Significant Biologically Mediated CO 2 Uptake in the Pacific Arctic During the Late Open Water Season
Significant Biologically Mediated CO 2 Uptake in the Pacific Arctic During the Late Open Water Season
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DOI：
10.1029/2018jc014568
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发表时间：
2019-02
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影响因子：
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通讯作者：
L. Juranek;Taro Takahashi;J. Mathis;R. Pickart
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文献类型：
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作者：
L. Juranek;Taro Takahashi;J. Mathis;R. Pickart
北极大气-海冰-海洋系统中基线的移动具有改变地球化学循环和生态系统动态的巨大潜力。特别是，开放水域持续时间增加对低营养级生产力和生物CO2封存的影响知之甚少。利用2011年10月和2012年10月在太平洋北极地区收集的表层海水溶解O2/Ar和pCO 2的高分辨率观测数据，我们评估了受O2/Ar饱和度（ΔO2/Ar）约束的生物代谢状态（自养与异养）的空间变异性以及净生物产量与pCO 2的海-气梯度（Δ pCO 2）之间的关系。我们发现Δ pCO 2和ΔO2/Ar之间存在稳健的关系（2011年和2012年的相关系数分别为-0.74和-0.61），这表明在该地区最大海洋吸收CO2的时间范围内，开放水域后期的生物生产是海气CO2梯度的重要决定因素。如ΔO2/Ar所示，生物生产中的斑块表明空间可变的营养供应机制，支持在通常强烈分层和营养有限的条件下的晚季生长。北极正在经历快速的变化。其中一个最显著的变化是北极沿海地区夏季无冰时间的延长，这可能会影响北极生态系统食物链底部微型海洋植物的生长模式。我们调查的增长在食物链的基础是如何应对这些海冰的变化在后期，“开放水域”期间。为了跟踪生长，我们测量了海洋表面的氧含量，这限制了海洋植物光合作用的生长和损失的平衡，然后被消耗和分解。我们还将净增长的空间格局与溶解在海洋表面的二氧化碳（CO2）气体的量相关联，以评估生物活动对吸收这种重要的温室气体进入海洋表面的潜在影响。我们发现了一个令人惊讶的增长和海洋吸收二氧化碳的地区之间的关系。这一发现很重要，因为它表明生物群落在以前的生长受到冰盖抑制的时间段内促进了二氧化碳的吸收。
Shifting baselines in the Arctic atmosphere‐sea ice‐ocean system have significant potential to alter biogeochemical cycling and ecosystem dynamics. In particular, the impact of increased open water duration on lower trophic level productivity and biological CO2 sequestration is poorly understood. Using high‐resolution observations of surface seawater dissolved O2/Ar and pCO2 collected in the Pacific Arctic in October 2011 and 2012, we evaluate spatial variability in biological metabolic status (autotrophy vs heterotrophy) as constrained by O2/Ar saturation (ΔO2/Ar) as well as the relationship between net biological production and the sea‐air gradient of pCO2 (ΔpCO2). We find a robust relationship between ΔpCO2 and ΔO2/Ar (correlation coefficient of −0.74 and −0.61 for 2011 and 2012, respectively), which suggests that biological production in the late open water season is an important determinant of the air‐sea CO2 gradient at a timeframe of maximal ocean uptake for CO2 in this region. Patchiness in biological production as indicated by ΔO2/Ar suggests spatially variable nutrient supply mechanisms supporting late season growth amidst a generally strongly stratified and nutrient‐limited condition. Plain Language Summary The Arctic is experiencing rapid change. One of the most notable changes is an increase in the length of time coastal areas of the Arctic are ice‐free in summer, which may affect the growth patterns of microscopic marine plants at the bottom of the food chain in Arctic ecosystems. We investigate how the growth at the base of the food chain is responding to these sea ice changes in the late, “open water” period. To track growth, we measure the oxygen content of the surface ocean, which constrains the balance of growth and loss as marine plants photosynthesize and then are consumed and decomposed. We also relate the spatial patterns of net growth to the amount of carbon dioxide (CO2) gas dissolved in the surface ocean to evaluate the potential impact of biological activity on the uptake of this important greenhouse gas into the surface ocean. We find a surprising relationship between growth and areas of CO2 uptake by the ocean. This finding is important because it suggests that the biological community facilitates carbon dioxide uptake during a timeframe when previously growth would be inhibited by ice cover.