Document Type : Case Study
Authors
1 Department of Geology, Faculty of Earth Sciences, Shahid Chamran University, Ahvaz, Iran
2 Department of Geology, Faculty of Earth Sciences, Shahid Chamran University , Ahvaz, Iran
3 Department of Mineral and Water Geology, Faculty of Earth Sciences, Shahid Beheshti University, Tehran, Iran
Abstract
The drinking water for Izeh, a city in Khuzestan, is sourced from karstic wells, which are affected by nitrate contamination due to a hydrogeological connection with the alluvial aquifer. This study investigates the variations in nitrate, ammonium, and nitrite concentrations in the urban aquifer and evaluates the denitrification process. Groundwater samples were collected from nine wells over six bi-monthly periods in the 2023-2024 water year to analyze various hydrochemical parameters. Results indicate that agricultural practices, particularly the application of chemical fertilizers, significantly increased nitrate levels from December 2023 to April 2024, with concentrations ranging from 14 to 152 mg/L. Notably, the northern area near the Miangaran wetland exhibited severe pollution from urban wastewater, resulting in intense denitrification and the lowest nitrate levels among the wells studied. The aquifer's hydrochemistry is influenced by gypsum from the Gachsaran formation, with sulfate, BOD, and COD playing significant roles in nitrate concentration, while nitrite and ammonium show limited correlation. The influx of nitrate from wastewater highlights the fluctuations in groundwater quality. Denitrification rates vary across the city, being highest in the northeastern region (depths < 5 m) and lowest in the southwestern area (depths 15-25 m). Overall, the study emphasizes the need for strategies to manage nitrate pollution in Izeh's drinking water supply.
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