CAREER: Air-ecosystem-water interactions of reactive nitrogen in urban systems

随着活性氮（Nr）的产生加速以满足全球粮食和燃料需求，关于过量氮对环境和健康影响的研究挑战变得越来越紧迫。虽然美国的大气沉积化学监测网络在全球范围内受到尊重，但这些网络是有意建立在农村地区，以监测沉积化学的区域变化。尽管研究记录了车辆排放的相对局部影响，并且车辆是美国氮氧化物排放的最大来源，但很少探索这些空间沉积模式对生态和水质的影响。与此同时，研究继续报告城市流域Nr保留率惊人地高，与这些系统高硝酸盐出口的预期相反，而硝酸盐出口到敏感的接收水域继续超过目标限制。我们假设，对城市Nr沉积通量的不良限制已经转化为对大气Nr作为营养源对城市生态系统、溪流和河流系统的影响的低估。本研究使用一套独特的分析方法，考察了人类活动与城市环境中大气、陆地和水生系统中Nr通量之间的紧密耦合。研究目标将填补城市Nr预算的主要知识空白，并将：1)比较城市和农村环境下Nr沉积通量、形态和来源；2)研究城市生态系统中Nr滞留的机制；3)评价大气硝酸盐作为水体富营养化源的作用。该项目将促进对地球系统科学中跨学科联系的理解-特别关注能源，环境和社会之间的相互作用。更广泛的项目目标是寻求改善跨学科地球科学教育的区域资源，并为阐明地球科学学科与社会的相关性创造新的途径。这些目标将通过侧重于以下目标的教育活动来实现：1)为匹兹堡地区代表性不足的青少年建立通往地球科学的新管道；2)提高地球系统科学素养，重点关注能源、环境和社会之间的协同作用；3)建立可持续的联盟，促进匹兹堡地区的地球科学教育。这些活动利用了匹兹堡大学现有的资源，包括用于地球和环境科学研究的区域稳定同位素实验室、移动空气质量研究实验室，以及新资助的美国国家科学基金会倡议，ENERGY-NET。能源网将匹兹堡大学的地球科学专家与匹兹堡五个卡内基博物馆之一的卡内基自然历史博物馆联系起来。该项目将这种合作扩展到位于匹兹堡市中心的卡内基科学中心。卡内基科学中心每年接待50万游客，并将作为计划中的城市沉积测量中心。该项目将与卡内基科学中心合作，将研究和监测数据整合到公共展览中，并利用大众宣传工作，让年轻人了解地球科学的职业意识和社会相关性。

As creation of reactive nitrogen (Nr) accelerates to meet global food and fuel demand, the research challenges regarding the environmental and health effects of excess N have become ever more pressing. While atmospheric deposition chemistry monitoring networks in the U.S. are globally respected, these networks were intentionally established in rural settings to monitor regional changes in deposition chemistry. Despite studies documenting the relatively local impact of vehicle emissions- and that vehicles are the largest source of nitrogen oxide emissions in the U.S., the ecological and water quality impacts of these spatial deposition patterns are rarely explored. Concomitantly, studies continue to report surprisingly high rates of urban watershed Nr retention, bucking expectations for high nitrate export from these systems, while nitrate export to sensitive receiving waters continues to exceed targeted limitations. We hypothesize that poor constraints on urban Nr deposition fluxes have translated into an underestimation of the influence of atmospheric Nr as a nutrient source to urban ecosystems, streams, and riverine systems. This research examines the tight coupling between human activities and fluxes of Nr across atmospheric, terrestrial and aquatic systems in urban environments using a unique suite of analytical approaches. Research goals will fill major knowledge gaps in urban Nr budgets and will: 1) compare Nr deposition fluxes, speciation, and sources in urban and rural environments; 2) examine mechanisms for Nr retention in urban ecosystems; and 3) evaluate the role of atmospheric nitrate as a eutrophication source to streams and rivers. This project will advance understanding of interdisciplinary connections in Earth system science - with a specific focus on interactions between energy, the environment, and society. Broader project aims seek to improve regional resources for interdisciplinary Geoscience education and to create new pathways for illuminating the relevance of Geoscience disciplines to society. These aims will be accomplished with educational activities focused on the following goals: 1) create new pipelines to the geosciences for under-represented teens in the Pittsburgh region; 2) advance Earth systems science literacy, focusing on synergies between energy, environment, and society; and 3) develop sustainable alliances to promote Geoscience education in the Pittsburgh region. These activities leverage existing resources at the University of Pittsburgh including the Regional Stable Isotope Laboratory for Earth and Environmental Science Research, the Mobile Air Quality Research Laboratory, and a newly funded NSF initiative, ENERGY-NET. ENERGY-NET links geosciences expertise at the University of Pittsburgh to one of five Carnegie Museums in Pittsburgh, the Carnegie Museum of Natural History. This project extends this collaboration to the Carnegie Science Center, located in downtown Pittsburgh. The Carnegie Science Center receives 500,000 visitors annually and will serve as the hub for planned urban deposition measurements. In partnership with the Carnegie Science Center, this project will integrate research and monitoring data into public exhibits and utilize popular outreach efforts to engage and inform youth regarding geosciences career awareness and societial relevance.