Effect of various organic materials on the mobility of heavy metals in soil

The mobility patterns of four divalent heavy metals—Zn²⁺, Cu²⁺, Pb²⁺ and Cd²⁺—were determined under varying acidities in an artificially contaminated sand and a naturally polluted soil after the addition of various organic materials—farm yard manure (FYM), peat, humic acid (HA) and tetraethylene pentamine (Tetren). Due to dissolution and decomplexation, the mobility of the heavy metals increased considerably upon progressive acidification. Metal pairs ZnCd and CuPb showed almost similar mobility patterns. In the case of artificially contaminated scand, the addition of FYM and peat enhance the mobility of heavy metals at lower pH values and decreased it at higher pHs. Humic acid and Tetren had little effect.