Relationship between land use and groundwater quality in six districts in the eastern region of Ghana

The chemical quality of groundwater in six district of the eastern region beneath the different types of land use areas of Ghana was examined to evaluate the effects of human activities on groundwater. Analyses indicate that groundwater in the studied area is fresh and generally suitable for most uses. The groundwater is generally characterised by a chemical facies of Ca-HCO3-, Na-Cl and mixed Na-Ca-HCO3 types and is weakly mineralised. Anthropogenic disturbances have had and continue to have an impact on the aquatic ecosystem of Ghana. High concentration of Cl- and TDS were found in wells in high residential areas while the highest levels of Na, Ca, SO4(2-) and NO3- were found in agricultural and high density residential areas. About 50% of boreholes sampled have elevated level of NO3(-)-N emanating from agricultural runoff.     

Assessment of groundwater quality and hydrogeochemistry of Manimuktha River basin, Tamil Nadu, India

Groundwater quality assessment study was carried out around Manimuktha river basin, Tamil Nadu, India. Twenty six bore well samples were analyzed for geochemical variations and quality of groundwater. Four major hydrochemical facies (Ca–HCO₃, Na–Cl, Mixed CaNaHCO₃, and mixed CaMgCl) were identified using a Piper trilinear diagram. Comparison of geochemical results with World Health Organization, United States Environmental Protection Agency, and Indian Standard Institution drinking water standards shows that all groundwater samples except few are suitable for drinking and irrigation purposes. The major groundwater pollutions are nitrate and phosphate ions due to sewage effluents and fertilizer applications. The study reveals that the groundwater quality changed due to anthropogenic and natural influence such as agricultural, natural weathering process.     

Monitoring of the physical parameters and evaluation of the chemical composition of river and groundwater in Calabar (Southeastern Nigeria)

A 12-month study was carried to assess the seasonal and tidal effects on the physical parameters of river and groundwater, which constitute the major potable water sources in Calabar (Nigeria). The study also included an evaluation of the chemical composition of the different water bodies and their relationship. The results show that there was a significant seasonal effect on dissolved oxygen (DO) and nitrate in groundwater on one hand, and on temperature, redox potential (Eh), and DO in river water on the other. Also, a significant tidal influence exists on DO in both river-and groundwater. Comparison between groundwater and river water show statistically significant difference in EC, TDS, Eh, DO, Na, Cl and NO(3). The significant differences in EC, TDS, Na and Cl are due to tidal flushing. The difference in Eh is due to geology of the area while, NO(3) is as a result of anthropogenic pollution. The concentrations of ions in the river and groundwater for the different seasons and tidal cycles show an inverse relationship, while the river water is generally more concentrated than the groundwater. Using a binary mixing model, estimates show that the degree of mixing of river water and groundwater is low, with values of between 1.93% and 2.76% respectively, in the western and eastern parts of the study area. The study concludes that tidal flushing, anthropogenic effects and oxygen supply during recharge contribute to the shaping of water chemistry in the area.     

Hydrogeochemical study of shallow carbonate aquifers, Rameswaram Island, India

Groundwater quality assessment has been carried out based on physicochemical parameters (pH, EC, TDS, CO(3), HCO(3), Cl, SO(4), PO(4), NO(2), Ca(+2), Mg(+2), Na(+) and K(+)) and metal concentration in the Rameswaram Island from 25 bore wells. The Langelier Saturation Index of the groundwater shows positive values (63% samples) with a tendency to deposit the CaCO(3) in the majority of water samples. Scatter plot (Ca + Mg/HCO(3)) suggests carbonate weathering process, which is the main contributor of Ca(2+), Mg(2+) and HCO(3) ions to the water. Gibbs diagram suggests rock-water interaction dominance and evaporation dominance which are responsible for the change in the quality of water in the study area. NaCl and mixed CaNaHCO(3) facies are two main hydrogeochemical facies of groundwater. Mathematical calculations and graphical plots of geochemical data reveal that the groundwater of Rameswaram Island is influenced by natural weathering of rocks, anthropogenic activities and seawater intrusion due to over exploitation. Weathering and dissolution of carbonate and gypsum minerals also control the concentration of major ions (Ca(+2), Mg(+2), Na(+) and K(+)) in the groundwater. The nutrient concentration of groundwater is controlled to a large extent by the fertilizers used in agricultural lands and aquaforms. Comparison of geochemical data shows that majority of the groundwater samples are suitable for drinking water and irrigation purposes.     

