金沙江一级支流龙川江水体化学组成和化学风化过程分析

Loads chemical weathering for the Longchuan River

对龙川江进行采样、测试及分析,发现河水有着较高的矿化度,HCO3-占河水总当量浓度的40%左右,SO42-和Ca2+浓度也相对较高,分别占阴、阳离子总量的10%和27%。通过相关分析和因子分析,得出流域内所发生的化学风化反应主要来自方解石、岩盐和镁硫酸盐风化的溶解。碳酸盐、蒸发盐和硅酸盐的风化过程对龙川江溶解质的贡献率分别占:39.3%、18.1%和12.5%,表明碳酸盐(如方解石)和蒸发盐(如镁硫酸盐)的反应是流域内最主要的化学风化过程。大气中的CO2通过参与岩石的风化过程对龙川江河流溶解质的贡献率为30.8%。龙川江水体中HCO3-约80.3%来自于碳酸盐风化过程,19.6%来自硅酸盐的风化。

The samples from the Longchuan River were collected,measured and analyzed.It was found that the river contained high concentration of TDS.The content of HCO3-accounted for 40% of the whole equivalent concentration of the river.The contents of SO42-and Ca2＋ were also high,and accounted for 10% of the total anions and 27% of the total captions,respectively.According to the correlation and factor analysis,Calcite weathering,Halite and Magnesium sulfate dissolution were the primary weathering processes.The atmospheric CO2,carbonates weathering,silicate weathering and evaporate weathering input had a contribution of 30.8%,39.3%,18.1% and 12.5%,respectively.The results suggested that the water chemistry was mainly controlled by the weathering processes of carbonates（calcite） and evaporates（magnesium sulfate）.The analysis of the composition loadings showed that 80.3% of HCO3-concentration originated from the carbonate weathering reactions while only 19.6% derived from delicate dissolution.