Chemical aspects of ground water quality in the shallow aquifers in selected districts of eastern Uttar Pradesh

Ground water has become one of the important sources of water for meeting the requirements of various sectors in the country in the last few decades. The rapid pace of agricultural development, industrialization and urbanization has resulted in the overexploitation and contamination of ground water resources in parts of the country, resulting in various adverse environmental impacts and threatening its long-term sustainability. The commonly observed contaminants such as Fluoride and Iron are geogenic, whereas contaminant such as nitrates owe their origin to various human activities including domestic sewerage, agricultural practices and industrial effluents. The chemical parameters like pH, EC, Fluoride, Sodium, Potassium, Calcium, magnesium,SAR, RSCc and Nitrate etc are main contituents defining the quality of ground water in unconfined aquifers. Therefore, presence of these parameters in ground water beyond the permissible limit in the absence of alternate source has been considered as ground water quality hot spots. The quality aspects of ground water is being monitored through tube well, hand pump and pond from which samples are collected in the month of May and analyzed for all the major inorganic parameters. Based on the results, it is found that ground water of the region are mostly of calcium bicarbonate (Ca-HCO₃) type and the total salinity of water is between 384–960 mg l⁻¹ (corresponding to electrical conductance of 0.6–1.5 dSm⁻¹ at 25°C). The observed SAR and RSC values ranged between 1.01 to 5.03 and -3.2 to 11.61 meq L⁻¹ respectively. The study shows that the presence of nitrate in the ground water does not exceeds WHO standard, 25% of the collected samples have more than permissible limits of fluoride concentration and 30% samples have iron concentration >1.0 mg L⁻¹.The hydro chemical study reveals almost all the samples have the good quality of water for agriculture.