Assessment of Impact of Mining on Water Quality and it’s Modelling

Abstract

Water is the most essential requirement for life. The most fundamental component of sustainable development is to ensure that the streams, rivers, lakes and oceans are not contaminated due to human activities. Water is extensively used for various mining operations, viz., wet drilling, dust suppression, ore processing, washing of heavy earth moving machinery (HEMM). Mine drainage, mine cooling, aqueous leaching and other mining processes has the potential to cause contamination of water bodies both surface and ground by discharging mine effluent and tailing seepage.
The ever increasing mining activities pose a serious threat to the water resources. The awareness towards environmental footprint of mining operations is consistently growing, but it often gets little attention. Environmental pollution is the price that we pay for our everyday use of minerals and its products.Contamination of water sources severely affects not only an individual species but the entire ecosystem and all the organisms living in the ecosystem, and also severely affect human health.
In the present work, water samples were collected from various sampling sites, followed by laboratory analysis and water quality modelling. Water sampling was done in the area surrounding TRB iron ore mine owned by Jindal Steel & Power Ltd, located in Tensa region of Sundergarh district in Odisha during October 2016. The location of sampling was so selected because of the nearness of mining site to residential areas. In recent years, the surrounding surface and ground water bodies were gradually contaminated due to the mining operations.
A total of 23 water quality parameters of the collected water samples, viz., Temperature, Conductivity, Oxidation Reduction Potential, pH, Acidity, Alkalinity, Dissolved Oxygen, Biochemical Oxygen Demand, Total Dissolved Solids, Total Hardness, Turbidity, Sulphate, Phosphate, Nitrate, Chloride, Fluoride, Sodium, Potassium, Calcium, Manganese, Iron, Copper and Nickel, were determined by laboratory analysis.
The water quality modelling was done using WA-WQI (Weighted Average - Water Quality Index) based on 11 water quality parameters, viz., pH, Conductivity, DO, TDS, Hardness, BOD, Sulphate, Chloride, Nitrate, Calcium and Iron.
Graphical modelling was done for all the determined water quality parameters in order to make the water quality analysis easily comprehensible. Graphical models of all the water quality parameters were created in QGIS (Quantum GIS) software using IDW (Inverse Distance Weighting) method, in which all the water quality parameters were interpolated and displayed for the area surrounding the sampling locations. Finally, a 3D graphical model of WA-WQI was created, represented as a DEM (Digital Elevation Model), where higher elevation indicates higher values of WA-WQI.
Based on the study of the experimental analysis data and the graphical models, it was concluded that turbidity values exceeded the permissible limit (1NTU according to IS-10500) in almost the entire study region; pH was below the permissible of 6.5 in half of the study region; iron, copper and manganese concentrations exceeded the permissible limits (0.3mg/l, 0.05mg/l and 0.1mg/l respectively) in the regions surrounding the sampling sites G1, S2 and S5; BOD value exceeded the permissible limit (5mg/l) in the regions surrounding the sampling sites G1 and S5; and nickel concentration exceeded the permissible limit (0.02mg/l) in the regions surrounding the sampling sites S5.
According to the WA-WQI ratings determined for the water samples, only G2 qualifies for excellent water quality; S1 and S3 have good water quality; G3, G4, G5 and S4 have poor water quality; and G1, S2, and S5 has very poor water quality. Although, it was inconclusive that if ground water sources are more polluted than surface water sources.