magnetic parameters such as X, SIRM, X_ARM X_fd% X_ARM/X, X_ARM/ SIRM etc. The main conclusions are as follows:1.The main sediment size of chongming island in shanghai ranges 4 to 63 μ m.. Clay and sand were both fewness. The other particle parameters of sediment along chongming island have few changes.2. contents of Cu , Zn , Pb, Cr, Ni, Cd in sediment varies with changes of place. In BaoZhen the concentration of Pb , Cd in sediment reaches maximum. In YingNan the contration of Cr in sediment is high. In middle reach of tidal flat from ChongMing Wetland the contentration of Zn , Ni in sediment reached maximum, the content of Cu in sediment was high not only in QianNong but also in low tidal flat of ChongMing Wetland.3. According to different method of environmental polluton evaluation, heavy metal contamination ranges from light to midst degree.4. Ferrimagnetic minerals dominated the magnetic characteristics of Chongming island sediment, pseudo-domain grains took superiority.5. The co-variations of heavy metal and magnetic parameters is probably due to the absorption of heavy metals by ferrimagnetic minerals.At the same time, the concentration of particle the radius less than 4um and the concentration of heavy metal co-vary as well. Depending on correlation of heavy metals, magnetic parametersXfd%, X_ARM/SIRM and the concentration of the particle with radius less than 4um, linear regression models were established to semi-quantitatively .6. After calculating the correlation coefficient between the heavy metal contents and magnetic parameters, it is found that the contents of Cu Cd Zn Ni Cr Pb and magnetic parametersX_fd% X_ARM/ SIRM had high correlation. According to the remarkable correlation of the heavy metal contents and magnetic parameters, the diagnostic models were set up: Zn=515.2336X_fd%+1.111842X_ARM/SIRM +31.62434; Cu=474.5772X_fd%+0.176716X_ARM/SIRM 5.314115;Cd=0.424793X_fd%+0.003629X_ARM/SIRM +0.097551; Pb=431.4754X_fd%+0.23225X_ARM/SIRM +2.26899 The study proved that these models had feasibility, while the magnetic parameters to make the model should be variable according to the geological aand hydrological conditions.