Responses to oil spills and pollutionIn scenarios other than disasters that occur in deep waters, such as the explosion at the oil drilling rig in the Gulf of Mexico in spring 2010, an oil spill disaster response is most effective while the slick is still drifting on the water surface. From a technical perspective, some countries prefer to use exclusively mechanical methods to contain oil spills, such as oil skimmers or booms that form floating barriers on the water, while others opt for chemical methods, mainly involving the use of dispersants, which are usually dropped on the slick in large quantities from aircraft. The effectiveness of these chemicals is heavily dependent on the type and condition of the oil, however. A further limiting factor is that these dispersants can generally only be used for a short time after the spill has occurred, as the chemical and physical processes described above begin to impair their effectiveness after only a few hours. If the oil slicks are drifting towards sensitive sections of shoreline, using these agents may be a sensible option, however. The dispersants drive the oil from the surface down into deeper waters, reducing the risk that seabirds or sensitive flora will become coated with oil. Following the explosion at the Deepwater Horizon drilling rig in 2010, however, the oil flowed out of the borehole at great depth and entered the entire water column, partly as a massive cloud of oil. Very little experience has been gained in responding to disasters of this type and on this scale. As an initial response, massive quantities of dispersants were deployed, with currently unforeseeable ecological consequences. Bioremediation can also be successfully deployed in suitable – i.e. nutrient-poor – marine areas. This involves seeding the water with nutrients to promote the growth of bacteria that break down oil.
- 4.17 > Although the quantities of oil being transported across the oceans have increased considerably since the 1970s, the amount of marine oil pollution caused by oil tanker disasters, technical defects or negligence has fallen dramatically. The sharp decrease in tanker traffic in the late 1970s was caused by the economic crisis which occurred during that period. The statistics cover oil spills above 7 tonnes; records of smaller spills are somewhat patchy.
- No matter which strategy is deployed, it can only be successful and effective as part of a broader national contingency plan in which well-trained emergency teams implement a coherent and well-thought-out response. In the US, Germany, other North Sea states and certain other countries, such contingency plans have been in place for a number of years. In these countries, the days when the authorities often failed to adopt a prompt, effective or appropriate response to oil spills due to a lack of clear responsibilities, equipment and personnel are over. On their own, however, technical management strategies are not enough. Global and regional agreements are required to protect the sea from oil pollution, and mechanisms need to be in place to monitor compliance with them. A positive example is the International Convention for the Prevention of Pollution from Ships,1973, as modified by the Protocol of 1978 relating thereto (MARPOL 73/78), which from 1983 formed the basis for the designation of marine protected areas where tanker traffic is wholly or partly restricted. As a result of the Convention, there was a reduction in the number of oil tanker disasters during the 1980s. In addition to other provisions on operational discharges of oil, MARPOL 73/78 also paved the way for the introduction of double hull tankers. The United States’ 1990 Oil Pollution Act and the International Management Code for the Safe Operation of Ships and for Pollution Prevention (ISM Code) adopted by the International Maritime Organization (IMO) in 1998 also contributed to the further decrease in oil pollution over subsequent decades.Further information on this topic is available here:
- 4.18 > Workers on a beach at the popular Gulf Shores resort in the US remove sacks of oil-covered algae. The resort, along the coast of Alabama, is one of the communities in the Gulf of Mexico which have been polluted by oil from the Deepwater Horizon disaster in June 2010.
The outlook for the future – cautious optimismMarine oil pollution has undoubtedly decreased in recent decades. International conventions, the designation of protected areas and the mandatory introduction of double hull tankers have all made a contribution here. At the same time, as the Deepwater Horizon disaster clearly demonstrates, the situation for the marine environment continues to give cause for concern. Furthermore, the illegal discharge of oil during tank-cleaning operations, which still accounts for one third of oil pollution, cannot be tackled effectively without more stringent controls and tough penalties. Combating oil pollution in shallow waters such as the Wadden Sea will also continue to be a problem in future as response vessels generally cannot operate in waters of less than 2 metres depth.