中尺度海洋锋面由于重力下沉和俯冲作用增强了碳输出。
Mesoscale ocean fronts enhance carbon export due to gravitational sinking and subduction.
作者信息
Stukel Michael R, Aluwihare Lihini I, Barbeau Katherine A, Chekalyuk Alexander M, Goericke Ralf, Miller Arthur J, Ohman Mark D, Ruacho Angel, Song Hajoon, Stephens Brandon M, Landry Michael R
机构信息
Earth, Ocean, and Atmospheric Science Department, Florida State University, Tallahassee, FL 32306;
Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093.
出版信息
Proc Natl Acad Sci U S A. 2017 Feb 7;114(6):1252-1257. doi: 10.1073/pnas.1609435114. Epub 2017 Jan 23.
Enhanced vertical carbon transport (gravitational sinking and subduction) at mesoscale ocean fronts may explain the demonstrated imbalance of new production and sinking particle export in coastal upwelling ecosystems. Based on flux assessments from U:Th disequilibrium and sediment traps, we found 2 to 3 times higher rates of gravitational particle export near a deep-water front (305 mg C⋅m⋅d) compared with adjacent water or to mean (nonfrontal) regional conditions. Elevated particle flux at the front was mechanistically linked to Fe-stressed diatoms and high mesozooplankton fecal pellet production. Using a data assimilative regional ocean model fit to measured conditions, we estimate that an additional ∼225 mg C⋅m⋅d was exported as subduction of particle-rich water at the front, highlighting a transport mechanism that is not captured by sediment traps and is poorly quantified by most models and in situ measurements. Mesoscale fronts may be responsible for over a quarter of total organic carbon sequestration in the California Current and other coastal upwelling ecosystems.
中尺度海洋锋面处增强的垂直碳传输（重力沉降和俯冲）可能解释了沿海上升流生态系统中已证实的新生产力与沉降颗粒输出之间的不平衡。基于铀钍不平衡和沉积物捕获器的通量评估，我们发现与相邻水体或区域平均（非锋面）条件相比，在深水锋面附近（305毫克碳·米⁻²·天⁻¹）重力颗粒输出速率高出2至3倍。锋面处颗粒通量的升高与铁胁迫的硅藻和高中型浮游动物粪便颗粒产量存在机制上的联系。使用拟合实测条件的数据同化区域海洋模型，我们估计在锋面处作为富含颗粒水体的俯冲额外输出了约225毫克碳·米⁻²·天⁻¹，突出了一种沉积物捕获器未捕捉到且大多数模型和现场测量量化不足的传输机制。中尺度锋面可能占加利福尼亚洋流和其他沿海上升流生态系统中总有机碳固存的四分之一以上。
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