Mingyue Li, Xuejun Sun, Shengnan Li, Jie Wang, Zijian Lu, Qianggong Zhang
State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
School of Environmental and Resource Sciences, Shanxi University, Taiyuan 030006, China.
Sci Total Environ. 2024 Apr 1;919:170810. doi: 10.1016/j.scitotenv.2024.170810. Epub 2024 Feb 8.
Mountain glaciers are essential for supplying water resources that sustain downstream communities and livelihoods, yet the hydrogeochemical dynamics at glacier terminals and the impact of glacier retreat on downstream water chemistry are not fully understood. This study addresses this by conducting comprehensive observations and analysis of water chemistry at refined spatial and temporal resolutions in the Lhasa River Valley Glacier No. 1 (LRVG-1) catchment, a vital source of drinking and irrigation water for the local population on the Tibetan Plateau. Our findings reveal a weakly alkaline water environment within this glacierized basin, with HCO and Ca as the dominant anions and cations, respectively, resulting in a hydrochemical pattern classified as HCO-Ca type. Solute concentrations increase along the glacier meltwater pathway, influenced by water-rock interaction, dilution, and diverse sources. The cations are predominantly from carbonate weathering, constituting 72.86 % of the total cations, followed by sulfide oxidation (11.08 %), glacier meltwater inputs (8.13 %), and silicate weathering (7.93 %). The contribution of cations from glacier meltwater diminishes as they travel along the glacier meltwater flow pathway. Our study indicates the localized yet significant impact of glacier meltwater on hydrochemistry, particularly in the vicinity of the glacier terminus. We recommend considering glacial meltwater and the entire glacier watershed as a continuum, essential for understanding the cumulative effects of glacier melt and human activities on water quality. This perspective is crucial for predicting future river chemistry trajectories in high-mountain basins and informing policy-making for water quality conservation across the Tibetan Plateau.
山岳冰川对于提供维持下游社区和生计的水资源至关重要，然而，冰川末端的水文地球化学动态以及冰川退缩对下游水化学的影响尚未得到充分了解。本研究通过对拉萨河谷1号冰川（LRVG - 1）集水区的水化学进行精细空间和时间分辨率的综合观测与分析来解决这一问题，该集水区是青藏高原当地居民重要的饮用水和灌溉水源。我们的研究结果揭示了这个冰川化盆地内弱碱性的水环境，其中HCO和Ca分别为主要阴离子和阳离子，形成了一种被归类为HCO - Ca型的水化学模式。溶质浓度沿着冰川融水路径增加，受到水 - 岩相互作用、稀释和多种来源的影响。阳离子主要来自碳酸盐风化，占总阳离子的72.86%，其次是硫化物氧化（11.08%）、冰川融水输入（8.13%）和硅酸盐风化（7.93%）。随着阳离子沿着冰川融水流路径流动，来自冰川融水的阳离子贡献逐渐减少。我们的研究表明冰川融水对水化学有局部但显著的影响，特别是在冰川末端附近。我们建议将冰川融水和整个冰川流域视为一个连续体，这对于理解冰川融化和人类活动对水质的累积影响至关重要。这一观点对于预测高山盆地未来的河流化学轨迹以及为青藏高原的水质保护政策制定提供信息至关重要。
