Study Of Heavy Metal Speciation In Soil By Microwave Sequential Extraction And The Relationship Between The Speciation And Heavy Metal In Plant

The microwave energy was applied to sequential extraction of speciation of heavy metals in soil on the basis of Tessier sequential extraction . Through the optimization of microwave extraction time and power , not only the analysis time was reduced from 17.5h to 14 min, but the extraction efficiency was improved as well. The efficiencies of the six elements were about 110% ~ 1110%.A realistic method ,which was simple, highly effective and not expensive for routing monitoring of speciation of heavy metals in soil was studied.The four-season orange in flowerpots had been cultivated for 2 years and the different doses of heavy metals were added to the soil in flowerpot.The experiment indicated that the contents of heavy metals in pulp and peel of the four-season orange correspondingly were enhanced when the contents of heavy metals in soil were increased . The heavy metal contents of four-season orange were not same in different organs or tissue , the normal tendency was that the content in orange peel was higher than that in pulp. However , the same organ or tissue of the four-season orange had the different abilities to absorb and concentrate heavy metals in soil.After the solution of heavy metals of Cu, Fe, Mn, Ni, Pb and Zn were added into the soil,the variation regularity for the distribution of heavy metal speciation with"ageing"time of 12 months was studied. From the experimental results, we could know that the soil pH value played an important role in the transformation of metal speciation.The soils were gradually acidified along with the increasing"ageing"time. The combination of heavy metals with the mineral or the organic matter in soil might be limited under the acidic condition. And this obviously resulted in increasing the contents of apparent exchangeable fraction of the heavy metals in the soil and also strengthening the harms to plant.