Brussee Marenka, Holmstrand Henry, Süß Michael, Davies Amelia, Gustafsson Örjan
Department of Environmental Science, Stockholm University, Stockholm 10691, Sweden.
Bolin Centre for Climate Research, Stockholm University, Stockholm 10691, Sweden.
Anal Chem. 2024 Nov 5;96(44):17631-17639. doi: 10.1021/acs.analchem.4c03525. Epub 2024 Oct 24.
A key challenge in climate change research is apportioning the greenhouse gas methane (CH) between various natural and anthropogenic sources. Isotopic source fingerprinting of CH releases, particularly with radiocarbon analysis, is a promising approach. Here, we establish an analytical protocol for preparing CH from seawater and other aqueous matrices for high-precision natural abundance radiocarbon measurement. Methane is stripped from water in the optionally field-operated system (STRIPS), followed by shore-based purification and conversion to carbon dioxide (CO) in the CH Isotope Preparation System (CHIPS) to allow Accelerator Mass Spectrometry analysis. The blank (±1σ) of the combined STRIPS and CHIPS is low (0.67 ± 0.12 μg C), allowing natural sample sizes down to 10 μg C-CH (i.e., 30 L samples of 40 nM CH). The full-system yield is >90% for both CH-spiked seawater and ambient samples from CH hotspots in the Baltic Sea and the Arctic Ocean. Furthermore, the radiocarbon isotope signal of CH remains constant through the multistage processing in the STRIPS and the CHIPS. The developed method thus allows for in-field sampling and sample size reduction followed by precise and CH-specific radiocarbon analysis. This enables powerful source apportionment of CH emitted from aquatic systems from the tropics to the polar regions.
气候变化研究中的一个关键挑战是在各种自然和人为来源之间分配温室气体甲烷（CH₄）。甲烷释放的同位素源指纹识别，特别是通过放射性碳分析，是一种很有前景的方法。在这里，我们建立了一种分析方案，用于从海水和其他水性基质中制备甲烷，以进行高精度的天然丰度放射性碳测量。在可选的现场操作系统（STRIPS）中从水中去除甲烷，然后在岸基进行纯化，并在甲烷同位素制备系统（CHIPS）中转化为二氧化碳（CO₂），以进行加速器质谱分析。STRIPS和CHIPS组合的空白（±1σ）很低（0.67±0.12μg C），允许低至10μg C-CH₄的天然样品量（即40 nM CH₄的30 L样品）。对于添加了CH₄的海水以及来自波罗的海和北冰洋CH₄热点的环境样品，全系统产率均>90%。此外，CH₄的放射性碳同位素信号在STRIPS和CHIPS的多阶段处理过程中保持恒定。因此，所开发的方法允许进行现场采样和减小样品量，随后进行精确的、针对CH₄的放射性碳分析。这使得能够对从热带地区到极地地区的水生系统排放的CH₄进行有力的源分配。
