Bringing the hidden environmental impacts of shipping to the surface

When a solution creates new problems

Scrubbers became widespread after 2015 when the International Maritime Organisation, IMO, tightened requirements for ships’ sulphur emissions. The technology washes sulphur dioxide out of flue gas and binds it in water, which is then discharged into the sea.

But this solution has proved problematic. DTU’s research has documented that scrubber water is acutely lethal to small crustaceans such as copepods, and that it contains heavy metals and tar-like substances that can harm plankton, fish and organisms on the seabed.

This is an example of how a solution may solve one problem but risks creating another. For when the IMO introduced stricter rules on sulphur emissions, it led to an increase in the use of scrubbers and thus to increased marine pollution, Marja Koski explains.

“Research can provide knowledge that ensures the shipping industry does not develop solutions that ultimately turn out to be worse than the original problem,” says Marja Koski, who is currently investigating the so-called cocktail effects of various ship-related chemicals on copepods.

“To understand how scrubber water or other complex pollution affects the marine environment, it is important to investigate how the chemical substances react with each other and create a combined load—the so-called cocktail effect—to which marine organisms react,” she says.

Risk of damaging ecosystems

Researchers at DTU Aqua are also focusing on Arctic waters, where climate change and melting sea ice is making new shipping routes possible thereby increasing ship traffic in one of the world’s most vulnerable ecosystems.

In addition, work is being carried out on assessments of new fuels such as ammonia, where the effects of potential spills in the marine environment are still poorly understood. And along with researchers at DTU Sustain, they are investigating a new treatment system for ships’ wastewater, which is being developed by DTU Sustain.

For Marja Koski, it is about helping the shipping industry move in a more sustainable direction:

“Without a deep understanding of the ocean’s processes, we do not know how we are affecting the sea. Nor do we know what we need to do to protect marine life, and we risk making decisions that harm ecosystems in the long term.”

The research is, among others, funded by the NORDEN // Orient Foundation and the Danish Maritime Foundation.