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已知的营养物和污染物向水生系统转移和在水生系统内转移的载体。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。在不列颠哥伦比亚省北部，大规模的松甲虫流行病改变了许多流域的水文功能。政府提出了一项建议，即收获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将增加。这些潜在的变化通过土壤侵蚀对陆水连通性的影响表明，溪流将接受更多的沉积物和有机物负荷。其中一些物质将作为土壤团聚体进入溪流，但也会发生絮凝的溪流过程。这些复合颗粒可以在砾石层中保留和分解，将营养物质输送到浅水和上覆水中。最近的研究表明，沉积物-鱼类生物量反馈回路有助于调节营养状况，从而调节鲑鱼产卵和砾石河床河流的生态功能。我建议调查这一过程是否在其他由不同类型有机物（农业肥料、藻华、森林凋落物）主导的河流系统中也起作用。我将量化人工溪流（水槽）中聚合体的产生、沉淀、储存和低氧释放产物。可以确定每种有机源物质的生物物理过程的大小和重要性，然后在自然河流中进行实地工作，将允许对水槽模拟结果进行比较。调查河流絮团/骨料的产生、命运和影响的基础研究将使用沉积学和微观技术，同时将测试应用于开发利用微生物DNA作为水文地貌示踪剂的新的沉积物示踪方法的研究。该项目提供了流域管理和水生栖息地恢复方面的关注，这些关注需要结合沉积物转移的地貌学知识和水生营养物质转移的生态信息。

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.