CAREER: Nitrogen exchange and removal in riparian wetlands - the role of vegetation

过量的生物可利用氮严重降低了美国中西部农业管理的溪流和河流的水质。大多数氮负荷在这一地区发生在高流量，洪水条件下，河流水文连接到河岸湿地。尽管有明确的证据表明，湿地脱氮，去除效率的机制是缺乏理解。利用野外实验，原位和遥感观测相结合，该项目研究了湿地植被如何调节河岸湿地的物理和生物不同区域的水传输和氮去除率之间的相互作用。需要这种知识来利用湿地的潜力，以减轻地表水质量退化。此外，管理水质的一个核心挑战是依赖自愿采取保护行动来减少氮的投入。该项目的教育和推广部分将提供机会，以一种引人入胜的环境和形式与社区成员分享与水质管理有关的科学。总的来说，这个项目响应了科学和社会的需求，概括了我们对湿地系统性能的理解，并确定了在地方、国家和全球农业足迹不断扩大的情况下解决水质受损问题的途径。这个项目的总体目标是促进科学和学生对河岸湿地植被在促进高流量期间氮去除方面的作用的理解，当发生大多数反应性氮负荷时的淹没条件。具体而言，本项目将在两个空间尺度上研究河岸湿地植被分布和结构对氮去除的影响。在河段尺度上，沿着研究河段的观测数据将量化湿地淹没深度和范围、与河道的水力交换率、植被结构和沿沿着河段的净氮去除。在植被冠层尺度上，将采用田间试验来测量氮转化和去除率作为流速和冠层内植被结构的函数。净氮去除率在冠层和到达尺度将通过模拟方法进行比较，以确定当地规模的相互作用是否可以解释净氮去除模式。该项目还旨在通过经验，沟通为重点的教育举措和学生主导的外展活动，同时提高学生的多样性，促进水质管理。教育活动的结构将首先通过课程中的主动学习来建立大学生的专业知识，然后让学生通过当地的科学中心及其成功的现有推广计划来教授他们所学到的知识。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

Excessive biologically available nitrogen has severely degraded water quality in streams and rivers of the agriculturally managed midwestern United States. Most nitrogen loading in this region occurs during high streamflow, flooded conditions when rivers are hydrologically connected to riparian wetlands. Despite clear evidence of wetland nitrogen removal, a mechanistic understanding of removal efficiency is lacking. Using a combination of field experiments, in situ and remote sensing observations, this project investigates how wetland vegetation regulates the interplay between water transport and nitrogen removal rates in physically and biologically distinct regions of riparian wetlands. This knowledge is required to harness the potential of wetlands to mitigate surface water quality degradation. In addition, a central challenge in managing water quality is the reliance on voluntary adoption of conservation actions to reduce nitrogen inputs. The education and outreach components of this project will provide opportunities to share science relevant to water quality stewardship with community members in an engaging setting and format. Overall, this project responds to a scientific and societal demand to generalize our understanding of wetlands system performance and identifies pathways to address impaired water quality under the expanding local, national and global footprint of agriculture.The overarching goal of this proposal is to advance scientific and student understanding of the role of riparian wetland vegetation in facilitating nitrogen removal during high streamflow, flooded conditions when most reactive nitrogen loading occurs. Specifically, this project will investigate the effect of riparian wetland vegetation distribution and structure on nitrogen removal at two spatial scales. At the reach scale, observational data along the study reach will quantify wetland inundation depth and extent, hydraulic exchange rate with the channel, vegetation structure and net nitrogen removal along the reach. At the vegetated canopy scale, field experiments will be used to measure nitrogen transformation and removal rates as a function of flow rate and in-canopy vegetation structure. Net nitrogen removal rates at canopy and reach scales will be compared via a modeling approach to determine whether local-scale interactions can explain net patterns in nitrogen removal. This project additionally seeks to promote water quality stewardship through an experiential, communication focused educational initiative and student led outreach activities while increasing student diversity. Educational activities will be structured to first build university student expertise via active learning in courses then have the students teach what they have learned through a local science center and its successful existing outreach program.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.