The Study Of Chemical Weathering In The Upstream Of The Yellow River Basin

The chemical composition of river water can be used to discriminate the ion sources of solute, identifying the geological factors, human activities, atmospheric precipitatio n influence on river water chemistry, which can provides indications of the chemica l weathering process of rock, weathering rates and associated CO 2 consumption with in the river. Hydrochemical investigations were carried out in the upstream of the Yellow River Basin, major ions in the river waters were determined to analyze the spatial variation characteristics of the major ions in July 2012, and the temporal river water samples were collected monthly at the Tang Naihe and Qing tongxia hydrologica l station from July 2013 to June 2014. Based on the ion content and chemical characteristics analysis in the upstream of the Yel ow river water, the key chemical weathering processes of the river basin was researched, and the main influences of the difference rock weathering were discussed. Then, the rocks chemical weathering rate and consumption of atmospheric CO2 in the process of the river basin rocks chemical weathering. The results are shown as follows:Based on the ion content and chemical characteristics analysis in the upstream of the Yel ow river water,we found that the chemical compositions of the river waters dominated by Ca2+, HCO3–; The TDS in river water change much in different seasons and space sections; The main hydrochemical type of river water was Ca—HCO3; It showed a negative correlation between ion content and river inflow; Gibbs and hydrochemistry triangle graph combining major ion element ratio analysis indicates that the catchment hydrochemistry mainly originated from carbonate rock weathering, but the evaporite rock became increasingly as the river went downstream, the silicate contribution was very smal.According to the Forward model results of watersheds water chemistry, the upstream of the Yel ow river in Tang Naihe, the silicate rock chemical weathering rates(SWR) is 2.1t/km2/a, the carbonate rock chemical weathering rates(CWR) is 21.2t/km2/a, the consumption rates of atmospheric CO2 in terms of silicate(?CO2sil) and carbonate(?CO2car) is 71×103mol/km2/a and 220×103mol/km2/a respectively. The SWR in Qing tongxia is 1.1t/km2/a, and the CWR is 14.5t/km2/a, the ?CO2sil and ?CO2car is 35×103mol/km2/a and 157×103mol/km2/a respectively. Overall, the upstream of the Yel ow river ?CO2sil and ?CO2car is 53×103mol/km2/a and 188×103mol/km2/a.The upstream of the Yel ow river SWR, CWR, ?CO2sil and ?CO2car is increased significantly in dry seasons, and decreased in wet season. The spatial variation characteristics of the SWR, CWR, ?CO2sil and ?CO2car were in a decreasing trend, this conclusion was consistent with the conclusions of the temporal river water samples.