Spatiotemporal assessment of water quality and geochemical evolution of Ugii Lake
DOI:
https://doi.org/10.5564/mjgg.v62i46.4151Keywords:
Ugii Lake, Water quality, Geochemical processes, Decision tree, Nitrogen pollutionAbstract
Ugii Lake, a shallow freshwater body in Mongolia’s semi-arid steppe zone, plays an important ecological and socioeconomic role. However, its water quality is increasingly influenced by both natural variability and human-induced pressures. This study investigates the seasonal and spatial dynamics of water chemistry in Ugii Lake by analyzing samples collected during three key periods November 2023 (late autumn), June 2024 (summer), and January 2025 (winter). A total of 24 samples were analyzed for major ions, nitrogen compounds, and supporting physicochemical indicators. To understand the processes shaping the lake’s hydrochemistry, we employed a combination of Piper diagram, ion ratio-based mixing, scatter plots, and multivariate statistical tools, including hierarchical cluster analysis (HCA) and decision tree modeling. The findings revealed that Ugii Lake water predominantly belongs to the Ca–Mg–HCO₃ type, consistent with carbonate and silicate mineral weathering. Notably, fluoride concentrations in several samples exceeded WHO drinking water guidelines, indicating possible natural geogenic enrichment. Ammonium levels were also elevated in certain areas, suggesting localized organic input or anthropogenic sources. Cluster analysis grouped water samples primarily by season, highlighting strong temporal patterns in water chemistry rather than spatial ones. Meanwhile, the decision tree analysis identified magnesium, fluoride, and ammonium as key predictors of total nitrogen concentrations, underscoring their geochemical and possibly anthropogenic origin.
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Copyright (c) 2025 Uuriintuya Gantsetseg, Odsuren Batdelger, Narangerel Serdyanjiv, Batnyam Tseveengerel, Odbaatar Enkhjargal, Purevsuren Munkhtur, Davaagatan Tuyagerel, Chao Han, Cheng Liu, Zhaode Wang
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