Cl Water Type Research Articles

Degradation of groundwater quality in the coastal aquifers of the USA

The objective of this study is to analyze groundwater types and the extent of seawater intrusion in terms of ion concentrations in groundwater sample using USGS monitoring wells. Groundwater quality indices [fsea, GQI (dom), GQI (mix), GQI (swi)] were used to estimate the spatial distributions of groundwater types in the US coastal aquifers. Results showed that the dominating groundwater chemistry in the study area was Na+ and Cl−. Results also indicated that seawater intrusion of groundwater occurred in the US coastal aquifers. Based on the results of GQI (mix) and GQI (dom), most of the wells fell under domain II in the Piper diagram, indicating that they were of the Na–Cl water type. Na–Cl and mixed Ca–Mg–Cl were determined to be the two dominant groundwater types in the coastal aquifers of the US seawater intrusion evident in the Palm Beach and Miami-Dade counties of Florida, the San Diego and Santa Barbara areas of California, and within Virginia and New Jersey on the east coast. As the sea level continues to rise further inland, Na–Cl concentration in groundwater will increase, particularly in aquifers along low-lying coasts.

Hydrogeochemistry of shallow groundwater in Ado-Ekiti Area, Southwestern Nigeria

This study examined the hydrogeochemistry of shallow groundwater in Ado-Ekiti Area, Southwestern Nigeria with a view to elucidating the suitability for domestic and agricultural activities. Twenty seven shallow wells' and three boreholes’ water were randomly sampled and subjected to physico-chemical and bacteriological analyses using standard methods. In-situ parameters (temperature (°C), pH and electrical conductivity (μS/cm)) were measured with Multi-parameter Testr™ 35 Series S/N: 1382654 while turbidity measurement was through the use of turbidity tubes. Major ions were analyzed spectrophotometrically except for HCO3− that was determined by titration while bacterial determination was carried out using membrane filtration method. The pH in porphyritic granite (PG) (av. 7.16), fine grained granite (FG) (av. 7.10) and migmatite (MG) (av. 7.51) were within approved standard for drinking water but weakly alkaline. All mean values of EC (μS/cm) on PG, FG and MG (421.11, 412.00 and 206.77), total dissolved solid (TDS) (mg/L) (315.85, 309.00 and 155.08), total hardness (TH) (mg/L) (133.92, 146.50 and 133.12) and turbidity (NTU) (3.73, 1.00 and 4.35) respectively fell within approved standard of drinking water. The order of anions abundance in the groundwater was Cl− > HCO3− > SO42− > NO3− > PO43− while that of the cations was Ca2+>Na+>Mg2+>K+. All sampled water tested positive to bacteriological analysis indicating that there was a greater risk that pathogens were present in the groundwater warranting its treatment before drinking. Characterization of groundwater of the study area revealed the dominance of Ca(Mg)–Cl(SO4) water type with Ca–Cl and Ca–HCO3 water types in the minority. Irrigation quality evaluation indicated that the groundwater system was suitable for irrigation purposes. The groundwater of the study area was low mineralized, with low residence time, chemically potable but bacteriologically infected. Rock types had significant influence on the ionic concentrations of the groundwater with more dissolved ions occurring in porphyritic granite.

Groundwater salinity and quality assessment using multivariate statistical and hydrogeochemical analysis along the Urmia Lake coastal in Azarshahr plain, North West of Iran

