MRI: Acquisition of Instrumentation for Measurement of Trace Gas Fluxes in the Arizona Highlands

普雷斯科特学院的杰克·赫林博士和蒂姆·克鲁斯博士获得了一笔资助。这项拨款提供的精密研究仪器将能够测量大气和陆地表面之间各种微量气体的交换。这项研究的主要目标是更好地了解亚利桑那州中部高地的氮循环。第二个目标是研究这些生态系统中氮和碳循环之间的关系。此外，这些仪器将在训练普雷斯科特学院的学生掌握这些分析技术方面发挥核心作用。最初，该仪器将被安装在美国西南部一个重要的植物群落chaparral，那里关于氮循环动力学的信息很少。Chaparral很有趣，因为它是美国固氮木本植物密度最高的地方之一，如果不是最高的话。由于潜在的通过生物固定的高氮输入，以及有利于极端干燥和潮湿事件的年降水制度，人们怀疑，内部灌木林生态系统可能至少周期性地支持高至非常高的氮氧化物排放率。具体来说，该设备将用于使用基于激光的技术对NO2、NO + NO2 （NOx）和N2O的交换进行连续、长期的测量。仪器塔还将配备一个测量垂直风的专用装置和一个测量二氧化碳和水浓度的装置。除了这些气体交换测量之外，还将进行气相色谱法对N2O排放的短期室内研究和NO排放的室内测量。这些室内研究将在灌木林和以人类改变氮循环为特征的其他生态系统中进行；其中包括经火处理的黄松林地、干旱农田和放牧牲畜的干旱草原。当研究完成后，研究结果将指导仪器的使用。随着来自许多学科的科学家努力更好地理解全球变化背后的过程，越来越清楚的是，生物与大气之间相互作用的知识需要得到改善。氮循环与全球变化之间的联系是直接的（由于N2O排放的温室效应）和间接的（由于氮有效性对主要温室气体CO2和CH4的净吸收或释放的影响）。对这些生态系统动态的充分理解，对于理解生物圈吸收目前由化石燃料燃烧释放的二氧化碳的潜力，以及理解生态系统将如何应对它们目前所面临的许多环境变化，是至关重要的。这些信息对目前正在努力应对全球气候变化等问题的政策制定者至关重要。这些问题的答案只能来自这种仪器的广泛网络；这就需要培训大量科学家掌握这些测量所涉及的专门技术。

A grant has been awarded to Dr. Jack Herring and Dr. Tim Crews at Prescott College. The sophisticated research instrumentation provided by this grant will allow measurement of the exchange of variety of trace gases between the atmosphere and the land surface. The primary goal of the research is to better understand the cycling of nitrogen in the highlands of central Arizona. A secondary goal is to study the relationship between the cycling of nitrogen and carbon in these ecosystems. Additionally, the instruments will play a central role in training students at Prescott College in these analytical techniques. Initially, the instrumentation will be installed in chaparral, an important plant community in the southwestern U.S. for which there is little information on the dynamics of nitrogen cycling. Chaparral is interesting because it has among the highest, if not the highest, density of nitrogen-fixing woody plants in the United States. Due to the potentially high inputs of nitrogen via biological fixation, and an annual precipitation regime that favors extreme drying and wetting events, it is suspected that the interior chaparral ecosystem may support at least periodically high to very high rates of nitrogen oxide emissions. Specifically, this equipment will be used to make continuous, long-term measurements of exchanges of NO2, NO + NO2 (NOx), and N2O using a laser-based technique. The instrument tower will also be equipped with a special device for measuring vertical winds and a device for measuring CO2 and H2O concentrations. In addition to these measurements of gas exchange,supporting short-term chamber studies of N2O emissions by gas chromatography and chamber measurements of NO emissions will be conducted. These chamber studies will be conducted both in chaparral and in other ecosystems that are characterized by human alteration of the N cycle; these include fire-treated ponderosa woodlands, arid agricultural land and livestock-grazed arid grasslands. The results will guide the use of the instrumentation when the chaparral study is completed. As scientists from many disciplines work toward a better understanding of the processes underlying global change, it becomes increasingly clear that the knowledge of the interactions between living organisms and the atmosphere needs to be improved. The linkage between nitrogen cycling and global change is both direct (due to the greenhouse effect of N2O emissions) and indirect (due to the effects of nitrogen availability on the net absorption or release of key greenhouse gases CO2 and CH4). A good understanding of these ecosystem dynamics is key tounderstanding the potential for the biosphere to absorb the CO2 currently being released by fossil fuel combustion as well as to understanding how ecosystems will respond to the many environmental changes they are now being exposed to. Such information is vital to policymakers who are currently wrestling with issues such as that of global climate change. The answers tothese questions will only come from extensive networks of such instrumentation; this will necessitate the training of large numbers of scientists in the specialized techniques involved in these measurements.