Oil Weathering Studies, Chemical and Physical Characterisation
Oil weathering studies are used to determine the potential impacts and behaviours of crude
oils in the environment.
Weathering methods are utilised to determine both physical and chemical changes that may
occur, to spilt oils, under a range of conditions. Weathering methods include;
- Natural Dispersion
- Emulsification and Biodegradation
Variables considered in weathering processes include:
- Composition of spilt oil
- Duration of weathering process
- Oil type
- Sea and air temperature
- Wave action
Via analysis of samples taken throughout the weathering process, it is possible to
determine changes in the physical and chemical characteristic of the oil.
Chemical characterisation focusses on the determination of toxic hydrocarbons and other
compounds present in crude oils. This information is utilised to identify the overall toxicity
and ‘fingerprint’ of the oil, which is imperative for future monitoring purposes.
Typical chemical compounds that can be examined include BTEX, Polycyclic Aromatic
Hydrocarbons (PAHs), Phenolics, Paraffinic Hydrocarbons and Sulphur compounds.
Biomarker compounds can be determined also, including a range of hopanes, steranes and
isoprenoids. Biomarkers are resistant to the oil weathering process and are present in ratios
which are characteristic to particular oils. Biomarker ratios can effectively provide a ‘fingerprint’
of the oil and is of significant value when assessing an oil spill.
Physical characterisation focusses on the determination of viscosity, density, evaporation rates and
pour point. It is important to see how such properties change when an oil weathers.
The physical properties of crude oils and their characteristics during the weathering process can be
used to assess the amenability of the oils to various spill response options and to particular items
of response equipment.