Contamination History and Sources of Heavy Metals in Lacustrine Sediment from Xijiu Lake,Taihu Lake Catchment,East China

摘要

Concentrations of Cd,Cr,Cu,Pb,Zn and Hg were analyzed in sediments of Xijiu Lake,Taihu Lake catchment,China.The state of heavy metal pollution was evaluated based on the geoaccumulation index (Igeo) and enrichment factors (EFs).Al and Ⅴ were selected as the concentration normalizing elements to yield the linear regression model,so that the anthropogenic sources of heavy metals were discerned.The anthropogenic accumulation fluxes of Pb,Zn and Hg in recent 100 years were calculated based on the accurate geochronology.Sediments in Xijiu Lake had been heavily contaminated by Cd; Cu,Pb,Zn and Hg pollution states were in a relative high level,while Cr in a lower level.The increasing concentrations of Cr in the sediment were influenced by both natural and anthropogenic input,while the other metals were mainly derived from the anthropogenic sources.In the past century.,the concentrations of Pb,Zn and Hg increased,and their anthropogenic accumulation fluxes increased by 0.1-47.3 mg.cm-2· a-1,2.4-398.1 mg· cm-2.a-1,3.7-110.3 ng-cm-2.a-1 respectively.Heavy metal pollution was closely related to the way and intensity of human activities in the region.In the early 20th century,the heavy metal accumulation should be mainly attributed to the urban development and fossil fuel consumptions surrounding the Taihu Lake,meanwhile the global atmospheric deposition since the industrial revolution was another important portion for Pb,Zn and Hg.The concentrations and anthropogenic fluxes of heavy metals increased with the industrial development in the catchment,reached their maximum during the middle 1970s and middle 1990s,and decreased since the middle 1990s with constraints on high pollution industries.