Groundwater quality assessment in the village of Lutfullapur Nawada, Loni, District Ghaziabad, Uttar Pradesh, India

The groundwater quality for drinking, domestic and irrigation in the village Lutfullapur Nawada, Loni, district Ghaziabad, U.P., India, has been assessed. Groundwater samples were collected, processed and analyzed for temperature, pH, conductivity, salinity, total alkalinity, carbonate alkalinity, bicarbonate alkalinity, total hardness, calcium hardness, magnesium hardness, total solids, total dissolved solids, total suspended solids, nitrate-nitrogen, chloride, fluoride, sulfate, phosphate, silica, sodium, potassium, calcium, magnesium, total chromium, cadmium, copper, iron, nickel, lead and zinc. A number of groundwater samples showed levels of electrical conductivity (EC), alkalinity, chloride, calcium, sodium, potassium and iron exceeding their permissible limits. Except iron, the other metals (Cr, Cd, Cu, Ni, Pb, and Zn) were analyzed below the permissible limits. The correlation matrices for 28 variables were performed. EC, salinity, TS and TDS had significant positive correlations among themselves and also with NO (3) (-) , Cl(-), alkalinity, Na(+), K(+), and Ca(2+). Fluoride was not significantly correlated with any of the parameters. NO (3) (-) was significantly positively correlated with Cl(-), alkalinity, Na(+), K(+) and Ca(2+). Chloride also correlated significantly with alkalinity, Na(+), K(+) and Ca(2+). Sodium showed a strong and positive correlation with K(+) and Ca(2+). pH was negatively correlated with most of the physicochemical parameters. This groundwater is classified as a normal sulfate and chloride type. Base-exchange indices classified 73% of the groundwater sources as the Na(+)-SO (4) (2-) type. The meteoric genesis indices demonstrated that 67% of groundwater sources belong to a deep meteoric water percolation type. Hydrochemical groundwater evaluations revealed that most of the groundwaters belong to the Na(+)-K(+)-Cl(-)-SO (4) (2-) type followed by Na(+)-K(+)-HCO (3) (-) type. Salinity, chlorinity and SAR indices indicated that majority of groundwater samples can be considered suitable for irrigation purposes.     

Major ion chemistry and weathering processes in the Midyan Basin, northwestern Saudi Arabia

Chemical characteristics of 72 groundwater samples collected from Midyan Basin have been studied to evaluate major ion chemistry together with the geochemical and weathering processes controlling the water composition. Water chemistry of the study area is mainly dominated by Na, Ca, SO₄, and Cl. The molar ratios of (Ca?+?Mg)/total cations, (Na?+?K)/total cations, (Ca?+?Mg)/(Na?+?K), (Ca?+?Mg)/(HCO₃?+?SO₄), (Ca?+?Mg)/HCO₃, and Na/Cl reveal that water chemistry of the Midyan Basin is controlled by evaporite dissolution (gypsum and/or anhydrite, and halite), silicate weathering, and minor contribution of carbonate weathering. The studied groundwater samples are largely undersaturated with respect to dolomite, gypsum, and anhydrite. These waters are capable of dissolving more of these minerals under suitable physicochemical conditions.     

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.     

Chemical characteristics of groundwater and assessment of groundwater quality in Varaha River Basin, Visakhapatnam District, Andhra Pradesh, India

