| Abstrakt: |
This study presented the geochemical characteristics of surface water in the Khangal river basin near the Erdenet mining area of Mongolia, aiming to study the spatiotemporal hydrochemical characteristics and evaluate the water quality. A total of 20 surface water samples were collected during the summer (June) and fall (September) seasons of 2021 and major ions and pollution indicators were analyzed. 83.3% of all samples were dominated by sulphate ions, of which 50% were sulphate-calcium and 33.3% were sulphate-calcium-magnesium type water. The results of major ions presented spatial and temporal differences. Electrical conductivity (EC) values of the Erdenet and Khangal river were increasing gradually with distance, especially after mixing with wastewater discharges (from the south side) at the Erdenet-3 site and tailing pond seepage water at the Khangal river-1, 2 sites, providing clear evidence of anthropogenic impacts. The water of the Erdenet and Khangal rivers had relatively high mineralization and hardness compared to other rivers in Mongolia, and the class and group were different or sulphate-class predominance. According to the research conducted in recent years, the amount of mineralization and hardness of the Khangal river water increased compared to 46 years ago or before the start of the industry’s operation, the mineralization increased by 2.05 times in 2021, and the chemical composition was changed. Nitrite nitrogen, which is a domestic pollutant, was found relatively high (0.28-0.3 mg/l) in the samples taken from the Erdenet River-3 site, and this was 4.2 times higher than the MNS 4586:1998 standard, and classified as “highly polluted” compared to the Surface Classification Norm. Altanbulag’s water had high mineralization, hardness, and sulphate ion predominance, which may be related to natural origin, but the sudden increase in these parameters indicated a significant influence from tailing pond seepage water. Based on the results, recommendations on how to prevent river water pollution were made and measures to be taken were included. The findings of the study could be useful for water quality management of the basin. [ABSTRACT FROM AUTHOR] |
