Stable Carbon Isotopes Suggest Large Terrestrial Carbon Inputs to the Global Ocean
Stable Carbon Isotopes Suggest Large Terrestrial Carbon Inputs to the Global Ocean
复制标题
稳定碳同位素表明全球海洋有大量陆地碳输入
DOI：
10.1029/2020gb006684
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发表时间：
2021
影响因子：
5.2
通讯作者：
Timmermann, Axel
中科院分区：
文献类型：
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作者：
Kwon, Eun Young;DeVries, Tim;Galbraith, Eric D.;Hwang, Jeomshik;Kim, Guebuem;Timmermann, Axel
碳通过河流、地下水和气溶胶从陆地向海洋的传输是全球碳循环的重要组成部分，必须了解这一点才能准确评估陆地和海洋中的人为CO2储存。目前的全球碳循环预算采用了陆地碳输入到海洋，从0.5 GtC/年到0.9 GtC/年不等，主要来自河流通量的估计。然而，由于难以进行全球评估，这些预算忽略了来自沿海生态系统和通过海底地下水排放的陆地碳输入（在本研究中统称为沿海边缘输入）。使用数值模型和全球分布的海洋稳定碳同位素观测，我们估计陆地碳输入海洋为1.4 ± 0.5 GtC/年，95%的沿海边缘输入（0.8 ± 0.5 GtC/年）发生在太平洋和印度洋。这种陆地碳通量在很大程度上由1.2 ± 0.5 GtC/年的大气排放量平衡，其中40%发生在监测不足的沿海地区，并且可能在以前基于观测的全球估计中被忽略。我们的研究结果表明，陆地-海洋过渡区的碳循环比以前认为的更动态，河流可能不是陆地碳进入海洋的唯一重要途径。
The transport of carbon from land to ocean, via rivers, groundwater, and aerosols, is an important component of the global carbon cycle that must be known to accurately assess anthropogenic CO2storage on land and in the ocean. Current global carbon cycle budgets have adopted terrestrial carbon inputs to the ocean ranging from 0.5 GtC/yr to 0.9 GtC/yr, derived mainly from estimates of riverine fluxes. However, these budgets ignore the terrestrial carbon inputs from coastal ecosystems and through submarine groundwater discharge (collectively referred to as coastal margin inputs in this study) due to difficulties in making global assessments. Using a numerical model and globally distributed ocean observations of stable carbon isotopes, we estimate terrestrial carbon inputs to the ocean at 1.4 ± 0.5 GtC/yr, with 95% of the coastal margin inputs (0.8 ± 0.5 GtC/yr) occurring in the Pacific and Indian Oceans. This terrestrial carbon flux is largely balanced by an efflux to the atmosphere of 1.2 ± 0.5 GtC/yr, 40% of which occurs in poorly monitored coastal regions and may have been overlooked in previous observation‐based global estimates. Our results suggest more dynamic cycling of carbon in the land‐ocean transition zone than previously thought, and that rivers may not be the only important pathway for terrestrial carbon to the ocean.