Data tables for Figs 3, 6, 9.docx

Dataset for the following manuscript: Sobocinska, A. & Baas, J.H. (2022, submitted) Effect of biological polymers on mobility and run-out distance of cohesive and non-cohesive sediment gravity. Marine Geology. Paper abstract: Lock-exchange experiments were carried out to investigate the effect of biologically cohesive extracellular polymeric substances (EPS) on the mobility of sediment gravity flows laden with physically cohesive clay, non-cohesive coarse silt and non-cohesive fine sand. The results reveal significant differences in the head velocity, run-out distance and deposit shape of these flows related to differences in physical cohesion, particle size, and EPS content. These differences are captured in a three-way coupling model of turbulent forces, cohesive forces, and particle settling velocity. In general, biological cohesion reduces flow mobility, demonstrated most clearly by a progressive decrease in the run-out distance of the silt and clay flows, as the EPS concentration is increased. This reduction in flow mobility is caused by the dominance of cohesive forces over turbulent forces, which comprise turbulence attenuation and the bulk settling of a biologically cohesive gel in which EPS form a pervasive network of bonds between the sediment particles. However, sand-laden gravity flows were found to behave in a markedly different way, in that the head velocity and run-out distance first increase and then decrease, as the EPS concentration is increased. The increase in sand flow mobility is inferred to be caused by a reduction in the settling velocity of the sand particles, as the EPS cause an increase in flow viscosity at EPS concentrations that are sufficiently low to maintain turbulent flow. Once the EPS concentration is high enough for turbulence attenuation, the sand flows start to agree with the silt and clay flows in establishing a negative correlation between flow mobility and EPS concentration caused by gelling. The experimental data also uncovered that deposits formed by EPS-rich, turbulence-attenuated flows are shorter and thicker and have more abrupt terminations than deposits formed by EPS-free or EPS-poor turbulent flows. The larger thickness of these deposits is partly caused by the ability of EPS to retain water and form matrix-supported textures. Earlier work has shown that EPS is common in many sedimentary environments, including those where sediment transport takes place regularly by particulate density currents. Combined with the increasing rate at which man-made structures, such as pylons and communication, appear in these environments, we argue that there is a need to incorporate the results of this study in applied models that aim to mitigate damage to such structures by sediment gravity flows.本数据集对应以下手稿：Sobocinska, A. 与 Baas, J.H.（2022年，已投稿）《生物聚合物对黏性与非黏性沉积物重力流运动能力及运移距离的影响》，刊载于《海洋地质学》（Marine Geology）。 论文摘要：研究通过锁交换实验（Lock-exchange experiments），探究了具有生物黏性的细胞外聚合物（Extracellular Polymeric Substances, EPS）对负载物理黏性黏土、非黏性粗粉砂及非黏性细砂的沉积物重力流运动能力的影响。结果显示，受物理黏性、颗粒粒径及EPS含量差异的影响，这类重力流的前锋速度、运移距离及沉积形态存在显著差异。上述差异可通过湍流作用力、黏性作用力与颗粒沉降速度的三元耦合模型进行刻画与阐释。 总体而言，生物黏性会降低重力流的运动能力：随着EPS浓度升高，粉砂与黏土重力流的运移距离逐步缩短，该现象直观印证了这一结论。该运动能力的下降源于黏性作用力相较于湍流作用力占据主导地位——具体表现为湍流被抑制，且EPS在沉积物颗粒间形成了广泛的键合网络，进而形成具有生物黏性的凝胶体并发生整体沉降。 但负载砂的重力流则表现出显著不同的行为特征：随着EPS浓度升高，其前锋速度与运移距离先升高后降低。研究推测，砂质重力流运动能力的提升源于砂颗粒沉降速度的降低：在EPS浓度较低时，EPS可提升流体黏度，同时维持湍流流动状态。当EPS浓度足够高以抑制湍流后，砂质重力流的运动能力与EPS浓度间会呈现负相关关系，与粉砂及黏土重力流的规律一致，这一变化由凝胶化作用导致。 实验数据还显示，相较于不含EPS或EPS含量较低的湍流重力流沉积，富含EPS且受湍流抑制的重力流所形成的沉积体更短更厚，且终止边界更为陡峭。这类沉积体厚度更大的部分原因在于EPS能够保留水分并形成基质支撑结构。 前期研究表明，EPS在诸多沉积环境中广泛存在，包括那些频繁发生颗粒密度流输运的区域。结合近年来这类环境中塔架、通信设施等人工构筑物的数量持续增长的现状，我们认为有必要将本研究的成果纳入应用模型，以缓解沉积物重力流对这类人工构筑物造成的破坏。