K. Rama Mohan

Assessment of heavy metal contamination in soils around chromite mining areas, Nuggihalli, Karnataka, India

Toxic heavy metals represent one of the possible environmental hazards from mine lands, which affect many countries having historic mining industries. The primary aim of the study was to investigate the degree of soil pollution occurring near chromite mines, and make a systematic evaluation of soil contamination based on geoaccumulation index, enrichment factor and pollution index. This paper presents the pollution load of toxic heavy metals (As, Ba, Co, Cr, Cu, Mo, Ni, Pb, Sr, V, Zn and Zr) in 57 soil samples collected around three different active (Tagdur), abandoned (Jambur) chromite mining sites as well residential zone around Chikkondanahalli of the Nuggihalli Schist Belt, Karnataka, India. Soil samples were analyzed for heavy metals by using Wavelength dispersive X-ray fluorescence spectrometry. Results indicated that elevated concentrations of Cr, Ni and Co in soils of the study area exceed the Soil Quality Guideline limits (SQGL). The high enrichment factor for Cr, Ni Co obtained in the soil samples show that there is a steady increase of toxic heavy metals risk in this area, which could be correlated with the past mining activity and post abandoned mining in the area. The data was also treated to study the geoaccumulation index, pollution index and spatial distribution of toxic elements. Emphasis need to be put on control measures of pollution and remediation techniques in the study area.

Assessment of Groundwater Quality and Identification of Hydrogeochemical Process in Hard Rock Terrain

Environmental geochemical studies are carried out to assess the groundwater quality and identification of hydrogeochemical process in hard rock terrain of Bhongir watershed nearer to the Greater Hyderabad. A total of thirty-eight groundwater samples were collected and analysed for important physicochemical parameters, anions and cations. The analytical data of alkalis (Na+ and K+) and alkaline earths (Ca2+ and Mg2+), reveal that high concentration of Na+ than others (Na > Ca > Mg > K) is probability due to the loss of Ca2+ and Mg2+ and gain of Na+ by the cation exchange process. Among the anions, bicarbonate is identified in majority of the samples in the following order HCO3 > Cl > SO4 which confirms that all carbonate minerals might have been dissolved and leached to the groundwater system. Most of the samples (81%) are exceeding the WHO allowable limits of electrical conductivity for drinking. The data sets further suggest that the water chemistry in the study area is not homogeneous and influenced by complex contamination sources and geochemical processes. Besides, highest concentration of nitrate (565.7 mg/L), sulphate (414 mg/L) and chloride (1444 mg/L) firmly suggests the impact of agricultural activities such as irrigation return flow, fertilizer application on water chemistry. The elevated concentrations of fluoride (i.e. maximum 4.1 mg/L) in most of the water samples (66%) reveal the origin and geochemical mechanisms, i.e. rock–water interaction is driving its enrichment. As majority of the parameters are above the permissible limit, the groundwater is not potable for drinking.