Temperature-dependent remineralization and carbon cycling in the warm Eocene oceans
Temperature-dependent remineralization and carbon cycling in the warm Eocene oceans
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DOI：
10.1016/j.palaeo.2014.05.019
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发表时间：
2014-11-01
影响因子：
3
通讯作者：
Ridgwell, Andy
中科院分区：
文献类型：
--
作者：
John, Eleanor H.;Wilson, Jamie D.;Ridgwell, Andy
异养细菌的代谢率比初级生产量的代谢率对温度更敏感(例如，Lopez-Urrutia等人，2006年；Regaudie-de-Gioux和Duarte，2012年)。因此，在较温暖的海洋中，较快的细菌呼吸速率可能会导致在水柱较高处下沉的有机物更有效地再矿化，从而影响气候变暖状态下的碳和营养循环。这得到了一系列重建的C-13三角洲(DIC)的支持：该深度剖面基于暖始新世(55.5-33.7 Ma)坦桑尼亚保存完好的浮游有孔虫组合，当时全球表层和深海温度超过了现代(John等人，2013年)。这些结果表明，上层水柱中的C-13增量(DIC)梯度相对较大，这支持这样一种假设，即在温暖的始新世海洋中，高代谢率导致更有效的有机物质循环，并减少有机碳的埋藏率(Olivarez Lyle和Lyle，2006)。较浅的再矿化深度也会导致氧最小区域的向上移动和加强，这与海洋生态系统的证据是一致的，该证据表明，在温暖的早、中期始新世，海洋生态系统集中在靠近地表的狭窄深度范围内。在这里，我们使用地球系统模型cGENIE，该模型包含了一个新的再矿化速率与温度的关系，以说明温度对颗粒有机碳通量的潜在影响，从而说明垂直增量C-13(DIC)梯度。模拟坦桑尼亚海岸外始新世三角洲C-13(DIC)垂直剖面与重建的三角洲C-13(DIC)剖面吻合很好，支持我们基于依赖温度的再矿化的解释。(C)爱思唯尔出版的2014年。
Metabolic rates in heterotrophic bacteria are more sensitive to temperature than rates of primary production (e.g., Lopez-Urrutia et al., 2006; Regaudie-de-Gioux and Duarte, 2012). Consequently, faster bacterial respiration rates in a warmer ocean may result in more efficient remineralization of sinking organic matter higher in the water column, with implications for carbon and nutrient cycling during warm climate states. This is supported by a series of reconstructed delta C-13(DIC): depth profiles based on well-preserved planktonic foraminifera assemblages from Tanzania from the warm Eocene epoch (55.5-33.7 Ma) when global surface and deep ocean temperatures exceeded those of the modern day (John et al., 2013). These results indicate relatively sharp delta C-13(DIC) gradients in the upper water column which supports the hypothesis that high metabolic rates in warm Eocene oceans led to more efficient recycling of organic matter and reduced burial rates of organic carbon (Olivarez Lyle and Lyle, 2006). Shallower remineralization depths would also cause an upward displacement and intensification of the oxygen minimum zone which is consistent with evidence for a pelagic ecosystem that was focused in a narrow depth range near the surface during the warm early and middle Eocene. Here we use the Earth System model, cGENIE, that incorporates a new temperature dependence of remineralization rates to illustrate the potential effects of temperature on particulate organic carbon fluxes and hence vertical delta C-13(DIC) gradients. Modeled delta C-13(DIC) vertical profiles off the coast of Tanzania for the Eocene agree well with the reconstructed delta C-13(DIC) profiles, supporting our interpretations based on temperature-dependent remineralization. (C) 2014 Published by Elsevier B.V.