Isotope Fractionation Effect During Soil Uptake of Methane, Carbon Monoxide, and Hydrogen

土壤吸收甲烷、一氧化碳和氢气过程中的同位素分馏效应这项建议是应环境地球化学和生物地球化学(EGB)征集，NSF 06-152的要求而提交的。它是由海洋科学和大气科学部门联合资助的。这项建议的目的是测量土壤吸收一氧化碳(CO)、甲烷(CH4)和氢气(H2)过程中的同位素分馏。对这些分馏效应进行量化很重要，这样大气中对这些温室气体的持续测量就可以充分利用同位素数据来确定特定的源和汇。这将大大提高我们对这些具有辐射重要性的痕量气体的全球循环的理解。PI建议使用土壤封闭物对同位素分馏效应进行经验性测量，并在顶部空间测量作为时间序列收集的空气样本。将利用土壤特性(如温度、湿度、孔隙度、成分等)将特定场地的数据外推到区域和全球尺度。总体而言，拟议的测量，与正在进行的CH4、CO同位素组成的时间序列测量和预期的H2测量相结合，将提供必要的框架，以确定土壤吸收对北方温带地区这些气体的浓度和同位素组成的季节性变化以及对其同位素组成的半球间不对称性的影响。

Isotope fractionation effect during soil uptake of methane, carbon monoxide and hydrogen This proposal was submitted in response to the Environmental Geochemistry and Biogeochemistry (EGB) solicitation, NSF 06-152. It is being jointly funded by the Divisions of Ocean Sciences and Atmospheric Science. The objective of this proposal is to measure isotope fractionation during soil uptake of carbon monoxide (CO), methane (CH4) and hydrogen (H2). These fractionation effects are important to quantify so that continued atmospheric measurements of these greenhouse gases can take full advantage of isotopic data to fingerprint specific sources and sinks. This will allow for a significant advancement in our understanding of the global cycles of these radiatively important trace gases. The PI's propose to empirically measure the isotopic fractionation effect using soil enclosures and measuring air samples collected as a time-series in the headspace. The site specific data will be extrapolated to regional and global scales using soil characteristics (e.g. temperature, moisture, porosity, composition, etc.). Overall, the proposed measurements, when coupled with on-going time series measurements of the isotopic composition of CH4, CO and anticipated measurements of H2, will provide the framework needed to determine the influence of soil uptake on the seasonal changes in the concentration and isotopic composition of these gases in temperate northern latitudes and on the interhemispheric asymmetry of their isotopic composition.