Influence of organic acids on the mobility of heavy metals in soil amended with some insecticides.

The mobility (Rf value) of some heavy metals, such as: Co, Zn, Ag, Cu, and Pb was measured through soil amended with some insecticides, such as: endosulfan, chlorpyrifos, dimethoate and methyl demeton using distilled water, formic, acetic and oxalic acids as mobile phase. The enhancement in the mobility of metal ions in all the amended soils formic, acetic and oxalic acids as mobile phase. The enhancement in the mobility of metal ions in all the amended soils followed the order: Co > Zn > Ag > Cu > Pb. On the otherhand the mobility followed the order: endosulfan > chlorpyrifos > dimethoate > methyl dementon for the amended insecticides and the order: formic > acetic > oxalic acids for the mobile phase in natural as well as amended soils. Mobility of ions increased upto a concentration of 0.25 mg 100 g-1 of soils thereafter it was decreased in all the systems. The results have been explained on the basis of the nature of heavy metals, insecticides, organic acids and the solubilities of the salts formed in the soil-insecticide-amended systems.