Chelate enhanced phytoremediation of soil containing a mixed contaminant

摘要

Greenhouse tests were conducted to study the effect of chelates on the phytoextraction of cadmium and lead, and the rhizodegradation of used engine oil present as a mixed contaminant in a sandy soil. Indian mustard plants were grown in test pot soil for 30 days and chelates ethy-lenediamine tetraacetic acid (EDTA) and ethylenediami-nedisuccinic acid (EDDS) were individually applied to the test soil. The soil was spiked earlier with 50 mg kg~(-1) of CdCl_2, 500 mg kg~(-1) of PbCl_2 and 500 mg kg~(-1) of used engine oil to form the mixed soil contaminant. At the same concentration of chelates, EDTA was found to be more effective than EDDS in increasing the concentration of metal contaminants Cd and Pb in the plant. Compared to EDDS, EDTA was also more effective in promoting rhizodegradation of the organic contaminant formed by used engine oil. The study demonstrated that the application of chelates to soils containing mixed contaminants such as heavy metals (Cd and Pb) and organics (used engine oil) can simultaneously assist metal accumulation at higher concentrations in the biomass of Indian mustard plant and also reduce the amount of used engine oil in the soil through rhizodegradation.