Pollution assessment and source apportionment of metals in paddy field of Salem, South India

Heavy metal accumulation in agricultural soils has been increased greatly by modern agronomical practices. The objectives of the present study are to assess the spatial distribution, source apportionment and pollution assessment of heavy metals in the paddy fields located at Salem, southern India. The mean values of studied heavy metal concentration (28.69, 8.45, 2.79, 1.28, 1.99, 1.59, and 0.12 mg kg⁻¹ for Fe, Mn, Cu, Ni, Pb, Zn, and Cd) in the paddy soils at all the sampling locations were below the Indian and European Union soil quality standards. The magnitude of metal enrichments/contamination was computed by contamination factor (CF), enrichment factor (EF), and geo-accumulation index (I_geo). Based on CF and I_geo values, medium contamination and very high to severe pollution was exhibited in Cd (1.15) and Mn (3.41), and Fe (5.77), respectively. Besides, exceptionally higher enrichment of soil metals (EF > 50) was shown in Cu (155.26), Ni (92.24), Pb (148.81), and Cd (1641.52). Multivariate statistical analysis also proved the Cu, Pb, Zn and Cd accumulation in the paddy soils through intensive agricultural practices including fertilizers, pesticides, and fungicides applications and transportation. Further, Ni and Fe contents in these soils are mainly due to parent materials. Although the Cd content in paddy soils was below the standards, the exceptionally higher EF values (1641.52) of Cd indicated more attention to minimize the existing modern agricultural practices in paddy fields to increase the productivity in a sustainable manner.