• M V Prasanna

      Articles written in Journal of Earth System Science

    • Identification of major sources controlling groundwater chemistry from a hard rockterrain – A case study from Mettur taluk, Salem district, Tamil Nadu, India

      K Srinivasamoorthy S Chidambaram M V Prasanna John Peter P Anandhan

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      The study area Mettur forms an important industrial town situated NW of Salem district. The geology of the area is mainly composed of Archean crystalline metamorphic complexes. To identify the major process activated for controlling the groundwater chemistry an attempt has been made by collecting a total of 46 groundwater samples for two different seasons, viz., pre-monsoon and post-monsoon. The groundwater chemistry is dominated by silicate weathering and (Na + Mg) and (Cl + SO4) accounts of about 90% of cations and anions. The contribution of (Ca +Mg) and (Na + K) to total cations and HCO3 indicates the domination of silicate weathering as major sources for cations. The plot for Na to Cl indicates higher Cl in both seasons, derived from Anthropogenic (human) sources from fertilizer, road salt, human and animal waste, and industrial applications, minor representations of Na also indicates source from weathering of silicate-bearing minerals. The plot for Na/Cl to EC indicates Na released from silicate weathering process which is also supported by higher HCO3 values in both the seasons. Ion exchange process is also activated in the study area which is indicated by shifting to right in plot for Ca +Mg to SO4 + HCO3. The plot of Na − Cl to Ca +Mg − HCO3 − SO4 confirms that Ca, Mg and Na concentrations in groundwater are derived from aquifer materials. Thermodynamic plot indicates that groundwater is in equilibrium with kaolinite, muscovite and chlorite minerals. Saturation index of silicate and carbonate minerals indicate oversaturation during pre-monsoon and undersaturation during post-monsoon, conforming dissolution and dilution process. In general, water chemistry is guided by complex weathering process, ion exchange along with influence of Cl ions from anthropogenic impact.

    • Hydrogeochemical analysis and evaluation of groundwater quality in the Gadilam river basin, Tamil Nadu, India

      M V Prasanna S Chidambaram A Shahul Hameed K Srinivasamoorthy

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      Water samples were collected from different formations of Gadilam river basin and analyzed to assess the major ion chemistry and suitability of water for domestic and drinking purposes. Chemical parameters of groundwater such as pH, electrical conductivity (EC), total dissolved solids (TDS), Sodium (Na+), Potassium (K+), Calcium (Ca+), Magnesium (Mg+), Bicarbonate (HCO$_{3}^-$), Sulphate (SO$_{4}^-$), Phosphate (PO$_{4}^-$) and Silica (H4SiO4) were determined. The geochemical study of the aquatic systems of the Gadilam river basin show that the groundwater is near-acidic to alkaline and mostly oxidizing in nature. Higher concentration of Sodium and Chloride indicates leaching of secondary salts and anthropogenic impact by industry and salt water intrusion. Spatial distribution of EC indicates anthropogenic impact in the downstream side of the basin. The concentration levels of trace metals such as Iron (Fe), Lead (Pb), Nickel (Ni), Bromide (Br), Iodide (I) and Aluminium (Al) have been compared with the world standard. Interpretation of data shows that some trace metals such as Al, Ni and Pb exceed the acceptable limit of world standard. Geophysical study was carried out to identify the weathered zone in the hard rock and contaminated zone by anthropogenic impact in the downstream of river Gadilam. A few of the groundwater samples in the study area were found to be unsuitable for domestic and drinking purposes.

    • Significance of saturation index of certain clay minerals in shallow coastal groundwater, in and around Kalpakkam, Tamil Nadu, India

      S Chidambaram U Karmegam P Sasidhar M V Prasanna R Manivannan S Arunachalam S Manikandan P Anandhan

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      The saturation index of clay minerals like Gibbsite, Kaolinite, Illite, Montmorillonite and Chlorite in groundwater were studied in detail by collecting 29 groundwater samples from the shallow coastal aquifers in and around Kalpakkam. The samples collected were analysed for major cations, anions and trace elements by using standard procedures. The study reveals that pH has a significant role in the saturation index (SI) of minerals. It also shows that the relationship of electrical conductivity to the SI of these minerals is not significant than that of the ionic strength, log pCO2 values, and alumina silica ratio have significant relation to the SI of these clay minerals. The SI of these clay minerals was spatially distributed to identify the areas of higher SI. Silica has good correlation to SI of Kaolinite, Gibbsite and Montmorillonite and Al has good correlation to SI of all the minerals except to that of Chlorite.

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