Biodegradation of water-accommodated aromatic oil compounds in Arctic seawater at 0 °C

• Published in: Chemosphere
• Main Authors: Gomes, Ana, Christensen, Jan H., Gründger, Friederike, Kjeldsen, Kasper Urup, Rysgaard, Søren, Vergeynst, Leendert
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2022
• Subjects: Aromatic hydrocarbon; Greenland; Marine ecosystem; Oil pollution; Oil-degrading bacteria; Water-accommodated fraction; Arctic; greenlandic
• Online Access: https://pure.au.dk/portal/da/publications/biodegradation-of-wateraccommodated-aromatic-oil-compounds-in-arctic-seawater-at-0-c(1e398921-2fbd-4ee8-b9ab-a0b744d463f6).html; https://doi.org/10.1016/j.chemosphere.2021.131751; http://www.scopus.com/inward/record.url?scp=85112306703&partnerID=8YFLogxK

Oil spills in Arctic marine environments are expected to increase concurrently with the expansion of shipping routes and petroleum exploitation into previously inaccessible ice-dominated regions. Most research on oil biodegradation focusses on the bulk oil, but the fate of the water-accommodated fraction (WAF), mainly composed of toxic aromatic compounds, is largely underexplored. To evaluate the bacterial degradation capacity of such dissolved aromatics in Greenlandic seawater, microcosms consisting of 0 °C seawater polluted with WAF were investigated over a 3-month period. With a half-life (t 1/2 ) of 26 days, m-xylene was the fastest degraded compound, as measured by gas chromatography - mass spectrometry. Substantial slower degradation was observed for ethylbenzene, naphthalenes, phenanthrene, acenaphthylene, acenaphthene and fluorenes with t 1/2 of 40–105 days. Colwellia, identified by 16S rRNA gene sequencing, was the main potential degrader of m-xylene. This genus occupied up to 47 % of the bacterial community until day 10 in the microcosms. Cycloclasticus and Zhongshania aliphaticivorans, potentially utilizing one-to three-ringed aromatics, replaced Colwellia between day 10 and 96 and occupied up to 6 % and 23 % of the community, respectively. Although most of the WAF can ultimately be eliminated in microcosms, our results suggest that the restoration of an oil-impacted Arctic environment may be slow as most analysed compounds had t 1/2 of over 2–3 months and the detrimental effects of a spill towards the marine ecosystem likely persist during this time.