Dissolved organic matter dynamics in stream ecosystems

人类活动引起的最明显的环境变化之一就是景观的改变。通常 * 这涉及以牺牲农业和城市地区为代价减少森林覆盖。几乎不可避免的是，由于土地和水之间的联系发生了变化，这些土地利用的变化影响到地表和地下沃茨的质量和数量。对于这些景观中的河流，新的景观连接可以改变 * 有机物质（通常以溶解有机碳（DOC）的碳单位测量），现在主要来自农作物，粪便和城市废物，而不是自然植被，土壤和湿地。与改造后的景观和河流的新联系也改变了河流碳的化学性质，这可以改变我们河流的健康功能。在这个项目中，我将研究如何DOC的质量变化 * 和数量在河流流域的对比土地利用从五大湖盆地在中南部安大略 *。这些数据将用于进一步研究土地利用的物理变化（例如，水流），化学 *（例如，营养素），和生物（例如，流食物网）改变DOC的加工和出口。在此过程中，我将测试农业和城市来源的DOC和营养物质如何影响微生物生长，食物网 * 组成和生态系统功能，如材料（落叶）的腐烂，藻类的营养吸收和 * 氮循环。最后，我将测试河流DOC对气候变化的反应，因为这些可能会受到温暖天气和干旱时期的影响。这项研究将帮助我们了解人类来源的材料（农业肥料和住宅废物）将如何影响水生系统的健康和完整性。

One of the most obvious environmental changes caused by humans is the alteration of the landscape. Usually*this involves the reduction of forested cover at the expense of agricultural and urban areas. Almost inevitably,*these changes in land use affect the quality and quantity of surface and subsurface waters because of altered*connections between the land and water. For rivers in these landscapes, new landscape connections can modify*organic matter (generally measured in carbon units as dissolved organic carbon, DOC) which now originates*primarily from agricultural crops, manure and urban waste instead of natural vegetation, soils and wetlands.*Novel linkages with modified landscape and rivers also change the chemistry of river carbon, which can*change the healthy functioning of our rivers. In this project, I will examine how the DOC changes in quality*and quantity in river watersheds of contrasting land use from the Great Lakes Basin in South-central Ontario.*These data will be used to further examine how land use alterations of physical (e.g., streamflow), chemical*(e.g., nutrients), and biological (e.g., stream foodwebs) alter the processing and export of DOC. In doing so, I*will test how agriculturally and urban-derived DOC and nutrients affects microbial growth, food web*composition, and ecosystem function such as the decay of materials (leaf-litter), nutrient uptake by algae and*nitrogen recycling. Finally, I will test for river DOC responses to climate change because these might be*affected by periods of warm weather and drought. This research will help us understand how human-derived*materials (agricultural fertilizers and residential waste) will affect the health and integrity of aquatic systems.