Organic carbon and microbial activity in marine sediments on a global scale throughout the Quaternary
Organic carbon and microbial activity in marine sediments on a global scale throughout the Quaternary
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DOI：
10.1016/j.gca.2020.07.017
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发表时间：
2020-10-01
影响因子：
5
通讯作者：
Amend, Jan P.
中科院分区：
文献类型：
--
作者：
LaRowe, Douglas E.;Arndt, Sandra;Amend, Jan P.
海洋沉积物中有机碳的微生物降解是多时间尺度上全球元素循环的关键驱动因素。然而，目前尚不清楚微生物在多大程度上改变了海洋沉积物中的有机碳，也不知道在全球范围内，微生物的有机碳处理速率如何随深度而变化，从而随埋藏时间而变化。为了更好地理解深层地下动态碳循环与生命极限之间的联系，我们将许多全球数据集与反应输运模型（RTM）结合起来，首先描述了整个第四纪沉积的海洋沉积物中的有机碳降解，其次描述了微生物活动的生物能量模型。RTM在全球范围内应用，识别了三种不同的沉积环境：陆架、边缘和深海带。结果包括颗粒有机碳的质量，POC，储存在三个沉积物深度层：生物扰动全新世（1.7 × 10(17) g C），非生物扰动全新世（2.5 × 10(18) g C）和更新世（1.4 × 10(20) g C）沉积物。在相同的三层中，POC的全球深度积分降解率分别为1.3 × 10（15）、1.3 × 10（14）和3.0 × 10(14) g C /年（-1）。还绘制了一些描绘POC分布的地图，以及已经退化的部分。利用POC降解作为微生物分解代谢活性的代表，整个第四纪POC的总异养处理估计在10（-11）和10(-6)g C cm(-3) yr（-1）之间，具体取决于沉积时间和地点。生物能量模型表明，实验室测定的微生物维持能力不能很好地预测沉积物生物量浓度，但通过将生物能量模型与本研究确定的POC降解率相结合，可以准确预测海洋沉积物中的细胞浓度。我们的模型可以用来定量描述全球范围内小于259万年的海洋沉积物的碳循环和微生物活动。(C) 2020 Elsevier Ltd.版权所有。
Microbial degradation of organic carbon in marine sediments is a key driver of global element cycles on multiple time scales. However, it is not known to what depth microorganisms alter organic carbon in marine sediments or how microbial rates of organic carbon processing change with depth, and thus time since burial, on a global scale. To better understand the connection between the dynamic carbon cycle and life's limits in the deep subsurface, we have combined a number of global data sets with a reaction transport model (RTM) describing first, organic carbon degradation in marine sediments deposited throughout the Quaternary Period and second, a bioenergetic model for microbial activity. The RTM is applied globally, recognizing three distinct depositional environments - continental shelf, margin and abyssal zones. The results include the masses of particulate organic carbon, POC, stored in three sediment-depth layers: bioturbated Holocene (1.7 x 10(17) g C), nonbioturbated Holocene (2.5 x 10(18) g C) and Pleistocene (1.4 x 10(20) g C) sediments. The global depth-integrated rates of POC degradation have been determined to be 1.3 x 10(15) , 1.3 x 10(14) and 3.0 x 10(14) g C yr(-1) for the same three layers, respectively. A number of maps depicting the distribution of POC, as well as the fraction that has been degraded have also been generated. Using POC degradation as a proxy for microbial catabolic activity, total heterotrophic processing of POC throughout the Quaternary is estimated to be between 10(-11) and 10(-6) g C cm(-3) yr(-1), depending on the time since deposition and location. Bioenergetic modeling reveals that laboratory-determined microbial maintenance powers are poor predictors of sediment biomass concentration, but that cell concentrations in marine sediments can be accurately predicted by combining bioenergetic models with the rates of POC degradation determined in this study. Our model can be used to quantitatively describe both the carbon cycle and microbial activity on a global scale for marine sediments less than 2.59 million years old. (C) 2020 Elsevier Ltd. All rights reserved.