Effect of Dissolved Organic Carbon (DOC) on Heavy Metal Mobility in Soils

Dissolved organic carbon plays an important role in both carbon cycling and chemistry of soils, through its influence on acidity, nutrient availability, metal toxicity and transport. Addition of biological waste materials such as sewage sludge, poultry and animal manures increases the amount of DOC in soils. The effect of DOC on heavy metal mobility was well recognized in this study. In organic matter rich soils, solubilization of organic matter leads to production of more amount of DOC which combines with heavy metals in soils and, thus, causes contamination to groundwater. The organic acids present in the DOC can act as chelating agents and enhance the mobilization of toxic heavy metals. In another way, it is beneficial that the toxic heavy metals are mobilized away from the ischolar_main zone, thus, preventing accumulation of heavy metals in usable parts of the plants.