Hydrological control points of biogeochemical cycling in suburbanizing stream corridors

加拿大的人口越来越多地居住在城市，需要更多的土地使用转换为城市和郊区环境。在安大略南部，目前1300万居民的人口预计到2040年将增长50%，需要扩建现有城镇。随着新的郊区发展，目前的土地规划者的目标是创造综合的自然遗产系统的绿色空间集中在现有的和扩大的河流走廊。这些郊区走廊的设计模仿自然系统，增加了河流弯曲和广泛的河岸带，河流附近的土地往往比高地环境更潮湿。在自然系统中，这些走廊特征增强了河流与陆地环境之间的连通性，从而提高了生物地球化学处理和物种生产及多样性的速度。这些经过改造的郊区河流走廊是否具有自然类似物的功能还有待检验。这项研究将解决四个主要问题的水文和生态地球化学功能的郊区和郊区河流走廊。(1)什么是水文相互作用沿着的高地河岸带流连续在郊区河流走廊，这些如何影响养分动态的溪流和河岸带？(2)在地下水-地表水相互作用和养分周转方面，郊区溪流（宽曲流弯曲，构造浅滩-水池序列）的形态特征是否模仿自然系统？(3)如何快速利用养分在高度修改郊区流，特别是在应对冬季冻融循环和极端降水事件？(4)不同的雨水管理池塘设计对下游养分动态的影响是否不同？本研究的总体目的是为这些受影响的河流廊道开发一个概念性的工作模型，以便该模型可以应用于未来的设计，以改善健康的郊区水生系统的创建和恢复。拟议的研究将为三名博士生，五名硕士生和11名本科论文学生（加上更多的现场和实验室助理）提供机会，以发展他们在环境科学方面的知识和技术技能。这些HQP将为加拿大的环境保护做出有意义的贡献，无论是在我的研究计划任职期间，还是在他们作为环境科学家的整个职业生涯中。

Canada's population is increasingly housed in cities, requiring increased land-use conversion to urban and suburban environments. In southern Ontario, the current population of 13 million residents is expected to grow by 50 % by 2040, requiring expansion of existing cities and towns. With new suburban development, current land planners aim to create integrated Natural Heritage Systems of green space centered on existing and expanded stream corridors. These suburban corridors are designed to mimic natural systems, with increased stream meander bends and extensive riparian zones, the land adjacent to the stream often wetter than the upland environment. In natural systems these corridor features enhance connectivity between the stream and the terrestrial environment, leading to greater rates of biogeochemical processing and species production and diversity. Whether these modified suburban stream corridors function as their natural analogues remains to be tested. This research will address four main questions on the hydrological and biogeochemical functioning of suburban and suburbanizing stream corridors. (1) What are the hydrological interactions along the upland-riparian zone-stream continuum in suburban stream corridors, and how do these affect nutrient dynamics within the streams and riparian zone? (2) Do the created morphologic features of suburban streams (wide meander bends, constructed riffle-pool sequences) mimic natural systems in terms of both groundwater-surface water interactions and nutrient turnover? (3) How quickly are nutrients utilized in highly modified suburban streams, particularly in response to winter freeze-thaw cycles and extreme precipitation events? (4) Do different stormwater management pond designs affect downstream nutrient dynamics differently? The overall purpose of this research is to develop a conceptual working model for these impacted stream corridors, such that the model can be applied to future designs for the improved creation and restoration of healthy suburban aquatic systems. The proposed research will provide opportunities for three PhD students, five MSc students, and 11 undergraduate thesis students (plus many more field and lab assistants) to develop their intellectual and technical skills in the environmental sciences to advanced levels. These HQP will make meaningful contributions to the environmental protection of Canada both during their tenure in my research program and throughout their careers as environmental scientists.