Analysis Of Form Transformation Of Copper And Lead Added To The Four Soil Of China

Copper, Lead (solution of Cu(NO3)2, Cu(OAC)2, Pb(NO3)2,Pb(OAC)2 ) were added into four typical soil (black soil, alluvial soil, yellow-cinnamon soil, Latosol) of china. Contaminant soils were reached the different exogenous Cu, Pb concentration: 0 (original soil), 200, 500, 1000 mg/kg. And then these contaminated soil were artificial cultivated for 5, 10, 20, 40, 60, 90, 180 days without change of environment condition in laboratory. The transformation of exogenous lead and copper in different soil were studied after the means of sequential extraction procedure. The main results as followed.(1) The content of Fe-Mn oxide-bound Cu was the predominant fraction in the four natural soil, with the other four forms of Cu followed by the organic, the residual, carbonate-bound, exchangeable. After 180 days of cultivating, there were great changes in the proportions of various forms in the four kinds soil between the natural and cultivated soils, in which the added heavy metals mostly transformed into the residual, the other forms followed by the carbonate-bound, Fe-Mn oxide-bound, organic bound, exchangeable fraction. In the original soils the organic bound Pb was the predominant fraction, followed by Fe-Mn oxide-bound, carbonate-bound, exchangeable, the residual fraction. After 180 days of cultivating, the ratios of the five forms were obviously different from those in the natural soil too. The added Pb were mostly transformed into residual fraction, followed by the carbonate-bound, Fe-Mn oxide-bound, organic bound, exchangeable fraction.(2) After adding dissolvable Cu salt, the speciation transformation of lead in various soil were greatly affected significantly with the comparing of single pb adding into soil. Especially in the latosol soil, the content of exchangeable form in the Cu-Pb combined pollution increased by 11 times than those in the single Pb pollution, while the carbonate decreased 4 times. It is indicated that there was a competitive adsorption between Cu and Pb after adding copper, the content of availability of lead was increased obviously. On the other hand, compared with a single -contaminated of copper, the speciation distribution of Cu were little effected by Pb in the Cu-Pb combined pollution. It may that copper was absorbed to soil tighter than lead done. (3) With the increase of the contents of Cu Pb added to experimental soils adsorption of copper of Cu,Pb in experimental soils increased obviously. Soil adsorption of copper, lead with the number of exogenous input of copper, lead concentration was increased. The percentage of the other three heavy mental forms (except exchangeable state and organic bound fraction) increase with its extent of concentration from external source.(4) Accompanying anions (OAC-, NO3-) had influence on the chemical speciation and transformation process of heavy metals complicatly as the time went on. The statistic results showed that there was no significantly difference (p> 0.05) between the extractable Cu content under the accompanying anions OAC- and NO3- in black soil, however the carbonate-bound copper had a significantly influence. And more,the statistic results showed that the content of extractable Cu and extractable Pb were different between in black soil and the Latosol (p<0.05). It was found that different accompanying anions has some influence on chemical speciation and of heavy metals during the transformation process in the soil, but the degree of influence also depends on the type of soil and species of cation coexisted in soil.