Nutrient Legacies and Time Lags: Understanding Catchment Biogeochemical Responses in Anthropogenic Landscapes

养分遗产和时间滞后：了解人类景观中的流域生物地球化学反应

• 批准号: RGPIN-2015-06024
• 负责人: Basu, Nandita
• 金额: $ 2.4万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=613889
• 关键词: Nutrient; Legacies; Time; Lags; Understanding

Excess nutrients associated with high levels of fertilizer application and concentrated livestock operations find their way into both ground and surface waters, leading to problems of hypoxia, aquatic toxicity and drinking water contamination. Reductions in fertilizer application or implementation of other best management practices (BMPs) have been carried out to improve water quality, but often they do not yield expected results. Such lack of response is attributed to buildups of legacy stores that can cause significant time lags between BMP implementation and water quality improvements. Understanding how the accumulation and depletion of anthropogenic legacies alter water quality is the focus of my research program. The research not only addresses a critical gap in global nutrient budgets, but also helps to create a practical framework for setting realistic, time-specific goals for water quality management. The Discovery research will build on my recent work, which provides new evidence of organic nitrogen (N) accumulation in agricultural soils and raises important questions regarding the role of N legacy in catchment-scale N dynamics: (1) What mechanisms control legacy N accumulation and depletion within agricultural landscapes? (2) How do such legacies contribute to time lags between changes in management practices and improvements in water quality? In the proposed work, a model will be developed to explore hypotheses regarding soil carbon-nitrogen dynamics and to clarify controls on N accumulation and depletion. The model will be validated using both existing datasets and project-specific fieldwork. In collaborative work at the Harrow Agricultural Research Station, depth-dependent accumulation of legacy N will be determined under a range of fertilizer treatments, and isotope analysis will be used for source detection of nitrate in drainage water. In addition, field studies will be carried out across an identified chronosequence to determine N concentration trajectories after agricultural land retirement. The vadose zone legacy model thus developed will be used in a spatially explicit framework to quantify time lags at a range of scales, from plot to field to catchment, for watersheds both within and outside Canada. This will lay the groundwork for a more global-scale analysis of the role of legacy-related time lags in nutrient loading to coastal waters. Research funded through the Discovery will increase fundamental understanding of N legacies in anthropogenic landscapes and their impacts on water quality. The project will leverage existing university strengths in water and ecohydrology and contribute positively to Canada’s economy by training of top HQP in the water and environmental sector. Research results will contribute significantly to the field of watershed-scale nutrient transport, thus allowing for more effective management of Canadian Water Resources.

与大量施肥和集中畜牧业活动有关的过量营养物进入地下和地表沃茨，导致缺氧、水生毒性和饮用水污染等问题。为改善水质，已采取减少化肥施用或实施其他最佳管理做法，但这些做法往往没有产生预期的效果。这种缺乏反应是由于遗留商店的积累，可能会导致BMP的实施和水质改善之间的显着时间滞后。了解人类遗产的积累和消耗如何改变水质是我的研究计划的重点。该研究不仅解决了全球营养预算的关键缺口，还有助于建立一个实用的框架，为水质管理制定现实的，有时间限制的目标。 发现研究将建立在我最近的工作，这提供了农业土壤中有机氮（N）积累的新证据，并提出了关于N遗产在流域尺度N动态中的作用的重要问题：（1）什么机制控制农业景观中的遗产N积累和消耗？(2)这些遗留问题如何造成管理做法的改变与水质的改善之间的时间差？ 在拟议的工作中，将开发一个模型来探索土壤碳氮动态的假设，并澄清控制氮积累和消耗。该模型将使用现有的数据集和具体项目的实地工作进行验证。在哈罗农业研究站的合作工作中，将在一系列肥料处理下确定遗留氮的深度依赖性积累，并将使用同位素分析来检测排水中硝酸盐的来源。此外，实地研究将在确定的时间序列，以确定农业用地退休后的N浓度轨迹。因此，开发的渗流区遗产模型将被用于在空间上明确的框架，以量化的时间滞后在一定范围内的规模，从地块到领域的集水区，在加拿大境内和境外的流域。这将为在全球范围内分析与遗产有关的时间滞后对沿海沃茨营养物负荷的作用奠定基础。 通过发现资助的研究将增加对人类景观中N遗产及其对水质影响的基本了解。该项目将利用现有大学在水和生态水文学方面的优势，通过培训水和环境部门的高级HQP，为加拿大经济做出积极贡献。研究结果将大大有助于流域规模的营养物运输领域，从而使加拿大水资源的更有效的管理。