Biomediation of submarine sediment gravity flow dynamics
Biomediation of submarine sediment gravity flow dynamics
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DOI：
10.1130/g46837.1
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发表时间：
2020-01-01
期刊：
影响因子：
5.8
通讯作者：
Baker, Megan L.
中科院分区：
文献类型：
--
作者：
Craig, Melissa J.;Baas, Jaco H.;Baker, Megan L.
沉积物重力流是沉积物和有机碳从大陆边缘向深海迁移的主要过程。高达40%的海洋有机碳库是由微生物产生的粘性胞外聚合物（EPS）。这些聚合物对沉积物重力流的影响尚未调查，尽管这些流量的经济和社会的重要性。我们提出的第一个EPS浓度测量深海沉积物，结合新的实验室数据，提供洞察到的粘土负载，物理粘性沉积物重力流的动态调制生物凝聚力。我们表明，EPS可以深刻地影响沉积物重力流的特征，演变和流失，并在深海和浅海一样普遍。过渡和层流塞流比湍流更容易受到EPS引起的流动特性变化的影响。在相对较低的浓度下，EPS显著降低了过渡流的水头流速和流出距离。每单位重量的生物凝聚力大于粘性粘土的物理凝聚力，并且可以对流动行为施加更强的控制。这些结果显着提高我们的理解的影响，未实现的生物成分的沉积物重力流。其影响范围很广，可能会影响沉积物重力流的预测模型，并促进我们对这些流动在全球范围内运输和掩埋有机碳的方式的理解。
Sediment gravity flows are the primary process by which sediment and organic carbon are transported from the continental margin to the deep ocean. Up to 40% of the total marine organic carbon pool is represented by cohesive extracellular polymeric substances (EPS) produced by microorganisms. The effect of these polymers on sediment gravity flows has not been investigated, despite the economic and societal importance of these flows. We present the first EPS concentrations measured in deep-sea sediment, combined with novel laboratory data that offer insights into the modulation of the dynamics of clay-laden, physically cohesive sediment gravity flows by biological cohesion. We show that EPS can profoundly affect the character, evolution, and runout of sediment gravity flows and are as prevalent in deep oceans as in shallow seas. Transitional and laminar plug flows are more susceptible to EPS-induced changes in flow properties than turbulent flows. At relatively low concentrations, EPS markedly decrease the head velocity and runout distance of transitional flows. This biological cohesion is greater, per unit weight, than the physical cohesion of cohesive clay and may exert a stronger control on flow behavior. These results significantly improve our understanding of the effects of an unrealized biological component of sediment gravity flows. The implications are wide ranging and may influence predictive models of sediment gravity flows and advance our understanding about the ways in which these flows transport and bury organic carbon globally.