Metabolism overrides photo‐oxidation in CO2 dynamics of Arctic permafrost streams
Metabolism overrides photo‐oxidation in CO2 dynamics of Arctic permafrost streams
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北极永久冻土流二氧化碳动力学中的新陈代谢超越了光氧化
DOI：
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发表时间：
2020
影响因子：
4.5
通讯作者：
R. Giesler
中科院分区：
文献类型：
--
作者：
Gerard Rocher‐Ros;T. Harms;R. Sponseller;M. Väisänen;C. Mörth;R. Giesler
全球变暖正在加强北极土壤中有机碳(C)向溪流的流动，在那里它可以被矿化成二氧化碳并释放到大气中。非生物光氧化可能驱动碳矿化，但这一过程还没有定量地与影响水生生态系统中二氧化碳动态的生物过程结合起来。我们测量了两个北极河流的CO2浓度和溶解无机C的同位素组成（δ13CDIC），并将其与全系统代谢估算相结合，以评估生物和非生物过程对河流C动力学的影响。二氧化碳浓度从夜间到白天持续下降，这一模式与光氧化是二氧化碳主要来源的假设相反。相反，观测到的白天CO2减少可以用光合速率来解释，光合速率与δ13CDIC值的日变化密切相关。然而，在模拟光合速率接近于零的日子里，δ13CDIC值仍然有显著的日变化，这表明代谢估计部分被光氧化消耗的氧气所掩盖。我们的结果表明，光氧化可能产生6-12 mmol CO2 - C m - 2 d - 1，这一范围与以前的实验室测量结果很好地对应。此外，这些北极河流的生态系统呼吸速率是已公布的光氧化速率的10倍，占总CO2逃逸量的33-80%。我们的研究结果表明，代谢活动是北极河流中二氧化碳产生的主要过程。因此，未来的水生二氧化碳排放可能取决于生物过程如何响应持续的环境变化。
Global warming is enhancing the mobilization of organic carbon (C) from Arctic soils into streams, where it can be mineralized to CO2 and released to the atmosphere. Abiotic photo‐oxidation might drive C mineralization, but this process has not been quantitatively integrated with biological processes that also influence CO2 dynamics in aquatic ecosystems. We measured CO2 concentrations and the isotopic composition of dissolved inorganic C (δ13CDIC) at diel resolution in two Arctic streams, and coupled this with whole‐system metabolism estimates to assess the effect of biotic and abiotic processes on stream C dynamics. CO2 concentrations consistently decreased from night to day, a pattern counter to the hypothesis that photo‐oxidation is the dominant source of CO2. Instead, the observed decrease in CO2 during daytime was explained by photosynthetic rates, which were strongly correlated with diurnal changes in δ13CDIC values. However, on days when modeled photosynthetic rates were near zero, there was still a significant diel change in δ13CDIC values, suggesting that metabolic estimates are partly masked by O2 consumption from photo‐oxidation. Our results suggest that 6–12 mmol CO2‐C m−2 d−1 may be generated from photo‐oxidation, a range that corresponds well to previous laboratory measurements. Moreover, ecosystem respiration rates were 10 times greater than published photo‐oxidation rates for these Arctic streams, and accounted for 33–80% of total CO2 evasion. Our results suggest that metabolic activity is the dominant process for CO2 production in Arctic streams. Thus, future aquatic CO2 emissions may depend on how biotic processes respond to the ongoing environmental change.
DOI：
10.1073/pnas.1811797116
发表时间：
2019-05
影响因子：
11.1
作者：
B. Wild;A. Andersson;L. Bröder;J. Vonk;G. Hugelius;J. McClelland;Wenjun Song;P. Raymond;Ö. Gustaf
通讯作者：
B. Wild;A. Andersson;L. Bröder;J. Vonk;G. Hugelius;J. McClelland;Wenjun Song;P. Raymond;Ö. Gustaf
干扰、营养物和先前的水流条件影响北极河流大型无脊椎动物群落结构和生产力
影响因子：
4.5
作者：
Kendrick, Michael R.;Hershey, Anne E.;Huryn, Alexander D.
通讯作者：
Huryn, Alexander D.