Chemical Weathering in the Upper Huang He (Yellow River) Draining the Eastern Qinghai-Tibet Plateau
Geochimica et Cosmochimica Acta, Vol. 69, No. 22, pp. 5279–5294, 2005 Copyright © 2005 Elsevier Ltd Printed in the USA. All rights reserved 0016-7037/05 $30.00 ϩ .00 doi:10.1016/j.gca.2005.07.001 Chemical weathering in the Upper Huang He (Yellow River) draining the eastern Qinghai-Tibet Plateau 1 1,2, 3 3 1 LINGLING WU, YOUNGSOOK HUH, *JIANHUA QIN, GU DU, and SUZAN VAN DER LEE 1Department of Geological Sciences, Northwestern University, 1850 Campus Drive, Evanston, Illinois 60208-2150 USA 2School of Earth and Environmental Sciences, Seoul National University, San 56-1, Sillim-dong, Gwanak-gu, Seoul 151-742, Korea 3Chengdu Institute of Geology and Mineral Resources, Chengdu, Sichuan 610082 P.R.C. (Received December 17, 2004; accepted in revised form July 5, 2005) Abstract—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, 87 86 dolomite, and atmospheric CO2 with moderate (0.710–0.715) Sr/ Sr 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 ϫ 3 four sources vary widely among samples.
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