Enhancement of oil dispersion and marine oil snow formation by surface-active biomasses from diatom

Following the Deepwater Horizon oil spill event, the formation of marine oil snow (MOS) has attracted much attention from marine environmental scientists. This study investigates the crude oil dispersion as well as the MOS formation in the presence of Phaeodactylum tricornutum and Chaetoceros sp. through laboratory experiments. Results indicate that oil dispersion is enhanced with the increasing oscillation time and diatom concentration. The P. tricornutum exhibits a more significant facilitation of oil dispersion, indicated by a lower oil-water interfacial tension. When the P. tricornutum concentration reached 1.0×10⁶ cells/mL, the oil dispersion efficiency reached 45.8%, and the volumetric mean diameter of the suspended oil was reduced from 90.6μm to 71.6μm. Diatom viability also affects oil dispersion and MOS formation. The diatom death and cell rupture result in the release of intracellular surface-active lipids and proteins, leading to a further reduction of oil-water interfacial tension and a higher quantity of oil dispersion. Much larger MOS is formed with dead diatoms due to the aggregation of cellular debris by the sticky polysaccharides. The outcomes of this study will add more scientific evidence for further understanding the fate and transport of marine oil spill, and direct the research and development of biological dispersant as an environmental friendly oil spill response technology.