Distribution And Speciation Of Heavy Metals And Environmental Pollution Assessment In Sediments Of Typical Areas, Xinjiang

This study selected the Ulunger lake and the Manas lake in Xinjiang as the sampling sites, samplingpoints mainly had been set in sewage drains, river entrance and the near densely populated areas, farmlands.It investigated the heavy metal contents, chemical fraction of heavy metal, the physicochemical property insediments of the Ulunger lake and the Manas lake; The total contents of Cu, Pb, Ni, Cr, Zn and Cd weredetermined by Atomic Absorption Spectrometry in sediments, chemical fraction of heavy metals werestudied by BCR three-step sequential extraction method; By multivariate statistical calculation, to analyzethe source of heavy metal and the relationship between the chemical fraction and the physicochemicalproperty; To evaluate heavy metal pollution in sediment by the Nemerow comprehensive pollution indexmethod and the ratio of secondary phase to primary phase. The main research conclusions were as follows:(1) Cu, Pb, Ni, Cr, Zn and Cd of heavy metals were detected in sediments of the Manas lake. Thecontent of Cd has obvious enrichment phenomenon, and the distribution was uneven, the levels of otherheavy metals were lower than the background values. In addition to Cd, the other elements mainly inresidual fraction, the acid extractable is low, while Cd was mainly in the acid extractable, the reducible andthe oxidizable.(2) Cu, Pb, Ni, Cr, Zn and Cd in sediments of the Ulunger lake were detected, the average levels ofCd was0.32μg/g, more than1.5times of background levels; Ni and Cd had the larger coefficients ofvariation, indicating the extent of influence by human activities; Cu, Pb, Zn mainly in the form of residualand reducible, and the distribution of Cd was: acid extractable> reducible state> oxidizable> residual.(3) The principal component analysis showed that heavy metals were divided into three main points,Ni, Cr and Pb were the first composition, these elements were mainly nature sources; Cu and Zn as thesecond principal components, and they were influenced by human activity. Cd was the third main point,mainly from farmland irrigation and the use of chemical fertilizers.(4) The pollution assessments of two lakes were compared by Nemerow comprehensive pollutionindex method and the ratio of secondary phase to primary phase. Manas lake was not polluted, and Ulungerlake was slightly contaminated. Cd was the main pollution elements in the two lakes, and Cd had strongpotential hazards.(5) Using the correlation analysis to explain the relationship among chemical fraction of heavy metals,pH, granularity and organic matter, the results showed that: acid extractable significantly was correlatedwith the pH; the residual as well as pH, granularity, organic matter; Oxidizable and organic matter had themost significant correlation; residual had no significant correlation with pH, granularity and organic matter.