Oil spills off the German coast
The quest for the best combat strategy
What benefits and risks does the use of dispersants pose? These and other questions are addressed in the report “The use of dispersants to combat oil spills in Germany at sea” recently published in the BfR Science series. Experts had looked into the topic on the occasion of an international workshop which took place at the Federal Institute for Risk Assessment (BfR). In order to mitigate the effects of oil spills, different measures can be taken including the use of dispersants. These are mixtures of substances which help to break up oil films on the surface of the water and to break them down into fine droplets, so-called dispersions. “Whether dispersants should be used cannot always be unequivocally established based on the current state of knowledge”, says Professor Dr. Dr. Andreas Hensel. “Here the relevant scenarios should be considered. Benefits and risks should be assessed and weighed up as part of a structured analysis.” This workshop report documents the current state of knowledge. This means that a basis for the development of a decision strategy for the use of these substance mixtures off German coasts is now available
Oil spills at sea can have devastating effects on the marine environment, coastal areas and human health. Apart from mechanical methods such as oil barriers or absorption of the oil, measures taken against such spills can also be in the form of chemical procedures – for example the use of dispersants. This term denotes substance mixtures which break up oil films on the surface of the water and which facilitate the formation of dispersions (i.e. fine droplets). As a result, sea birds and coasts should hardly come into contact with the oil or not at all. In addition, the enlargement of the surface of the oil can accelerate natural degradation processes.
However, the dispersion in the water also increases the bioavailability of the oil components. This means that additional or different risks can arise for humans and the environment. This situation became clear in the last few years after combating the disaster of the oil drilling rig Deepwater Horizon in the Golf of Mexico. Toxic effects on organisms living in the water and sediment become stronger. When using dispersants, the risks for emergency personnel and affected local residents should also be taken into account, as they can be exposed to additional harmful aerosols (fine oil dispersant droplets), especially when the sea is choppy. An international debate is therefore currently taking place about the use of dispersants to combat mineral oil following ship disasters. Scientific risk assessment for German coastal waters is not available yet. The report that has now been published and which makes accessible the findings of an international workshop now offers a solid foundation for such scientific assessment.
The report shows that currents in the sea are decisive for the potential success of dispersants. By means of current simulators, regions in the German bay can be identified where the use of dispersants could be advantageous in case of an oil spill – to the extent that contamination may be prevented in especially sensitive areas. So far, no complete analytical strategy is available that can systematically evaluate the benefits and risks for humans and the environment (net environmental benefit analysis, NEBA) on a scientific basis. The analyses show the regions of the North Sea, however, for which such analyses could be useful.
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