Geochemistry of sediment archives of agricultural lands with reference to past mining in Goa, west-coast of India

Abstract

The impact of iron ore mining on agricultural lands through quantitative determination of major elements ( Fe, Mn and Al) and minor elements(Cu, Zn, Pb, Ni and Cr) was assessed. A total of 54 soil core samples were collected from 3 mine affected areas viz., Mayem agriculture field (MF), Pernem agriculture field (PF) and Sanvordem agricultural field (SF) in Goa. Different pollution indices were used to assess the pollution status of the samples. Major elements and trace metal concentrations were assessed through enrichment factor (EF), Contamination factor (CF), Pollution load index (PLI) and geo-accumulation index (Igeo). Enrichment factors showed significant moderate enrichment for Fe, Pb and Cr in MF and SF cores can be attributed to anthropogenic factors. Contamination factors for Mn and Pb were high in MF core. While, SF core showed considerable contamination for Pb. Pollution load index indicated that MF and SF cores are polluted (PLI greater than 1) and PF core is unpolluted (less than 1). Igeo values in MF core showed moderately to strongly polluted with Fe and Cr, Whereas SF core was moderately polluted with Pb. While higher values of metals in MF and SF can be attributed to the steep slopes of dumps and unconsolidated nature which gets washed down in the agricultural lands enhancing the metal concentrations.