Assessment of single extraction methods for the prediction of bioavailability of metals to Brassica juncea L. Czern. (var. Vaibhav) grown on tannery waste contaminated soil

Various single extractant (DTPA, EDTA, NH4NO3, CaCl2, and NaNO3 was used to evaluate the bioavailability of heavy metals from tannery wastewater contaminated soil and translocation of metals to the plant of Brassica juncea L. Czern. (var. Vaibhav). The extraction capacity of the metals was found in the order: EDTA > DTPA > NH4NO3 > CaCl2 > NaNO3 - Cluster analysis between different extractants showed close relationship between DTPA, CaCl2, NH4NO3 except EDTA and NaN03, which showed dispersed relationship. Principal components analysis (PCA) applied to metals extracted with EDTA showed different grouping of metals (i) Na, Co, Pb, Ni and (ii) K, Mn, Zn, Cr, in the loading plot which showed similar availability from contaminated soil. PCA applied on metals accumulation data in the plants also exhibited different grouping of variables (i) Cu, Co, Ni, Cd and (ii) Mn, Zn, Ph, Fe showed almost similar accumulation pattern in the plants. The data displayed positive loading for Mn and negative loading for Cr with PC2. Cd and Zn have shown high loadings in PC1 and PC2, respectively. The translocation of most of the tested metals (Pb, Mn, Cd, Ni, Fe) in the shoot of the plant was found better except Cr, Cu, Co and K The correlation analysis between different extractable metals and metal accumulation in the shoot of the plant showed significant positive correlation with Ph and Cr. Overall, extraction capacity and cluster analysis augmented that EDTA was found suitable extractant for tannery wastewater contaminated soil to B. juncea. (C) 2007 Elsevier B.V. All rights reserved.