Oil Spill Dispersant Effectiveness testing is essential to making informed decisions for the potential use of dispersants. Chemical dispersants can be tested to determine their effectiveness on particular crude oils. There is not a single chemical dispersant that is effective on all crude oils. The Mackay Nadeau Steelman (MNS) dispersant performance test is used to determine how well various chemical dispersants work on various types of oils under given conditions, water salinities and temperatures. This method is believed to simulate ocean conditions more accurately than shaking, stirring or pumping methods. The relative performances of different chemical dispersants are tested under the same environmental conditions of the crude oil. Dispersant effectiveness is best tested over a wide range of environmental conditions and on weathered oils at various time periods as this also impacts on dispersant choice. Dispersant/oil dose ratios can be tested so that dose efficiency curves can be produced. The ‘window of opportunity’ for dispersant use can then be determined.
The Australian Maritime Safety Authority (AMSA) recognises the Mackay Dispersant Performance test as the only efficiency test acceptable.