Methane Oxidation Rates by AMS: Use of low-level 14C-CH4 and Accelerator Mass Spectrometry to Determine Rates of Water Column Aerobic and Anaerobic Methane Oxidation

AMS 测定甲烷氧化速率：使用低浓度 14C-CH4 和加速器质谱测定水柱需氧和厌氧甲烷氧化速率

• 批准号: 0622759
• 负责人: Ellen Druffel
• 金额: --
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-03-01 至 2011-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0622759&HistoricalAwards=false
• 关键词: Methane; Oxidation; Rates; AMS; Use

ABSTRACTOCE-0622759Our understanding of methane geochemistry in the ocean depends to a large extent on measurements of methane oxidation rates in oxic and anoxic waters and sediments. Relatively few oxidation rate measurements are available for seawater, which has low methane concentrations (~10 nM to 10 uM). Because of the specific activity of 14C-CH4, rate measurements involving addition of this tracer require additions at concentrations higher than ambient and extrapolation of rates measured at several concentrations back to in situ concentrations. A research team at the University of California at Irvine is setting out to overcome these analytical limitations. With support from this grant, they will exploit the high sensitivity of Accelerator Mass Spectrometry (AMS) to measure methane oxidation rates with only small changes in the CH4 pool size. This approach also lowers the activity level of tracer 14C-CH4 concentrations to levels that are close to being exempt from regulations covering transportation and handling of radioisotopes. They expect to make two advances in the use of 14CCH4 in determination of methane oxidation rates: 1) conducting parallel measurements of methane oxidation rate in the Cariaco Basin involving low-level 14C-CH4 and established 3H-CH4 tracer techniques, and 2) developing methods that will allow the use of 14C-CH4 at activity levels that are below those regulated as hazardous waste. The use of these low tracer activities in future measurements will simplify shipping, relax the requirement that radioisotope tracer experiments be performed on large ships with isotope vans, and should permit wider application of these measurements in remote locations and time series measurements. This project will have a number of broader impacts. The research will involve one graduate student one undergraduate student. The senior principal investigator is active as a board member of the Long Beach Aquarium of the Pacific's Marine Conservation Research Institute. MCRI's commitment to outreach and education in the ethnically-diverse Long Beach community should facilitate contact with community groups and students. The junior principal investigator and her other colleagues have developed a short course to introduce young scientists to the use of radiocarbon in carbon cycle science. The goals of the course are (1) to educate a new group of young scientists in the science of the global carbon (C) cycle and (2) to introduce them to the technology of AMS radiocarbon measurements and the applications of radiocarbon to C cycle studies.

Abstractoce-0622759我们对海洋中甲烷地球化学的理解在很大程度上取决于对甲烷和缺氧水和沉积物中甲烷氧化速率的测量。相对较少的氧化速率测量可用于甲烷浓度低（约10 nm至10 um）的海水。由于14C-CH4的特定活性，涉及添加此示踪剂的速率测量需要在高于环境的浓度下添加添加，并且在几个浓度的原位浓度下测量的速率外推。加利福尼亚大学尔湾分校的一个研究团队正在着手克服这些分析局限性。在这笔赠款的支持下，他们将利用加速器质谱法（AMS）的高灵敏度来测量甲烷氧化速率，而CH4池尺寸只有很小的变化。这种方法还将示踪剂14C-CH4浓度的活性水平降低至几乎不受涵盖放射性同位素运输和处理的法规的水平。 他们期望在确定甲烷氧化速率时使用14CCH4在使用14CCH4方面取得了成功：1）在Cari​​aco盆地中对甲烷氧化速率进行平行测量，涉及低水平14C-CH4并确定3H-CH4示踪技术，以及2）在活动级别上使用14C-CH4的方法，这些方法是浪费了下面的浪费。在将来的测量中，使用这些低示踪剂活动将简化运输，放松放射性同位素示踪剂实验的要求，以同位素货车在大型船上进行，并应允许在偏远的位置和时间序列测量中更广泛地应用这些测量值。该项目将产生更广泛的影响。 该研究将涉及一名研究生一名本科生。这位高级首席研究员积极担任太平洋海洋保护研究所长滩水族馆的董事会成员。 MCRI致力于在种族多样性的长滩社区中宣传和教育的承诺，应促进与社区团体和学生的接触。初级首席研究员和她的其他同事已经开发了一门简短的课程，向年轻科学家介绍了在碳循环科学中使用放射性碳。该课程的目标是（1）在全球碳（C）周期和（2）中教育一群新的年轻科学家，并将其引入AMS放射性碳测量技术以及放射性碳对C周期研究的应用。