Biodegradation, photooxidation and dissolution of petroleum compounds in an Arctic fjord during summer

Increased economic activity in the Arctic may increase the risk of oil spills. Yet, little is known about the degradation of oil spills by solar radiation and the impact of nutrient limitation on oil biodegradation under Arctic conditions. We deployed adsorbents coated with thin oil films for up to 4 months in a fjord in SW Greenland to simulate and investigate in situ biodegradation and photooxidation of dispersed oil droplets. Oil compound depletion by dissolution, biodegradation and photooxidation was untangled by GC-MS-based oil fingerprinting. Biodegradation was limited by low nutrient concentrations, reaching 97% removal of nC13-26-alkanes only after 112 days. Sequencing of bacterial DNA showed the slow development of a bacterial biofilm on the oil films predominated by the known oil degrading bacteria Oleispira, Alkanindiges and Cycloclasticus. These taxa could be related to biodegradation of shorter-chain (≤C26) alkanes, longer-chain (≥C16) and branched alkanes, and polycyclic aromatic compounds (...