Phytoremediation for Defending Heavy Metal Stress in Weed Flora

Degradation of natural resources is perhaps one of the gravest lapses mankind has ever made in its journey of progress and development. Land, air and water resources are worst affected due to anthropogenic interventions. Heavy metal contamination is of special concern due to widespread reports emanating both from India and abroad about various diseases and disorders observed both in human and livestock due to metal toxicity. The use of specially selected and engineered metal accumulating plants for environmental clean up is an emerging frontline technology called ‘Phytoremediation’ which describes a system wherein plants alone or in association with soil organisms can remove or transform contaminants into harmless and often valuable forms. Excessive heavy metal accumulation can be toxic to most plants leading to reduction in seed germination, root growth and biomass production; inhibition of chlorophyll biosynthesis as well as disturbance in cellular metabolism and chromosome distortion. For studying the heavy metals load of sewage and sludge and their effect on crop quality in relation to non applied sites, solid sludge and leafy vegetable plants such as Amaranthus spp., Ipomoea spp, Basella spp. (Pui), Spinacia oleracea (Palak), were collected from seven STPs viz. Howrah, Garulia, Bhatpara, Nabadwip, Srirampur, Kona, Chandannager, and from the Periurban areas viz., Nadia/Chakdaha/Ektapur(N/C/E), Nadia/Chakdaha/Pumlia(N/C/P), Nadia/Chakdaha/Sikarpur(N/C/S), Nadia/Chakdaha/Tatla(N/C/T). The results suggest that leafy vegetables like Amaranthus have more scavenging capacity for Cd and Pb, while Spinacia oleracea has more scavenging capacity for Cr. Therefore, if these plants are cultivated in sites abundant with above heavy metals, these would scavenge the heavy metal toxicity from the soil.

Heavy metal contamination is of special concern due to widespread reports emanating both from India and abroad about various diseases and disorders observed both in human and livestock due to metal toxicity.

Amaranthus viridis (red) is the best accumulator of Pb and Cd, but the best Cr accumulator is Spinachea oleracea. Phytoremediation test showed that the amounts of heavy metals decreased in polluted soils under the effect of these weeds plants.

These weeds can be utilized as effective accumulators for phytoremediation of heavy metal-polluted soils based on the total numbers of bands, banding pattern, intensity of bands, specific presence or absence of bands.