长江上游侵蚀作用的水文地球化学及锶同位素

The elementary compositions of river water in Yangtze River source area, which are derived from rain, snow, evaporate, carbonate and silicate. Major cations in main tributaries of Tongtian River named Chumar River and Tuotuo River, Na+, Ca2+ and Mg2+, account for 97% or above in total cation. Ratios of Ca/Na, Mg/Na and K/Na are relatively low, and specific value of 87Sr/86Sr ranges from 0.708954±20 to 0.711860±11, which shows that elementary compositions of rivers next to Yangtze River source area mainly come from evaporate rocks. Major cations of Tuotuo River source area originated from north slope of Tanggula Mountain, Ca2+, Mg2+ and Na+, account for 97% which are more than Chumar River.. But the ratio of Ca/Na, Mg/Na and K/Na is relatively high, and 87Sr/86Sr were changes from 0.705534±16 to 0.722856±14, which includes that elementary compositions of rivers are mostly from carbonate and silicate. By analyzing the data, it's know that Na+ and Cl- rooted in evaporate occupy dominant position of chemical composition in Yangtze River source area. Further more, Cl- content of river water drops off markedly from upstream to downstream, which just is the showing of feature that chemical erosion on evaporate rocks is relatively strong in river source area under high sea level -frigid and arid area. Using mass balance equation (Zriv = Zrw + Zsil + Zcar + Zeva), hydrochemistry component and isotope fractionation and inversion theory is applied to analyze the characteristic for sediment sand, suspended and dissolved load. End-member values of silicate rock and carbonate rock are confirmed by analyzing the relation between Sr isotope ration and major element value, and different river water element content proportion in carbonate rocks and silicate rocks can be rough estimated.

研究长江上游河水中悬移质和溶解质中主要元素、微量元素与锶同位素比值的变化，雨水化学万分贡献和沿岸石风化的化学成分与锶同位素比值变化。分析河水中悬移质和溶解质来源，计算各类岩石的风化速率、河流侵蚀速率。探讨人类活动、青藏高原抬升和全球温室效应对河流侵蚀作用的影响建立长江上游物质运移平衡数据库。.