Hydrogeochemical Evaluation Research Articles

Hydrogeochemical evaluation of fractured Limestone aquifer by applying a geochemical model in eastern Nile Valley, Egypt

Rock water interactions play an important role in the flow of groundwater. Groundwater samples were collected from deep production wells with depths ranging from 120 to 230 m. Complete chemical analysis of 40 groundwater samples was collected from the fractured limestone aquifer including major cations (Na+, K+, Ca2+, Mg2+) and major anions (Cl−, SO4 2−, HCO3 −, CO3 2−). A geochemical modeling (NETPATH Software) was applied for environmental simulate net geochemical mass-balance reactions between initial and final waters along a hydrologic flow path. This program simulates selected evolutionary waters for every possible combination of the plausible phases that account for the composition of a selected set of chemical constraints in the system. The groundwater of the Eocene aquifer mainly belongs to fairly fresh water with salinity contents ranging from 228 to 3595 ppm. The measured groundwater levels range between 8 and 25 m near the river Nile to the limestone plateau (eastwards). Consequently, groundwater flows from east to westward toward the river Nile. Groundwater aquifer in the study area is mainly composed of fractured limestone; the saturated states of the PCO2, calcite, aragonite, dolomite, siderite, gypsum, anhydrite, hematite, and goethite in addition to H2 gas were estimated. The undersaturated state of carbon dioxide reflects closed conditions and very low probability of recent recharge, and it reveals also the high tendency of water to precipitates carbonate species. Undersaturation by carbonate minerals is only restricted to some pockets distributed on the different places of the aquifer in the study area. The majority of groundwater samples of Eocene aquifer in the study area indicated that groundwater is not suitable for irrigation with treatment and requires good drainage.

Hydrogeochemical evaluation of Umut geothermal field (SW Turkey)

Tekkehamam geothermal field is located in the South of Menderes Graben (Aegean region) and is one of the most important geothermal sites of Western Anatolia. Umut geothermal field is a part of the Tekkehamam field. This study was conducted in order to determine the origin and hydrogeochemical properties of the geothermal waters. For this purpose, sampling was done in order to check the chemistry of the water, and 18O, 2H isotope analyses done at four wells, nine natural springs and three cold water sources. According to the results of the chemical analysis, the geothermal waters were determined to be of Na + K-SO4 type. Additionally, 14C and 3H analyses were done in selected well and spring waters for the purpose of age determination of groundwater; most of the waters were determined to be submodern. Geothermometer calculations show that the reservoir temperature for the Umut geothermal field ranges between 148 and 180 °C. Stable isotope results indicate that Umut geothermal waters are meteoric in origin. Mixing between shallow and deep waters is the dominant subsurface process that determines the physical and chemical character of the waters.

Recharge sources and hydro geochemical evaluations of Na2SO4 deposits in the Acıgöl Lake (Denizli, Turkey)

Acıgöl Lake is the second largest alkaline lake in the world and is in a region that is one of the most important sodium sulphate production fields in Turkey. The present study focuses on determination of sources of the Na2SO4 deposits with main-trace element contents based on hydro-geochemical studies in the lake basin. The geological and hydrogeological properties of the study area were primarily determined. To identify the hydrogeochemical characteristics of spring/groundwater and lake water, chemical analyses results were evaluated with graphical plots such as Piper, Gibbs and Chadha diagrams and the conceptual hydrogeological model was prepared for the area. Mineral paragenesis of the lake sediments mainly consist of gypsum, aragonite, halite, calcite, dolomite, quartz, muscovite, smectite and illite besides tenardite, mirabilite and bloedite minerals. The dominant hydro geochemical facies are Na-SO4, Na-Cl, Ca-Mg-HCO3 and Ca-Mg-SO4 which are due to water-rock interaction. The mean Na, Ca, SO4, Cl and Mg concentrations in the spring waters are 221.27, 152.62, 374.81, 185.46 and 58.50 ppm respectively; whereas mean concentrations in the lake waters for Na, Ca, SO4, Cl and Mg ions are 22 507, 646, 16 186, 35 691 and 2399 ppm respectively. These major elements have very high concentrations in the lake waters due to the evaporation leading to enrichment. The main mechanism controlling water chemistry in the Acıgöl Lake basin is the process of water–rock interaction. The enrichment of these elements in the springs waters originate from lithological units such as sedimentary, ophiolitic and young magmatic rocks.

