Runoff generation and phosphorus mobilization in agricultural landscapes

以农业为主的集水区的非点源磷出口是一个全球性问题，也是加拿大许多地区的优先领域，在这些地区，在大型湖泊中观察到有害藻华（HABs）的频率越来越高。尽管实施了有益管理措施（BMPs）来减少磷的损失，但在某些地区，磷负荷并没有减少，实际上还在增加。现有的磷输出模型和管理策略主要针对降雨事件驱动的地表径流，而不能有效地解决冬季过程和融雪期。这一时期代表了我们对农业地区磷动员的科学认识的重大差距。在全球许多中纬度地区，冬季是径流和磷的主要年通量，因此有必要了解冬季和早春磷损失的驱动因素。***本提案的目标，以及我的研究计划的短期目标是提高对冬季条件对磷供应和运输过程的影响的科学认识，以及它们如何相互作用以驱动地表和地下径流中的磷转移。需要提高对农业流域地表和地下径流生成和磷动员动态的科学理解，以制定和实施通过这两种途径减少磷负荷的有效策略。对气候驱动因素在这些过程中的作用的理解，也将有助于深入了解农业系统如何应对气候变化，如果条件从预测的以雪为主转变为以降水为主、土壤霜冻减少的话。***实地调查将与在实地和滑铁卢大学实验室进行的新颖实验相结合，并将培训四名研究生作为这项工作的一部分。我提议的研究将对环境和经济产生重大影响，因为它解决了与气候（和气候变化）以及与农业管理（即人工排水）相关的问题。最重要的是，这项研究的目标是冬季，并且基于观测现场数据，因此解决了一个重要的知识差距。**

Phosphorus (P) export from non-point sources in agriculture-dominated catchments is a global issue, and a priority area for many regions in Canada, where Harmful Algal Blooms (HABs) have been observed in large lakes with increasing frequency. Despite the implementation of Beneficial Management Practices (BMPs) to reduce P loss, P loads are not decreasing and in fact are increasing in some regions. Existing models for P export and management strategies largely target rainfall event-driven surface runoff and do not effectively address winter processes and the snowmelt period. This period represents a significant gap in our scientific understanding of P mobilization in agricultural regions. In many midlatitude regions globally, the winter period is the dominant annual flux for both runoff and P. Thus, an understanding of the drivers of P loss in winter and early spring is needed.***The objective of this proposal, and the short-term objective of my research program is to improve scientific understanding of the impacts of winter conditions on P supply and transport processes, and how these interact to drive P transfer in surface and subsurface runoff. An improved scientific understanding of runoff generation and P mobilization dynamics in both surface and subsurface pathways in agricultural catchments is needed to develop and implement effective strategies that reduce P loads via both of these pathways. An understanding of the role of climate drivers on these processes will also provide insight into how agricultural systems may respond to climate change, if conditions shift from snow-dominated to more precipitation dominated with reduced soil frost as has been projected.***Field investigations will be coupled with novel experiments done in the field and in the laboratory at the University of Waterloo, and four graduate students will be trained as part of this work. My proposed research will have significant environmental and economic impacts as it addresses issues related to climate (and climate change) and issues that are relevant to agricultural management (i.e. artificial drainage). Most importantly, this research targets the winter period, and is based on observational field data, and therefore addresses a significant knowledge gap. **