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首先感谢杨立铮先生对“不同岩溶动力系统的碳稳定同位素和地球化学特征及其意义”一文的兴趣和提出的疑问,今作如下答复: (1)在讨论用碳稳定同位素示踪物质的来源之前,我们必须了解碳所处的3种相态的同位素是不同的。据Denies等的研究,5℃(接近黄龙水点的温度)时开放系统条件下达到同位素交换平衡时,气相CO_2与液相HCO_3~-之间的同位素富集系数为9.7‰,即HCO_3~-(液相)相对于CO_2(气相)的δ~(13)C值重9.7‰,对于黄龙地区所研究的泉水而言,已测得从该泉水所释放的CO_2气的δ~(13)C=-6.8‰,则平衡时水中的δ~(3)C(HCO_3~-)=-6.8‰+9.7‰=2.9‰,这与黄龙沟水点(8个)实测的HCO_3~-的平均同位素组成δ~(13)C=3.01‰相当吻合,这说明,一方面系统是开放的,另一方面气相CO_2与水中HCO_3~-达到了碳同位素交换平衡。另据Denies等的研究可知,液相HCO_3~-与固相CaCO_3之间的同位素
First of all, I would like to thank Mr. Yang Lizheng for his interest and questions raised in his article “Carbon stable isotopes and geochemical characteristics of different karst dynamical systems and their implications”. The following reply is made as follows: (1) Before discussing the sources of carbon stable isotope tracers , We must understand that the carbon isotopes of the three phases are different. According to the study of Denies et al., The isotopic enrichment coefficient between gaseous CO 2 and liquid HCO 3 - is 9.7 ‰ at 5 ℃ (close to the temperature of Huanglong water point) when the isotope exchange equilibrium is reached under the open system conditions, ie HCO 3 - (Liquid) relative to that of CO_2 (gas) is 9.7 ‰. For the studied waters in Huanglong, the δ ~ (13) C = -6.8 ‰, then the δ ~ (3) C (HCO_3 ~ -) = 6.8 ‰ + 9.7 ‰ = 2.9 ‰ in water at equilibrium, which is in agreement with the measured average HCO_3 ~ The composition of δ ~ (13) C = 3.01 ‰ is in good agreement, which shows that on the one hand the system is open, on the other hand, the gas phase CO_2 and HCO_3 ~ in the water reach the carbon isotope exchange equilibrium. According to Denies et al., It is known that the isotope between the liquid phase HCO 3 - and the solid phase CaCO 3