Major ion chemistry of shallow groundwater of a fast growing city of Central India

Nagpur City located in semiarid area of central India is a fast-growing industrial centre. In recent years, rapid development has created an increased demand for drinking water, which is increasingly being fulfilled by groundwater abstraction. The present study was undertaken to assess major ion chemistry of shallow groundwater to understand geochemical evolution of groundwater and water quality for promoting sustainable development and effective management of groundwater resources. A total of 47 water samples were collected from shallow aquifer of selected parts of the city and the water chemistry of various ions viz. Ca^2 +, Mg^2 +, Na⁺, K⁺, CO₃  ^2-_{3}^{\ \, 2-}, HCO₃  ^-_{3}^{\ \, -}, Cl⁻, SO₄  ^2-_{4}^{\ \,2-} and NO₃  ^-_{3}^{\ \,-} are carried out. The chemical relationships in Piper diagram identify Ca–HCO₃–Cl and mixed Ca–Na–HCO₃–Cl as most prevalent water types. Alkaline earth exceeds alkalis and weak acids exceed strong acids. Ionic ratios and Gibb’s diagram suggest that silicate rock weathering and anthropogenic activities are the main processes that determine the ionic composition in the study area. The nitrate appeared as a major problem of safe drinking water in this region. We recorded highest nitrate concentration, i.e., 411 mg/l in one of the dug well. A comparison of groundwater quality in relation to drinking water quality standards revealed that about half of the shallow aquifer samples are not suitable for drinking.     

Groundwater quality and its suitability for domestic and agricultural use in Tondiar river basin,Tamil Nadu,India

Assessment of suitability of groundwater for domestic and agricultural purposes was carried out in Tondiar river basin, Tamil Nadu, India. The study area covers an area of 315 km² and lies in a semiarid region. Groundwater is the major source for domestic and agricultural activity in this area. Groundwater samples were collected from 45 wells during pre-monsoon and post-monsoon period in the year 2006. The water samples were analysed for physical and chemical characteristics. Suitability of groundwater for irrigation was evaluated based on salinity hazard, sodium percent, sodium adsorption ratio, residual sodium carbonate, US salinity diagram, Wilcox’s diagram, Kelly’s ratio and permeability index. Ca-HCO₃, mixed Ca–Mg–Cl and Na–Cl were the dominant groundwater types. High hardness and electrical conductivity in this area makes the groundwater unsuitable for drinking and agricultural purposes. Concentration of trace elements (Mn, Cu, Zn, Pb and Ni) did not exceed the permissible limit for drinking and agricultural purposes. Majority of the groundwater samples were unsuitable for domestic and agricultural purposes except for 31% and 36%, which were suitable for drinking and irrigation purposes, respectively.     

Application of water quality index for groundwater quality assessment: Thirumanimuttar sub-basin, Tamilnadu, India

An attempt has been made to understand the hydrogeochemical parameters to develop water quality index in Thirumanimuttar sub-basin. A total of 148 groundwater samples were collected and analyzed for major cations and anions. The domination of cations and anions was in the order of Na>Mg>Ca>K for cations and Cl>HCO₃ >SO₄ in anions. The hydrogeochemical facies indicate alkalis (Na and K) exceed alkaline earths (Ca and Mg) and strong acids (Cl and SO₄) exceed weak acid (HCO₃). Water quality index rating was calculated to quantify overall water quality for human consumption. The PRM samples exhibit poor quality in greater percentage when compared with POM due to effective leaching of ions, over exploitation of groundwater, direct discharge of effluents and agricultural impact. The overlay of WQI with chloride and EC correspond to the same locations indicating the poor quality of groundwater in the study area. SAR, Na%, and TH were noted higher during both the seasons indicating most of the groundwater locations not suitable for irrigation purposes.     

Hydrogeochemical characterization of contaminated groundwater in Patancheru industrial area,southern India

The groundwater is one of the most contaminated natural resources in Patancheru industrial area due to unplanned and haphazard industrial growth and urbanization without following basic pollution control norms. The rapid industrialization initiated in early 1970 has started showing up its after effects few years later in the form of physiochemical contamination of the both surface and groundwater bodies of the area. It has resulted in local people being deprived of safe drinking water, plant and aquatic life has severely affected, and situation is deteriorating over the years in the area in spite of some preventive and remedial measures being initiated. The focus of the present study is to understand the chemical characteristics of groundwater and geochemical processes the contaminant water is undergoing which are normally imprinted in its ionic assemblages. The water samples collected in pre- and post-monsoon seasons from forty two groundwater and four surface water sources were analyzed for major constituents such as Ca²⁺, Mg²⁺, Na⁺, K⁺, CO₃⁻, HCO₃⁻, Cl⁻, SO₄²⁻, NO₃⁻, and F⁻, and selected samples were tested for ten important trace metals like Fe, Pb, Bi, Mn, Cr, Co, Ni, Cu, Zn, and Cd. Na⁺ among cations and Cl⁻ among anions dominate the water in both the seasons where as Ca²⁺, HCO₃⁻, and Cl⁻ show significant reduction in their ionic strength in post-monsoon. The groundwater in general is of mixed type, but most of it belong to Na⁺–Cl⁻, Na⁺–HCO₃⁻, Ca²⁺–Mg²⁺–HCO₃⁻, and Ca²⁺–Mg²⁺–Cl⁻ facies. The Na⁺ and Ca²⁺ are in the transitional state with Na⁺ replacing Ca²⁺ and HCO₃⁻–Cl⁻ due to physiochemical changes in the aquifer system. The evaluation of hydrochemistry through various ionic indices, ratios, and plots suggest that silicate–carbonate weathering, ion exchange, dissolution, and evaporation processes are responsible for origin of the present chemical status of the groundwater which is also controlled by the contamination from extraneous sources that could have accelerated the dissolution processes. Gibbs plots authenticate that the evolution of water chemistry is influenced by interaction of percolating water with aquifer matrix apart from anthropogenic enrichment of elements which get over concentrated due to evaporation.     