Study on chemical characteristics of groundwater and impacts of groundwater quality on human health, plant growth, and industrial sector is essential to control and improve the water quality in every part of the country. The area of the Varaha River Basin is chosen for the present study, where the Precambrian Eastern Ghats underlain the Recent sediments. Groundwater quality is of mostly brackish and very hard, caused by the sources of geogenic, anthropogenic, and marine origin. The resulting groundwater is characterized by Na(+)?>?Mg(2+)?>?Ca(2+)?:?[Formula: see text]?>?Cl(-)?>?[Formula: see text], Na(+)?>?Mg(2+)?>?Ca(2+)?:?[Formula: see text]?>?Cl(-)?>?[Formula: see text]?>?[Formula: see text], Na(+)?>?Mg(2+)?>?Ca(2+)?:?[Formula: see text]?>?Cl(-), and Na(+)?>?Mg(2+)?>?Ca(2+)?:?Cl(-)?>?[Formula: see text]?>?[Formula: see text] facies, following the topographical and water flow-path conditions. The genetic geochemical evolution of groundwater ([Formula: see text] and Cl(-)-[Formula: see text] types under major group of [Formula: see text]) and the hydrogeochemical signatures (Na(+)/Cl(-), >1 and [Formula: see text]/Cl(-), <1) indicate that the groundwater is of originally fresh quality, but is subsequently modified to brackish by the influences of anthropogenic and marine sources, which also supported by the statistical analysis. The concentrations of total dissolved solids (TDS), TH, Mg(2+), Na(+), K(+), [Formula: see text], Cl(-), [Formula: see text], and F(-) are above the recommended limits prescribed for drinking water in many locations. The quality of groundwater is of mostly moderate in comparison with the salinity hazard versus sodium hazard, the total salt concentration versus percent sodium, the residual sodium carbonate, and the magnesium hazard, but is of mostly suitable with respect to the permeability index for irrigation. The higher concentrations of TDS, TH, [Formula: see text], Cl(-), and [Formula: see text] in the groundwater cause the undesirable effects of incrustation and corrosion in many locations. Appropriate management measures are, therefore, suggested to improve the groundwater quality.     

Major ion chemistry and hydrochemical studies of groundwater of parts of Palar river basin, Tamil Nadu, India

Groundwater is almost globally important for human consumption as well as for the support of habitat and for maintaining the quality of base flow to rivers, while its quality assessment is essential to ensure sustainable safe use of the resources for drinking, agricultural, and industrial purposes. In the current study, 50 groundwater samples were collected from parts of Palar river basin to assess water quality and investigate hydrochemical nature by analyzing the major cations (Ca, Mg, Na, K) and anions (HCO(3), Cl, F,SO(4), NO(3), PO(4),CO(3), HCO(3), and F) besides some physical and chemical parameters (pH, electrical conductivity, alkalinity, and total hardness). Also, geographic information system-based groundwater quality mapping in the form of visually communicating contour maps was developed using ArcGIS-9.2 to delineate spatial variation in physicochemical characteristics of groundwater samples. Wilcox classification and US Salinity Laboratory hazard diagram suggests that 52% of the groundwater fall in the field of C2-S1, indicating water of medium salinity and low sodium, which can be used for irrigation in almost all types of soil with little danger of exchangeable sodium. Remaining 48% is falling under C1-SI, indicating water of low salinity and low sodium.     

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.     

Factors controlling the salinity in groundwater in parts of Guntur district, Andhra Pradesh, India

Groundwater chemistry has been studied to examine the associated hydrogeochemical processes operating for the development of salinity in the groundwater in parts of Guntur district, Andhra Pradesh, India. The study area is underlain by charnockites and granitic gneisses associated with schists of the Precambrian Eastern Ghats. Groundwater is the main resource for irrigation besides drinking. Chemical parameters, pH, EC, TDS, Ca²⁺, Mg²⁺, Na⁺, K⁺, , , Cl⁻, , , F⁻ and SiO₂, are taken into account. Groundwater is of brackish type. Na⁺−Cl⁻ facies dominates the groundwater. Examination of compositional relations and mineral saturation states shows that the ion exchange of Ca²⁺ for adsorbed Na⁺, evapotranspiration, dissolution of soil salts, dissolution of NaCl and CaSO₄, and precipitation of CaCO₃ are the dominant hydrogeochemical processes associated with the groundwater composition in the area. Evapotranspiration causes accumulation of salts in the soil/weathered zone. These salts reach the water table by leaching through infiltrating recharge water. A positive relation between depth to water table and TDS with season supports this inference. The effects of human activities, such as intensive and long-term irrigation, irrigation-return-flow, application of unlimited agricultural fertilizers and recycling of saline groundwater, act to further increase the salinity in the groundwater. Therefore, the groundwater quality increases towards the flow path, while the post-monsoon groundwater shows higher concentrations of TDS, Na⁺, Mg²⁺, Cl⁻, , , F⁻ and SiO₂ ions. The study could help to understand the hydrogeochemical characteristics of the aquifer system for taking effective management measures to mitigate the inferior groundwater quality for sustainable development.     

