Life on the margin: implications of ocean acidification on Mg-calcite, high latitude and cold-water marine calcifiers
Life on the margin: implications of ocean acidification on Mg-calcite, high latitude and cold-water marine calcifiers
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DOI：
10.3354/meps07639
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发表时间：
2008-01-01
影响因子：
2.5
通讯作者：
Bates, Nicholas R.
中科院分区：
文献类型：
--
作者：
Andersson, Andreas J.;Mackenzie, Fred T.;Bates, Nicholas R.
未来人为排放的二氧化碳和由此造成的海洋酸化可能对海洋钙化生物和生态系统造成严重后果。海洋钙化生物沉积含有大量镁的钙化硬部分，即镁方解石，以及生活在高纬度和/或冷水环境中的钙化生物体面临海洋酸化和海水碳酸盐饱和度降低的直接风险，因为它们目前浸没在相对于它们分泌的碳酸盐相仅略微过饱和的海水中。根据目前的二氧化碳排放率，模型计算表明，高纬度海洋沃茨可能在短短几十年内达到文石的不饱和状态。因此，在此发生之前，这些沃茨相对于溶解度高于文石的溶解度的Mg-方解石矿物将是不饱和的。同样，在本世纪，热带表层海水中的MgCO 3含量可能低于12摩尔%（mol%）的镁方解石矿物。由于表层海水化学的这些变化和人为CO2进一步渗透到海洋内部，我们认为：（1）在许多海洋环境中，方解石硬部分的镁含量将减少，（2）沉积稳定碳酸盐矿物（如方解石和低镁方解石）的钙化物的相对比例，碳酸盐沉积物中镁的平均含量会降低。此外，冷水珊瑚和其他钙化生物目前存在的最高纬度和最深深度将分别向低纬度和浅深度移动。这些变化表明，人类排放的二氧化碳可能正在推动海洋走向一个“方解石海”的特征。'
Future anthropogenic emissions of CO2 and the resulting ocean acidification may have severe consequences for marine calcifying organisms and ecosystems. Marine calcifiers depositing calcitic hard parts that contain significant concentrations of magnesium, i.e. Mg-calcite, and calcifying organisms living in high latitude and/or cold-water environments are at immediate risk to ocean acidification and decreasing seawater carbonate saturation because they are currently immersed in seawater that is just slightly supersaturated with respect to the carbonate phases they secrete. Under the present rate Of CO2 emissions, model calculations show that high latitude ocean waters could reach undersaturation with respect to aragonite in just a few decades. Thus, before this happens these waters will be undersaturated with respect to Mg-calcite minerals of higher solubility than that of aragonite. Similarly, tropical surface seawater could become undersaturated with respect to Mg-calcite minerals containing >= 12 mole percent (mol%) MgCO3 during this century. As a result of these changes in surface seawater chemistry and further penetration of anthropogenic CO2 into the ocean interior, we suggest that (1) the magnesium content of calcitic hard parts will decrease in many ocean environments, (2) the relative proportion of calcifiers depositing stable carbonate minerals, such as calcite and low Mg-calcite, will increase and (3) the average magnesium content of carbonate sediments will decrease. Furthermore, the highest latitude and deepest depth at which cold-water corals and other calcifiers currently exist will move towards lower latitudes and shallower depth, respectively. These changes suggest that anthropogenic emissions of CO2 may be currently pushing the oceans towards an episode characteristic of a 'calcite sea.'