Evaluation of the impacts of mine drainage from a coal waste pile on the surrounding environment at Smolnica, southern Poland

Mine drainage impacts from a coal waste pile at Smolnica, Poland have been monitored. Groundwater in an unconfined aquifer downgradient from the pile has near-neutral pH, but high concentrations of sulfate (up to 3,827 mg/l), chloride (up to 903 mg/l), and sodium (up to 2,606 mg/l). Concentrations of iron and manganese are elevated only locally, and concentrations of other metals are low. The behavior of sulfate seems to be conservative in the downgradient aquifer, and gypsum may only be precipitating locally. Concentrations of iron and manganese seem to be controlled by the precipitation of ferric oxide and hydroxides and rhodochrosite, respectively. Complete neutralization of mine drainage by carbonates is consistent with high concentrations of calcium (up to 470 mg/l) and magnesium (up to 563 mg/l) and also with high strontium concentrations of up to 3.08 mg/l, observed in groundwater downgradient from the pile. Hydraulic head profiles at two sites within the river bottom sediments indicate upward flow toward the river with large local differences in groundwater recharge. Water chemistry profiles in the river bottom sediments and geochemical modeling suggest conservative behavior of Na, Cl, and SO₄ and precipitation of Fe and Mn at the groundwater/river water interface. Mine drainage enters the Bierawka River and causes increasing sulfate concentrations. In contrast, concentrations of sodium and chloride in the Bierawka River decrease downgradient from the pile because water in the river upgradient from the pile is already highly contaminated by these species from the discharge of mining waters. Concentrations of Fe and Mn in the river water are low, as a consequence of the precipitation of Fe and Mn oxide and hydroxides. Direct geochemical modeling was able to reproduce measured concentrations of conservative species (e.g., Na, Cl, and SO₄), but errors for metals and Ba were relatively large. In addition, calculated P_CO2 values in the river water are very high, suggesting that equilibrium with atmospheric P_CO2 and P_O2 has not been reached, and at least some reactions should be modeled as kinetic processes. High concentrations of Na, Cl, and SO₄ contribute to the contamination of the Odra River, which is joined by the Bierawka River farther downgradient, thus limiting the use of river water for recreation and other purposes.     

The hydrochemistry of groundwater in the Densu River Basin, Ghana

Hydrochemical analyses of groundwater samples were used to establish the hydrochemistry of groundwater in the Densu River Basin. The groundwater was weakly acidic, moderately mineralized, fresh to brackish with conductivity ranging from of 96.6 μS cm^???1 in the North to 10,070 μS cm^???1 in the South. Densu River basin have special economic significance, representing the countries greatest hydrostructure with freshwater. Chemical constituents are generally low in the North and high in the South. The order of relative abundance of major cations in the groundwater is Na^?+??> Ca^2?+??> Mg^2?+??> K^?+? while that of anions is Cl^????> HCO $_{3}^{-} >$ SO $_{4}^{2-} >$ NO $_{3}^{-}$ . Four main chemical water types were delineated in the Basin. These include Ca–Mg–HCO₃, Mg–Ca–Cl, Na–Cl, and mixed waters in which neither a particular cation nor anion dominates. Silicate weathering and ion exchange are probably the main processes through which major ions enter the groundwater system. Anthropogenic activities were found to have greatly impacted negatively on the quality of the groundwater.     

Assessment of hydrogeochemical characteristics of groundwater in parts of Hindon–Yamuna interfluve region,Baghpat District,Western Uttar Pradesh

The present study has been carried out to assess groundwater quality in parts of Hindon–Yamuna interfluve region of western Uttar Pradesh. Fifty-five groundwater samples were collected from hand pumps in post-monsoon 2005 and pre-monsoon 2006 period, respectively, covering an area of about 1,345 km². Physical and chemical parameters of groundwater such as electrical conductivity, pH, total dissolved solid, Na, K, Ca, Mg, HCO₃, Cl, and SO₄ were determined. Concentration of the chemical constituents in groundwater of the study area varies spatially and temporarily. Interpretation of analytical data of major ion chemistry helps to identify three chemical types of groundwater i.e. ‘mixed’, ‘mixed bicarbonate’ and ‘alkali bicarbonate’ types. The species likely to occur in groundwater of the study area are Ca-HCO₃, Mg-HCO₃, Ca-SO₄, Na-Cl, Na-SO₄, Na-HCO₃, K-Cl, and some other possible species of K, depending on its abundance. The groundwater of the study area comes under the category of moderately hard to very hard, mildly acidic to slightly alkaline in nature. There is anomalously high concentration of major ions, particularly, Na, K, SO₄, and Cl. High SO₄ and K values may be related to anthropogenic influences, rather than through some natural process. Sodium along with Cl may be added to the system through sewage pollution and leachate percolation.     