Hydrogeochemical characteristics of a volcanic-sedimentary aquifer with special emphasis on Fe and Mn content: A case study in Mexico

Previous studies performed on the volcanic-sedimentary aquifer of the Tenancingo Valley (Mexico) reports high concentrations of Fe, Mn, and NO3−, and water from several wells receives purification treatments due to presence of Fe and Mn. These studies have not achieved conclusive results regarding the origin of Fe and Mn, nor have hydrogeochemical evaluations of the aquifer been performed. The present study aimed to evaluate the physicochemical characteristics of the water and identify the geochemical processes that determine presence of Fe and Mn in groundwater. This characterization was based on physicochemical data from well and spring samples (16 samples) during dry and rainy seasons (June and November 2012, respectively).The EC, temperature and pH ranged from 125 to 793μScm−1, 14.5 to 24.9°C and 6.5 to 8.5pH units, respectively. The Eh values ranged from −219 to 327mV, indicating the existence of both reducing and oxidizing zones. Presence of Fe and Mn was detected in both springs and wells; concentrations were higher in well, exceeding 4mgFeL−1 and 0.5mgMnL−1. Content of Si ranged from 12 to 47mgL−1.A model of the hydrogeochemical behavior of the aquifer was created to highlight the following: i) processes involved in water-rock interactions, including fluctuations in silicate levels that determine anionic and cationic content of water, and ii) redox reactions as the major control processes of Fe and Mn.Water quality for human use is restricted by Fe and Mn content and pH. For irrigation use, significant limitations were not presented.

Assessment of groundwater quality for drinking and agricultural purposes of a few selected areas in Tamil Nadu South India: a GIS-based study

Hydro-geochemical evaluation is becoming very significant to determine the process involved in the chemical evolution of groundwater. Supply of contaminated drinking water in rural communities is a continuing health issue, leading many resource users to unknowingly consume water with elevated levels of harmful chemicals. The process of pollution risk assessment requires the integration of data that are spatially changeable in nature, making geographic information system (GIS) a perfect tool for such assessments. In this study, GIS was applied to evaluate groundwater quality in Nilakottai block which is one of the endemic fluorosis blocks of Tamil Nadu, South India. The obtained maps may assist water quality personnel in managing and controlling pollution of the study area. The suitability of groundwater quality for drinking and agricultural purposes in the selected area was assessed by measuring physicochemical parameters. For this purpose, 55 water samples were collected from different places of the study area. F− ion leaching depends on groundwater chemistry, including pH and concentrations of HCO3 −, Na+, and Ca2+. HCO3 − and F− were found to have good positive correlation (r = 0.400). Hydro-geochemical classification of ground water samples throws more light on the possible link between the presences of various ions and their contribution to groundwater chemistry. The GIS maps clearly show the presence of Na–Cl, mixed Ca–Mg–Cl and Ca–Cl as the predominant species in specific regions having a direct bearing on water quality. The relative concentrations of the ions occur in the order Na+ > Mg2+ > Ca2+ and Cl− > HCO3 − > SO4 2−. Water quality index (WQI) was calculated to determine the suitability of water for drinking purpose. The WQI values revealed that all groundwater samples were above 100, which is the permissible limit and, therefore, waters above this level cannot be used for human consumption. Calculated values of Percent Na (%Na), Sodium adsorption ratio (SAR) and Magnesium hazard (MH) indicate that most of the groundwater samples are not suitable even for irrigation of most crops. Rainwater harvesting techniques should be promoted in this study area. Supply of drinking water within the permissible limit should be emphasized.

