Chelating impact assessment of biological and chemical chelates on metal extraction from contaminated soils

Soil contamination is the result of uncontrolled waste dumping and poor practices by humans. of all the pollutants heavy metals are of particular concern due to their atmospheric deposition,leaching capacity and non-biodegradability. heavy metal containing effluent is discharged into the agricultural fields and water bodies. this results in the accumulation of heavy metals in soil and the crops grown on that soil. studies have revealed detrimental impacts on soil fertility and the poor health of animals and humans. phytoextraction is widely researched for remediation of heavy metal contaminated soil. to enhance the effect of phytoextraction heavy metals have to be available to the plants in soluble form. in this study the potential of different chelating agents was assessed in solubilizing the heavy metals making easy for plants to uptake them. for this purpose efficient chemical and biological chelating agent had to be identified. along with that an optimum dose and application time for chemical chelating agent was determined. ethylenediamine tetraacetic acid (edta),diethylene triamine pentaacetic acid (dtpa),nitriloacetic acid (nta) were applied to the soil,containing pb,cr,cu and cd,at different concentrations and application time. aspergillus niger and aspergillus flavus were incubated in soil for different time periods. in correspondence with findings of the study,pb and cr were best solubilized by 5mm edta. for cd and cu 5mm dtpa carried out efficient chelation. nta showed relatively inadequate solubilisation,although for cr it performed equal to edta. a. niger and a. flavus instead of solubilizing adsorbed the metals in their biomass. adsorption was mainly carried out by a. niger.