Collaborative Research: Impacts of urbanization on nitrogen biogeochemistry in xeric ecosystems

城市化极大地改变了半干旱生态系统中氮化合物的迁移和转化。特别是，饮用水的硝酸盐污染在城市地区日益令人担忧，特别是在干旱和半干旱环境中，在这些环境中，城市径流得到积极管理，以补充地下水和增加供水。然而，水资源管理者和城市规划者缺乏关于什么生态系统特征对控制这种回灌水的质量最重要的信息，特别是它的硝酸盐浓度。这项研究将量化暴雨径流中硝酸盐的来源、运输和去向如何随亚利桑那州图森和凤凰城(CAP LTER)的城市土地利用密度和类型而变化。将描述硝酸盐出口的季节模式，并将使用新的同位素示踪技术来了解硝酸盐的来源和控制半干旱城市化梯度上氮素转化的机制。这些机制将被建模并整合到交互式可视化产品中，这些产品将有助于关于城市发展模式和暴雨水管理方法的决策。这项研究将有助于确定干旱和半干旱沙漠中地表水和地下水硝酸盐污染的来源。在这些地区，水是宝贵的，但地下水和地表水的污染事件不断增加，威胁到这一重要资源。这项研究协调了地方(图森，凤凰城)、州(亚利桑那州)和联邦(国家大气沉积计划/环境保护局)的资源，以关注具有地方、区域和全球影响的问题。该项目将吸引公民科学家志愿者，培训研究生和本科生进行与政策相关的研究，促进科学家与决策者之间的互动，并开发可移植的可视化工具。

Urbanization dramatically modifies the movement and transformations of nitrogen (N) compounds in semi-arid ecosystems. In particular, nitrate contamination of drinking water is a growing concern in urban areas, especially in arid and semi-arid environments, where urban runoff is actively-managed to recharge groundwater and augment water supplies. Water managers and urban planners, however, lack information on what ecosystem characteristics are most important in controlling the quality of this recharged water, especially its nitrate concentrations. This research will quantify how sources, transport, and fate of nitrate in storm runoff vary with the density and type of urban land use in Tucson and Phoenix (CAP LTER), Arizona watersheds. Seasonal patterns of nitrate export will be characterized, and new isotopic tracer techniques will be used to understand nitrate sources and mechanisms controlling nitrogen transformations along semi-arid urbanization gradients. These mechanisms will be modeled and integrated into interactive visualization products that will aid in decision-making regarding urban development patterns and storm water management approaches.This research will help identify sources of surface water and groundwater nitrate contamination in arid and semi-arid deserts. Water is precious in these regions, yet increasing incidences of contamination of ground and surface waters threaten this vital resource. This research coordinates local (Tucson, Phoenix), state (Arizona), and federal (National Atmospheric Deposition Program/Environmental Protection Agency) resources to focus on a problem that has local, regional and global implications. The project will engage citizen-scientist volunteers, train graduate and undergraduate students in policy-relevant research, foster interactions between scientists and decision makers, and develop transferable visualization tools.