Increased environmental pressure from ships
Ida-Maja Hassellöv,
Professor of Maritime Environmental Science,
Department of Mechanics and Maritime Sciences,
Chalmers University of Technology,
Sweden
In the transition to sustainable transport, following the EU white paper (2011), the ambition is to reduce climate impact by 60% by 2050 and at the same time cope with increasing transport demands. One cornerstone of the proposed solutions is to encourage a shift from road-based transport to rail and, in further extent, shipping. However, the assumptions that shipping is always a climate and environmental friendlier mode of transport is not correct. If the environmental impact from shipping on the marine environment is also taken into account, there is an obvious, but overlooked, goal conflict between transport strategies and environmental consideration. This is particularly pronounced in the Baltic Sea, where the HELCOM Second Holistic Assessment of the Ecosystem Health of the Baltic Sea concludes that Good Environmental Status with respect to eutrophication and hazardous substances respectively, are not in sight in most parts of the Baltic Sea. Hence, any additional ship operating in the Baltic Sea, or any additional distance travelled by the existing fleet, will actually be a step in the wrong direction, increasing the environmental pressure from ships on the vulnerable marine environment.
Ships can be compared with floating industries that during operation are giving rise to several different sources of stressors identified in the EU Marine Strategy Framework Directive (MSFD); e.g. contaminants, nutrients, acidifying substances, non-indigenous species, energy pollution including noise. If briefly going through the different on-board systems that contributes to the pressure on the marine environment, most ships are painted with toxic antifouling paints to prevent marine growth on the hull and minimize the ships resistance when moving through water. Thereby the fuel consumption is reduced, which of course is also good for the environment, but in the Baltic Sea the leakage of copper from anti-fouling paints is estimated to be more than 280 tons annually. This can be compared to all other natural and anthropogenic waterborne inputs of 890 tons. Still clean ship hulls are also important from another perspective; spreading of non-indigenous species transported on hulls, and ballast water make shipping a major vector for this severe threat to marine ecosystems and the natural biodiversity. Black water or sewage, and grey water from sinks, shower, laundry and kitchen are mixtures of organic matter, nutrients and cleaning agents. Tank water may contain residuals of whatever has been transported in the tanks, however there are some required prewash for the most toxic substances, which are left in port. Analogously to the strive to reduce hull growth it is important to eliminate growth inside the cooling system, why often toxic metals are released in the cooling water. Bilge water is also a mixture, primarily condense water from the engine room, with cleaning agents and residuals of fuel oil and lubricants. Most ships use oil for propeller shaft lubrication, which can imply a constant leakage of these oils that often are more toxic than fuel oils. From the atmosphere, we also have indirect deposition of especially nitrogen and sulphur oxides, along with particulate matter. Following the stricter regulation of maximum allowed sulphur content in marine fuels, an increasing number of ships have installed an exhaust gas cleaning system, also know a scrubber. In the scrubber the ship exhausts are led through a fine spray of water that reduce the emissions of acidifying sulphur oxides to the atmosphere. Unfortunately, also other pollutants are washed out and the scrubber water is a potent mixture and in the simplest form, open-loop scrubbers, large volumes (typically 500m3*h-1) of heavily polluted water are immediately discharged back to the sea. In 2018 there were 99 ships equipped with scrubbers operating in the Baltic Sea. These ships constituted less than 2% of the total number of ships operating in the area during that year, yet the ships with scrubbers caused 10-100 fold the loads of metals and polycyclic aromatic hydrocarbons to the Baltic Sea, compared with the load from all other onboard liquid waste streams from all other ships. Still it is allowed to run open-loop scrubbers in this sensitive brackish inland sea.
Most of these onboard systems are regulated individually, primarily through the International Convention for the Prevention of Pollution from Ships (MARPOL) by the International Maritime Organization. However, from an environmental management perspective, many of the subsystems contain the same sort of stressors included in the MSFD descriptors, but they are not assessed in a holistic way by the shipping regulations. The ships’ compliance to the regulatory frameworks is assessed within the Port State Control system, in Europe through the Paris Memorandum of understanding that produce black-, grey- and white listing of ships and flag states depending on the ships’ performance. If looking at the number of reported deficiencies as a proxy for potential environmental pressure, the ships on the black lists certainly pose a risk to the marine environment, having the highest average number of reported deficiencies per ship. However, if looking at the total number of reported deficiencies among ships operating in the Baltic Sea it is the much larger number of ships from white listed countries that together pose the potential highest pressure on the marine environment.
To conclude, if fulfilling the shift from land-based transport to shipping, it is important to realize that the pressure on the marine environment will increase if more ships operates, or the existing fleet travels additional distances, in the Baltic Sea. It is essential to make a holistic review of the impact of shipping on the marine environment to prevent further deterioration of the Baltic Sea due to uninformed decisions.
This article is based on the author’s findings published in the following fora:
Email: ida-maja@chalmers.se
Expert article 2879
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