The AbKharvar channel is 7 km long in Behbahan Plain located in an arid to semi-arid zone. Since it has restricted water resources, preserving its quality is very important. To investigate the contamination possibility, 6 places were sampled in the studied area. The water samples were analyzed for heavy elements As, Fe, Pb, Se, Zn, Mn, Cr, anions Cl-, SO42-, NO3-, CO3-, HCO3-, and cations Ca2+, Na+, Mg2+, K+, And important water quality parameters including Ph, EC, and TDS, using ICP-OES, FAES, OAS, titration, drying and conductivity methods. The pH levels in all samples are within the WHO standard and the standard of wastewater discharged to surface water and agricultural uses. The concentration of SO42- anion and Mg2+, Na+, Ca2+ cations, and important water quality factors including EC, and TDS in the sample taken from the Maroon River (S6) exceeds the allowed levels of WHO standard for drinking water. Geochemical data show that water chemistry is influenced by processes including evaporation, water-rock interactions, and human activities.

Dasht Gour is located in the northeast of Bushehr province and the study area of Dalki-Shabankare. In the past, this plain had good potential in quantity and quality, and now, with 303 unauthorized agricultural wells, it is considered one of the prohibited and critical plains. Through the selective monitoring network with 26 exploitation wells and the analysis of underground water samples in a period of 9 years (1388-1397), the hydrogeochemical characteristics of the Dasht Gour aquifer were analyzed. The analysis of hydrogeochemical diagrams and maps in the Arc GIS environment showed that in the studied aquifer, the dominant anion is sulfate, and the dominant cation is calcium. Total dissolved solids have increased to 355 mg during the nine years. The waters are mainly calcium sulfate, and salinity has increased by 1221 units with an annual average of 136 microsiemens/cm. The influencing factor and water quality control is the presence of the Aghajari formations and Bakhtiari conglomerate.

In order to assess the quality of Fariman-Torbat-e-Jam groundwater resources and investigate the factors affecting the quality of groundwater, 26 groundwater samples (depth of tube wells between 70 and 260 m) were collected and analyzed for major ios, nitrate, and potentially toxic elements. pH and electrical conductivity were measured at the field. The type and facies of the samples changed from Na-HCO3 in the recharge zone to Na-Cl in the middle of the plain, and finally to Na-SO4 in the discharge zone. The results indicated the water equilibrium with carbonate minerals (calcite, dolomite, and aragonite); evaporation, dissolution and reverse ion exchange are the natural factors affecting the chemical composition of the samples. The study samples are classified as intermediate to high saline waters (class III, EC between 1300-3000 µs/cm) and are suitable for irrigation crops which can tolerate saline waters. The calculation of water quality index (WQI) revealed that the groundwater of the recharge zone (exposure of limestone rock units) is suitable for drinking usage, whereas the quality samples collected from the discharge zone (exposure of shale and evaporate rock units) is too weak. Calculation of Langelier Index indicated that the samples are not suitable for industrial applications. The Torbat-e-Jam aquifer is polluted with As, Pb (>10 µg/l), and Cd (>3 µs/cm) mainly because of natural (exposure of shales and volcanic rocks) and anthropogenic factors (agricultural practices and discharge of residential wastewaters.

