Researchers find scrubber water harmful at the tiniest of concentrations
When researchers in the EU-funded project Emerge studied the effect of scrubber water on aquatic organisms, they found harmful effects even at the tiniest of concentrations. The findings add new insights to the problem with ships' exhaust gas cleaning systems – known as scrubbers – that allow ships to continue to use cheaper heavy fuel oil while still complying with the 2020 sulphur emissions rules.
“We see and find effects at much lower levels than what has previously been reported. We are five laboratories in Europe that have done ecotoxicological tests on different organisms and we all come to the same conclusion – this is very toxic”, says Maria Granberg, marine ecotoxicologist at IVL Swedish Environmental Research Institute.
Since the International Maritime Organisation (IMO) in 2020 introduced stricter rules on sulphur emissions, many ships have installed exhaust gas cleaning systems called scrubbers. These are systems that shower the exhaust gases with seawater, which is then rinsed back into the sea.
– The scrubber technology allows shipping companies to continue using the cheaper high-sulphur bunker oil instead of switching to more environmentally friendly fuels. What happens is that pollutants that would have ended up in the air are released directly into the sea instead," says Maria Granberg.
At Kristineberg research station, IVL ecotoxicologists are studying the effects of the scrubber water on marine organisms, especially their eggs and larvae that live in the open water. This is part of the EU project Emerge, where IVL is responsible for coordinating the ecotoxicological studies being carried out.
In the project, five research institutes have evaluated the effects of scrubber water from ships sailing the route from northern Europe through the English Channel and across the Mediterranean to Turkey. The scrubber water tested comes from so-called open systems, where very large quantities of seawater are used to clean the flue gases, which are discharged untreated back into the sea. Scrubber discharges contain heavy metals, nitrates and polycyclic aromatic hydrocarbons.
A pinch is enough to cause damage
In ecotoxicological tests, all five research institutes studying the scrubber discharges in the EMERGE project found negative impacts at concentrations as low as 0.001 per cent.
“The scrubber water is heavily contaminated and contains heavy metals, polyaromatic hydrocarbons, soot particles, nitrogen compounds and is also acidic. Many shipping lanes also run along coastal stretches where the marine environment is most biodiverse, and there is a high risk that we will see significant environmental impacts from scrubber systems,” says Maria Granberg.
Emerge researchers have also identified problems with the emissions to air from the scrubber systems. Measurements on board ships show that there are still major problems with emissions of particulate matter and other pollutants.
– The sulphur rules were designed to address the problems of sulphur oxide and particulate emissions to air by switching to low-sulphur fuel. The scrubber solution takes care of the sulphur but does not reduce particulate emissions as intended. So, it's not a good solution for air quality either," says Erik Fridell, transport researcher at IVL.
EMERGE (Evaluation, control and Mitigation of the Environmental impacts of Shipping Emissions) is an innovative four year project funded by the European Commission under the Horizon 2020 programme.
The project aims at quantifying and evaluating the effects of potential emission reduction solutions for shipping in Europe and developing effective strategies and measures to reduce the environmental impacts of shipping.
EMERGE will systematically analyze the complex interactions between technological options, pollutant emissions and dispersion, and the environment. Read more at emerge-h2020.eu External link, opens in new window.