Isolation of Methane from Ambient Water and Preparation for Source-Diagnostic Natural Abundance Radiocarbon Analysis
Year: 2024
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide A key challenge in climate change research is apportioning the greenhouse gas methane (CH 4 ) between various natural and anthropogenic sources. Isotopic source fingerprinting of CH 4 releases, particularly with radiocarbon analysis, is a promising approach. Here, we establish an analytical protocol for preparing CH 4 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 2 ) in the CH 4 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 4 (i.e., 30 L samples of 40 nM CH 4 ). The full-system yield is >90% for both CH 4 -spiked seawater and ambient samples from CH 4 hotspots in the Baltic Sea and the Arctic Ocean. Furthermore, the radiocarbon isotope signal of CH 4 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 4 -specific radiocarbon analysis. This enables powerful source apportionment of CH 4 emitted from aquatic systems from the tropics to the polar regions.
Source: Analytical Chemistry
Authors: Marenka Brussee, Henry Holmstrand, Michael Süß, Amelia Davies, Örjan Gustafsson
Institutions: Stockholm University, Bolin Centre for Climate Research
Language: English
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDG: Climate action
Open Access status: hybrid
Estimated APC paid: $4,500
OpenAlex ID: W4403737426