Hydrochemical characteristics and water quality assessment of snow cover in the northeastern tibet plateau

Abstract

Snow cover as an important water resource is essential for regional water environment system. The Three-Rivers Headwater Region (THR) in the Tibetan Plateau is the source of the Yellow River, the Yangtze River and the Lantsang River with fragile ecological environment and large snow cover. The analysis of hydrochemistry in snow cover can provide reliable data for the research of environmental changes. Snow cover samples in 57 sites across the THR region were collected, and arsenic (As) and major ions were analyzed to investigate the distribution characteristics. The snow cover samples were weakly alkaline with water type of SO4–Cl–Ca–Mg. The As concentration varied from 0.24 to 6.12 μg/L with average value of 1.25 μg/L. Major ions and As have similar distribution characteristics, with higher levels in the northern part of the study area due to anthropogenic influence and special geography. Qualitative and semi-quantitative analysis of snow cover samples based on principal component analysis and absolute principal component score-multiple linear regression indicated that As was substantially controlled by burning of fossil fuels and local mining activities, while major ions mainly derived from terrestrial dust, human activities and marine sources. Although there were different trajectories at the sampling points, the air mass in THR was mainly controlled by the westerly circulation. The water quality of THR was excellent with water quality index <50. This work will shed lights for the migration and transformation of pollutants in the Tibet Plateau and for assessing the impact of human activities on geochemical cycling of pollutants.