Erosional Sorting of Fine Marine Sediments

细颗粒沉积物在潮间带沃茨的迁移影响到加拿大海岸带的健康和可持续利用。海岸线对海平面上升的反应、沿海沃茨的可航行性以及人类和其他生物体受到沉积物所含污染物的影响都取决于细沉积物的迁移。使问题复杂化的是，所有这些影响都与细海洋沉积物的可分选性有关，但人们对这一点并不十分了解。 这项研究的目的是提高对影响细海洋沉积物侵蚀分选性的因素的认识，并最终将这种认识纳入细沉积物输运模型。 从概念上讲，侵蚀分选性只是描述了在海底沉积物侵蚀过程中将不同大小的颗粒彼此分离的难易程度。“细沉积物”一词适用于平均粒径小于63微米的沉积物。几十年来，沉积学家将细沉积物颗粒视为不可分选的，这一假设导致对海底和悬浮液中细沉积物粒度分布和浓度的预测不佳。它也导致了粗糙的模型的流动性的颗粒附着的物质。然而，最近的研究表明，细沉积物是可分选的， 分选性取决于生物和非生物因素的相互作用。 这项研究将集中在五个因素，可能主导的精细海洋沉积物的分选：沉积物质地，沉积物含水量，丰富的沉积物附着（epipelic）硅藻，丰富的细菌，和浓度和沉积物外聚合物的物质（EPS）的属性。这些因素将结合实地研究，实验室实验和建模进行研究。

The transport of fine sediment in intertidal waters affects the health and sustainable uses of the coastal zone in Canada. The response of the shoreline to sea level rise, navigability of coastal waters and exposure of humans and other organisms to sediment-bound contaminants all depend on fine sediment transport. To complicate matters, all of these effects are tied to the sortability of fine marine sediment, which is not well understood. The goal of this research is to improve understanding of the factors that affect the erosional sortability of fine marine sediment and ultimately to incorporate this understanding into models of fine sediment transport. Conceptually, erosional sortability simply describes how easy or difficult it is to separate particles of different sizes from one another during erosion of sediment from the seabed. "Fine sediment" is the term applied to sediments with mean particle diameters less than 63 micrometres. For decades, sedimentologists treated fine sediment particles as non-sortable, a hypothesis that led to poor predictions of fine sediment size distributions and concentrations in the seabed and in suspension. It also led to crude models for the mobility of particle-attached substances. Recent studies have shown, however, that fine sediments are sortable, but that the sortability depends on the interaction of biotic and abiotic factors. This research will focus on five factors that are likely to dominate the sortability of fine marine sediments: sediment texture, sediment water content, abundance of sediment-attached (epipelic) diatoms, abundance of bacteria, and concentration and properties of sediment exopolymeric substances (EPS). These factors will be examined with a combination of field studies, laboratory experiments, and modeling.