RAPID: Using a drought-enhanced nitrate pulse to understand stream N retention and processing

氮添加是现代农业的基石，但施肥影响了内陆和沿海沃茨，增加了氮浓度，支持水生植物过度生长，降低了氧浓度，并引发有害藻类大量繁殖。由于2012年的极端干旱，中西部土壤积累了氮，预计这些氮将在夏末或秋季降水中进入河流网络。这种预期的全流域氮脉冲提供了一个即时和无与伦比的机会，记录氮如何进入流，并量化氮的运输，衰减和命运，因为它通过流网络移动。将扩大现有的溪流监测网络，利用2012年秋季重大降水事件期间和之后的短期机会收集水样，描述农业景观中氮的移动和处理情况，施肥的意外后果对资源管理人员来说是一个日益重要的问题。该项目将增加我们对氮如何从农田进入并通过河流网络的理解，并且将在预计未来几十年将更加常见的气候条件下这样做。此外，该项目将支持五名早期职业科学家以及内布拉斯加大学林肯分校、爱荷华州大学和科学院之间的合作。包括科学院将提供机会，本科研究和指导本科生的教师和研究生。

Nitrogen addition is a cornerstone of modern agriculture, but fertilization has impacted inland and coastal waters by increasing nitrogen concentrations, supporting excessive growth of aquatic plants, reducing oxygen concentrations, and triggering harmful algal blooms. Because of extreme drought in 2012, Midwestern soils have accumulated nitrogen that is expected to be driven into river networks by late summer or fall precipitation. This anticipated landscape-wide nitrogen pulse offers an immediate and unparalleled opportunity to record how nitrogen enters streams, and to quantify the transport, attenuation, and fate of nitrogen as it moves through stream networks. An existing stream monitoring network will be expanded and used to collect water samples during and after major precipitation events in fall 2012, taking advantage of a short-term opportunity to characterize nitrogen movement and processing in an agricultural landscape.Unintended consequences of fertilization are an increasingly important issue for resource managers. This project will add to our understanding of how nitrogen moves from agricultural lands into and through stream networks, and it will do so under climate conditions that are expected to be more common in the coming decades. Additionally, this project will support five early career scientists and a collaboration between the University of Nebraska-Lincoln, the University of Iowa, and Coe College. Inclusion of Coe College will provide opportunities for undergraduate research and mentoring of undergraduate students by faculty and graduate students.