22-EPN3-130: Biosignatures in Icelandic geothermal aerosols
January 22, 2024

22-EPN3-130: Biosignatures in Icelandic geothermal aerosols

Visit by Mark Fox-Powell and Ben Stephens (Open University, UK) to TA1 – Iceland Field Sites, MATIS
Dates of visit: 23-31 August 2023

The aim of our project was to capture and study microscopic aerosols ejected from bubbling geothermal springs in Iceland, as an analogue for the formation of cryovolcanic plumes at icy moons such as Enceladus. This project built on a successful Europlanet-funded field campaign in 2022. Our objectives in 2023 were to (i) comprehensively map size-dependent aerosol fluxes with increasing distance and elevation from the springs; and (ii) to collect simultaneous samples for microbiological and elemental analyses at multiple downwind locations.

We focused our investigations on Olkelduhals hot springs, near Hverageroi, where a pool with circum-neutral pH supporting thick microbial streamers experiences constant moderate gas flux. Our data from 2022 showed that this spring is a prolific and constant source of aerosols. We found that downwind aerosol size distributions changed with distance and with elevation from the spring. Four complete aerosol sample sets were taken downwind of the spring; each requiring a full field day. A background (upwind) air sample was also taken. Comprehensive samples for geochemical and microbiological analyses were taken from the spring, along with the collection of volatile and semi-volatile organic compounds using thermal desorption tubes. The sample set will form the basis of a new PhD studentship, beginning in October 2023 at the Open University, which will investigate the chemical composition, biomass content and microbial diversity of aerosols, and the volatile profiles of geothermal gases. Our data will provide the first insights from natural analogues into the formation of aerosols within cryovolcanic plumes.