Arsenic distribution along different hydrogeomorphic zones in parts of the Brahmaputra River Valley, Assam (India)

The spatial distribution of arsenic (As) concentrations along three classified hydrogeomorphological zones in the Brahmaputra River Valley in Assam (India) have been investigated: zone I, comprising the piedmont and alluvial fans; zone II, comprising the runoff areas; and zone III, comprising the discharge zones. Groundwater (150 samples) from shallow hand-pumped and public water supply wells (2–60 m in depth) was analysed for chemical composition to examine the geochemical processes controlling As mobilization. As concentrations up to 0.134 mg/L were recorded, with concentrations below the World Health Organization and the Bureau of Indian Standards drinking-water limits of 0.01 mg/L being found mainly in the proximal recharge areas. Eh and other redox indicators (i.e., dissolved oxygen, Fe, Mn and As) indicate that, except for samples taken in the recharge zone, groundwater is reducing and exhibits a systematic decrease in redox conditions along the runoff and discharge zones. Hydrogeochemical evaluation indicated that zone I, located along the proximal recharge areas, is characterized by low As concentration, while zones II and III are areas with high and moderate concentrations, respectively. Systematic changes in As concentrations along the three zones support the view that areas of active recharge with high hydraulic gradient are potential areas hosting low-As aquifers.

Evaluation of fluoride enrichment processes in groundwater of Chimakurthy granitic pluton complex in Prakasam District India

Hydrogeochemical evaluation of aquifers belonging to Chimakurthy granitic pluton complex reveals wide spatial and temporal variation in F- distribution. F- concentration in groundwater of different aquifers varies from 1in almost all the samples of three sampling sessions establish silicate weathering. Ca2+/Mg2+, Na+/Ca2+, Ca2+, Mg2+ and HCO3- ratios authenticate carbonate dissolution is responsible for alkali earths addition. Sodic rich and calcium depleted water together with balanced alkalinity has enabled F- enrichment. Presence of fluorite as accessory mineral apart from occurrence of F- in mineral lattice of biotite, hornblende, muscovite, and pyroxene were the potential sources of F- to the percolating pore waters. Though F- was abundantly available in solid solution the receptive hydrochemical character of solute was governing the F- adsorption which could be one of the strong reasons for uneven distribution of F- with in similar petrological setup. Key words: Water-rock interaction, fluoride, groundwater, Chimakurthy, gabbro, hydrogeochemistry.

Impact of intensive groundwater exploitation on an unprotected covered karst aquifer: a case study in Kermanshah Province, western Iran

Islam Abad region, located in the southwestern of Kermanshah Province, is a karst region where over-exploitation from the deep karst water resources has directly affected the water balance of the whole area. Using a combination of geophysical investigations and analysis of well log data and other relevant hydrogeological studies, we looked for the actual relationship between over-exploitation from deep-water wells, penetrated into the covered karst aquifer, and the drying out of some of the main karst springs throughout the study area. In total, 20 piezometric wells and 4 main karst springs have been chosen for groundwater monitoring network. By integrating GIS processing system and a classical water balance method together with hydrogeology and hydrogeochemical spatial maps, critical zones of human impacts on groundwater resources, made by water extraction for agricultural demand, were identified. Results show that water balance in the Islam Abad basin is in clear disequilibrium, since 2.15 mcm of water depletes from the main aquifers of the study area, annually. This volume of water shortage has resulted in a 7 m groundwater level decline in the last decade, which caused both drying out and reduction in discharge rate of some of the main karst springs throughout the study area. Depths of penetration of deep-water wells into the covered karst aquifer vary from 1 to 93 m. Hydrogeochemical evaluations, including ion relations and hydrogeochemical diagrams, show interactions between karst and alluvium aquifers. Results showed a broad connection between these two resources and, therefore any pressure on alluvium aquifer will affect the karst aquifer, especially by excessive deep-water wells drilling in mutual alluvial and covered karst aquifers.

