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首页> 外文期刊>Geochimica et Cosmochimica Acta: Journal of the Geochemical Society and the Meteoritical Society >Chemical weathering in the Upper Huang He (Yellow River) draining the eastern Qinghai-Tibet Plateau
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Chemical weathering in the Upper Huang He (Yellow River) draining the eastern Qinghai-Tibet Plateau

机译：青藏高原东部流域黄河上游的化学风化

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摘要

We examined the fluvial geochemistry of the Huang He (Yellow River) in its headwaters to determine natural chemical weathering rates on the northeastern Qinghai-Tibet Plateau, where anthropogenic impact is considered small. Qualitative treatment of the major element composition demonstrates the dominance of carbonate and evaporite dissolution. Most samples are supersaturated with respect to calcite, dolomite, and atmospheric CO2 with moderate (0.710-0.715) Sr-87/Sr-86 ratios, while six out of 21 total samples have especially high concentrations of Na, Ca, Mg, Cl, and SO4 from weathering of evaporites. We used inversion model calculations to apportion the total dissolved cations to rain-, evaporite-, carbonate-, and silicate-origin. The samples are either carbonate- or evaporite-dominated, but the relative contributions of the four sources vary widely among samples. Net CO2 consumption rates by silicate weathering (6-120 X 10(3) mol/km(2)/yr) are low and have a relative uncertainty of similar to 40%. We extended the inversion model calculation to literature data for rivers draining orogenic zones worldwide. The Ganges-Brahmaputra draining the Himalayan front has higher CO2 consumption rates (110-570 X 10(3) mol/km(2)/yr) and more radiogenic Sr-87/Sr-86 (0.715-1.24) than the Upper Huang He, but the rivers at higher latitudes are similar to or lower than the Upper Huang He in CO2 uptake by silicate weathering. In these orogenic zones, silicate weathering rates are only weakly coupled with temperature and become independent of runoff above similar to 800 mm/yr. Copyright (c) 2005 Elsevier Ltd.
机译：我们研究了黄河（黄河）上游的河流地球化学，以确定在东北青藏高原上的自然化学风化率，在该地区人为影响较小。主要元素组成的定性处理表明碳酸盐和蒸发岩溶解占主导地位。对于方解石，白云石和大气CO2，大多数样品的Sr-87 / Sr-86比率为（0.710-0.715）时过饱和，而21种样品中有6种的Na，Ca，Mg，Cl，和蒸发物风化产生的SO4。我们使用反演模型计算将总溶解阳离子分配给雨水，蒸发岩，碳酸盐和硅酸盐来源。样品以碳酸盐或蒸发岩为主，但四种来源的相对贡献在样品之间差异很大。硅酸盐风化的净CO2消耗率（6-120 X 10（3）mol / km（2）/ yr）低，相对不确定度接近40％。我们将反演模型的计算扩展到了全世界造山带排水河流的文献数据。排泄喜马拉雅山前线的恒河-布拉马普特拉河的二氧化碳消耗率较高（110-570 X 10（3）mol / km（2）/年），且放射源性Sr-87 / Sr-86（0.715-1.24）比黄河上游地区高他，但较高纬度的河流在硅酸盐风化作用下的二氧化碳吸收量上等于或低于黄河上游。在这些造山带中，硅酸盐的风化率仅与温度弱耦合，并且与高于800 mm / yr的径流无关。版权所有（c）2005 Elsevier Ltd.

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