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为讨论岩溶地表河中等流域尺度无机碳通量的动态变化过程及其影响因素,于2014年1月至12月对漓江流域桂林断面及阳朔断面河水进行为期一个水文年的采样观测,每月定期采样分析。结果表明,这个过程主要受水循环过程控制,除岩溶水化学特征沿途发生变化之外,水体SIc和SId值也逐渐偏正,溶蚀能力逐渐降低,所产生的无机碳通量仍然不断增加,且呈现出旱季低雨季高的特征。通过计算,桂林断面无机碳通量为7.42×10~7 kgCO_2·a~(-1),阳朔断面为27.9×10~7 kgCO_2·a~(-1),其中桂林断面碳酸盐岩风化所产生的无机碳通量和硅酸盐岩风化所产生的无机碳通量分别占总通量的72.67%和5.21%,阳朔断面分别占87.51%和2.89%,表明硅酸盐岩风化的贡献率沿途不断减小,碳酸盐岩风化的贡献率不断增加。桂林断面以上流域碳汇强度为2.69×10~4 kgCO_2·km~(-2)·a~(-1),桂林到阳朔断面流域碳汇强度为9.89×10~4 kgCO_2·km~(-2)·a~(-1),相差近5倍,除沿途大气降水、支流补给、水生生物可能产生的有机碳埋藏等原因外,外源水补给所形成的混合溶蚀作用对岩溶区无机碳通量的增加起着不可忽视的作用。
In order to discuss the process of the dynamic changes of inorganic carbon flux at the middle and lower reaches of the karst surface river and its influential factors, a sampling period of one hydrological year was observed in the Guilin section and the Yangshuo section of the Lijiang River basin from January to December 2014, Sampling analysis. The results show that this process is mainly controlled by the water cycle process. In addition to the changes in the chemical characteristics of karst water along the route, the SIc and SId values of water bodies gradually become more positive, and the erosion abilities gradually decrease. The inorganic carbon fluxes generated continue to increase, The characteristics of the high dry season low rainy season. The calculated results show that the inorganic carbon flux in Guilin section is 7.42 × 10 ~ 7 kgCO 2 · a -1, and the section of Yangshuo is 27.9 × 10 ~ 7 kgCO 2 · a -1, of which the weathering place of carbonate rock in Guilin section The inorganic carbon fluxes and inorganic carbon fluxes produced by weathering of silicate rocks accounted for 72.67% and 5.21% of the total flux, respectively, and the Yangshuo section accounted for 87.51% and 2.89%, respectively, indicating that the contribution rate of silicate weathering Along the way, the contribution rate of carbonate weathering continues to increase. The carbon intensity of the catchment above the Guilin section is 2.69 × 10 ~ 4 kgCO_2 · km ~ (-2) · a -1, and the carbon sink intensity of the Guilin-Yangshuo section reaches 9.89 × 10 ~ 4 kgCO_2 · km ~ (-2) ) · A ~ (-1), a difference of nearly 5 times. In addition to the atmospheric erosion, tributary supplies along the way, organic carbon buried by aquatic organisms and other reasons, The amount of increase plays a role that can not be ignored.