The Deep Ocean's Carbon Exhaust.
The Deep Ocean's Carbon Exhaust.
复制标题
深海的碳排放。
DOI：
10.1029/2021gb007156
复制
发表时间：
2022-07
影响因子：
5.2
通讯作者：
Sarmiento, Jorge L.
中科院分区：
文献类型：
--
作者：
Chen, Haidi;Haumann, F. Alexander;Talley, Lynne D.;Johnson, Kenneth S.;Sarmiento, Jorge L.
深海通过南大洋的上升流向大气释放了大量旧的、工业化前的二氧化碳(CO2)，这抵消了其他地方发生的海洋碳吸收。南大洋二氧化碳的这种释放与全球气候有关，因为它的变化可能会在很长一段时间内改变大气中的二氧化碳水平，还会影响目前南大洋吸收人为二氧化碳的潜力。在这里，全年的浮标剖面测量表明，二氧化碳的释放来自亚南极锋面和冬季海冰边缘之间的一条上升水的带状地带。这一高二氧化碳次表层水带与印度-太平洋深水的27.8万公斤m−-3等中密度面露头相吻合。它的二氧化碳潜在分压比当前大气二氧化碳水平(∆二氧化碳)高出175%±332%μ大气压。基于船舶的测量表明，IPDW在海洋中显示出明显的∆二氧化碳最大值，这是由有机碳的再矿化作用设定的，起源于北太平洋和印度洋盆地。在这一IPDW层以下，碳含量向下增加，而∆二氧化碳减少。这种垂直∆二氧化碳分压的大部分下降是由于温度降低和碳酸钙溶解比例增加导致碱度增加所致。这两个因素限制了二氧化碳从高碳含量的深水向更南端的地表露头排放。我们的结果表明，南大洋CO2通量对未来可能的上升流变化的响应对垂直再矿化和溶解剖面所设置的次表层碳化学很敏感。深海二氧化碳释放源于次北极锋和海冰边缘之间次表层水中的高二氧化碳分压最大次表层二氧化碳与上升流的印度洋-太平洋深水(IPDW)有关，后者富含再矿化的有机碳高碱度和低温极限二氧化碳的释放来自IPDW南部的高碳含量深水
The deep ocean releases large amounts of old, pre‐industrial carbon dioxide (CO2) to the atmosphere through upwelling in the Southern Ocean, which counters the marine carbon uptake occurring elsewhere. This Southern Ocean CO2 release is relevant to the global climate because its changes could alter atmospheric CO2 levels on long time scales, and also affects the present‐day potential of the Southern Ocean to take up anthropogenic CO2. Here, year‐round profiling float measurements show that this CO2 release arises from a zonal band of upwelling waters between the Subantarctic Front and wintertime sea‐ice edge. This band of high CO2 subsurface water coincides with the outcropping of the 27.8 kg m−3 isoneutral density surface that characterizes Indo‐Pacific Deep Water (IPDW). It has a potential partial pressure of CO2 exceeding current atmospheric CO2 levels (∆PCO2) by 175 ± 32 μatm. Ship‐based measurements reveal that IPDW exhibits a distinct ∆PCO2 maximum in the ocean, which is set by remineralization of organic carbon and originates from the northern Pacific and Indian Ocean basins. Below this IPDW layer, the carbon content increases downwards, whereas ∆PCO2 decreases. Most of this vertical ∆PCO2 decline results from decreasing temperatures and increasing alkalinity due to an increased fraction of calcium carbonate dissolution. These two factors limit the CO2 outgassing from the high‐carbon content deep waters on more southerly surface outcrops. Our results imply that the response of Southern Ocean CO2 fluxes to possible future changes in upwelling are sensitive to the subsurface carbon chemistry set by the vertical remineralization and dissolution profiles. Deep ocean CO2 release arises from high potential CO2 partial pressure in subsurface water between the Subantarctic Front and sea‐ice edge Maximum subsurface potential CO2 is connected to the outcrop of upwelling Indo‐Pacific Deep Water (IPDW), rich in remineralized organic carbon High alkalinity and low temperature limit CO2 release from higher carbon‐content deep water outcropping south of IPDW