Spatiotemporal Variability and Sources of DIC in Permafrost Catchments of the Yangtze River Source Region: Insights From Stable Carbon Isotope and Water Chemistry
Spatiotemporal Variability and Sources of DIC in Permafrost Catchments of the Yangtze River Source Region: Insights From Stable Carbon Isotope and Water Chemistry
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长江源区多年冻土流域DIC时空变化及来源：来自稳定碳同位素和水化学的见解
DOI：
10.1029/2019wr025343
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发表时间：
2020-01
影响因子：
5.4
通讯作者：
Peter A. Raymond
中科院分区：
文献类型：
--
作者：
Chunlin Song;Genxu Wang;Tianxu Mao;Kewei Huang;Xiangyang Sun;Zhaoyong Hu;Ruiying Chang;Xiaopeng Chen;Peter A. Raymond
河流溶解无机碳（DIC）输出在区域和全球碳循环中发挥着核心作用。在这里，我们调查了DIC的时空变化和来源，在长江源区（YRSR）的8个集水区与可变的冻土覆盖和季节性解冻的活动层。YRSR集水区富含DIC（平均25 mg C L−1），并输出3.51 g m−2 yr−1的DIC。温度、活动层、水流路径和流量的季节性变化可以改变DIC和DIC的稳定碳同位素（δ 13 C-DIC）。δ 13 C-DIC值在解冻期最大，表明活动层解冻期间土壤呼吸的CO2可以通过H2 CO 3风化促进碳酸氢盐的产生。从空间上看，δ 13 C-DIC值在下游增加，可能是由于CO2释气以及永久冻土覆盖和径流的变化。我们发现，季节性解冻活动层中的蒸发岩溶解和硅酸盐风化分别贡献了44.2%和30.9%的HCO 3-，而地下水和雨水分别贡献了16.7%和7.3%的HCO 3-。纯碳酸盐岩风化在DIC生成中的作用可以忽略不计。这些结果与δ 13 C-DIC源近似结果一致。从融化初期到融化期，硅酸盐风化增加，反映了活动层融化和随后的水文变化的影响。硅酸盐风化作用每年消耗1.25 × 1010 mol CO2，而蒸发岩溶解作用可产生CO2并中和该CO2汇。本研究为长江下游DIC输出过程提供了新的认识。随着冻土的退化，河流DIC的量、源和汇也可能发生时空变化。
Riverine dissolved inorganic carbon (DIC) exports play a central role in the regional and global carbon cycles. Here, we investigated the spatiotemporal variability and sources of DIC in eight catchments in the Yangtze River source region (YRSR) with variable permafrost coverage and seasonally thawed active layers. The YRSR catchments are DIC‐rich (averagely 25 mg C L−1) and export 3.51 g m−2 yr−1 of DIC. The seasonal changes of temperature, active layer, flow path, and discharge can alter DIC and stable carbon isotope of DIC (δ13C‐DIC). The most depleted δ13C‐DIC values were found in the thawed period, suggesting the soil‐respired CO2 during the active layer thaw period can promote bicarbonate production via H2CO3 weathering. Spatially, δ13C‐DIC values increased downstream, likely due to CO2 outgassing and changed permafrost coverage and runoff. We found that evaporite dissolution and silicate weathering in the seasonally thawed active layer contributed 44.2% and 30.9% of stream HCO3‐, respectively, while groundwater and rainwater contributed 16.7% and 7.3% of HCO3‐, respectively. Pure carbonate rock weathering played a negligible role in DIC production. These results were compatible with δ13C‐DIC source approximation results. Silicate weathering increased from initial thaw to thawed period, reflecting the active layer thaw and subsequent hydrology change impacts. Silicate weathering consumed 1.25 × 1010 mol of CO2 annually, while evaporite dissolution may produce CO2 and neutralize this CO2 sink. This study provides new understanding of the riverine DIC export processes of the YRSR. As permafrost degrades, the quantity, sources, and sinks of riverine DIC may also change spatiotemporally.
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影响因子：
3.7
作者：
Parnell AC;Inger R;Bearhop S;Jackson AL
通讯作者：
Jackson AL
影响因子：
3.4
作者：
Weihua Wu;Jiedong Yang;Shijin Xu;H. Yin
通讯作者：
Weihua Wu;Jiedong Yang;Shijin Xu;H. Yin
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
影响因子：
2.7
作者：
Chunlin Song;Genxu Wang;Tianxu Mao;Xiaopeng Chen;Kewei Huang;Xiangyang Sun;Zhaoyong Hu
通讯作者：
Zhaoyong Hu
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
影响因子：
18.3
作者：
S. Serikova;O. Pokrovsky;P. Ala‐aho;V. Kazantsev;S. Kirpotin;S. Kopysov;I. Krickov;H. Laudon
通讯作者：
S. Serikova;O. Pokrovsky;P. Ala‐aho;V. Kazantsev;S. Kirpotin;S. Kopysov;I. Krickov;H. Laudon