Heavy Metal Contamination Research Paper

Industrial revolution during last few decades is the main factor for enhancement of toxic metal contamination in the biosphere1. Heavy metal contamination is a serious environmental hazard for the agricultural soil, human, plants and animals. The most toxic heavy metals are Pb, Hg, As, Cd, Sn, Cr, Zn and Cu 2. These heavy metals are a group of 65 metallic elements with density greater than 5 gm/cm3. Among all heavy metals cadmium is one such heavy metal that is most hazardous 3 and has deleterious effects on agricultural ecosystem, environment and human health. There are many sources are reported for cadmium contamination including, use of Cd-containing sewage sludge, industrial emission, application of phosphate fertilizers and municipal

But most of hyperaccumulaors plants are slow growing and usually produce limited amounts of biomass. Selection of plants either accumulators or hyper-accumulators is the very important in the phytoremediation45. Those plants that accumulate metal at high concentration are termed as ‘Hyperaccumulators'46. If shoots of plant contain > 100 mg Cd kg−1, > 1000 mg Ni, Pb and Cu kg−1 or > 10000 mg Zn and Mn kg−1 (dry weight), then they are known as “Hyperaccumulators”47. Hyperaccumulation generally exhibited on a dry weight basis, from about 2000 ppm (0.2%) for more toxic elements (Cd, Pb, As, Hg, Cr) to above 2% for the less toxic ones (Zn, Ni, Cu)S. There is approximately 45 hyperaccumulator’s plant families are reported. Some important families are Brassicaceae, Euphorbiaceae, Asteraceae, Fabaceae, Lamiaceae and Scrophulariaceae 48 and approximately 500 plant species have been reported as hyperaccumulator49. Brassicaceae family has various types of hyperaccumlators50. Indian mustard is used as one of the most applicable species for phytoremediation with lower metal accumulating potential with higher growth