Chapter 2 – Soil Contamination with Metals: Sources, Types and Implications

Growing use of chemicals in agricultural fields and heavy industrialization is responsible for introducing and mobilization of heavy metals into the biosphere. In addition, application of industrial and urban effluents in agricultural fields is responsible for further mobilization of heavy metals into the biosphere and ensuing in a serious threat to the environment and public health. Presence of metal ions such as Zn, Mn, Fe, Cu, Pb, Cd, Ni and Cr in agricultural inputs, especially, sewage sludge, may gradually build up their concentrations in soil. Even the essential nutrients become toxic to plant growth after reaching a certain threshold. Plants may survive under high metal concentrations by sequestering metal ions into their tissues, exposing secondary consumers (human or animals) to the risk of metal toxicity. Heavy metal-polluted soil environments can be reclaimed through the application of chemicals, soil amendments or phytoaccumulators. Out of the three options, phytoremediation is a cost-effective and sustainable method of reclamation of metal-polluted environments.