In the present study, the aim was to investigate groundwater quality and salinity in one of the highly affected areas along the hyper-saline Urmia Lake. Accordingly, physicochemical parameters from 77 groundwater wells were assessed using multivariate statistics and hydrogeochemical analysis in case of groundwater salinity and quality of Azarshahr plain. Based on the electric conductivity of the water, the results show that almost 41% of the wells are freshwater (< 1000 µS/cm), 18% slightly saline water (1000–3000 µS/cm), and 42% moderately saline water (3000–10,000 µS/cm). Based on Gibbs plot, rock weathering was a dominant process in the plain so that about 80.7% of the samples fall under very hard class. Results from Principle Component Analysis and Hierarchical Cluster Analysis divided the groundwater into four distinct zones: cluster 1 in the western area of the plain is known as recharge zone (Ca–HCO3 water type), cluster 2 northwest of the study area is influenced by saline water up-coning during agriculture pumping (Ca–Cl water type), cluster 3 north of the study area is affected by rock weathering (Ca–HCO3–Cl water type), and finally cluster 4 in the central plain is mostly influenced by wastewater and agricultural fertilizers (Ca–SO4–Cl water type). It was also found that there are high concentrations of TDS, Cl−, and SO42− in the agricultural areas which was also showing an increasing trend within 2010–2014. Finally, it was found that agricultural activity, contamination and salinization from irrigation, use of fertilities, and up-coning salt water during pumping are among the factors in deterioration of groundwater resources in the studied area.

Isotope hydrology and geothermometry of the thermal springs, Damavand volcanic region, Iran

The chemo-isotopic characteristics, geothermal activity and water origin of the 5 thermal and 7 non-thermal springs have been investigated in Damavand volcanic region, northern Iran. The Damavand thermal waters are characterized by outlet temperature values of 23 to 65 °C and the Ca–Cl or Ca-SO4 water types. Stable isotope values of 49 monthly precipitation samples from 5 stations at 2500 to 3200 m elevations were also measured in the study area and Damavand meteoric water line (DMWL) was drawn as δD = 7.64 × δ18O + 8.93 (R2 = 0.98, n = 49). It has a lower slope and intercept than the global meteoric water line (GMWL) due to isotope kinetic fractionation effects during precipitation. The δ18O = (−0.0018 × H(m.a.s.l.) − 3.12) equation was derived based on precipitation data. The reservoir temperature was estimated to be 110–135 °C based on different geothermometers. Damavand volcano can be considered as the main heat source for the thermal springs in the region. The conductive process along with the mixing of thermal waters with shallow cold groundwaters is the main cooling mechanisms. Almost, all the thermal waters fall near the LMWL and within prediction interval area, indicating meteoric origin and no significant effect of water-rock interaction. The Damavand geothermal reservoir is fed by local meteoric water from altitudes of 2500 to 4100 m and circulates at least 500 m deep, near the magma chamber.

Groundwater as an alternative source to irregular surface water in the O'Kiep area, Namaqualand, South Africa

Water insecurity is a growing concern globally and the role of groundwater and aquifers in buffering the effects of climate variability and change is increasingly acknowledged due to extended periods of drought in arid regions. Water security can only be fully realised with a more robust understanding of groundwater as a water resource, especially in the O'Kiep area which is in Namaqualand, South Africa. Results of analyses of groundwater samples (n = 8) indicated that pH values met acceptable standards for drinking, while the total dissolved solids (TDS) and electrical conductivity (EC) were however not within the recommended limits. The chemical composition of the groundwater indicated Eh values −34.1 to −87.2 mV, indicative of reducing geochemical conditions with the most abundant ions being Cl-, SO42-, NO3-, F-, Na+, Ca2+, Mg2+ and K+. Furthermore, some of the ions were not within the guidelines, i.e. Cl−, SO42+, Na+, Ca2+ and Mg2+, but all the potential toxic elements, namely: Al, S, As, Cd, Cr, Co, Cu, Fe, Mn, Hg, Ni, Se, V, Zn and CN, were within acceptable values for drinking groundwater as recommended by the SANS241-1 (2015) and WHO (2011). Hydrogeochemical characteristics of the water indicated that the continuous consumption of the groundwater without pretreatment might result in possible human health risk as the Groundwater Quality Index (GWQI) confirmed that the groundwater quality could be classified as being of moderate concern. Furthermore, the hydrogeochemical indices (CaCO3/Cl and Mg/Ca) and cationic exchange values indicated that the aquifer is of inland origin while the piper trilinear diagram revealed that the groundwater type in the area is categorised as sodium – potassium – chloride – sulphate- (Na–K–Cl–SO4), carbonate – chloride – sulphate- (CaCO3–Cl–SO4) and sodium – chloride (Na–Cl) type water. Additionally, the Sodium Adsorption Ratio (SAR) values up to 11.7 indicated that the groundwater is brackish and its excessive usage may have undesirable effect on plant growth. Therefore, this study recommends the consideration of suitable measures to improve the GWQI for the benefit of the community which have access to limited water resources.

