Geogenic and Biogenic Volatile Organic Compounds in an Arctic Permafrost Landscape

Future warming of the Arctic may increase emissions of VOCs and GHGs, such as methane (CH₄), into the atmosphere. Disintegration of cryospheric caps (permafrost and glaciers) can lead to increase in geogenic carbon emissions, alongside active layer biogenic emissions, and geogenic sources represent an overlooked feedback of atmospheric forcing from permafrost melting. However, the magnitudes, diversity, and partitioning of geogenic and biogenic VOCs and associated CH₄ remain unknown, and therefore, we have limited understanding of how important different VOC and CH₄ sources are for atmospheric interactions of melting Arctic permafrost landscapes.

We studied VOC and CH₄ emissions in Nuussuaq (70°29′57.16″ N, 54°10′35.91″ W) in west Greenland with known natural geogenic gas and oil seeps. During a 10-day period, we collected gas samples from in situ gas seeps at lakes on top of geological fault zones, springs, and permafrost thaw ponds to capture the variation in VOC and CH₄ compositions and emission rates in areas with different geogenic impacts. Furthermore, we measured net fluxes of VOCs, CH₄, N₂O and CO₂ across a geomorphological and soil gradient (alluvial fan with sand to hydromorphic palsa rich in organic matter) underlain by permafrost, to gain insight into spatial drivers of diversity and partitioning of VOC and GHG fluxes in an Arctic landscape.

Preliminary results for VOCs across the geomorphological gradient show significant contribution to terrestrial emissions from vegetation, dominated by moss and Arctic shrubs, especially from the terpenes (+)-α-longipinene and (+)-camphor. Emission rates from waterbodies and wetland were smaller compared to terrestrial emissions, but VOC diversity was high, including compounds like acetone, 2-methylbutane, 2-ethyl-1-hexanol, benzaldehyde, and benzonitrile – potentially originating from both geogenic and biogenic sources. However, terpenes dominating terrestrial emissions were also observed abundantly in the water samples. In addition to VOCs, we will also present the flux data on CH₄, N₂O and CO₂ and VOC data for lakes and springs to corroborate whether geogenic VOC’s are emitted.