Heavy metal accumulation in agricultural soils around a coal fired thermal power plant (Farakka) in India.

Agricultural soils around the ash dumping sites of one of the largest thermal power plant (TPP) in India located at Farakka, West Bengal were assessed for some heavy metal (Pb, Cd, Cr, As, Cu, Zn, Ni and Fe) distribution in association with other physicochemical components and compared with the control soils collected from far away of TPP. The toxic group metals (Pb, Cd, Cr and As) were well differentiated by their higher values of variability and non-normal distribution from the biologically essential metals (Cu, Zn, Ni and Fe). The statistical analysis of the heavy metals revealed that the two probable sources (Eigen values) in affected soils are responsible for their distribution; the more dominant one contributed the toxic metals and less dominating source contributed the essential heavy metals. While in control soils, no distinct separation of sources of the metals were found out signifying that the natural common sources could play active role in metal distributions. Although EF (Enrichment Factor) values of toxic metals are higher with large fraction of anthropogenic sources, yet (Igeo) (Geo-accumulation Index) values indicate moderate to unpolluted condition of the soils in respect to Pb, Cd and As. The calculated PLI (Pollution Load Index) values (1.88) considering all the metals also support the findings. Since there are no other sources of industrial effluents in the study area except the TPP, it can be said that the enrichment of these metals is solely attributed to their input from the ash contamination. For this, considerable degree of enrichment of toxic group of metals occurred in these soils.