Conceptual hydrogeological and numerical groundwater flow modelling around the Moab Khutsong deep gold mine, South Africa.

Prediction of response to fissure water pumping from a shaft on the surrounding areas is conducted with a numerical model, which was refined using environmental stable isotope (ESI), Tritium and hydrochemical datasets. The numerical model domain covers the local carbonate rock units mainly because it is known to be the main source of groundwater.Based on the hydrochemical dataset of the fissure water pumped at the shaft, strong signature of Na–Cl type water originating from the seepage of a waste rock dump as well as polluted water from mine offices, loading/unloading and parking lot areas, is evident. The environmental isotope data demonstrated that fissure water intercepted at the shaft has strong footprint of surface water and polluted groundwater from nearby areas. The 30-year numerical model prediction indicates that pumping at a rate of 2500 m3/day or more would cause the radius of influence to expand to areas where the central tailings storage facility is located and could possibly draw highly acidic water. Interception of acid rock drainage could cause sever corrosion of pump infrastructure, enhance dolomite dissolution and local ground subsidence as well as possibly compromise the structural integrity of the central tailings dam.It is recommended that the current groundwater monitoring network be revised for taking proactive action. The study highlights the relevance of integrating various sets of data to improve understanding of the conceptual flow before any numerical modelling is attempted.

Geochemical assessment of fluoride enrichment and nitrate contamination in groundwater in hard-rock aquifer by using graphical and statistical methods

This systematic study was carried out with objective to delineate the various sources responsible for $$\hbox {NO}_{3}^{-}$$ contamination and $$\hbox {F}^{-}$$ enrichment by utilizing statistical and graphical methods. Since Central Ground Water Board, India, indicated susceptibility of $$\hbox {NO}_{3}^{-}$$ contamination and $$\hbox {F}^{-}$$ enrichment, in most of the groundwater, $$\hbox {NO}_{3}^{-}$$ and $$\hbox {F}^{-}$$ concentration primarily observed $${>}45$$ and $${>}1.5~\hbox {mg/L}$$ , respectively, i.e., higher than the permissible limit for drinking water. Water Quality Index (WQI) indicates $${\sim }22.81\%$$ groundwater are good-water, $${\sim }71.14\%$$ groundwater poor-water, $${\sim }5.37\%$$ very poor-water and 0.67% unsuitable for drinking purpose. Piper diagram indicates $${\sim }59.73\%$$ groundwater hydrogeochemical facies are Ca–Mg– $$\hbox {HCO}_{3 }$$ water-types, $${\sim }28.19\%$$ Ca–Mg– $$\hbox {SO}_{4}$$ –Cl water-types, $${\sim }8.72\%$$ Na–K– $$\hbox {SO}_{4}$$ –Cl water-types and 3.36% Na–K– $$\hbox {HCO}_{3 }$$ water-types. This classification indicates dissolution and mixing are mainly controlling groundwater chemistry. Salinity diagram indicate $${\sim }44.30\%$$ groundwater under in low sodium and medium salinity hazard, $${\sim }49.66\%$$ groundwater fall under low sodium and high salinity hazard, $${\sim }3.36\%$$ groundwater fall under very-high salinity hazard. Sodium adsorption ratio indicates $${\sim }97\%$$ groundwater are in excellent condition for irrigation. The spatial distribution of $$\hbox {NO}_{3}^{-}$$ indicates significant contribution of fertilizer from agriculture lands. Fluoride enrichment occurs in groundwater through the dissolution of fluoride-rich minerals. By reducing the consumption of fertilizer and stress over groundwater, the water quality can be improved.

