Collaborative Research: Landscape and regional scale studies of nitrogen gas flux

了解景观、区域和全球尺度的氮循环是当前环境科学面临的重大挑战。大量所谓的氮缺失在所有尺度上都主导着氮平衡，并使处理过量氮污染对对流层臭氧水平、沿海富营养化和饮用水质量的影响以及确定大气氮沉积到流域的临界负荷的努力复杂化。氮平衡的不确定性导致了对作为过量氮的潜在命运的氮气通量的兴趣增加。然而，这些通量难以量化，因为有问题的测量技术，高度的空间和时间变异性，以及缺乏方法来缩放点测量到更大的区域。一个特别的挑战是，小区域（热点）和短暂的时期（热时刻）占氮气通量活动的高比例。最近有改进的方法来测量氮气通量和在景观和区域尺度上的氮循环过程的水文和地球化学控制的缩放和建模的前景。因此，时间已经成熟的关键重新评估的重要性，氮气通量生态系统氮平衡。这项研究将产生与紧迫和全球重要的环境问题（氮污染）相关的信息，将涉及研究生和代表性不足的群体，并将与大学，管理和政策领域的教育和推广工作相结合。

Understanding the nitrogen cycle at landscape, regional and global scales is a great current challenge in environmental science. Large amounts of so-called missing nitrogen dominate nitrogen balances at all scales and have complicated efforts to address the effects of excess nitrogen pollution on tropospheric ozone levels, coastal eutrophication and drinking water quality, and to determine critical loads for atmospheric nitrogen deposition to watersheds. Uncertainty about nitrogen balances has led to increased interest in nitrogen gas fluxes as a potential fate of excess nitrogen. However, these fluxes are difficult to quantify because of problematic measurement techniques, high spatial and temporal variability, and a lack of methods for scaling point measurements to larger areas. A particular challenge is that small areas (hotspots) and brief periods (hot moments) account for a high percentage of nitrogen gas flux activity. There have been recent improvements in the methods for measuring nitrogen gas fluxes and in prospects for scaling and modeling the hydrologic and biogeochemical controls on nitrogen cycle processes at landscape and regional scales. Thus, the time is ripe for a critical re-assessment of the importance of nitrogen gas fluxes to ecosystem nitrogen balances. This research will produce information relevant to a pressing and globally important environmental problem (nitrogen pollution), will involve graduate students and underrepresented groups, and will be coupled to education and outreach efforts in University, management and policy arenas.