Groundwater geochemistry in the Alisadr, Hamadan, western Iran

The chemical composition of 59 well water samples throughout the Alisadr area, Hamadan, western Iran was determined in order to describe the background ion concentration and to identify the major hydrogeochemical processes that control the observed groundwater chemistry. The hydrochemical types, Ca–HCO₃, Ca–SO₄, dominate the largest part of the groundwater followed by water types Ca–Cl and Mg–HCO₃. Total hardness indicated that 30% of groundwater samples fell in the very hard water category. Ninety-seven percent of the water samples showed nitrate ( ${\rm NO}_{3}^{-})$ concentrations above the human affected value (13 mg l^???1 ${\rm NO}_{3}^{-})$ , while 15% exceeded the maximum acceptable level (50 mg l^???1 ${\rm NO}_{3}^{-})$ according to WHO regulations. With respect to sodium adsorption ratio, the groundwater can be used for irrigation on almost all soils with little danger of the developing harmful levels of exchangeable Na^?+?. But with respect to electrical conductivity, the water quality for irrigation was low to medium, providing the necessary drainage to avoid the buildup of toxic salt concentrations. Geochemical modeling using PHREEQC enabled prediction of the saturation state of minerals and indicated the dissolution and precipitation reactions occurring in the groundwater. Groundwaters were undersaturated with respect to amorphous silica. Stability diagram indicated that the dominant cluster of groundwater samples fell into the K-feldspar field.     

Evaluating the last remnants of Butea monosperma (Lam.) Kuntze Forest for their in situ conservation: a case study

This paper summarizes the findings obtained in a monitoring study to understand the sources and processes affecting the quality of shallow and deep groundwater near central air conditioning plant site in Trombay region by making use of physicochemical and biological analyses. All the measured parameters of the groundwaters indicate that the groundwater quality is good and within permissible limits set by (Indian Bureau of Standards 1990). Shallow groundwater is dominantly of Na–HCO₃ type whereas deep groundwater is of Ca–Mg–HCO₃ type. The groundwater chemistry is mainly influenced by dissolution of minerals and base exchange processes. High total dissolved solids in shallow groundwater compared to deeper ones indicate faster circulation of groundwater in deep zone preferably through fissures and fractures whereas groundwater flow is sluggish in shallow zone. The characteristic ionic ratio values and absence of bromide point to the fact that seawater has no influence on groundwater system.     

An attempt to evaluate the recharge source and extent using hydrogeochemistry and stable isotopes in North Henan Plain,China

A thorough understanding of groundwater recharge source, particularly its rate, is usually a prerequisite for effective water resources management. In this paper, we report the impact of Yellow River water seepage from the North Henan Plain, using both hydrogeochemical and stable isotopic analysis data. Seven Yellow River water samples, 10 groundwater samples from a river-parallel transect, and 36 groundwater samples from four different perpendicular transects to the Yellow River in the western, middle, and eastern plain were collected and analyzed. It inferred that cation exchange of Ca²⁺ and/or Mg²⁺ for Na⁺ occurred in groundwaters because of the dissolution of carbonate rocks. The hydrogeochemical results indicate that western piedmont lateral groundwater and the Yellow River are both important sources of groundwater recharge for the western transect of the North Henan Plain, while the former is a greater recharge source for the middle transect, and the latter is a greater recharge source for the eastern transect. Stable isotope data support Yellow River water incursion into the groundwater. The approximate distance (based on chloride concentration) from the Yellow River to border of the impact zone is17.43–23.40 km in the western plain, 52.46 km in the middle plain, and 49.82 km in the eastern plain.     

