长江三角洲地区土壤地球化学基准值及其应用探讨

通过对基准值、背景值概念的进一步分析,确定了以沉积环境作为土壤地球化学基准值求取的基本单元,以各基本单元的面积加权法求取区域土壤地球化学基准值的方法。利用长江三角洲地区完成的多目标区域地球化学调查数据,求取了该区的土壤地球化学基准值,并对基准值特征进行了分析和应用探讨。结果表明:各沉积环境有其特征的指示元素或组合,F、Cl、Br、I、Ca和Mg元素组合可反映海相沉积物的新老和比例;N、S、OrgC组合,I、Hg组合和Y、Ce、La等稀土和稀有元素组合分别指示湖相、泻湖相和陆相沉积环境。Hg、Cd等为全区富集的污染元素;土壤中亲石元素、稀有和稀土元素稳定;I和CaO易流失。部分元素的土壤清洁级界限值采用X0+2S0能较好地反映土壤污染的分布。研究区土壤中养分Co、Na2O几乎全部为适宜区,K、N、Fe、B、Cu、Cl、Mg、S含量丰富,Zn、Mn和P、Mo、Si相对缺乏。

Soil Geochemical Baselines of the Yangtze River Delta and Their Significances

Based on the analysis of the concepts of baseline and background value,the depositional environments are determined as the basic units to solve the soil geochemical baseline and the regional soil geochemical baseline are solved by means of area-weighed method.By using the data obtained from the multipurpose regional geochemical survey in the Yangtze River Delta,the regional soil geochemical baselines of the region are gained,and their characteristics and applications are discussed.The conclusions are as follows:Various depositional environment is of its particular indicator element association.F-Cl-Br-I-Ca-Mg association reflects the relative age and proportion of marine sediments,N-S-OrgC,I-Hg and Y-Ce-La association indicates respectively the lake facies,lagoonal facies and terrestrial facies depositional environment.Hg and Cd as the pollution elements enriched in soils of the whole area;lithophile elements,rare elements and REE behaved steady;I and CaO lost easily.X0+2S0 adopted as the boundary values of soil pollution division of a part of elements can reflect the distribution of soil pollution.There were the fitting content nutrient elements Co and Na2O,abundant K,N,Fe,B,Cu,Cl,Mg and S,relatively poor Zn,Mn,P,Mo and Si in soils of the area.