Kurdistan University of Medical Sciences Journal of Advances in Environmental Health Research 2676-3478 9 3 2021 07 01 Assessment of Groundwater Quality in the Jajrood River Basin, Tehran, Iran: A Coupled Physicochemical and Hydrogeochemical Study 237 254 133303 10.32598/JAEHR.9.3.1221 EN Maeyan Givi Department of Environmental Health Engineering, Faculty of Public Health and Biomedical Engineering, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran. 0000-0002-0219-2507 Mahsa Jahangiri-Rad Water Purification Research Center, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran. 0000-0002-1626-4014 Hamidreza Tashauoei Department of Environmental Health Engineering, Faculty of Public Health and Biomedical Engineering, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran. 0000-0002-2754-8709 Journal Article 2021 05 08 <strong>Background:</strong><strong> </strong>The physicochemical composition of groundwater is affected by the quantity and quality of surrounding aquifers which are in turn recharging from adjacent river waters.<br /><strong>Methods: </strong>In the present study, 20 surface and 16 groundwater samples were collected in pre- and post-monsoon season from the Jajrood River basin, Tehran, Iran. The samples were analyzed for 18 physicochemical water quality characteristics to assess the river and groundwater qualities. Hydrogeochemical analyses of groundwater samples were also performed to determine the Water Quality Index (WQI) for drinking and evaluate factors governing the water quality characteristic in the study area. Accordingly, the Piper diagram and Gibbs and Chadha plots were drawn to assess seasonal variations in hydrochemical facies and processes in the basin. Subsurface soil samples were also examined with respect to the structure, elemental composition, and multi-elemental trace analysis.<br /><strong>Results:</strong> Results showed the abundance of major ions in the order of Ca⁺² >Na⁺>Mg⁺²>K⁺ for cations and HCO₃^- >SO₄^2- >Cl^- >NO₃^- >F^- for anions. In general, all drinking groundwater samples met WHO permissible limits except for Chemical Oxygen Demand (COD) and HCO₃^-. Moreover, the water is categorized as Ca-Mg-HCO₃ type. Subsurface soil analyses demonstrated quartz and calcium carbonate as the main phases of soil structure, suggesting the enrichment of groundwater with temporary hardness.<br /><strong>Conclusion:</strong> Overall, the groundwater quality was suitable for drinking and agricultural activities. https://jaehr.muk.ac.ir/article_133303_82579bca5a0c3deb6bd3e431df08cf32.pdf