Preliminary assessment of groundwater hydrogeochemistry within Gilan,a northern province of Iran

In four basins of Gilan province, groundwater samples were collected from 127 piezometric wells to investigate the hydrogeochemistry of groundwater, and additionally its suitability for drinking and irrigation purposes. The average concentrations of major cations and anions follow the order of Ca²⁺?>?Na⁺?>?Mg²⁺?>?K⁺ and \( {\mathrm{HCO}}_3^{-}>{\mathrm{Cl}}^{-}>{\mathrm{SO}}_4^{2-}>{\mathrm{CO}}_3^{2-} \), respectively. Using Piper diagram delineation, CaMgHCO₃ was determined as the main hydrogeochemical facies of groundwater. According to Piper diagrams, Gibbs plots, and ionic ratios, silicate weathering and ion exchange are the major processes regulating the groundwater hydrochemistry. Furthermore, saturation indices (SIs) revealed that carbonate precipitation also plays an important role in aquifers. Among the processes, weathering of silicate minerals seems to be the dominant process. Comparing the analyzed major ions and physicochemical parameters with the WHO guideline values indicates that the potability of most groundwater samples is generally acceptable. Electrical conductivity (EC) and total dissolved solid (TDS) measurements along with sodium percentage (SP), sodium adsorption ratio (SAR), Kelley’s index (KI), and residual sodium carbonate (RSC) calculations suggest that groundwater in many areas is suitable for irrigation use. Nonetheless, total hardness (TH) values ranging as high as 650.0 mg/l reveal many groundwater samples to be classified as hard and very hard, indicating a requirement for long-term monitoring and further evaluation. The present study shows that the groundwater quality in Lahijan, Astaneh, and to a lesser extent Fouman drainage basins is lower than in Talesh. Therefore, intense monitoring programs towards enhanced water management practices are recommended before poorer quality groundwater is further utilized.     

Statistical approaches for hydrogeochemical characterization of groundwater in West Delhi, India

Parametric statistical approaches, correlations and multiple linear regressions were used to develop models for the interpretation of hydrogeochemical parameters in the Western part of Delhi state, India. The hydrogeochemical parameters indicated that the groundwater quality is not safe for consumption. The water is moderately saline and the salinity level is increasing over time. There is also the problem of nitrate pollution. The correlation between electrical conductivity (EC) and other water quality parameters except potassium (K(+)), nitrate (NO(3)(-)) and bicarbonate (HCO(3)(-)) is significantly positive and Ca(++)+ Mg(++)/Na(+)+ K(+) is significantly negative. In predicting EC, the multiple R(2) values of 0.996 and 0.985 indicate that 99.6% and 98.5% variability in the observed EC could be ascribed to the combined effect of Na(+), HCO(3)(-), Cl(-), SO(4)(--), NO(3)(-) and Ca(++)+ Mg(++) for the year of 2005 and 2006 respectively. Out of 99.6% of the variability in EC in 2005, 51.2% was due to Cl(-) alone, and 8.5%, 12.5%, 6.1%, 14.7% and 6.7% were due to Na(+), HCO(3)(-), SO(4)(--), NO(3)(-) and Ca(++) + Mg(++). Similarly in 2006, out of 98.5% of the variability in EC, 48.5% was due to Cl(-) alone, and 10.4%, 12.7%, 5.3%, 17.2% and 4.4% were due to Na(+), HCO(3)(-), SO(4)(--), NO(3)(-) and Ca(++)+ Mg(++). The analysis shows that a good correlation exists between EC, Cl(-) and SO(4)(--) either individually or in combination with other ions and the multiple regression models can predict EC at 5% level of significance.     

Chemical dynamics of the Sava riverine system

Presented here is a study of the geochemical dynamics of the entire River Sava watershed, a major tributary of the River Danube which has not previously been investigated. The sampling was performed at 33 selected locations along the main channel of the stream and at its largest tributaries during three sampling seasons (fall 2005, spring 2006 and fall 2006), going from headwater locations to the mouth near the confluence with the Danube. Almost 80% of the solutes are derived from carbonate mineral weathering and represent over 50% of specific HCO(3)(-) flux normalized to unit basin area at the mouth of the Danube. Statistical analysis indicates that agricultural and industrial sources contribute significantly to increased Na(+), K(+), Cl(-), SO(4)(2-) and NO(3)(-) concentrations in tributary waters. Different processes control the water chemistry along the course of the Sava's drainage-the upper reaches are largely regulated by contributions from carbonate mineral weathering, the middle reaches are influenced by agricultural activity and biological processes related to eutrophication, while the lower reaches tend to have more pronounced parameters related to the industrial processing along with leakages from municipal sanitary systems of these higher population density areas.     