AbstractThe Ziarat River is one of the tributaries of the Qarah-su catchment, and a part of this river flows through Gorgan City. To investigate the environmental HYDROGEOCHEMISTRY of the river, 11 water samples were collected. Physicochemical parameters, the concentrations of major ions and metals, and the biological parameters were analyzed. The obtained results show that pH and EC of the water samples vary from 7.2 to 7.9, and from 701 to 1422 μS/cm, respectively. The highest pH and EC values were observed near the discharging point of cowshed effluents and the Ziarat hot spring, respectively. Based on hydrogeochemical studies, the chemical composition of water samples is mainly controlled by the dissolution process. The water type changed from Ca-SO4 upstream to Na-Cl downstream, probably because of natural and anthropogenic factors.Regarding the major ion concentrations, all water samples are in the acceptable range for drinking usage. Based on the Wilcox diagram, and regarding the calculated residual sodium carbonate and sodium percentage values, the studied water samples are suitable for drinking and agricultural purposes; however, regarding the values of the magnesium hazard index, most of the samples are not appropriate for agricultural usage. Metal pollution indices show that studied samples are highly polluted, especially those samples that were collected at the wastewater discharge points. The values of dissolved oxygen in all samples are within the permissible limits. However, in some stations, BOD and COD levels are higher than permissible values, and the highest amount of these parameters is observed near the discharging point of the cowshed and agricultural effluents. All water samples are microbially polluted, and the lowest microbial pollution is observed in upstream stations. The values of Water Quality Indices indicate that all studied samples are classified as low and very low quality.  INTRODUCTIONRivers are one of the most important sources of freshwater supply, holding approximately 2000 km3 of water worldwide (Panneerselvam et al., 2021). According to the United Nations report, populationgrowth in urban areas worldwide will be duplicated by 2050, which is associated with negative environmental impacts, including adverse chemical, biological, and physical changes in river water quality (Zhu et al., 2021). Therefore, assessing and monitoring the hydrogeochemical characteristics of rivers are important steps in environmental management. River water quality may change through natural and anthropogenic factors (Hiruy et al., 2022). Wherever rivers pass through large urban areas, severe water contamination is possible due to the input of untreated wastewater as well as urban runoff discharges (Sekharan et al., 2022).The Ziarat River, with a length of about 42 km, is one of the tributaries of the Qarasu watershed in Golestan Province, about 8 km of which flows within the city of Gorgan. The Qarasu River discharges into the Caspian Sea. Ziarat River receives various amounts of untreated sewage and wastewater during its flow path, therefore a significant reduction in water quality is likely. The aims of the present study are: to evaluate the hydrogeochemical quality of the Ziarat River water, to compare the hydrogeochemical characteristics of samples collected upstream and downstream, and to investigate the impact of the pollutant discharges on the water quality.  MATERIALS AND METHODS11 sampling stations were selected based on the geology of the area, land uses, and location of potential pollutant sources. pH, EC, TDS, DO and temperature values were measured in situ. The collected water samples were immediately transported to the laboratory and stored at 4˚C until analysis. The turbidity of the samples was measured by a turbidimeter. The concentrations of Na and K were measured by a flame photometer. Mg, Ca, Cl, and HCO3 values were determined by titration, and the concentrations of SO4, NO3, and PO4 were measured by a spectrophotometer. The concentration of potentially toxic elements in the water samples was measured by an atomic absorption spectrometer (AAS) device. BOD was measured by manometry and COD was determined using a spectrophotometer. A nine-tube MPN 9 method was applied to investigate bacteriological water contamination.  RESULTS The turbidity value of the studied samples varied between 3 and 529 (average value of 163.63) NTU, and except for one sample, the value of this parameter in all samples exceeded the World Health Organization standard (5 NTU). The pH and EC of the samples changes from 7.20 to 7.9, and from 701 to 1422 µS/cm, respectively. Based on pH and EC values, all studied samples were within the permissible limit for drinking and agricultural usage. The TDS values varied between 443 and 898 (average value of 621) mg/L. All studied samples were within the permissible range for drinking in terms of TDS values. The water samples were classified as very hard and hard. The concentrations of major ions in most of the studied samples were within the permissible limit for drinking. Based on the statistical analyses and Saturation Index values, the water chemistry was dominantly controlled by dissolution. While the facies-type of water samples in upstream was Ca-SO4, it changed to Na-Cl downstream. Based on the standard values provided by WHO and regarding the calculated RSC and Na % values, the samples were suitable for drinking and irrigation purposes; however, based on the MH index values, most of the samples are unsuitable for irrigation. HEI index values showed that 64% of the samples were categorized as low level of pollution, 27% as medium level of pollution, and 9% as high level of pollution. The HPI index of water samples also showed that 36% of the studied samples were polluted by potentially toxic elements. The values of Contamination Degree (Cd) showed that 64 % of the studied samples were classified as low level of pollution, 9% as medium level pollution, and 27% as high level of pollution. Overall, the obtained results indicated that the highest level of metal pollution was observed in urban areas. The dissolved oxygen (DO) content of all samples was lower than the permissible value of 5 mg/L. BOD and COD values were higher than the acceptable limits (5 and 10 mg/L, respectively) in about 50% of the studied samples. Moreover, the highest BOD and COD values were measured at the sampling sites adjacent to the discharge of dairy farm effluent and agricultural runoff. All the studied water samples were microbially contaminated. The National Sanitation FoundationWater Quality and Oregon Quality Indices values showed that all samples were of very bad (50>NSFWQI>26) and bad (60>OWQI>0) quality.  DISCUSSION AND CONCLUSIONThe facies and type of water samples were significantly changed because of both natural and anthropogenic factors. The obtained results showed that the water chemistry was mostly controlled by dissolution. Most sampling sites are polluted with potentially toxic elements, and the highest level of metal pollution was detected in sampling sites that were affected by a discharge of urban wastewater. The values of BOD and COD exceeded the permissible limits in about 50% of the sampling sites and their highest values were observed at the discharge site of dairy wastewater and agricultural runoff. All water samples were microbially polluted. The obtained results in the present study show that controlling and managing the input of anthropogenic pollutants into the Ziarat River is of crucial importance to protect the health of water consumers and to reduce the pollutant load entering the Caspian Sea.  REFERENCESHiruy, A.M., Mohammed, J., Haileselassie, M.M., Acharya, K., Butte, G., TamiruHaile, A., Walsh, C., Werner, D. 2022. Spatiotemporal variation in urban wastewater pollution impacts on river microbiomes and associated hazards in the Akaki catchment, Addis Ababa, Ethiopia. Science of the Total Environment, 826, 153912. (In Persian).Panneerselvam, B., Muniraj, K., Thomas, M., Ravichandran, N. and Bidorn, B., 2021. Identifying influencing groundwater parameters on human health associated with irrigation indices using the Automatic Linear Model (ALM) in a semi-arid region in India. Environmental Research, 202, p.111778. https://doi.org/10.1016/j.envres .2021.111778Sekharan, S., Samal, D.R., Phuleria, H.C., Chandel, M.K., Gedam, S., Kumar, R., Sethi, V., Supate, A.R. and Karmakar, S., 2022. River pollution monitoring over an industrial catchment in the urban ecosystem: Challenges and proposed geospatial framework. Environmental Challenges, 7, p.100496. https://doi.org/10.1016/j.envc. 2022.100496Zhu, Y., Chen, Z. and Asif, Z., 2021. Identification of point source emission in river pollution incidents based on Bayesian inference and genetic algorithm: Inverse modeling, sensitivity, and uncertainty analysis. Environmental Pollution, 285, p.117497. https://doi.org/10.1016/j.envpol.2021.117497

