Expanded oxygen minimum zones during the late Paleocene-early Eocene: Hints from multiproxy comparison and ocean modeling
Expanded oxygen minimum zones during the late Paleocene-early Eocene: Hints from multiproxy comparison and ocean modeling
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DOI：
10.1002/2016pa003020
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发表时间：
2016-12
期刊：
影响因子：
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通讯作者：
Xiaoli Zhou;Ellen Thomas;A. Winguth;A. Ridgwell;H. Scher;B. Hoogakker;R. Rickaby;Zunli Lu
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文献类型：
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作者：
Xiaoli Zhou;Ellen Thomas;A. Winguth;A. Ridgwell;H. Scher;B. Hoogakker;R. Rickaby;Zunli Lu
人类活动造成的变暖很可能在未来导致海洋氧气的消耗。脱氧和变暖之间的关系的重要见解可以从地质记录中收集，但证据是有限的，因为很少有海洋氧化记录可用于过去的温室气候条件。我们使用I/Ca在底栖有孔虫重建晚古新世通过早始新世底和孔隙水氧化还原条件在南大西洋和南印度洋，并比较我们的结果与来自Mn的形态和Ce异常的鱼牙齿。我们的结论是，氧气浓度较低的沃茨广泛分布在中等深度（1.5-2公里），而底部沃茨在最深的地方，在东南大西洋（>3公里），含氧更多。底栖有孔虫I/Ca值在古新世晚期较高，特别是在低氧的网站，比在良好的含氧现代网站，表明古新世晚期海水总碘浓度高于今天。基于代理的底层水氧合模式与综合气候模型（社区气候系统模型第3版）模拟的站点间O2梯度一致，但模拟的溶解O2绝对值较低（< ~35 µmol/kg），而地球系统模型（网格启用的综合地球系统模型）获得的O2值较高（~60-100 µmol/kg）。如果要解决过去的海洋氧化的细节，多代理数据以及边界条件和模型参数化的改进是必要的。
Anthropogenic warming could well drive depletion of oceanic oxygen in the future. Important insight into the relationship between deoxygenation and warming can be gleaned from the geological record, but evidence is limited because few ocean oxygenation records are available for past greenhouse climate conditions. We use I/Ca in benthic foraminifera to reconstruct late Paleocene through early Eocene bottom and pore water redox conditions in the South Atlantic and Southern Indian Oceans and compare our results with those derived from Mn speciation and the Ce anomaly in fish teeth. We conclude that waters with lower oxygen concentrations were widespread at intermediate depths (1.5–2 km), whereas bottom waters were more oxygenated at the deepest site, in the Southeast Atlantic Ocean (>3 km). Epifaunal benthic foraminiferal I/Ca values were higher in the late Paleocene, especially at low-oxygen sites, than at well-oxygenated modern sites, indicating higher seawater total iodine concentrations in the late Paleocene than today. The proxy-based bottom water oxygenation pattern agrees with the site-to-site O2 gradient as simulated in a comprehensive climate model (Community Climate System Model Version 3), but the simulated absolute dissolved O2 values are low (< ~35 µmol/kg), while higher O2 values (~60–100 µmol/kg) were obtained in an Earth system model (Grid ENabled Integrated Earth system model). Multiproxy data together with improvements in boundary conditions and model parameterization are necessary if the details of past oceanographic oxygenation are to be resolved.