Assessment of groundwater quality of the Tatlicay aquifer and relation to the adjacent evaporitic formations (Cankiri,Turkey)

One of the most important hydrogeologic problems in and adjacent areas of evaporitic formations is severe quality degradation of groundwaters. These kinds of groundwaters contain high content of dissolved solids and generally have some limitations for use. Tatlicay basin (north-central Turkey) is an example to effects of the evaporites on groundwater quality in the adjacent alluvium aquifer. Gypsum and anhydrites in the two evaporite formations (Bayindir and Bozkir) effect of the groundwater quality in the alluvium adversely, by dissolution of the evaporites by surface drainage and infiltration into the alluvium aquifer (widespread effect) and by infiltration of low quality gypsum springs (local effect) into the aquifer. Evaporitic formations significantly increased EC, TDS, Ca and SO₄ parameters in the alluvium aquifer in the central and downstream regions. EC has increased roughly from 500–800 to 1,700–2,000 μS/cm, Ca has roughly increased from 3–4 to 10 meq/l, SO₄ has increased 0.5–1 to 11–12 meq/l. Consequently, three clusters were distinguished in the basin; (1) nonevaporitic waters in low TDS, Na, Ca, Mg, Cl and SO₄, (2) diluted waters in high TDS and relatively high Cl, moderate-relatively high Na, Ca, Mg, SO₄, (3) gypsum springs in highest TDS, Ca, SO₄, but moderate Mg and low Na, Cl.     

The occurrence and hydrochemistry of fluoride and boron in carbonate aquifer system, central and western Estonia

Silurian–Ordovician (S–O) aquifer system is an important drinking water source of central and western Estonia. The fluoride and boron contents of groundwater in aquifer system vary considerably. The fluoride concentration in 60 collected groundwater samples ranged from 0.1 to 6.1 mg/l with a mean of 1.95 mg/l in the study area. Boron content in groundwater varied from 0.05 mg/l to 2.1 mg/l with a mean value of 0.66 mg/l. Considering the requirements of EU Directive 98/83/EC and the Estonian requirements for drinking water quality, the limit value for fluoride (1.5 mg/l) and for boron (1.0 mg/l) is exceeded in 47 and 28 % of wells, respectively. Groundwater with high fluoride and boron concentrations is found mainly in western Estonia and deeper portion of aquifer system, where groundwater chemical type is HCO₃–Cl–Na–Mg–Ca, water is alkaline, and its Ca²⁺ content is low. Groundwater of the study area is undersaturated with respect to fluorite and near to equilibrium phase with respect to calcite. The comparison of TDS versus Na/(Na?+?Ca) and Cl/(Cl?+?HCO₃) points to the dominance of rock weathering as the main process, which promotes the availability of fluoride and boron in the groundwater. The geological sources of B in S–O aquifer system have not been studied so far, but the dissolution of fluorides from carbonate rocks (F?=?100–400 mg/kg) and K-bentonites (F?=?2,800–4,500 mg/kg) contributes to the formation of F-rich groundwater.     

Evaluation of groundwater suitability for domestic,irrigational, and industrial purposes: a case study from Thirumanimuttar river basin,Tamilnadu, India

The Thirumanimuttar sub-basin forms an important groundwater province in south India, facing serious deficiency in both quality and quantity of groundwater due to increased demand associated with rapid population explosion, agricultural growth and industrial activities. A total of 194 groundwater samples were collected and 15 water quality parameters were analyzed using standard procedures. Na⁺, Cl⁻, Ca^2 +, HCO₃^-_{3}^{-}, Mg^2 + and SO₄^2-_{4}^{2-} concentration ions are more dominant in both seasons. The total dissolved solids and electrical conductivity was observed good correlation with Na⁺, Cl⁻, HCO₃^-_{3}^{-}, Ca^2 +, Mg^2 +, Cl⁻, PO₄^3-_{4}^{3-} and NO₃^- _{3}^{- } ions indicating dominance of plagioclase feldspar weathering, anthropogenic input and over drafting of groundwater irrespective of seasons. The Hill–Piper diagram indicates alkaline earths exceed the alkalis, an increase of weak acids was noted during both the seasons. For assessing the groundwater for irrigation suitability parameters like total hardness, sodium adsorption ratio, residual sodium carbonate (RSC), permeability index, and sodium percentage are also calculated. Permanent hardness was noted in higher during both the seasons due to discharge of untreated effluents and ion exchange process. The RSC indicates 56% of the samples are not suitable for irrigation purposes in both seasons, if continuously used will affect the crop yield. From the results, nearly 72% of the samples are not suitable for irrigation.