Influence of Environmental Factors on Biodegradation of Dispersed Diesel Oil in Seawater

Dispersants have been widely used to treat oil spills in marine environments for decades. Researches show that the efficacy of the various commercial dispersants is specific to the dispersant product used. Some dispersants increase and some decrease biodegradation of spilled oils in marine environments. To evaluate the biodegradation of diesel oil treated with the dispersant Guang Ming (GM) that was widely used in China, laboratory experiments were performed under simulated marine conditions at different salinities and water temperatures with varied dispersant additions. The results indicate that the concentration of dispersant added to oil-polluted seawater, as well as seawater salinity and water temperature are important factors affecting biodegradation of diesel oil. The addition of dispersant is optimal when added in the dispersant/oil ratio of 2:10 (v/v), and the biodegradation rate reaches the maximum value when the salinity is 33 parts per thousand (ppt) and the water temperature is 30 degrees C. This study will help evaluate the natural resource damages by better understanding the fate of diesel oil during oil spills in relation to environmental claims.