Summary
Despite the widespread use and transport of fuels in Antarctica, there is very limited data available on the behaviour and weathering of these fuels in the Antarctic marine environment. The potential impacts of a fuel spill on marine biota are largely unknown. Evaporation into the atmosphere is the process responsible for the majority of the mass loss during the weathering of a fuel spill of diesel fuels like Special Antarctic Blend (SAB) and Marine Gas Oil (MGO). Evaporation plays a lesser role for heavier fuels used in Antarctica like the Intermediate Fuel Oil (IFO). In addition, dissolution of fuel compounds into the seawater is one of the main processes responsible for the toxicity of fuel spills to marine organisms. Understanding the kinetics of these processes is crucial in modeling and predicting the effects of a spill. Dissolution and evaporation rates were measured in the lab by a slow stirring method and evaporation versus time experiments. Detailed gas chromatograph-mass spectrometry analyses were performed on the different fuels and the corresponding water accommodated fractions (WAFs) in order to identify and quantify all of the hydrocarbons dissolved in the aqueous phase and determine their partition coefficients. This experimental data and literature data for individual hydrocarbons were used for the creation of a mathematical model that estimates the combined weathering effect of the two processes on the fuel spill. The model takes into account the specific conditions of the Antarctic marine environment such as seawater temperature and salinity, but it can also be adjusted for other regions. Generally the predictions of this model were found to agree well with the experimental data as long as certain constraints are met. Therefore the model can be used as a tool for risk assessment by predicting the fate of the fuel compounds present in the spill.