Variation of stream dissolved organic carbon quantity, character and ecosystem function in a changing landscape

人类活动引起的最明显的环境变化之一就是景观的改变。这通常涉及以牺牲农业和城市地区为代价减少森林覆盖。土地使用的这些变化几乎不可避免地会影响地表水和地下沃茨的水质和水量，因为土地与水之间的联系发生了变化。对于这些景观中的河流，修改后的连接意味着有机物质（通常以溶解有机碳（DOC）的碳单位来衡量）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。这种“改良”的DOC对我们河流的健康功能有很大的影响。在这个项目中，我将研究如何DOC的质量和数量的变化，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。我的研究计划将进一步调查定义河流结构和生产的物理和生物过程之间的因果关系。我将研究重要的生物，化学和物理因素，与DOC的变化。我将进一步测试农业和城市来源的DOC和营养物质如何影响细菌生长，食物网和几个生态系统功能，如分解，营养吸收和氮的循环。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（农业和住宅废物）将如何影响水生群落的健康和完整性。

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 water quality and quantity in surface and subsurface waters because of altered connections between the land and water. For rivers in these landscapes, modified connections mean that organic matter (generally measured in carbon unites as dissolved organic carbon, DOC) originates primarily from agricultural crops, manure and urban waste instead of natural vegetation, soils and wetlands. This 'modified' DOC can have large implications for 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. My research program will further investigate the cause and effect relationships among the physical and biological processes that define river structure and production. I will examine important biological, chemical, and physical factors that change with DOC. I will further test how agriculturally and urban-derived DOC and nutrients affects bacterial growth, food webs and several ecosystem functions such as decomposition, nutrient uptake and the cycling of nitrogen. Finally, I will test for riverine 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 and residential waste) will affect the health and integrity of aquatic communities.