Geological constructors and hydrogeclogical characteristics are amang the effective factors in relation to quality of ground water. In this study in order to investigate ground water qualitatively, a number of water resources have been closen and main onions and cations existent in them were measured and also electrical conductivity, total dissolved solid, sodium adsorption ratio and hardness were measured and differences them were investigated. The investigations show that the water is of sodium bicarbonate type. Also investigations of waters in view of pot ability and suitable for irrigation in view of pot ability is between good to medium level, and in view of being suitable for irrigation more than 60 percent of samples are in category S1C2 and S1C3 show between good to medium level.

For better understand of hydrogeochemical processes in the Salmas plain aquifer, this study adopted graphical methods and multivariate statistical techniques to analyze groundwater samples. The results of the Piper diagram and expanded Durov diagram reveals that the major groundwater type is Ca-(Mg)-HCO3 and mixing groundwater type exists in southeast of the Salmas plain. Hierarchical Cluster Analysis (HCA) identified five classes of groundwater type (HC1 to HC5). The hierarchical cluster analysis is able to show the influence of nitrate concentration in classification while the graphical methods cannot. The Stiff diagrams of five classes (HC1 to HC5) show three different sources of groundwater samples. The HC1 to HC3 classes indicate groundwater with limestone and dolomite origin. In HC4 class, Na+ and Clˉ are the dominate ions in groundwater samples and shows saline waters. The HC5 shows mixing groundwater. Using Factor Analysis (FA), we identified three factors that accounted for 85. 03% of the total variance of the dataset. Factors 1 and 2 are reflected the natural hydrogeochemical processes and factor 3 is anthropogenic in the Salmas plain.