Hydrogeochemical evaluation of groundwater quality and seasonal variation in East Bokaro coalfield region, Jharkhand

Groundwater samples collected from the East Bokaro coalfield of Jharkhand state, India during the dry and rainy seasons of the year 2012. Samples were analyzed for the assessment of groundwater quality in the study area. The results of the chemical analysis indicate that the pH values were found alkaline in nature during both the season. The major cations in groundwater was in the order of Na+>Ca2+>Mg2+>K+ during the dry season while Ca2+>Na+>Mg2+>K+ during the rainy season. The abundance of the major anions was of HCO3->SO42->Cl->NO3->F- did not change on the seasonal basis. The average NO3-concentration was exceeded the desirable limit for drinking water as per Indian standard in the rainy season. Silicate weathering was inferred to be a dominant process, controlling the groundwater chemistry in both seasons, with lesser contributions by carbonate weathering and ion exchange. Leaching of salts from the unsaturated zone also has a major impact on groundwater quality during the rainy season. The water quality data indicate that groundwater is generally suitable for irrigation. However, higher salinity and residual sodium carbonate values at some sites may limit groundwater use and therefore an adequate drainage and water management plan for the study area is required.

Hydrogeochemical processes of fluoride enrichment in Chimakurthy pluton, Prakasam District, Andhra Pradesh, India

Thirty-six groundwater samples were collected from Chimakurthy area, Prakasam District, Andhra Pradesh. On hydrogeochemical evaluation, it was found to be contaminated. Based on fluoride concentration, the samples were segregated into Group A, Group B, and Group C. Fluoride concentration varies from 0.23 to 9.84 mg/l, with the mean value of 2.01 mg/l; 44 % of the tested samples had F− > 1.50 mg/l. Apart from F−, the water was contaminated with NO3 − and Cl− implying both geogenic and anthropogenic pollution of the aquifer. Ionic dominance pattern was unique in samples with low, moderate to high F− concentrations. Na+ and HCO3 − were progressively increasing along with F− from Group A to C, whereas Ca2+ and Mg2+ were depleting. Groundwater facies were unique among different group samples especially in end members with low and high F− concentration suggesting that F− dissolution was strongly influenced by the chemical nature of solution. Na+/Cl− molar ratio was >1, whereas Na+ + K+:Tz+ and Ca2+ + Mg2+:Tz+ ratios were <1 in all samples indicating that Na+ was released from silicate weathering process. It also confirms that F− was contributed from lithogenic sources of aquifer material. Mean molecular ratios of <1 for Ca2+:Mg2+ in Group B samples and 1–1.2 in Groups A and C support that the Ca2+ and Mg2+ were added into aquatic medium by calcite and dolomite dissolution. Contradictory distribution of F− in north (low) and south (high) indicates that availability of F− minerals in aquifer matrix influenced the rate of F− absorption in accompanying water. Variation in F− concentration in groundwater of the core area (south) supports the hypothesis of aquatic chemistry acting as catalyst in F− dissolution into formation waters even though the aquifer was enriched with F− minerals. Very high F− in groundwater in the contact zone of country rock and plutonic intrusive indicates that F− mineralization occurred under geothermal conditions. The fracture network in disturbed and fragile contact zone has facilitated development of potential aquifers and enhancement in F− concentration.

Multidisciplinary approach to evaluate groundwater salinity in Saveh Plain, Iran

Salinity is one of the most important groundwater quality problems in arid and semi-arid regions, such as Saveh Plain, Iran. Principal component analysis and factor analysis (PCA/FA) in collaboration with structural equation modelling (SEM) revealed that Na+, Cl−, EC, TDS, and salinity significantly influenced the groundwater quality in the study area. The spatial distribution map of factor score one represents high loading of salinity on the central, eastern, and south-eastern side of the plain. Groundwater quality evaluation using TDS versus total hardness suggested that around 90 % of the total samples are hard-brackish type, representing their unsuitability for drinking purposes. Ionic abundance is in the order of Na+ > Mg2+ > Ca2+ > K+ and Cl− > SO4 2− > HCO3 −, indicating that the groundwater facies varied from Na–Mg–Ca–Cl, Na–Mg–Cl to Na–Cl types. Hydrogeochemical evaluation showed that the salinity in the groundwater had geogenic sources mostly from the evaporitic formation in the study area. Bivariate plots of Ca2+/Na+ vs HCO3 − and Ca2+/Na+ vs Mg2+/Na+ supported that evaporite dissolution and silicate weathering are the major sources of the salinity process in the Saveh Plain.

