Assessing Geoavailability of Zinc, Copper, Nickel, Lead and Cadmium in Polluted Soils Using Short Sequential Extraction Scheme

An attempt has been made to assess the geoavailability of heavy metals in polluted soils using short sequential fractionation schemes. For this purpose, 25 composite soil samples were collected from various locations (across India) of which had a history of receiving sewage sludge, municipal solid waste, polluted river water and industrial effluents. Four composite soil samples were also collected from adjacent fields which had not received contaminated amendments. Zinc (Zn), copper (Cu), nickel (Ni), lead (Pb) and cadmium (Cd) were extracted from the soil solution plus exchangeable, carbonate bound, Fe and Mn oxides bound, and organic matter bound fractions. Copper (53.0%) was largely adsorbed by the organic fractions, while a significant amount of Zn (56.6%), Ni (78.4%), Pb (57.4%), and Cd (59.7%) was extracted from the Fe/Mn oxide bound fraction. Regression analysis revealed that water-soluble plus exchangeable pool of Zn, Cu, Ni, Pb and Cd contributed positively towards the uptake of these elements by spinach and wheat under pot experiment. Behaviour, transport and the ultimate fate of heavy metals in the soil environment depend largely on their association with different geochemical fractions of the soil which is related to the mineralogical origin of the metals.