Effects of chemical dispersant and seasonal conditions on the fate of spilled oil – modelling of a hypothetical spill near Saint John, NB

The proposed Energy East pipeline project has raised concerns about potential oil spills in Saint John, New Brunswick. While environmental conditions could pose challenges for using mechanical recovery methods if a spill occurs, chemical dispersant could be an alternative. However, the application of chemical dispersant in shallow water and costal zones remains an issue of debate. Furthermore, the effectiveness of chemical dispersant under different seasonal conditions is yet to be determined. This study attempts to describe a modelling effort to understand the probable distribution of petroleum hydrocarbons in Port Saint John following a hypothetical release of crude oil to which dispersant is applied during different seasons. A three-dimensional model was used to simulate the transport of oil with a release of 1,000 m3 of Arabian light crude in the summer and winter. A stochastic approach took into account the uncertainties of environmental inputs. The results were a significant reduction of oil ashore, and enhanced biodegradation with dispersant application. However, these effects were accompanied by an increase of oil in the sediment and water column, which is a concern. While the results are only conclusive for the selected scenarios of summer and winter, the method could be applied to other months and seasons to support more detailed analysis regarding dispersant application.