Ability Of Several Amendments On Remediation Of Soils Contaminated With Heavy Metals

Heavy metal contaminated of soil is a worldwide problem that affects a large number of sites. The accumulation of heavy metals in soils is an important issue be-cause of hard-degradation, hysteretic and irreversible. The proportional of soil contaminated with heavy metals is close to 20% of the available cultivated area in China. Therefore, it is critical to develop efficient, low cost, and environmentally friendly technologies for the remediation of contaminated soils.In this study, the transformation of Cu, Zn, Ni, Pb, Cd, and Cr in the soil-plant system was investigated, the remediation efficiency of different amendments(zeolite, oyster shells, eggshell, diatomite, and polyacrylamide) and sustainability of remediation efficiency were researched. The changes of pH values, DTPA-extractable heavy metals(Cu, Zn, Pb, Ni and Cd) contents and speciation in soils with the application of amendments was determined. In addition, Plant enzyme activities(SOD, MDA, H2O2, CAT) and metal subcellular partitioning were analyzed to assess the effects of amendments on the remediation of heavy metal contaminated soil. Meanwhile, the in-situ field experiment was used to further evaluate the remediation efficiency of polluted soils with selected amendments. Results are shown as follows:(1)With the addition of amendments, the accumulation of Cu、Zn、Ni and Cd in su zhou qing(Brassica chinensis L.) was greatly decreased, the levels of SOD and MDA in plant leaves were reduced, soil pH values increased significantly, DTPA-extractable metal concentration decreased markedly. A negative correlation was found between soil pH values and the concentrations of DTPA-extractable metal in soils, while a positive correlation was observed between the amount of metals in su zhou qing(Brassica chinensis L.) and the concentrations of DTPA-extractable metal.(2)Experiments for the long-term remediation efficiency indicated that the accumulation of metals in roots, stems and leaves of crown daisy(Chrysanthemum tcoronarium L.) decreased with the addition of amendments, the soil pH values were stillmarkedlyhigherthanthatofcontrol.theexchangeablefractionmetalsweredecreasedbyasequentialextractionprocedure.theactivitiesofsodandmdaincrowndaisyleavesweredecreased,thecontentsofcatwasincreased.resultsofmetalsubcellularpartitioningshowedthattheproportionofbindingtometalbiologicallydetoxifiedmetalfraction(bdm,hsf+mrg)incrowndaisy(chrysanthemumcoronariuml.)leaveswereincreased.(3)theresultofin-situfieldremediationexperimentssuggestedthattheconcentrationsofcuandcrinthesuzhouqing(brassicachinensisl.)wasslightlydecreasedwiththeadditionofamendmentsinsoils.insixplants,theaccumulationofheavymetalsinshanghaiqingwaslowerthanothers,itmightberecommendedasalocalvegetablesplantingcultivar.