Chalmers examine finds ship exhaust fuel scrubbers liable for as much as 9% of sure hazardous emissions into Baltic Sea


New analysis from Chalmers College of Know-how, Sweden, finds that the discharge water from ships’ exhaust fuel remedy programs—i.e., scrubbers—is liable for as much as 9% of sure emissions of carcinogenic and environmentally dangerous substances within the Baltic Sea—significantly greater than was beforehand identified. Moreover, the variety of ships geared up with scrubbers have tripled for the reason that examine was carried out.

The Baltic Sea is without doubt one of the most polluted sea areas on the earth as a result of northerly geographic location, pure hydrographic properties, massive catchment space and the semi-enclosed character of the brackish inland sea.


Comparability of masses (kg/yr) of PAHs from direct discharges from ships and atmospheric deposition to the Baltic Sea. The hundreds from atmospheric deposition ought to be handled as indicative on account of massive uncertainties. Ytreberg et al.

The researchers’ examine was commissioned by the Swedish Transport Company and the Swedish Company for Marine and Water Administration to analyze the environmental impression from scrubbers within the Baltic Sea, in comparison with different sources of environmental contaminants.

For a few years, we’ve flagged the truth that scrubbers account for disproportionately massive emissions of hazardous and acidifying substances into the marine atmosphere. Regardless of this message, we have now seen a major improve within the variety of scrubber installations as it’s economically helpful for the shipowner. Due to this fact, it is vitally necessary that authorities and decision-makers now react and implement measures to scale back transport’s emissions and impression on the marine atmosphere.

—Ida-Maja Hassellöv, Professor and researcher on the Division of Maritime Research at Chalmers

A scrubber is used on ships to scrub exhaust gases, primarily to scale back emissions of sulfur oxides to the environment. Nonetheless, washing the exhaust gases in seawater entice different contaminants within the seawater and ends in the discharge of hazardous substances to the marine atmosphere.

Within the Chalmers examine, printed as an open-access paper within the Marine Air pollution Bulletin, the researchers discovered that greater than 200 million cubic meters of environmentally hazardous scrubber water had been discharged from ships that used exhaust fuel cleansing programs within the Baltic Sea in only one yr.

The examine confirmed that scrubber wash water accounts for as much as 9% of the emissions of sure cancer-causing polycyclic fragrant hydrocarbons (PAHs) into the Baltic Sea. The examine additionally revealed that ships painted with copper-based antifouling paints account for a 3rd of the entire provide of copper to the Baltic Sea.

Copper in antifouling paints is already a identified environmental drawback because the steel can’t be degraded within the atmosphere and due to this fact results in excessive ranges in water, sediment, and soil. However precisely how a lot of the load of copper boat and ship site visitors accounts for, has beforehand been unknown. Additionally, the cancer-causing PAHs are troublesome to degrade and may unfold extensively within the atmosphere earlier than breaking down.

Our outcomes present that transport accounts for a major proportion of hazardous substances to the Baltic Sea, above all by antifouling paints and discharge of wash water from open loop scrubbers. PAHs are extremely poisonous to each people and aquatic organisms as they’re, amongst different issues, carcinogenic. Price noting is that the examine’s information was collected in 2018, and at the moment there have been roughly 180 ships with scrubbers within the Baltic Sea. Since then, these ships have elevated considerably and in 2021 there have been nearly 600 ships geared up with scrubbers within the Baltic Sea.

—lead creator Erik Ytreberg, Affiliate Professor and researcher on the Division of Maritime Research at Chalmers

The brand new analysis outcomes have led the Swedish Transport Company and the Swedish Company for Marine and Water Administration to suggest a ban on the discharge of scrubber water into the inner waters of the Baltic Sea. If the Swedish politicians comply with the road of the researchers and the authorities, Sweden would be the first nation within the Nordic area to introduce the ban.

Scrubbers are presently put in on greater than 4,000 ships world wide. Within the Baltic Sea space, solely Germany already applies the identical laws, despite the fact that a number of different nations in Europe regulate scrubber discharges of their ports. The Chalmers researchers welcome the proposal however hope for much more intensive regulation sooner or later.

The proposal that Sweden ought to ban the discharge of wash water into Swedish inland waters is sweet, however on the similar time it signifies that only one–2 p.c of the discharges that happen from scrubbers within the Baltic Sea at the moment can be regulated. Sweden might additionally suggest a ban in our territorial waters, which might imply that roughly 15–17 p.c of emissions to the Baltic Sea may very well be regulated. However the greatest impact would clearly come from a global ban, the place all of the nations across the Baltic Sea agree on a joint regulation of the discharge of scrubber water.

—Erik Ytreberg


  • Erik Ytreberg, Katarina Hansson, Anna Lunde Hermansson, Rasmus Parsmo, Maria Lagerström, Jukka-Pekka Jalkanen, Ida-Maja Hassellöv (2022) “Metallic and PAH masses from ships and boats, relative different sources, within the Baltic Sea,”
    Marine Air pollution Bulletin,
    Quantity 182, doi: 10.1016/j.marpolbul.2022.113904


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