Hydrogeological Classification and the Correlation of Groundwater Chemistry with Basin Flow in the South-Western Part of Bangladesh

Attempt has been made to find the relationship between the basin groundwater flow and the current water chemistry of south-western part of Bangladesh considering their lithological distribution and aquifer condition. The correlation of water chemistry and basin groundwater flow is depicted in the conceptual model. The water-types of shallow groundwater are predominantly Mg-Na-HCO3 and Ca- Mg-Na-HCO3 type. In the deep aquifer of upper delta plain is predominately Na-Cl, Ca-HCO3 and Mg- HCO3 type. In the lower delta plain Na-Cl type of water mainly occurs in the shallow aquifer and occasionally Ca-HCO3, Ca-Mg-Na-HCO3 and Mg-HCO3 type may also occur in shallow aquifer of the eastern part of lower delta plain which could have originated from the recent recharge of rain water. Na- Cl type water is also found in the deep aquifer of lower delta plain. The origin of Na-Cl type water in the deep aquifer of lower delta part might be connate water or present day sea water intrusion. Fresh water occurring in the deep aquifer in the lower delta area is mostly of Mg-Ca-HCO3 and Na-HClO3 types. This type of water originate from intermediate or deep basin flow from the northern part of Bangladesh. The probable source of deep groundwater is Holocene marine transgression (Khan et al. 2000) occurred in 3000–7000 cal years BP and the deep groundwater of Upper Delta plain and Lower Delta plain is clearly influenced by deep basin flow coming from north part of BangladeshJournal of Bangladesh Academy of Sciences, Vol. 42, No. 1, 41-54, 2018

Hydrochemical and statistical modeling of groundwater quality in two constrasting geological terrains of southwestern Nigeria

Groundwater evolution and its quality assessment in two contrasting geological terrains of southwestern Nigeria was undertaken. A total of 22 groundwater samples were collected with 11 groundwater samples representative of each geological terrain. The results of the water quality assessment showed that the waters from both environments are generally dominated by Ca2+, Cl−, and HCO3− ions. Okitipupa groundwaters are fresh, more acidic and of better quality due to its lesser total dissolved solids and other dissolved chemical ions that are of health concern than Ore groundwaters. Most of the major anions and cations in the water samples fall within World Health Organization (WHO) permissible limits but Water Quality Index (WQI) of Ore groundwater exhibit poor quality in greater proportion compared to Okitipupa groundwater which are all of good quality. Irrigation water quality results (SAR, MAR, RSC, PI and SSP) revealed that all the water samples from the two environments are suitable for agricultural purposes. However, the basement complex groundwaters are however of low, medium and high salinity hazard (SH) while the coastal sedimentary basin sourced groundwaters are made up of low and medium salinity hazard. Gibbs diagram revealed two similar mechanisms such as evaporation-crystallization and rock-weathering. From the Piper’s trilinear plots for the two environments, Ca–Cl water type predominate but Ca–HCO3 and Ca–SO4 water types can also be found in these environments. Deductions from the hydrogeochemical analysis and different statistical inferences employed for this study resulted in a model that establish the conjunctive imprints of anthropogenic and geogenic activities influencing the increasing dissolved chemical constituents in the groundwaters. This was actually resulted from the contrasting geological environments from where the waters were sourced. Nevertheless, groundwater from the two environments are suitable for domestic and irrigation purposes.

