RUI: Investigating Natural Seepage of Light Alkanes from Oil and Natural Gas Deposits

由于碳氢化合物在大气化学的各个方面都很重要，因此确定碳氢化合物的来源(源)以及它们从大气中移出的各种途径(汇)是相当重要的。特定碳氢化合物在有限时间段(通常为一年)内的总来源强度可以针对不同大小的地理区域确定--针对各个城市、地区、国家和地球。最近引起关注的一个可能被低估的甲烷来源是地质排放，包括热源渗漏。自然渗漏被归类为宏观渗漏，它涉及从大通风口排出气体，或微渗漏，它是不可见的。虽然宏观渗漏被估计为甲烷的较大来源，但微渗漏最近被估计为相对重要的甲烷来源(每年在10至25 Tg之间)。然而，这一估计是粗略的，因为大多数微渗漏研究集中在欧洲和少数几个西部国家的遗址上。研究发现，微渗漏通量的范围很大，取决于各种因素，包括季节、海岸影响，以及各种地质因素，如土壤类型、沉积深度和附近断层的接近程度。该项目将有助于更好地了解甲烷和六种低碳烷烃(乙烷、丙烷、正丁烷、异丁烷、正戊烷和异戊烷)的区域、国家和全球预算。具体地说，通过自然渗漏排放的石油和天然气的贡献将通过使用七种气体的通量室测量来量化。这个项目的工作非常适合本科生。帮助建立甲烷分析系统的学生将学到大量关于气相色谱的知识，以补充他们在仪器分析课程中学到的知识。从事数据收集工作的学生将深入了解大气化学野外工作，并学习如何使用高度专业化的分析系统分析样品。这项工作还将允许学生学习大气化学的某些方面，这是他们目前在LMU没有教授的一门学科。学生还将学习数据分析，包括识别、积分和量化色谱峰，以及计算不同低碳烷烃的通量。学生还将充分参与数据的传播，包括在会议上的陈述和撰写期刊文章。

Because of the importance of hydrocarbons in various facets of atmospheric chemistry, determining where the hydrocarbons come from (sources) and the various pathways by which they are removed from the atmosphere (sinks) is of considerable importance. The total source strength for a particular hydrocarbon over a finite time period (usually a year) can be determined for geographical areas of various sizes - for individual cities, regions, countries, and the planet. One potentially underreported source of methane that has recently attracted attention is geologic emissions, including thermogenically derived seepage. Natural seepage is categorized as macroseepage, which involves outgassing from large vents, or microseepage, which is not visible. Although macroseepage is estimated to be a larger source of methane, microseepage has recently been estimated to be a relatively significant methane source (between 10 and 25 Tg annually). However, this estimation is rough, as the majority of microseepage studies have focused on sites in Europe and a handful of western states. The studies have found a wide range in microseepage fluxes that depend on a variety of factors including season, coastal influence, and a wide variety of geological factors such as soil type, depth of deposit, and proximity of nearby faults. This project will lead to a better understanding of the regional, national, and global budgets of methane and six light alkanes (ethane, propane, n-butane, i-butane, n-pentane, and i-pentane). Specifically, the contribution of oil and natural gas emissions via natural seepage will be quantified using flux chamber measurements for the seven gases. The work on this project is well suited to undergraduates. The students who help build the methane analytical system will learn a great deal about gas chromatography to supplement their knowledge gained in an Instrumental Analysis course. Students that work on the data collection will gain an insight into Atmospheric Chemistry field work and learn how to analyze samples using highly specialized analytical systems. This work will also allow students to learn some aspects of Atmospheric Chemistry, a subject that they are not currently taught at LMU. Students will also work on data analysis, which will include identifying, integrating, and quantifying chromatography peaks and calculating flux rates of different light alkanes. Students will also be fully involved in the dissemination of data including presentations at conferences and writing journal articles.