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首页> 外文期刊>Frontiers in Marine Science >Seawater carbonate chemistry distributions across the Eastern South Pacific Ocean sampled as part of the GEOTRACES project and changes in marine carbonate chemistry over the past twenty years
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Seawater carbonate chemistry distributions across the Eastern South Pacific Ocean sampled as part of the GEOTRACES project and changes in marine carbonate chemistry over the past twenty years

机译：作为GEOTRACES项目的一部分，采样了整个南太平洋东部的海水碳酸盐化学分布以及过去20年中海洋碳酸盐化学的变化

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The US GEOTRACES Eastern Pacific Zonal Transect in 2013 provided an opportunity to complement studies of the sources, sinks, and internal cycling of trace elements and isotopes (TEIs) with observations of seawater carbon dioxide (CO2)–carbonate chemistry. Across the Peru-Tahiti section, very large horizontal gradients in surface/mixed layer dissolved inorganic carbon (DIC) and total alkalinity (TA) from the nutrient-rich, low-oxygen coastal upwelling region adjacent to Peru to the oligotrophic central Pacific. Near the coast of Peru, upwelling of CO2 rich waters from the oxygen deficient zone (ODZ) impinged at the surface with very high partial pressures of CO2 (pCO2; >800-1,200 μatm), and low pH (7.55 to 7.8). These waters were also undersaturated with respect to aragonite, a common calcium carbonate (CaCO3) mineral. These chemical conditions are not conducive to pelagic and shelf calcification, with shelf calcareous sediments vulnerable to CaCO3 dissolution, and to the future impacts of ocean acidification. A comparison to earlier data collected from 1991 to 1994 suggests that surface dissolved inorganic carbon (DIC) and pCO2 have increased by as much as 3% and 20%, respectively, while pH and saturation state for aragonite (Waragonite) have decreased by as much as 0.063 and 0.54, respectively. In intermediate waters (~200-500 m), dissolved oxygen has decreased (loss of up to -43 μmoles kg-1) and nitrate increased (gain of up to 5 μmoles kg-1) over the past twenty years and this likely reflects the westward expansion of the ODZ across the central Eastern South Pacific Ocean. Over the same period, DIC and pCO2 increased by as much as +45 μmoles kg-1 and +145 μatm, respectively, while pH and Waragonite decreased by -0.091 and -0.45, respectively. Such rapid change in pH and CO2–carbonate chemistry over the past twenty years has implications for changing the thermodynamics and solubility of intermediate water TEIs, but also for the marine ecosystem of the upper waters, especially for the vertically migrating community present in the eastern South Pacific.
机译：2013年，美国GEOTRACES东太平洋分区样带提供了一个机会，可以利用海水二氧化碳（CO2）-碳酸盐化学的观测资料补充痕量元素和同位素（TEI）的来源，汇和内部循环。在秘鲁-塔希提岛的整个区域，地表/混合层中的很大的水平梯度溶解了无机碳（DIC）和总碱度（TA），这些碳来自邻近秘鲁的营养丰富，低氧的沿海上升流区到贫营养中太平洋。在秘鲁海岸附近，来自缺氧区（ODZ）的富含CO2的水上升流冲击到地表，CO2的分压非常高（pCO2;> 800-1,200μatm），pH低（7.55至7.8）。这些水也相对于文石（一种常见的碳酸钙（CaCO3）矿物）而言不饱和。这些化学条件不利于上层和陆架钙化，陆架钙质沉积物易受CaCO3溶解，并不利于海洋酸化的未来影响。与1991年至1994年收集的早期数据进行的比较表明，表面溶解的无机碳（DIC）和pCO2分别增加了3％和20％，而文石（Waragonite）的pH和饱和态下降了同样多。分别为0.063和0.54。在过去的20年中，在中间水域（〜200-500 m）中，溶解氧减少了（损失高达-43μmoleskg-1），硝酸盐增加了（损失高达5μmolkg-1）。 ODZ向东扩展至整个南太平洋中部。在同一时期，DIC和pCO2分别增加了+45μmoleskg-1和+145μatm，而pH和Waragonite分别减少了-0.091和-0.45。在过去的20年中，pH和CO2-碳酸盐化学物质的这种快速变化对改变中间水TEI的热力学和溶解度具有影响，但对上层水域的海洋生态系统也有影响，特别是对于南部东部存在的垂直迁移群落而言太平洋。

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