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对乌江丰水期河水硫酸盐的硫同位素组成特征进行了研究。SO42-平均浓度为0.48 mmol/L,δ34S值为-11.5‰~8.3‰,干流河水δ34S值为-6.7‰~-3.9‰。河水的硫同位素组成主要受岩石风化及大气降水的影响,具有明显的区域性分异特征:上游碳酸盐岩地区河水的SO42-浓度高而δ34S值低,SO42-主要来源于煤中黄铁矿的氧化、矿床硫化物的氧化和大气降水;下游碳酸盐岩夹碎屑岩地区河水中的SO42-浓度低而δ34S值高,SO42-主要来源于大气降水和石膏溶解,煤中黄铁矿氧化生成的硫酸盐所占比重较低。乌江河水向贵州省外输出的SO42-通量为172×1010g/a,丰水期占全年SO42-输出总量的72%。来自煤、硫化物、雨水和蒸发岩的硫对丰水期河水中SO42-的平均贡献分别为:50%、25%、20%和5%。H2SO4对碳酸盐岩的侵蚀速率为35.1 t/km2/a(17.5 mm/ka),由此降低大气CO2消耗速率3.66×105mol/km2/a。
The characteristics of sulfur isotope composition of sulfate in Wujiang river were studied. The average concentration of SO42- was 0.48 mmol / L, the δ34S value was -11.5 ‰ ~ 8.3 ‰, and the δ34S value of the mainstream river water was -6.7 ‰ -3.9 ‰. The sulfur isotope composition of the river water is mainly affected by rock weathering and atmospheric precipitation, and has obvious regional differentiation: the concentration of SO42- in the upper reaches of carbonate waters is high but the value of δ34S is low, SO42- mainly comes from the yellow iron in coal The oxidation of ore, the oxidation of ore deposits and the precipitation of the atmosphere. The concentration of SO42- in the lower reaches of the carbonate clastic clastic rocks is low while the δ34S value is high. SO42- mainly comes from precipitation and gypsum dissolution in the coal. Sulfate produced by ore oxidation has a lower share. The output of SO2 2- from Wujiang River to Guizhou Province is 172 × 1010 g / a, and the wet season accounts for 72% of the total SO42- output of the year. The average contributions of sulfur from coal, sulfide, rainwater and evaporites to SO42- in flood waters are 50%, 25%, 20% and 5%, respectively. The erosion rate of carbonate rock by H2SO4 is 35.1 t / km2 / a (17.5 mm / ka), which reduces the atmospheric CO2 consumption rate by 3.66 × 105 mol / km2 / a.