The decline in water quality, particularly in river water, is a significant concern, especially in semi-arid areas and tourist destinations such as Ladakh. Periodic assessment of water quality could be a crucial step for ensuring its potability and serve as a foundation for formulating effective policies for sustainable water resource management. Consequently, this research aimed to analyze the periodic variations in the water quality of Indus River for domestic and agricultural use, focusing on the impact of geochemical processes within the basin. Various physicochemical parameters namely temperature, pH, electrical conductivity, turbidity, total dissolved solids, total hardness, total alkalinity, K+, Na+, Mg2+, Ca2+, Cl−, SO42−, SiO2, HCO3−, CO32−, and NO3− for sixty-five water samples from seven key locations were assessed during three distinct periods: April–May (early melting period, EMP), July–August (peak melting period, PMP), and October–November (late melting period, LMP), 2023. The ion contents found were in the following order: Ca2+ > Na+ > Mg2+ > K+ and HCO3− > SO42− > Cl− > SiO2 > NO3− > F−, reflecting Ca-HCO3 water types. However, temporal and spatial variation in ion content and hydrochemical facies were observed when the water moved downstream and confluences with the Zanskar River to give calcium‑magnesium-sulphate facies. Water quality indices- Canadian Council of the Ministers of the Environment Water Quality Index (CCMEWQI) and Weighted Arithmetic Water Quality Index (WAWQI) were employed to assess the water quality over these periods, identify long-term trends, evaluate the water quality status, and provide insights into immediate conditions. WAWQI values recorded for EMP (56.89–509.53), PMP (289.82–3419.23), and LMP (55.16–159.14) found were poor to unsuitable for drinking while using CCMEWQI, it was in the marginal range. Additionally, the Wilcox diagram and other important irrigational indices like Percent sodium, Sodium Absorption Ratio, Residual Sodium Carbonate, Magnesium hazard, Permeability Index, Kelly's ratio, Ryznar stability index indicated the suitability of the water for agricultural use in all the periods. Apart from arsenic (54 μg/L), all other heavy metal ions measured were within the permissible limits according to the Heavy Metal Pollution index. Principal Component Analysis identified different principal components contributing to the hydrochemistry of the river water whereas correlational analysis was conducted to understand the correlation among different parameters and their potential source in water. Rapid carbonate mineral reactions and sulphate reduction were found to affect the alkalinity and hardness of the water. This study will serve as a scientific reference and methodological guide for researchers- to understand water chemistry; committee awareness on health and agricultural impacts; and policymakers for decision-making on water use, policy, and conservation.

中文翻译：

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印度拉达克半干旱地区印度河水文地球化学调查和水质评价


水质下降，尤其是河水质量下降，是一个重大问题，尤其是在半干旱地区和拉达克等旅游目的地。定期评估水质可能是确保其可饮用性的关键步骤，并作为制定可持续水资源管理有效政策的基础。因此，本研究旨在分析印度河家庭和农业用水水质的周期性变化，重点关注流域内地球化学过程的影响。在三个不同的时期评估了来自 7 个关键地点的 65 个水样的各种物理化学参数，即温度、pH 值、电导率、浊度、总溶解固体、总硬度、总碱度、K+、Na+、Mg2+、Ca2+、Cl−、SO42−、SiO2、HCO3−、CO32− 和 NO3−：4 月至 5 月（早期熔化期，EMP）、7 月至 8 月（熔化高峰期，PMP）和 10 月至 11 月（晚期熔化期、 LMP），2023 年。发现的离子含量按以下顺序排列：Ca2+ > Na+ > Mg2+ > K+ 和 HCO3− > SO42− > Cl− > SiO2 > NO3− > F−，反映了 Ca-HCO3 水的类型。然而，当水向下游移动并与 Zanskar 河汇合时，观察到离子含量和水化学相的时间和空间变化，形成钙-镁-硫酸盐相。水质指数 - 加拿大环境部长理事会水质指数 （CCMEWQI） 和加权算术水质指数 （WAWQI） 用于评估这些时期的水质，确定长期趋势，评估水质状况，并提供对即时状况的见解。EMP （56.89–509.53）、PMP （289.82–3419.23） 和 LMP （55.16–159） 记录的 WAWQI 值。14） 发现使用 CCMEWQI 时较差或不适合饮用，处于边缘范围内。此外，Wilcox 图和其他重要的灌溉指标，如钠百分比、钠吸收率、残余碳酸钠、镁危害、渗透率指数、凯利比率、Ryznar 稳定性指数表明水在所有时期都适合农业使用。除砷 （54 μg/L） 外，所有其他测得的重金属离子均在重金属污染指数的准许限度内。主成分分析确定了影响河水水化学的不同主成分，而进行相关性分析以了解不同参数与其在水中的潜在来源之间的相关性。发现碳酸盐矿物的快速反应和硫酸盐还原会影响水的碱度和硬度。这项研究将作为研究人员的科学参考和方法指南——了解水化学;委员会对健康和农业影响的认识;以及政策制定者在用水、政策和保护方面做出决策。