Ecological Geochemistry Study On Heavy Metal High Background Value Area Soil In Jiangxi Dayu

In this paper,according to the research on heavy metal ecological geochemistry about soil,rice,surface water,shallow groundwater and rock in soil heavy metal high background value areas in Jiangxi Dayu,the supergene geochemical behavior and the ecological geochemistry effects of heavy metals ware revealed.By 1:250000 multi-target regional geochemical survey in Dayu county with 1367.63km2 area,the distribution,abnormal accumulations and assemblage characteristics of heavy metals as As,Cd,Hg,Cu,Pb,Zn,Ni and Cr had been obtained,the ecological geochemical studyabout four abnormal areas had been made.The results show that the heavy metal content of surface soil,surface water and shallow groundwater exceeded in Dayu.Surrounding tungsten polymetallic mine and farmlands along Zhang river,the nearer from the mine or Zhang river,the more heavy metal content had.Along the Zhang river from upstream to downstream,the surface soil pollution ware in gradually reduced gradient zone state.In valley plain,the abnormal distribution of As and Cd of soil had been influenced by the exploitation of mineral Resources and the fluvial transportation.In mountain areas,the abnormal distribution of As and Cd of soil was related to high rock geochemical background.Study on occurrence mode of heavy metals of soil shows that the main occurrence of Cd of surface soil ware in high activity and toxicity ion exchange state.Judged from the vertical section,the mobile contents of As,Cd and other elements of surface soil had a higher proportion,the mobile contents decreased rapidly and the stable state content increased rapidly as the depth increased.The result shows that the heavy metal input to the soil existed in more harmful mobile state.The discussion about the influence law of As,Cd and other heavy metals geochemical behavior of soil caused by pH and organic matter show that in acid to strong acid soil PH had no obvious effect on the As bioavailability and a negative correlation with Cd in ion exchange state.The harmfulecological effects of heavy metal elements focused on the following two points:first,Cd,Hg and As of rice exceed the standard limits greatly in abnormal area.second,environmental geochemical hazard to the vulnerable groups.Rice showed the most strong bioaccumulation on Cd,then Hg,Cu,Zn and other elements.Cd has highetr ability of migration in the soil-rice system which responses to the change of the Cd element in regional soil actively is the highest risk element to the ecological geochemical environment in Dayu region.