Application of multi-method approach to assess groundwater–surface water interactions, for catchment management

Globally, the dependence of river systems to delayed discharge of subsurface water to augment flows during dry seasons is well documented. Discharge of fresh subsurface water can dilute concentrated river flow quality during reduced flow. Observed and reported results on the Berg River’s declining water quantity and quality are a concern to the regions socio-economic growth and environmental integrity. Understanding the role of subsurface water discharges on the quantity and quality of receiving surface water courses can improve their management during dry periods. A case study was designed and implemented in the upper Berg River catchment in the Western Cape Province of South Africa to assess the influence of groundwater–surface water interaction on water quantity and quality. This study aimed to quantify and characterize the quality of subsurface water available in the upper catchment to improve observed declining water quality downstream. Hydrograph separation provided estimates of water fluxes during 2012–2014 low and high flow periods, while hydrochemical analysis provided insights on impacts of major land use activity in this catchment on water resources. Hydrograph separation analysis indicated that the Berg River is 37.9% dependent on subsurface water discharges annually. Dominant Na–Cl-type water indicates the quality of water from the upper Berg River is largely affected by natural processes including short residence times of aquifer water, rock–water interactions and atmospheric deposition of NaCl ions. These results provide insights for suggesting management options to be implemented to protect subsurface water for continued dilution and water resources management in the lower catchments.

Characterizing Major Controls on Spatial and Seasonal Variations in Chemical Composition of Surface and Pore Brine of Maharlu Lake, Southern Iran

Maharlu Lake with Na–Cl water type is the terminal point of a closed basin in southern Iran. A total of 10 water samples from two rivers discharging to the lake and 78 water samples of surface and pore brine of Maharlu Lake have been collected from different depths (surface, 20, 50 and 100 cm) of four sampling stations along the lake during a period of lake water-level fluctuation (November 2014–July 2015). To investigate chemical interaction between lake surface water and shallow pore water and to understand the major factors governing chemical composition of Maharlu brine, concentrations of major and minor (boron, bromide and lithium) solutes, pH and total dissolved solids have been measured in collected water samples. Saturation indices of evaporite minerals in collected water samples have been also calculated. The chemical behavior of dissolved solutes and evaporative evolution of the lake brine during a hydrological period have been simulated using PHREEQC. The results of our investigations indicated that chemical composition of lake surface water and pore brine of Maharlu Lake are mainly connected with lake water-level fluctuations and distance from input rivers (and depth), respectively. Hydrochemical investigations and statistical analysis showed that the brines chemistry of Maharlu is mainly controlled by three processes: brine evaporative evolution, dissolution–precipitation and diagenetic evolution of secondary carbonates.

Assessment of hydrogeochemical status of groundwater in a coastal region of Southeast coast of India

A study was conducted in a coastal region of Cuddalore district of Tamil Nadu, India, to identify the hydrogeochemical processes controlling the groundwater chemistry. The major geological units of the study area are sandstone, clay, alluvium, and laterite soils of Tertiary and Quaternary age. A total of 64 groundwater samples were measured for major ions and stable isotopes. Higher electrical conductivity values indicate the poor quality groundwater along the coastal region. Saline water intrusion mainly affects the hydrochemical composition of the aquifer water reflected by Na–Cl-type waters. Cl−/(Cl− + HCO3−) ratio also indicates the mixing of fresh groundwater with saline water. The results of δD and δ18O analyses show that isotopic compositions of groundwater ranges from − 7.7 to − 2.1‰ for δ18O and from − 55.6 to − 18.5‰ for δD. Correlation and factor analysis were carried out to find the association of ions and to determine the major factors controlling the groundwater chemistry of the region. The study indicates that ion exchange, weathering, salt water intrusion along the coast, and anthropogenic impacts are the major controlling factors for the groundwater chemistry of the region.

