Sources Of Heavy Metal Pollution

The word ‘heavy metal’ is often used to cover a wide range of elements, which form an important class of pollutants. Heavy metal(s) are widespread pollutants of great concern as they are not degradable and thus persistent in the environment. These metals are used in various industries from which their residues are consequently released into the environment. The release of these metals in various forms in the environment causes numerous changess to microbial communities and their activities. The common sources of heavy metal pollution include discharge from industries such as electroplating, plastics manufacturing, fertilizer producing plants and wastes left after mining and metallurgical processes (Zouboulis et al., 2004).

Although some heavy

Their fate in soil depends on the chemical state of the element in the contaminating material. The hazards associated with polluted soils, are the contamination of the food chain. Closely related to the bioavailability of toxic elements (i.e. Ability to enter the different compartments of the food chain) and primarily to the phytoavailability (i.e. Availability to plants). Plants are important part of the natural ecosystems and agro ecosystems, and are the first part or level of the terrestrial food chain. When plants are grown on polluted soils they become a potential threat to human and animal health, as they may accumulate high levels of toxic elements (e.g. Metals) in their tissues, for example, the Itai-Itai disease caused by cadmium-contaminated

Some of these activities include mining and smelting of metals, burning of fossil fuels, use of fertilizers and pesticides in agriculture and municipal waste disposal etc., Raskin et al. (1994). A Physiological and biochemical process causes Growth reduction, Oancea et al. (2005). Thus if the decline in plant growth reduction occurs continuously the yield is reduced, which eventually leads to food insecurity. Therefore, the management and control of heavy metal polluted soils cannot be overemphasized. Various methods of managing and controlling, metal polluted soils exist; they range from physical and chemical methods to biological methods. Most physical and chemical methods (such as encapsulation, solidification, stabilization, electron kinetics, vitrification, vapor extraction, and soil washing and flushing) are expensive and do not make the soil suitable for plant growth (Marques et al.,