Assessing causes of quality deterioration of groundwater in Puttalam, Sri Lanka, using isotope and hydrochemical tools

ABSTRACTExtensive extraction of groundwater has resulted in deterioration of the groundwater quality in the Puttalam area in the northwestern coastal zone of Sri Lanka. This situation led us to carry out the present comprehensive study based on environmental isotopic (18O, 2H, 3H) and geochemical evaluation to understand the root cause for water quality deterioration. The isotopic data suggest that the surface water and shallow groundwaters are subjected to intensive evaporation and, as a result, increase in their salinity. Deep groundwater of the area is mostly recharged by direct infiltration of rainwater and at few places by nearby surface water bodies. The salinity increase of deep groundwater depends on the specific hydrogeological zones and would be due to dissolution of salts which are precipitated in soil through the seawater spray over the time, dissolution of minerals in geological matrix and leaching of salts from salterns. The quality of the deep groundwater is relatively good in the granitic gneiss zone and nearby areas outside the sedimentary aquifer. There is no evidence from isotope and hydrogeochemical evaluation for seawater intrusion into groundwater in the Puttalam area.

First groundwater chemical status assessment of the Buna River-Protected Landscape (Albania)

The Buna River-Protected Landscape is a Managed Nature Reserve and Ramsar site because of its high biodiversity; the water resources at this site represent a crucial element for the ecosystem conservation, especially for the avifauna and ichthyofauna. Water-quality assessment and monitoring are important to the water resource’s ecological value and the health of local populations to improve and promote sustainable agriculture and ecotourism. This paper reports a hydrogeochemical evaluation of sampled waters from the Buna River-Protected Landscape in northern Albania. There exist no previous studies that assess the environmental status of the local groundwater resources. Geochemical surveys of groundwater were conducted in October 2012, and February and June 2013 within the framework of the “International Union of Conservation of Nature”, granted by the Italian Ministry of Foreign Affairs. Twenty samples were analysed to (1) study several parameters with respect to 2000/60/EC and 2006/118/EC, which pose risk for environmental health and (2) evaluate the water quality and all processes that can influence it. The sampled groundwater was classified as calcium bicarbonate, and no evidence of saline intrusion phenomena was obtained, even in the area closest to the coast. Areas with a greater anthropogenic presence show NO3 levels above the European Union thresholds, probably due to the lack of wastewater management systems. A major concern is represented by the widespread presence of organochlorine pesticides, especially with reference to the Hexachlorocyclohexane isomers that have concentrations widely above the thresholds suggested by the European Union.

Orientation hydrogeochemical survey in Jebal-e-Barez area, SE Iran

Geochemical data from 67 spring locations within the 3780 km2, in Jebal-e-Barez area, south eastern of Iran, were analyzed with the purpose of developing a suitable regional geochemical exploration method for Cu–Au ± Mo mineralization in such potential area. Statistical data analyses, graphical methods, and geochemical characteristics of waters and mineral saturation indices were used to identify mineralization potential regions. Hydrogeochemical data of samples suggested that the groundwater is mostly Ca + Mg + HCO3 type (67.16 %). The sulfate-type waters are mainly clustered around the mineralization occurrences. The groundwaters have low concentrations of base metal and Cu, Au, Mo and SO4 can be used as direct indicators of Cu mineralization in study area. Ni is an indicator of Cu mineralization and travertine springs distribution impress the hydrogeochemical evaluation. On this basis, it is concluded hydrogeochemical exploration can be used as an effective regional exploration method.