Hydrogeochemical characterization of water mineralization in Tebessa-Kasserine karst system (Tuniso-Algerian Transboundry basin)

Carbonate aquifers provide large parts of the water supply for more than a quarter of the world’s population. The geochemical assessment of these heterogeneous aquifers is a valuable endeavor to ensure a rational management and protection of groundwater resources. To secure its durability, regard to increasing water demands and climate challenges make the problem of prevalence of water scarcity, vulnerability, and drought conditions extremely complicated. In Tebessa–Kasserine basin (Tuniso-Algerian international border), karst aquifers are receiving increasing interest, as the area has typical karst landscape and the hydrogeological system mostly consists of carbonates formation. Thus, a thorough understanding of aquifer behavior and water mineralization origin using geochemical and statistical tools can lead to relevant information regarding karst processes, groundwater chemistry, and protection. Subsequently, this study represents a pioneer baseline of the hydrogeochemical characterization of karst features in this international border area and it aims to identify the origin of karst water mineralization, its spatial distribution, and factors influencing water composition. The hydrogeochemical assessment of the sampled waters shifts from low mineralized Ca-HCO3 waters to Ca-SO4 and Na–Cl water types. TDS values range from 10 to 490.66 mg/l. A Gibbs diagram indicates that karst waters have been recently recharged by direct rainfall infiltration. Water quality gets modified along pathways and dissolution, formations weathering, and ion exchange processes seem to be the predominant geochemical factors influencing water mineralization. The PCA confirms the spatial variability of water types and indicates that it largely depends on aquifer lithology and on geographical position of water points.

Geochemical evaluation of thermal springs in Odisha, India

The Indian state of Odisha has a number of thermal springs. These thermal springs are located at eight places (Attri, Tarabalo, Deulajhari, Magarmuhan, Bankhol, Badaberena, Taptapani and Boden) and belong to Mahanadi Geothermal Province, which is an Archean/Pre-Cambrian Geothermal Province. The thermal water discharging from these springs shows moderately acidic to moderately alkaline character (pH: 5.05–8.93) and the temperature ranges from 28 (Boden) to 58 °C (Tarabalo). Total dissolved solids (TDS) also shows a wide variation between 16.9 (Bankhol) and 595 mg/L (Deulajhari). A wide variation in the chemical characteristics of the thermal waters has been observed as they are located in different geological settings. Based on water chemistry, all the thermal springs can broadly be grouped into three water types: Na–Cl, Ca–HCO3 and Na–HCO3. The thermal spring water from Attri, Tarabalo and Deulajhari belongs to Na–Cl water type which is due to the circulation through granitic rocks. Higher concentrations of Cl and F in these thermal waters further suggest limited mixing and longer residence time as compared to the other areas where Ca–HCO3 and Na–HCO3 water types were found. Anion variation diagram clearly indicates that the thermal waters from Attri, Tarabalo and Deulajhari are fast ascending and fall in the mature water field; thus, their chemical signatures can be used to determine the reservoir temperature. However, in other areas, water chemistry is shaped by near-surface groundwater mixing processes and thus the chemical geothermometers may not be applicable to determine the reservoir temperature. No appreciable temporal variations have been observed in the water chemistry of the thermal waters.

Assessment of hydrogeochemistry and contamination of Varamin deep aquifer, Tehran Province, Iran

The present study investigates the hydrogeochemistry and contamination of Varamin deep aquifer located in the southeast of Tehran province, Iran. The study also evaluates groundwater suitability for irrigation uses. The hydrogeochemical study was conducted by collecting and analyzing 154 groundwater samples seasonally during 2014. Based on evolutionary sequence of Chebotarev, the aquifer is in the stage of SO4 + HCO3 in the north half of the plain and it has evolved into SO4 + Cl in the south half. The unusual increase in TDS and Cl− toward the western boundaries of the aquifer indicates some anomalies. These anomalies have originated from discharge of untreated wastewater of Tehran city in these areas. The studied aquifer contains four dominant groundwater types including Na–Ca–SO4 (55%), Na–Ca–HCO3 (22%), Na–Cl (13%) and Ca–Cl (10%). The spatial distributions of Na–Cl and Ca–Cl water types coincide with observed anomalies. Ionic relationships of SO42− versus Cl− and Na+ versus Cl− confirm that water–rock interaction and anthropogenic contribution are main sources of these ions in the groundwater. The main processes governing the chemistry of the groundwater are the dissolution of calcite, dolomite and gypsum along the flow path, and direct ion exchange. Reverse ion exchange controls the groundwater chemistry in the areas contaminated with untreated wastewater. Based on Na% and SAR, 10.3 and 27% of water samples are unsuitable for irrigation purposes, respectively. Regarding residual sodium carbonate, there is no treat for crop yields. Only 6% of water samples represent magnesium adsorption ratios more than 50% which are harmful and unsuitable for irrigation.

