EPS mechanisms in aggregation and dispersion of oil: roller tank experiment using Skeletonema, POC-PON-EOE-TEP-CSP

This is an experiment of a series investigating the mechanisms driving the incorporation of oil into diatom aggregates using a water accommodated fraction (WAF) of oil. The diatom Skeletonema CCMP strain #775 was used to assess the effect of oil on marine snow formation and the incorporation of oil in marine snow. A control and a WAF was prepared from Macondo oil (Deepwater Horizon oil spill in the Gulf of Mexico, April 2010). Roller tank experiments mimic in situ conditions of the ocean in that continuous sinking of particles is possible (infinity water column). Once aggregates > 1mm (operationally defined) formed, they were harvested separately from the surrounding seawater, which contains non-aggregates cells or small aggregates. Both fractions were analyzed separately, so that the fraction of material incorporated within aggregates may be calculated. Samples were analyzed for particulate organic carbon (POC) and nitrogen (PON), the isotopes Carbon-13 and Nitrogen-15, estimated oil equivalent (EOE), transparent exopolymer particles (TEP), and coomassie-stained particles (CSP).