北京东郊土壤中某些重金属的含量、形态、相互关系及其在环境质量评价中的意义

本文讨论了土壤中某些重金属的含量、形态、它们之间的关系以及它们在环境质量评价中的意义.在野外情况下.残留态是镉的主要形态.用NH_4OAC提取的六种重金属百分率的序列为:Cd(12.97)>Cu(1.32)>Ni(1.06)>Zn(0.51)>Pb(0.24)>Cr(0.09).DTPA提取的序列为:Cd(33.10)>Cu(20.52)>Zn(4.25)>Ni(1.19)>Pb(0.93)>Cr(0.16).土壤中镉的存在形态取决于应用到土壤中的镉化物的种类.北京东郊土壤中相当一部分镉是以较易溶解的镉化物存在的.土壤中重金属的总量之间,NH_4OAC提取的、DTPA提取的量和总量之间都显著相关.用相关方程计算的六种重金属的含量进行了一次土壤质量综台评价.计算的评价值与实际评价值十分一致

CONTENT, STATE AND CORRELATION OF SOME OF THE HEAVY METALS IN SOILS OF EAST SUBURB OF BEIJING AND ITS SIGNIFICANCE IN ENVIRONMENTAL QUALITY ASSESSMENT

An investigation on content, state of some of the heavy metals, its relationship between them in soil, and its significance in environmental quality assessment was conducted.In field conditions, the major residual form is that of cadmium under treatment. The order of percent of six metals extracted with NH₄OAC is Cd(12.97)>Cu(1.32)>Ni(1.06)>Zn(0.61)>Pb(0.24)>Cr(0.09), while that of six metals extracted with DTPA is Cd(33.10)>Cu(20.52)>Zn(4.25) >Ni (1.19)>Pb(0.92)>Cr(0.16).The existing form of cadmium in soil depends on the cadmium compound applied to soil. A considerable amount of cadmium was found in more soluble form in soil in east suburb of Beijing.An important correlation exists among contents of heavy metals, those with NH4OAC and DTPA extracted and total content in soil.A comprehensive assessment on concentration of six heavy metals was made by calculating with the correlation equation. The calculated assessment values agree well with the practical assessment values.