Impact of past iron ore mining on the sediment cores of rivers of Goa, west-coast of India

Abstract

In order to assess the long-term contamination history of pollutants due to intense mining activities in the adjoining areas of rivers of northern Goa, sediment core samples collected from three rivers viz, the Bicholim (BR), the Mandovi (MR) and the Terekhol (TR) were analysed for texture, Organic Carbon (OC), major elements (Fe, Al, Ca and Mg) and trace metals (Mn, Cu, Zn, Pb, Ni and Cr). Depositional environment of the cores was assessed based on the color and the distribution of OC. Environmental parameters such as contamination factor, geo accumulation, enrichment factor and pollution load index were used to assess the extent of pollution. In addition, correlation coefficients were calculated to understand their relationships among the major elements and trace metals and their sources. The study revealed that the Bicholim river is strongly polluted with Fe & Mn and moderately polluted with Pb and Cr. Whereas, the Mandovi river is moderately polluted with Mn and Pb. On the other hand, Terekhol River (though unpolluted in the past) is getting polluted with Cu and Cr during recent years because of human interference. The results indicate that mining has a considerable impact on the Bicholim and Mandovi river sediments which in turn affect the ecology of bottom-dwelling organisms.