Sammendrag
Oil-related aggregates (ORAs) may result from interactions between chemically dispersed oil and particles (both biological and mineral) and have received considerable attention since the Deepwater Horizon oil spill. In a 3-year project we will investigate the relationship between chemically dispersed oil and ORAs. Microbial community dynamics in ORAs and the surrounding seawater will be studied by 16S rDNA amplicon based microbiome profiling. Experiments will be performed in microcosm systems with small-droplet oil dispersions in natural seawater, amended with diatoms representative for selected conditions and mineral particles and incubated on a slowly rotating carousel to avoid settling. Parallel analyses of oil compounds and degradation products will assess the impact of ORAs in hydrocarbon biodegradation. We will also investigate the effect of different seawater temperatures (from Arctic to tropical), oil dilution after dispersant treatment, and sinking velocities of aggregates. Finally, the microbial communities involved in degradation of sedimented ORAs will be characterized.