In order to study the influence of coal layers in the coal-bearing region of Kerman on the quality of water resources, ten water samples were taken in the north of Kerman and analyzed by ICP-OES method. Chemical analysis showed that in most of samples, there is no contamination of heavy elements of Ag, Cd, Pb, Co, Ni, Sr, Cu, Cr, Zn. Low concentration of heavy elements is due to the fact that groundwater resources are mostly recharged from surface waters of carbonate high mountains. In this condition, surface and contact time with coal layers is not sufficient to lead to contamination. In addition, oxidizing environment has decreased the solubility of most heavy elements. surface adsorption of clay minerals and organic material in the coal-bearing shales may result in elimination of elements in the groundwater indicating of their buffering potential. It appears that because of association of carbon with other biophile elements such as sulfur in coal layers may produce bisulfide ions in reducing condition and provide sulfate ions in oxidizing condition. Reposing coal layers in carbonate formation has created a carbonate-sulfur system in groundwater of the region so that drawing Eh-pH diagrams for water samples indicates that HCO3-,SO42-, and HS- species of dominant anions are present in region groundwater.

Rivers are the key resources for drinking and agricultural purposes and the assessment of water quality is very important. In this study, a detailed investigation has been made for identifying the natural and anthropogenic processes that offected the quality of Gorganrood and its tributaries water in the Gonbad-e-Kavoos district. The Gorganrood is the longest river in the Golestan province (NE of Iran). During previous years, various wastewaters (i. e. domestic, agricultural and industrial) produced in Gonbad-e-Kavoos district have been discharged into the Gorganrood. To evaluate the chemical quality of water in the study area, 37 water and 6 wastewater samples were collected. The physicochemical parameters including pH and EC were determined in situ by an EC/ pH meters. The concentration of major ions was measured using the standard methods. The piper and Wilcox diagrams were used to assess the water type and water quality for irrigation, respectively. Scatter diagrams were used to assess the hydrochemical processes influencing the chemistry of the water samples. Results of this study indicate that the pH and EC values of the water samples decrease in the city district. This is due to the discharge of urban wastewaters with lower EC and pH values which leads to the dilution of the river water. The lower concentration of nitrate in water samples collected in the city district is probably due to the denitrification process. Results show that the prevailing water types of Gorganrood and its tributaries are Na-SO4 2-and Na-HCO3-, respectively. The entrance of tributaries enhances the Gorganrood water quality for drinking and agricultural puposes. Along the river course, the natural processes of halite-gypsum-anhydrite dissolution and ion exchange, as well as anthropogenic factors (discharge of agricultural and urban wastewaters) deteriorate the water quality.

Rudbar Lorestan Dam and Power Plant locates on the High Zagros structural zone, according to the geological map of Iran. The Dalan Formation, Permian age, forms the geological structure of dam body foundation and a portion of its reservoir. Meanwhile, outcrops of an Upper Cretaceous formation, called Sarvak Formation, are exposed out beside the Dalan Formation, due to effect of thrust faults. The main sources of Rudbar Lorestan river are precipitation and drainage of groundwater. The karstification process in carbonate sediments at the site was expected to be expanded well, due to geological and climate conditions. However, based on the evidences of karstic features, which could make a drainage network, have not seen. Both confined and unconfined aquifers present in the site. In this regard, presence of artesian boreholes is a good evidence for confined aquifer. The dominant types of ground water are calcic bicarbonate and sulfate, based on chemical analysis of 22 samples, collected from six sources of water at the site, In this manner, the types of water of the Rudbar river, Kish spring and outlet of access tunnel T2 are calcic bicarbonate, because of recharge from unconfined aquifers and short residence time. However, the type of water of artesian boreholes, i.e. TG-4 and RB-8, and inlet of the access tunnel T2, are calcic sulfate, based on contact of water with sulfate minerals and long residence time in confined aquifers.

Travertine deposits in Azarshahr, NW Iran, are one of the most extensive travertine deposits in the world. The process of travertine deposit is currently active in the several springs. It was used a multidisciplinary approach to determine the source of fluids and structural characteristics of travertine springs. Results of in-situ measurements and type of travertine deposits, demonstrate that the springs are of thermogenic type with hydrothermal sources. Hydrogeochemical diagrams and ionic ratios represent that the type of spring waters are calcium carbonate, with increased sodium and chloride ions levels due to mixing with brine waters. Geophysical studies showed that these brines originated from the Urmia Lake or related brines, which are intruded through fracture systems to relay zones of faults and mixed with hydrothermal bicarbonate-saturated fluids. This phenomenon shows that hydrochemistry of travertine springs are affected by Urmia Lake or related brines.