ABSTRACT
Soil contamination results when hazardous substances are either spilled or buried directly in the soil. Prominent sources contributing to soil contamination are mining, smelting, vehicle emissions, indiscriminate use of agricultural chemicals, and disposal of municipal and industrial sludge. Once pollutants enter into the soil, their concentrations continuously increase and accumulate through food chain. Many agricultural, industrial, and urban wastes are not degraded easily. Major contaminants found in the soil include heavy metals, inorganic ions and salts, and many organic compounds (such as lipids, proteins, DNA, fatty acids, hydrocarbons, PAHs, alcohols, etc.). The effects of pollution on soil are quite alarming, causing huge disturbances in the ecological balance and health of living creatures on earth. Crops and plants grown on polluted soils can accumulate poison to an extent deemed unfit for human consumption. Bioremediation practiced by humankind such as composting, sewage treatment, and fermentation utilize microbial degradation processes. Indigenous and enhanced microorganisms degrade industrial solvents, polychlorinated biphenyls, explosives, and many different agricultural chemicals including pesticides. Biotechnology in bioremediation is to find a plant species and microorganisms resistant or tolerant to a particular contaminant, with a view to maximizing its potential for soil remediation.