Application of multivariate statistical techniques in the assessment of groundwater quality in seawater intrusion area in Bafra Plain, Turkey

Multivariate statistical techniques such as cluster analysis and principal component analysis were performed on 28 groundwater wells in Bafra Plain. Cluster analysis results show that the groundwater in the study area is classified into three groups (A, B, and C), and factor analysis indicates that groundwater is composed of 89.64 % of total variance of 12 variables and is mainly affected by three factors. Factor 1 (seawater salinization) includes concentrations of electrical conductivity, TDS, Cl^?, Na⁺, and sodium adsorption ratio, factor 2 (mixing water) includes δ¹⁸O, δD, and T, and factor 3 (fresh) includes Ca²⁺. For determination of the source of water, Ca/Cl, Cl/HCO₃, Mg/Cl, and Ca/Na as initials and Mg/Ca and SO₄/Cl as molar rates which were identified, the rates had been found to be very useful. Cluster analysis was made by using these rates and the waters were classified in two groups (group 1 and group 2). First group waters were affected by seawater, and the second group were very less affected by freshwater or seawater. According to the comparison of two different parameters, group 1 comprised group A and group B-2, -3, and -4 from the same wells, and group 2 comprised group B-1 and group C from the same well. As a result of this study, it could be said that multivariate statistical methods gave very useful results for the determination of the source.     

Nitrate leaching to shallow groundwater systems from agricultural fields with different management practices

Monitoring the concentration of NO(3)-N from agricultural fields to the subsurface and shallow ground water resources have received considerable interest worldwide, since agriculture has been identified as a major source of nitrate-nitrogen (NO(3)-N) pollution of groundwater systems in intensively farmed watersheds. A study was conducted to quantify the impact of two tillage practices viz. chisel plow (CP) and no till (NT) with liquid swine manure application on nitrate leaching to the shallow ground water system under corn-soybean production system. This study is part of the long-term field experiments conducted at Iowa State University using completely randomized block design. The NO(3)-N concentrations in the shallow ground water were monitored at three depths viz., a network of subsurface drains at a depth of 1.2 m and piezometers at depths of 1.8 m and 2.4 m. Results of this study showed that the average NO(3)-N concentration during the study period was 16.1 mg l(-1), 14.4 mg l(-1) and 11.8 mg l(-1) at 1.2 m, 1.8 m and 2.4 m depths, respectively implying significant amount of NO(3)-N leaching past the subsurface drain depth of 1.2 m into the shallow groundwater but the NO(3)-N concentration decreases with the depth. The NO(3)-N concentrations in shallow groundwater were significantly higher under the chisel plow system in comparison with the no till method of tillage. Fall application of liquid swine manure caused more leaching in comparison with the spring application. Higher NO(3)-N concentration was observed under corn in comparison with the soybean plots. An in-depth analysis of the data showed a definite relationship between the NO(3)-N concentration in subsurface drain water at a depth of 1.2 m and shallow groundwater at depths of 1.8 m and 2.4 m depths.     

Iron content in groundwaters of Visakhapatnam environs, Andhra Pradesh, India

Trace elements are essential for human health. However, excess concentrations of these elements cause health disorders. A study has been carried out in Visakhapatnam environs, Andhra Pradesh, India to ascertain the causes for the origin and distribution of iron content in the groundwaters. Fifty groundwater samples are collected and analyzed for iron. The content of iron ranges from 400 to 780 μg/l. A comparison of groundwater data with rock and soil chemistry suggests that the concentration of iron (400–530 μg/l) in the groundwaters is derived from the rocks and soils due to geogenic processes. This concentration is taken as a natural occurrence of iron in the groundwaters of the study area for assessing the causes for its next higher content (>530 μg/l). Relatively higher concentration of iron (540–550 μg/l) is observed at some well waters, where the wells are located nearby municipal wastewaters, while the very high concentration of iron (610–780 μg/l) is observed in the industrially polluted groundwater zones, indicating the impact of anthropogenic activities on the groundwater system. These activities mask the concentration of iron caused by geogenic origin. Hence, both the geogenic and anthropogenic activities degrade the groundwater quality. Drinking water standards indicate that the iron content in all the groundwater samples exceeds the permissible limit (300 μg/l) recommended for drinking purpose, causing the health disorders. Necessity of close monitoring of groundwater quality for assessing the impact of geogenic and anthropogenic sources with reference to land use/land cover activities is emphasized in the present study area to protect the groundwater resources from the pollution.