Fluoride and iodine enrichment in groundwater of North China Plain: Evidences from speciation analysis and geochemical modeling

To better understand the enrichment of fluoride and iodine in groundwater at North China Plain (NCP), speciation analysis and geochemical modeling were conducted to identify the key hydrochemical processes controlling their mobilization in groundwater system. Groundwater fluoride and iodine concentrations ranged from 0.18 to 5.59mg/L and from 1.51 to 1106μg/L, respectively, and approximately 63% and 32.3% of groundwater fluoride and iodine were higher than the guidelines for drinking water (1.5mg/L and 150μg/L). High fluoride concentration (>1.5mg/L) can be detected in groundwater from the flow-through and discharge areas of NCP, and high iodine groundwater (>150μg/L) is mainly scattered in the coastal area. Na-HCO3/Cl type water resulted from water-rock interaction and seawater intrusion favors fluoride and iodine enrichment in groundwater. Speciation analysis results indicate that (1) fluoride complexes in groundwater are dominated by free fluoride, the negative charge of which favors fluoride enrichment in groundwater under basic conditions, and (2) iodide, iodate and organic iodine co-occur in groundwater at NCP with iodide as the dominant species. The geochemical modeling results indicate that groundwater fluoride is mainly associated with the saturation states of fluorite and calcite, as well as the adsorption equilibrium onto goethite and gibbsite, including the competitive adsorption between fluoride and carbonate. Groundwater iodine is mainly controlled by redox potential and pH condition of groundwater system. Reducing condition favors the mobilization and enrichment of groundwater iodide, which has the highest mobility among iodine species. Under reducing condition, reductive dissolution of iron (oxy)hydroxides is a potential geochemical process responsible for iodine release from sediment into groundwater. Under (sub)oxidizing condition, as groundwater pH over the ‘point of zero charge’ of iron (oxy)hydroxides, the lowering adsorption capacity of groundwater iodide/iodate on minerals leads to the release of sediment iodine into groundwater.

Identification of hydrogeochemical processes and pollution sources of groundwater resources in the Marand plain, northwest of Iran

The main aims of the present study are to identify the major factors affecting hydrogeochemistry of groundwater resources in the Marand plain, NW Iran and to evaluate the potential sources of major and trace elements using multivariate statistical analysis such as hierarchical clustering analysis (HCA) and factor analysis (FA). To achieve these goals, groundwater samples were collected in three sampling periods in September 2013, May 2014 and September 2014 and analyzed with regard to ions (e.g., Ca2+, Mg2+, Na+ and K+, HCO3−, SO42−, Cl−, F− and NO3−) and trace metals (e.g., Cr, Pb, Cd, Mn, Fe, Al and As). The piper diagrams show that the majority of samples belong to Na–Cl water type and are followed by Ca–HCO3 and mixed Ca–Na–HCO3. Cross-plots show that weathering and dissolution of different rocks and minerals, ion exchange, reverse ion exchange and anthropogenic activities, especially agricultural activities, influence the hydrogeochemistry of the study area. The results of the FA demonstrate that 6 factors with 81.7% of total variance are effective in the overall hydrogeochemistry, which are attributed to geogenic and anthropogenic impacts. The HCA categorizes the samples into two clusters. Samples of cluster C1, which appear to have higher values of some trace metals like Pb and As, are spatially located at the eastern and central parts of the plain, while samples of cluster C2, which express the salinization of the groundwater, are situated mainly westward with few local exceptions.