Hydrogeochemical evaluation of groundwater of Bhaktapur Municipality, Nepal

The present study aims to evaluate groundwater hydrogeochemistry of Bhaktapur Municipality, Nepal with respect to water types, chemical elements and their statistical variability. Samples were collected in pre-monsoon (April–June), monsoon (July–August) and post-monsoon (October–November) seasons in 2007. Laboratory analysis of samples revealed inter-seasonal variability, primarily attributed to hydrogeochemical processes. All or most of the samples exceeded the World Health Organization (WHO) guideline value (GLV) for iron, conductivity and turbidity, while none of the samples exceeded WHO GLV for hardness and arsenic with minor fraction exceeding GLV for chloride content. Higher ammonia content in well water and highest phosphate concentration occurred for stone spout in pre-monsoon season. Principle component analysis highlighted three principle components while the dendrogram divided the sampling sites into four and two clusters, respectively, for well water and stone spout water sampling sites. Saturation index computed through WATEQ4F model revealed that ferrihydrite, siderite, strengite and vivianite minerals were in under-saturated state, while goethite was in supersaturated condition for each type of samples (well water and stone spout water) in both pre- and post-monsoon seasons depicting their tendency to precipitate. High degree of supersaturation in goethite mineral indicated response to temperature gradient of the reactions, while under-saturation for other minerals indicated the effect of dilution.

Hydrogeochemical characterization of the southern sector of the Alburni Massif, Campania region, Italy

The Alburni Massif represents one of the most important karst regions of the Southern Apennines, and it has a high potential as a water resource. This paper reports a hydrogeochemical evaluation of sampled waters from the southern sector of the Alburni Massif (Campania region, Italy). Five water samples were analysed (three from natural springs and two from wells) to i) evaluate the hydrogeochemical properties of the waters in the study area and ii) understand the groundwater flow in this system. Waters sampled were classified as Ca-HCO3 due to enrichment from different alkaline elements (Ara+ + k+) and carbonate (HCO3- + CO32). This classification is in agreement with the lithologies present in this area. Groundwater flow was connected to the fault line passing through the south-west sector of the complex, which divides the Massff into two large structures situated to the east and the west.

Hydrogeochemical evaluation of calcareous eolianite aquifer with saline soil in a semiarid area

The aim of this study is to evaluate the groundwater geochemistry in Burg Elarab area as an example of a calcareous eolianite aquifer that is covered with saline soil in a semiarid climatic condition. To conduct this study, 37 groundwater samples were taped from the production wells in addition to two surface water samples from Mallahet Mariut Lake and Bahig Canal. To elucidate the origin of dissolved ions and the geochemical processes influencing this groundwater, combinations of geomorphological, pedological, hydrogeological, hydrochemical, and statistical approaches were considered. Results suggest that the groundwater flows from both sides of the plain to the central area. Soil type and salinity and the intruded brackish lake water are the main factors controlling the groundwater chemistry. Chemically, the groundwater samples were classified into three groups. Group 1 samples have higher salinity range and characterize the area close to Mallahet Mariut and are influenced by cation exchange processes. Group 2 samples have an intermediate salinity range, occupy most of the plain area, and receive water from direct infiltrations and mixing between different recharge sources. Group 3 samples have low salinity range and limited areal extent and characterize the groundwater flowing from the Mariut Tableland. Reverse ion exchange is the predominant process in the latter group. Calcite precipitation is a general phenomenon characterizing all the groundwater types in the study area.

Hydrogeochemical Evaluation of Groundwater in Ibillo, Akoko-Edo Local Government Area, Edo State Nigeria

Ibillo town, located in Edo State, Southsouth Nigeria, is an important agricultural and commercial center. In recent years, rapid development has created an increase in demand for groundwater and frequently facing water scarcity as well as quality problems. Hydrogeochemical evaluations of ionic abundance in groundwater systems in Ibillo was conducted by collecting a total of 50 groundwater samples for Dry and Rainy seasons, and were subjected to analysis for chemical and microbial characteristics. The study reveal that pH in the area is slightly acidic to alkaline ranging from 5.9 to 8.1. The electrical conductivity and total dissolved solids (TDS) values was noted higher during the rainy season. The abundance of major ions in the groundwater is in the order of K>Na>Ca>Mg =Cl>HCO3>SO4>NO3. Total hardness, Na, Fe, Mn, Cu, Cl, HCO3, SO4, NO3, Fl, NO2 and PO4 do not exceed the WHO permissible limit during both seasons. Ca and Mg in majority of the groundwater samples are within the permissible limit with few exceptions irrespective of seasons. K, Pb and Ni exceed the permissible limit during both seasons while Cr, Zn and Ba concentrations partially conform to the WHO limits irrespective of seasons. Most of the groundwater samples examined have high E. coli and total bacterial counts. A comparison of the results with relevant standards show that the water require various form of treatment to bring the microbial contents to standards required for domestic and industrial uses respectively. The type of water that predominates in the study area is Na-K-Cl type and mixed type. Besides, suitability of water for irrigation is evaluated based on sodium adsorption ratio, sodium percent and salinity hazard. It is observed that majority of samples irrespective of seasons fall in “excellent-good” zone indicating water is fit for irrigation purposes. The groundwater in this study area can be said to be partially good for industrial sectors but it require a little treatment for it to be completely suitable for industry.

