bioRxiv preprint doi: https://doi.org/10.1101/348011; this version posted June 15, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license. 1 Gas seepage pockmark microbiomes suggest the presence of 2 sedimentary coal seams in the Öxarfjörður graben of NE-Iceland 3 4 Guðný Vala Þorsteinsdóttir1,2, Anett Blischke3, M. Auður Sigurbjörnsdóttir1, Finnbogi Óskarsson4, 5 Þórarinn Sveinn Arnarson5, Kristinn P. Magnússon1,2,6, and Oddur Vilhelmsson1,6 6 7 1University of Akureyri, Faculty of Natural Resource Sciences, Borgir v. Nordurslod, 600 8 Akureyri, Iceland. 9 2Icelandic Institute of Natural History, Borgir v. Nordurslod, 600 Akureyri, Iceland 10 3Íslenskar orkurannsóknir / Iceland GeoSurvey (ISOR), Akureyri Branch, Rangarvollum, 600 11 Akureyri, Iceland 12 4Íslenskar orkurannsóknir / Iceland GeoSurvey (ISOR), Department of Geothermal 13 Engineering, Grensasvegi 9, 108 Reykjavik, Iceland 14 5Orkustofnun / The Icelandic Energy Authority, Grensasvegi 9, 108 Reykjavik, Iceland 15 6Biomedical Center, University of Iceland, Vatnsmyrarvegur 16, 101 Reykjavik, Iceland 16 17 Correspondence: Oddur Vilhelmsson,
[email protected] 18 19 Abstract 20 Natural gas seepage pockmarks present ideal environments for bioprospecting for 21 alkane and aromatic degraders, and investigation of microbial populations with 22 potentially unique adaptations to the presence of hydrocarbons. On-shore seepage 23 pockmarks are found at two disparate sites in the Jökulsá-á-Fjöllum delta in NE Iceland. 24 The origin and composition of headspace gas samples from the pockmarks were analysed 25 by GC-MS and stable isotope analysis, revealing a mixture of thermogenic and biogenic 26 gases with considerable inter-site variability.