Constraints on water chemistry by chemical weathering in the Lake Qinghai catchment, northeastern Tibetan Plateau (China): clues from Sr and its isotopic geochemistry

Jin, Zhangdong; Yu, Jimin; Wang, Sumin; Zhang, Fei; Shi, Yuewei; You, Chen-Feng

Constraints on water chemistry by chemical weathering in the Lake Qinghai catchment, northeastern Tibetan Plateau (China): clues from Sr and its isotopic geochemistry | Impact de l’altération météorique sur la chimie de l’eau du bassin versant du lac Qinghai, Nord-Est du Plateau tibétain (Chine): indications fournies par Sr et ses isotopes Condicionamientos en la química del agua por meteorización química en la cuenca del Lago Qinghai, en el noreste de la meseta Tibetana (China): Claves a partir del Sr y su geoquímica isotópica 青海湖流域化学风化对水化学组成的制约 : 来自Sr及其同位素地球化学的线索 Constrangimentos à qualidade química da água em função da meteorização química na bacia do Lago Qinghai, Nordeste do Planalto Tibetano (China): inferências a partir do Sr e dos seus isótopos geoquímicos Контроль химического выветривания водяной химией в бассейне озера Цинхая: Ниточки от геохимии Sr и его изотопов

2009

Lake water, river water, and groundwater from the Lake Qinghai catchment in the northeastern Tibetan Plateau, China have been analyzed and the results demonstrate that the chemical components and ⁸⁷Sr/⁸⁶Sr ratios of the waters are strictly constrained by the age and rock types of the tributaries, especially for groundwater. Dissolved ions in the Lake Qinghai catchment are derived from carbonate weathering and part from silicate sources. The chemistry of Buha River water, the largest tributary within the catchment, underlain by the late Paleozoic marine limestone and sandstones, constrains carbonate-dominated compositions of the lake water, being buffered by the waters from the other tributaries and probably by groundwater. The variation of ⁸⁷Sr/⁸⁶Sr ratios with cation concentrations places constraint on the Sr-isotopic compositions of the main subcatchments surrounding Lake Qinghai. The relative significance of river-water sources from different tributaries (possibly groundwater as well) in controlling the Sr distribution in Lake Qinghai provides the potential to link the influence of hydrological processes to past biological and physical parameters in the lake. The potential role of groundwater input in the water budget and chemistry of the lake emphasizes the need to further understand hydrogeological processes within the Lake Qinghai system.

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