南京地区土壤沉积物中重金属形态研究

FRACTIONATION OF HEAVY METALS IN SOILS FROM NANJING

对南京地区４个环境单元———公路干线、金属冶炼厂、大型生活垃圾场和江河滩涂土壤沉积物中重金属元素（Ｃｕ，Ｐｂ，Ｃｏ，Ｆｅ，Ｎｉ，Ｍｎ）化学形态进行了分级提取实验研究．结果表明，有效态中，Ｃｕ以有机态为主，Ｐｂ以交换态为主，Ｃｏ、Ｍｎ以铁锰氧化物态为主，Ｆｅ、Ｎｉ有效态均小于其总量的１０％，并主要集中在铁锰氧化物态中．以大气为传播媒介的重金属人为叠加沉积（公路、工厂）其铁锰氧化物态含量相对较多，以水为传播媒介的重金属人为叠加沉积（垃圾场、江河滩涂）其有机态含量相对较多研究区土壤中重金属对植物的危害在所研究元素中最直接可能的元素是Ｐｂ，其次是Ｃｏ和Ｃｕ，Ｎｉ的直接可能性最小．

Four areas, a metal smelter, a large plot of rubbish from human daily life and a shoal of river in Nanjing, were studied for metal fractionation in soil by sequential extraction of Cu, Pb, Co, Fe, Ni, Mn. The extraction effect were evaluated by the measurement of Ca, Al and Si content from each extraction step as well as the result of X ray analysis. It was demonstrated that the available Cu is mainly bound to organic matter, Pb to exchangeable, Co and Mn to Fe Mn oxides. Available Fe and Ni are less than 10% of their total content and mainly in the Fe Mn oxides. In residue, Mn is 22 8%—33 4% of its total contents and Co is 24 5%—67 1% its total contents,while others are more than 50%. Heavy metals inputed through air (highway, smelter) are mainly bound to Fe Mn oxides and those brought in by water (plot of rubbish, shoal of river) mainly bound to organic matter. For availability to vegetation in Nanjing region, Pb is the most important one, Co and Cu are next, Ni is least