生物成因碳库的产生维持了南大洋的碳汇。
Biogenic carbon pool production maintains the Southern Ocean carbon sink.
机构信息
Department of Ocean Sciences, University of California, Santa Cruz, CA 95064.
National Oceanic and Atmospheric Administration, Pacific Marine Environmental Laboratory, Seattle, WA 98115.
出版信息
Proc Natl Acad Sci U S A. 2023 May 2;120(18):e2217909120. doi: 10.1073/pnas.2217909120. Epub 2023 Apr 26.
Through biological activity, marine dissolved inorganic carbon (DIC) is transformed into different types of biogenic carbon available for export to the ocean interior, including particulate organic carbon (POC), dissolved organic carbon (DOC), and particulate inorganic carbon (PIC). Each biogenic carbon pool has a different export efficiency that impacts the vertical ocean carbon gradient and drives natural air-sea carbon dioxide gas (CO) exchange. In the Southern Ocean (SO), which presently accounts for ~40% of the anthropogenic ocean carbon sink, it is unclear how the production of each biogenic carbon pool contributes to the contemporary air-sea CO exchange. Based on 107 independent observations of the seasonal cycle from 63 biogeochemical profiling floats, we provide the basin-scale estimate of distinct biogenic carbon pool production. We find significant meridional variability with enhanced POC production in the subantarctic and polar Antarctic sectors and enhanced DOC production in the subtropical and sea-ice-dominated sectors. PIC production peaks between 47°S and 57°S near the "great calcite belt." Relative to an abiotic SO, organic carbon production enhances CO uptake by 2.80 ± 0.28 Pg C y, while PIC production diminishes CO uptake by 0.27 ± 0.21 Pg C y. Without organic carbon production, the SO would be a CO source to the atmosphere. Our findings emphasize the importance of DOC and PIC production, in addition to the well-recognized role of POC production, in shaping the influence of carbon export on air-sea CO exchange.
通过生物活性,海洋溶解无机碳 (DIC) 转化为不同类型的生源碳,可输送到海洋内部,包括颗粒有机碳 (POC)、溶解有机碳 (DOC) 和颗粒无机碳 (PIC)。每个生源碳库的输出效率不同,这会影响海洋的垂直碳梯度,并驱动自然的大气-海洋二氧化碳气体 (CO) 交换。在目前占人为海洋碳汇的 40%左右的南大洋 (SO),不清楚每个生源碳库的产生如何对当代大气-海洋 CO 交换做出贡献。基于 63 个生物地球化学剖面浮标 107 个独立观测的季节性周期,我们提供了不同生源碳库产生的流域尺度估计。我们发现了显著的纬向变化,在亚热带和以海冰为主的区域,DOC 产生增强,在亚南极和极地南极区域,POC 产生增强。PIC 产生的峰值在南纬 47°和 57°之间,靠近“大方解石带”。与非生物 SO 相比,有机碳的产生增加了 2.80±0.28 Pg C y 的 CO 吸收,而 PIC 的产生减少了 0.27±0.21 Pg C y 的 CO 吸收。如果没有有机碳的产生,南大洋将成为大气中的 CO 源。我们的研究结果强调了 DOC 和 PIC 产生的重要性,除了众所周知的 POC 产生的作用外,它们对碳输出对大气-海洋 CO 交换的影响也很重要。