Fine sediment and organic matter interactions: bio-physical effects of aggregated sediments on streams

絮凝或聚集的土壤和沉积物是营养物质和污染物转移到水生系统和水生系统内部的已知媒介。它们在水生系统中的行为和停留时间是河流、湖泊和海洋中物质输送和滞留的调节因素。在公元前北部，大规模的松甲虫疫情改变了许多流域的水文功能。各国政府已经提出了一项建议，即收割这些地区，并将其转变为农业。这与预测的气候变暖相结合，意味着许多流域的田间耕作和施肥都将增加。这些潜在变化通过土壤侵蚀对陆地-水生连通性的影响表明，溪流将接受更多的沉积物和有机物负荷。这些物质中的一部分将作为土壤集合体被输送到溪流中，但也会发生河流的絮凝过程。这些复合颗粒可以在砾石床中保留和分解，将营养物质输送到地下和上覆水中。最近的研究表明，沉积物-鱼类生物量反馈环有助于调节营养状态，从而调节鲑鱼产卵的砾石床河流的生态功能。我建议调查这一过程是否在其他以不同类型有机质(农业化肥、藻华、森林凋落物)为主的河流系统中运行。我将量化人工河流(水槽)中团聚体的生成、沉淀、储存和低尿释放产物。可以确定每种有机来源材料的生物物理过程的大小和重要性，然后在天然河流中进行实地工作，以便对水槽模拟结果进行比较。将利用沉积学和微观技术对河水絮体/集合体的产生、去向和影响进行基础研究，同时将测试以微生物DNA作为水文地貌示踪剂开发新的沉积物示踪方法的应用研究。该项目为流域管理和水生生物栖息地恢复提供了需要综合掌握泥沙转移地貌知识和水生营养物质转移生态信息的问题。

Flocculated or aggregated soils and sediment are a known vector for nutrient and contaminant transfers to and within aquatic systems. Their behavior and residence time in aquatic systems is a regulating factor in the delivery and retention of materials in rivers, lakes and oceans. In northern BC the massive pine beetle epidemic has altered the hydrologic functioning of many watersheds. A suggestion to harvest these regions and change to an agricultural has been suggested by governments. This, in combination with predicted climate warming, implies an increase in field tillage and fertilization in many watersheds. The effect of these potential changes on terrestrial-aquatic connectivity, via soil erosion, suggests that streams will be receiving increased loads of sediment and organic matter. Some of this material will be delivered to the streams as soil aggregates but as well an instream process of flocculation will occur. These composite particles can be retained and decomposed in the gravel bed delivering nutrients to the hyporeic and overlying water. Recent work indicates that a sediment-fish biomass feedback loop helps regulate the nutrient status, and therefore ecological functioning of salmon spawning, gravel-bed rivers. I propose to investigate if this process operates in other stream systems, dominated by different types of organic matter (agricultural fertilizers, algal blooms, forest litter). I will quantify the generation, settling, storage, and hyporeic release products of aggregates in artificial streams (flumes). The magnitude and significance of the bio-physical processes for each of the organic source materials can be determined and then field work in natural rivers will allow a comparison of the flume simulated results. Basic research investigating riverine floc/aggregate generation, fate and effect will use sedimentological and microscopic techniques, while applied research into the development of a new sediment tracing method using microbial DNA as a hydro-geomorphic tracer will be tested. This project delivers to watershed management and aquatic habitat restoration concerns that require combined geomorphic knowledge of sediment transfers and ecological information regarding aquatic nutrient transfers.