Importance of active layer freeze-thaw cycles on the riverine dissolved carbon export on the Qinghai-Tibet Plateau permafrost region
Importance of active layer freeze-thaw cycles on the riverine dissolved carbon export on the Qinghai-Tibet Plateau permafrost region
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青藏高原多年冻土区活动层冻融循环对河流溶解碳输出的重要性
DOI：
10.7717/peerj.7146
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发表时间：
2019-06
期刊：
影响因子：
2.7
通讯作者：
Zhaoyong Hu
中科院分区：
文献类型：
--
作者：
Chunlin Song;Genxu Wang;Tianxu Mao;Xiaopeng Chen;Kewei Huang;Xiangyang Sun;Zhaoyong Hu
青藏高原多年冻土退化严重，对水文和地球化学过程产生影响。然而，冻土变化如何影响河流碳输出仍不确定。在这里，我们调查了季节变化的溶解无机和有机碳（DIC和DOC）在流动季节在位于中部QTP永久冻土区的流域。结果表明，河流DIC浓度（27.81 ± 9.75 mg L−1）远高于DOC浓度（6.57 ± 2.24 mg L−1）。DIC和DOC通量分别为3.95和0.94 g C m−2 year−1。DIC浓度增加，从最初的解冻期（5月）冻结期（10月），而DOC浓度保持相对稳定。日溶解碳浓度与基流的相关性比与总径流的相关性更密切。在空间上，平均DIC和DOC浓度与植被覆盖度呈正相关，而与裸地覆盖度呈负相关。DIC浓度增加，由于增加的土壤interflow，更多的解冻释放的碳，更多的地下水的贡献，并可能更多的碳酸盐风化土壤CO2形成碳酸盐和冻结深度。DIC和DOC通量随解冻深度的增加而增加，随冻结层厚度的增加而减小。河流溶解碳输出的季节性高度依赖于活动层融化和冻结过程，这突出了冻土变化对河流碳输出的重要性。未来QTP冻土区的变暖可能会改变河流碳输出的数量和机制。
The Qinghai-Tibet Plateau (QTP) is experiencing severe permafrost degradation, which can affect the hydrological and biogeochemical processes. Yet how the permafrost change affects riverine carbon export remains uncertain. Here, we investigated the seasonal variations of dissolved inorganic and organic carbon (DIC and DOC) during flow seasons in a watershed located in the central QTP permafrost region. The results showed that riverine DIC concentrations (27.81 ± 9.75 mg L−1) were much higher than DOC concentrations (6.57 ± 2.24 mg L−1). DIC and DOC fluxes were 3.95 and 0.94 g C m−2 year−1, respectively. DIC concentrations increased from initial thaw (May) to freeze period (October), while DOC concentrations remained relatively steady. Daily dissolved carbon concentrations were more closely correlated with baseflow than that with total runoff. Spatially, average DIC and DOC concentrations were positively correlated with vegetation coverage but negatively correlated with bare land coverage. DIC concentrations increased with the thawed and frozen depths due to increased soil interflow, more thaw-released carbon, more groundwater contribution, and possibly more carbonate weathering by soil CO2 formed carbonic acid. The DIC and DOC fluxes increased with thawed depth and decreased with frozen layer thickness. The seasonality of riverine dissolved carbon export was highly dependent on active layer thawing and freezing processes, which highlights the importance of changing permafrost for riverine carbon export. Future warming in the QTP permafrost region may alter the quantity and mechanisms of riverine carbon export.
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影响因子：
5.2
作者：
J. Vonk;P. Mann;S. Davydov;A. Davydova;R. Spencer;J. Schade;W. V. Sobczak;N. Zimov;S. Zimov;E. Bulygina;T. Eglinton;R. Max Holmes
通讯作者：
J. Vonk;P. Mann;S. Davydov;A. Davydova;R. Spencer;J. Schade;W. V. Sobczak;N. Zimov;S. Zimov;E. Bulygina;T. Eglinton;R. Max Holmes
影响因子：
3.4
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作者：
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通讯作者：
Tingjun Zhang;O. Frauenfeld;M. Serreze;A. Etringer;C. Oelke;J. McCreight;R. Barry;D. Gilichinsky-D.-Gilichins
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影响因子：
3.2
作者：
Song Chunlin;Wang Genxu;Liu Guangsheng;Mao Tianxu;Sun Xiangyang;Chen Xiaopeng
通讯作者：
Chen Xiaopeng
影响因子：
5.2
作者：
S. Tank;K. Frey;R. Striegl;P. Raymond;R. Holmes;J. McClelland;B. Peterson
通讯作者：
S. Tank;K. Frey;R. Striegl;P. Raymond;R. Holmes;J. McClelland;B. Peterson