Potential Cr oxidation and metal interaction in bush bean plants grown on tannery sludge amended soil

摘要

A study was conducted to predict the potential Cr~(3+)oxidation, heavy metal availability and accumulation in bush bean plants grown on a culture soil amended with tannery sludge. Tannery sludge amendments (0,0.77, 1.54, 3.08 and 6.16 g tannery sludge/kg soil) were characterized and the main heavy metals identified (Cr, Mn, Fe, K, and Zn) later on singly extracted with EDTA for availability assessment. Total oxidable Cr~(3+) determination showed high tendency of Cr to be oxidized but it was prevented by neutral alkaline soil pH, despite the reactive Mn presence. Different patterns of metal availability were observed and available Cr increased with tannery sludge amendments, suggesting organic complexation as the main mobility mechanism for Cr uptake by plants. In bush bean plants metals were mainly accumulated in the roots, diminishing in the upper part with minimal translocation to pods and seeds. Important correlations were observed between metals and soil physico-chemical properties and also noticeable synergistic and antagonistic metal interactions in vegetable tissues were recorded.