Abstract Studying the temporal dynamics and fluxes of riverine dissolved carbon is crucial in understanding the regional and global carbon cycles under various climatic conditions. Here, we studied the behaviors and fluxes of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) responding to various hydrologic conditions in the Min River, originated from Tibetan Plateau. The DIC concentrations decreased with increasing runoff, partially reflecting dilution effect, which may be ascribed to the shortened fluid transit time and then the reduced contact time with rocks. Nevertheless, DOC concentrations were positively correlated with runoff, which can be attributed to that a large amount of soil organic carbon flowed into the river as a result of the strong flushing effect. The negative relationship between δ13CDIC and runoff could be explained by soil CO2 influx and organic matter degradation during the high flow season. ΔDIC (the production of DIC with changing hydrologic conditions) had a strong positive correlation with water temperature due to the accelerated DIC production rates by high temperature, which always co-varied with intense precipitation in Asian monsoonal regions. The mean DIC/DOC ratio in the Min River was 15.09, and the DOC and DIC fluxes were 1.1 and 15.2 t C km−2 yr−1, respectively, for the studied year. And the DOC and DIC fluxes varied dramatically with runoff changes, suggesting that hydrologic conditions were critical factors for the variations in dissolved carbon export. This study shows that carbon dynamics of rivers draining from the Tibetan Plateau are greatly affected by short-term climatic variabilities, which has implications for understanding global carbon cycle under future climate change.

中文翻译：

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青藏高原岷江水文温度耦合对溶解碳时间动态的影响

摘要 研究河流溶解碳的时间动态和通量对于理解不同气候条件下的区域和全球碳循环至关重要。在这里，我们研究了源自青藏高原的岷江中溶解无机碳 (DIC) 和溶解有机碳 (DOC) 的行为和通量对各种水文条件的响应。DIC 浓度随着径流的增加而降低，部分反映了稀释效应，这可能是由于流体通过时间缩短，然后与岩石接触时间减少。尽管如此，DOC 浓度与径流呈正相关，这可能是由于强烈的冲刷效应导致大量土壤有机碳流入河流。δ13​​CDIC 与径流之间的负相关可以用高流量季节土壤 CO2 流入和有机质降解来解释。ΔDIC（随水文条件变化而产生的 DIC）与水温有很强的正相关，因为高温会加速 DIC 的产生，这总是与亚洲季风区的强降水共同变化。岷江平均 DIC/DOC 比值为 15.09，研究年份 DOC 和 DIC 通量分别为 1.1 和 15.2 t C km-2 yr-1。并且 DOC 和 DIC 通量随径流变化而显着变化，表明水文条件是溶解碳输出变化的关键因素。