Mining has impacted Bicholim, Mandovi rivers: Study

PANJIM: Iron ore mining activities have had a considerable impact on the Bicholim and Mandovi river sediments, which in turn affect the ecology of bottom-dwelling organism. Mining activities, which are under suspension for the last 15 months, can also influence the concentration of metals in the Zuari estuary.

This was revealed in a study conducted by Cynthia Gaonkar and Vishnu Matta of the department of Marine Science of Goa University. 

In a two different studies conducted, they have assessed the impact of past iron ore mining on the sediment cores of rivers of Goa, and impact of mining on metal concentration in waters of the Zuari estuary.

In the first study, which has been published in the ‘Research Journal of Environmental and Earth Sciences’, the researchers said that 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 were collected from three rivers, Bicholim, Mandovi and Tiracol. 

The sediments 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 colour 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,” the study mentioned.

 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 iron and manganese (Fe & Mn) and moderately polluted with lead (Pb) and Chromium (Cr),” the study revealed. 

“Whereas, the Mandovi river is moderately polluted with Mn and Pb. On the other hand, Tiracol River (though unpolluted in the past) is getting polluted with Copper (Cu) and Cr during recent years because of human interference,” it added.

“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,” the study concluded.

As far as the Zuari estuary is concerned, the study exemplified that concentrations of trace metals in waters of the Zuari estuary were significantly less when compared to the periods of rampant mining activity around Goa, indicating that mining can influence the concentration of metals in the Zuari estuary.