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的重要性，确定碳氢化合物从哪里来（来源）以及它们从大气中被清除的各种途径（汇）是相当重要的。特定碳氢化合物在有限时间内（通常是一年）的总来源强度可以确定为不同大小的地理区域-单个城市，地区，国家和地球。最近引起注意的一种可能被低估的甲烷来源是地质排放，包括热源性渗漏。自然渗流分为宏观渗流和微渗流两类，前者涉及从大型喷口排出气体，后者不可见。虽然宏观渗流被认为是一个更大的甲烷来源，但微渗流最近被认为是一个相对重要的甲烷来源（每年10至25 Tg）。然而，这种估计是粗略的，因为大多数微渗流研究都集中在欧洲和少数西方国家的遗址上。研究发现，微渗流通量的范围很大，这取决于多种因素，包括季节、海岸影响，以及各种地质因素，如土壤类型、沉积物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轻烷烃（乙烷、丙烷、正丁烷、正丁烷、正戊烷和正戊烷）的区域、国家和全球预算。具体地说，将使用通量室对7种气体的测量来量化通过自然渗流产生的石油和天然气排放的贡献。这个项目的工作很适合本科生。帮助建立甲烷分析系统的学生将学习到大量有关气相色谱的知识，以补充他们在仪器分析课程中所学到的知识。从事数据收集工作的学生将深入了解大气化学领域的工作，并学习如何使用高度专业化的分析系统分析样品。这项工作还将使学生学习大气化学的一些方面，这是他们目前在LMU没有教授的学科。学生还将进行数据分析，包括识别、整合和定量色谱峰，以及计算不同轻烷烃的通量率。学生还将充分参与数据的传播，包括在会议上的演讲和撰写期刊文章。

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.