@article { author = {Daneshian, Hassan and Kalantari, Nasrollaha and Alijani, Farshad}, title = {Hydrochemistry and Stable Isotopes Characteristics of Groundwater in an Urban Aquifer, Southwest of Iran}, journal = {Geopersia}, volume = {11}, number = {1}, pages = {81-100}, year = {2021}, publisher = {University of Tehran}, issn = {2228-7817}, eissn = {2228-7825}, doi = {10.22059/geope.2020.294287.648520}, abstract = {The effect of different recharge sources on the chemical evolution of an urban aquifer, Behbahan plain, southwest of Iran, has been studied using hydrogeochemistry and stable isotopes (18O and 2H). Groundwater samples were collected from 40 water wells in June 2017 and April 2018 as the dry and wet periods, respectively. The water samples were analyzed for the determination of major ions, nitrate, fluoride, and bromide for both periods and stable isotopes concentrations only for the dry period. The main hydrochemical characteristics of groundwater sources in the Behbahan plain were determined as natural groundwater recharge (R) and discharge (D) areas, Marun (M) and Bonehbasht (B) irrigation and drainage networks, contact with gypsum bedrock (G) of the Gachsaran formation, and waste water of Behbahan City (T). The hydrochemical maps of electrical conductivity, chloride, ionic ratios, stable isotopes, and nitrate concentrations was investigated to determine anomalous groundwater zones associated with urban sources of groundwater pollution. Characteristic bivariate composition diagrams and cluster analysis (CA) method were employed to identify the hydrochemical processes and to evaluate the recharge sources. Two major water types Ca–SO4 and Ca (Na)–SO4(Cl) were present in the Behbahan groundwater plain. The high concentrations of SO42–, Ca2+, and Mg2+ were reflected in moderate to high total dissolved solids (TDS) (about 3000 mg/l). The dominant hydrogeochemaical processes in the aquifer were the dissolution of gypsum and somewhat halite, dedolomitization, scant normal and reverse cation exchange, and mixing. The main sources of the nitrate pollution of groundwater were leaching of organic manure applied to cultivated areas as well as wastewater of Behbahan City. The minimum and maximum concentrations of nitrate in groundwater of the Behbahan plain were 5 to 105 mg/Land 5 to 150 mg/L in dry and wet periods, respectively. About one–third of groundwater samples in the Behbahan plain had NO3– concentrations above the drinking water standard (45 mg/L). Five distinct recharge sources were recognized for the Behbahan aquifers based on the characteristics of 2H and 18O isotopes. The hydrochemical characteristics and stable isotope indicators of the groundwater recharge sources are disturbed as a result of the mixing process.}, keywords = {hydrochemistry,stable isotopes,Groundwater,Nitrate,Iran}, title_fa = {-}, abstract_fa = {}, keywords_fa = {}, url = {https://geopersia.ut.ac.ir/article_77006.html}, eprint = {https://geopersia.ut.ac.ir/article_77006_e6b97cce2d1c02bbf095b4067fffe28a.pdf} }