Interaction of Soil Nitrogen and Water Cycles Control Trace N-Gas Production

在不同雨季和旱季的几个系统中，控制一氧化氮(NO)和一氧化二氮(N20)产生的时间变化的因素将被研究。更具体地说，研究人员将研究：1)干燥土壤中无机N和N0产生的生物和非生物过程；2)干燥土壤湿润时微量N-气体的来源；3)土壤水分和基质有效性变化下的硝化种群动态；4)硝化菌和反硝化菌产生N0的来源和控制；(5)影响土壤中N0和N20逃逸的因素。这些研究将在三个西海岸生态系统的土壤上进行--加利福尼亚州的橡树草原和针叶林生态系统，以及墨西哥的落叶林。将使用最先进的技术来研究土壤和微生物种群中的氮循环。这些技术包括氮循环工作中的15N同位素稀释技术和微生物种群工作中的荧光抗体和微量放射自显影技术。流程级研究的各个方面最终将通过建模集成在一起。这项研究的意义在于，它将帮助我们了解土壤水分的变化如何影响两种重要痕量气体N0和N20的产生。一氧化氮之所以引起人们的兴趣，是因为它参与了对流层反应，其中包括产生臭氧，臭氧是低层大气中的一种主要污染物。一氧化二氮之所以引起人们的兴趣，是因为它是一种高效的温室气体，因此与全球气候变化有关。费尔斯通博士在土壤氮素动态这一复杂领域的生产力方面有着非常出色的记录。为她提供的机构支持是优越的。

The factors controlling temporal variations of nitric oxide (NO) and nitrous oxide (N20) production in several systems with distinct wet and dry seasons will be investigated. More specifically, the researchers will examine: 1) biotic and abiotic processes of inorganic-N and N0 production in dry soil; 2) the origin of trace N-gas flushes when dry soils are wetted; 3) dynamics of nitrifying populations under changing soil moisture and substrate availability; 4) origin and control of N0 production by nitrifiers and denitrifiers; and 5) factors affecting escape of N0 and N20 from soil. These studies will be carried out on soils taken from three west-coast ecosystems - the oak-grasslands and coniferous forest ecosystems of California and the deciduous forests of Mexico. State-of-the-art techniques for studying nitrogen cycling in soils and microbial populations will be used. These include 15N isotope dilution techniques in the nitrogen cycling work and fluorescent antibody and micro-autoradiography techniques in the microbial population work. Various aspects of the process-level research will ultimately be integrated through modeling. The significance of this research is that it will help us to understand how changes in soil moisture content affect the production of two important trace gases, N0 and N20. Nitric oxide is of interest because of its involvement in tropospheric reactions which, among other things, create ozone, a major pollutant in the lower atmosphere. Nitrous oxide is of interest because it is a highly efficient greenhouse gas and so is involved in global climate change. Dr. Firestone has a very good record of productivity working in the complex area of soil-N dynamics. The institutional support available to her is superior.