Hydrogeochemistry of groundwater and anthropogenic control over dolomitization reactions in alluvial sediments of the Deoria district: Ganga plain,India |
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| Authors: | Vikram Bhardwaj Dhruv Sen Singh A K Singh |
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| Institution: | (1) Centre of Advanced Study in Geology, University of Lucknow, Lucknow, 226007, India;(2) Central Institute of Mining and Fuel Research, Barwa Road, Dhanbad, 826 001, India |
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| Abstract: | Groundwater is a critical resource in Deoria district, as it is the main source of drinking water and irrigation. The aquifer
has deteriorated to a high degree, during the last two to three decades, in quality and quantity due to high population growth
and environmental pollution. More than 90% of the population get their drinking water from subsurface waters. Fifteen wells
were sampled in June 2006 to probe the hydrogeochemical components that influence the water quality. The results show that
groundwater have EC, TDS, Na+, Mg2+, HCO3− and TH higher than the WHO, 1997 maximum desirable limits. A hydrogeochemical numerical model for carbonate minerals was
constructed using the PHREEQC package. The regression analysis shows that there are three groups of elements which are significantly
and positively correlated. The main hydrochemical facies of the aquifer (Ca + Mg–HCO3) represents 33.33% of the total wells. The geochemical modeling demonstrated that the reactions responsible for the hydrochemical
evolution in the area fall into three categories: (1) dissolution of salts, (2) precipitation of dolomite, (3) ion exchange.
Solubility of dolomite, calcite, aragonite and gypsum were assessed in terms of the saturation index. The thermodynamic prerequisites
for dolomite supersaturation reactions are satisfied by subsurface waters, since they are supersaturated with respect to dolomite,
undersaturated (or in equilibrium) with respect to calcite, and undersaturated with respect to gypsum. The Ca2+ versus SO42− and Mg2+ versus SO42− trends are also compatible with homologous trends resulting from dolomite supersaturation. |
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