Impact of reclaimed water in the watercourse of Huai River on groundwater from Chaobai River basin, Northern China

Reclaimed water is efficient for replenishing the dry rivers in northern China, but regional groundwater may be at risk from pollution. Therefore, samples of reclaimed water, river water, and groundwater were collected at the Huai River in the Chaobai River basin in 2010. The water chemistry and isotopic compositions of the samples were analyzed in the laboratory. The reclaimed water had stable compositions of water chemistry and isotopes, and the Na·Ca-HCO3·Cl water type. The water chemistry of the river water was consistent with that of the reclaimed water. A June peak of total nitrogen was the prominent characteristic in the shallow groundwater, which also had the Na·Ca-HCO3·Cl water type. However, the water chemistry and isotopes in most of the deep groundwater remained stable, and the water type was Ca·Mg-HCO3. The amount of reclaimed water recharging the groundwater was about 2.5 × 107 m3/yr. All of the shallow groundwater was impacted by the reclaimed water, with the mixing proportion of reclaimed water ranging from 42% to 80 % in the dry season and from 20% to 86% in the wet season. Only one deep well, with proportions of 67% (dry season) and 28% (wet season), was impacted. TDS, EC, and major ions (Na, K, Cl, NH4-N, NO2-N, and NO3-N) were increased in the impacted wells.

Assessment of groundwater quality and its suitability for agricultural usage in and around Rangampeta area, Andhra Pradesh, south India

The aim of this study is to assess the groundwater quality of Rangampeta area for irrigation and domestic purposes. The groundwater samples were analyzed for distribution of chemical elements Ca, Mg, Na, K, Si, HCO3, CO3, Cl and SO4. It also includes pH, electrical conductivity, total hardness, non carbonate hardness and total alkalinity. The parameters like sodium absorption ratio, adjusted sodium absorption ratio, sodium percentage, potential salinity, permeability index and residual sodium carbonate were calculated. The dominant hydrochemical facies of groundwater are Ca–Mg–Cl and Na–Cl Water Types. The Gibbs’s diagram plots suggest that the chemical weathering of rock forming minerals is the major driving force controlling water chemistry in this area. The positive chloro-alkaline indices revealed that the groundwater has suffered ion exchange between Na and K of water with Ca and Mg of soil during its flow.

Analysis and Assessment of Hydrochemical Characteristics of Maragheh-Bonab Plain Aquifer, Northwest of Iran

The present study aims at assessing the hydrochemistry of the groundwater system of the Maragheh-Bonab Plain located in the East Azarbaijan Province, northwest of Iran. The groundwater is used mainly for drinking, agriculture and industry. The study also discusses the issue of the industrial untreated wastewater discharge to the Plain aquifer that is a high Ca-Cl water type with TDS value of about 150 g/L. The hydrogeochemical study is conducted by collecting and analyzing the groundwater samples from July and September of 2013. The studied system contains three major groundwater types, namely Ca–Mg–HCO3, Na–Cl, and non-dominant water, based on the analysis of the major ions. The main processes contributing to chemical compositions in the groundwater are the dissolution along the flow path, dedolomitisation, ion exchange reactions, and the mixing with wastewater. According to the computed water quality index (WQI) ranging from 25.45 to 194.35, the groundwater in the plain can be categorized into “excellent water”, “good water”, and “poor water”. There is a resemblance between the spatial distribution of the WQI and hydrochemical water types in the Piper diagram. The “excellent” quality water broadly coincides with the Ca-Mg-HCO3 water type. The “poor” water matches with the Na–Cl water type, and the “good” quality water coincides with blended water. The results indicate that this aquifer suffers from intense human activities which are forcing the aquifer into a critical condition.