Role of EDTA in arsenic mobilization and its uptake by maize grown on an As-polluted soil

摘要

EDTA amendments are widely used for micronutrient fertilization in arid soils, besides their effectiveness in the remediation process of heavy metal from contaminated soils. However, the persistence of EDTA in arsenic contaminated soil may have further negative effects on the grown plants. To investigate the influences of EDTA on soil As, a pot experiment was conducted using a sandy clay loam As-polluted soil treated with gradual rates of EDTA (0,1.0, 2.5 and 5 mmol kg~(-1)) and planted with maize for two months. The key findings reveal that EDTA applications increased AB-DTPA extractable and water soluble As significantly. Such increases seemed to be the main reasons behind the increase in As uptake by maize plants as the addition of EDTA at the rates of 1.0, 2.5 and 5.0 mmol kg~(-1) increased significantly As uptake by shoots 1.5, 2.4 and 3.0 folds, respectively compared to the untreated soil. On the other hand, As uptake by roots did not increase significantly except with the highest application rates of 2.5 and 5.0 mmol kg~(-1). The results also show that arsenic translocation factor (TF) values were too low to attain successful phy-toextraction. In conclusion, the bioavailable fraction of As is important to investigate the phytoextraction and phytotoxicity of As.