Effect of Saline Water Bodies on the Hydrogeochemical Evaluation of Groundwater at Kalpakkam Coastal Site, Tamil Nadu

Abstract Geochemical signatures of groundwater in Kalpakkam plant site were used to identify the geochemistry of the unconfined coastal aquifer. Ground water samples collected from 14 borewells around the study area were studied for four different seasons viz. Summer, South-west monsoon, North-east monsoon and Post-monsoon to identify the major geochemical processes activated in the study area. Data obtained through chemical analyses of groundwater samples were used for graphical plots and geochemical calculations. Piper, Chloro alkaline indices and Chadda’s diagram were determined for geochemical classification of the groundwaters. Identified geochemical processes were verified and quantified using hydrogeochemical aqueous speciation model, PHREEQC to find out the Saturation Indices (SI) of the possible minerals of the study area. It was observed that majority of the bore well samples were under saturated with respect to minerals such as Gypsum, Aragonite and oversaturated with respect to dolomite and calcite. Parameters such as ion exchange and reverse ion exchange, saline water incursion were observed due to the presence of saline water bodies in addition to dissolution of minerals.

Hydrogeochemical evaluation of thermal, mineral and cold waters between Bursa city and Mount Uludağ in the South Marmara region of Turkey

The province of Bursa is located at the juxtaposition of the West Anatolian extensional zone and the middle and southern branches of the North Anatolian Fault in Turkey. Mount Uludağ, which has the highest elevation in Western Anatolia, is also located in the region. The Uludağ Massif, whose age is Oligocene, is a leucogranite pluton where numerous thermal, mineral and cold spring water discharges have been observed. These waters are extensively investigated for the first time in this study. Thermal waters discharge in the center of the city of Bursa, north of the Uludağ Pluton, and are utilized for balneology and spa purposes in hotels, while mineral waters discharge along a narrow tectonic valley southwest of the Pluton. Mineral waters are bottled and marketed by a few companies in the region. Cold spring waters discharge at different altitudes from Uludağ to the Bursa Plain. Temperatures of thermal waters vary between 37 and 80°C in the area of study. Thermal spring waters have been observed of two different compositions due to varying aquifer types: the Çekirge region thermal waters are characterized by Ca–HCO3 type water, while the Kükürtlü region thermal waters, are represented by Na–HCO3 type water, and have the highest temperatures due to deeper zone interaction in the reservoir. Both mineral and cold spring waters are characterized by Ca–HCO3 type water. In the study area, electrical conductivity values vary from 556 to 1352μS/cm in thermal waters, while cold water values change between 37 and 472μS/cm, and mineral and brackish waters values vary from 1402 to 4500μS/cm. Investigation of water–rock interaction effects shows different values for thermal and mineral waters. The δ18O values of thermal waters in the region are between −10.09 and −10.87‰, whereas the δ18O values of mineral waters are between −7.14 and −8.81‰. Isotopic signatures of all springs suggest a local meteoric origin of the feed waters from higher levels of the Uludağ Pluton. In the study area, the most effective water–rock interaction can be observed in mineral waters. An additional important process is cold water mixing; creating low thermal water temperatures in the study area. Thermal waters in the region show a close relationship with surface water and this effect can be clearly monitored by physical, chemical and isotope analyses during rainy seasons.