Biological influences on coastal muddy sediment structure following resuspension
Biological influences on coastal muddy sediment structure following resuspension
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DOI：
10.1002/lno.12213
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发表时间：
2022-09
影响因子：
4.5
通讯作者：
W. C. Clemo;Katelyn D. Giles;K. Dorgan
中科院分区：
文献类型：
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作者：
W. C. Clemo;Katelyn D. Giles;K. Dorgan
浅海淤泥质沉积物对全球养分循环和碳储存非常重要，并为各种生物群落提供了栖息地。来自物理扰动（如风暴和飓风）的底部剪切应力使沿海泥浆重新悬浮，破坏了它们的内聚结构。然而，生物过程与物理过程如何影响物理扰动的天然泥浆的重新固结，人们知之甚少。我们比较了物理扰动后与泥浆压实和粘聚力有关的沉积物性质的恢复。我们假设，恢复凝聚力将需要更长的时间比压实和表面和地下的凝聚力的变化将发生在不同的时间尺度。我们收集了泥质沉积物芯，并在实验室中重新悬浮顶部5厘米，以模拟风暴扰动。在再悬浮后的几个时间点（1-30 d），我们测量了沉积物的性质，提供了压实（沉积物高度，孔隙度，粒度分布，声速）和表面和地下凝聚力（侵蚀性，断裂行为，外聚物[EPS]）的指标。压实和凝聚力迅速增加后的第一个1-2天，再悬浮，并继续缓慢增加2周。然而，在2至4周之间，次表层凝聚力增加，浊度降低，与沉积物重新稳定一致。相比之下，地下压实减少，侵蚀质量增加，表明不稳定。我们将这种明显的不稳定归因于小型底栖动物的延迟活动。令人惊讶的是，EPS浓度并不能解释凝聚力的变化。这些结果突出了在预测物理扰动后沉积物结构的恢复时，包括生物参数的重要性。这项工作的影响，了解沿海沉积物输运动力学频繁扰动沉积物。
Shallow coastal muddy sediments are important for global nutrient cycling and carbon storage and provide a habitat for diverse communities of organisms. Bottom shear stress from physical disturbances such as storms and hurricanes resuspend coastal muds, disrupting their cohesive structure. How biological vs. physical processes affect reconsolidation of physically disturbed natural muds, however, is poorly understood. We compare the recovery of sediment properties related to compaction and cohesion of muds following physical disturbance. We hypothesized that recovery of cohesion would take longer than compaction and that changes in surface and subsurface cohesion would occur on different timescales. We collected muddy sediment cores and resuspended the top 5 cm in the lab to simulate storm disturbance. At several timepoints following resuspension (1–30 d), we measured sediment properties providing metrics of compaction (sediment height, porosity, grain size distribution, sound speed) and of surface and subsurface cohesion (erodibility, fracture behavior, exopolymeric substances [EPS]). Compaction and cohesion increased rapidly over the first 1–2 d after resuspension and continued to slowly increase for 2 weeks. Between 2 and 4 weeks, however, subsurface cohesion increased and turbidity decreased, consistent with sediment restabilization. In contrast, subsurface compaction decreased and eroded mass increased, suggesting destabilization. We attribute this apparent destabilization to delayed activity of small‐bodied infauna. Surprisingly, EPS concentration did not explain cohesion changes. These results highlight the importance of including biological parameters when predicting the recovery of sediment structure following a physical disturbance. This work has implications for understanding coastal sediment transport dynamics in frequently disturbed sediments.