Air pollution from maritime
transportation is a major environmental pressure. Sulphur oxides released from
the burning of marine fuels react with water in the air to form acid rain and are responsible for a variety of
health and environmental impacts. In 2008, the International Maritime Organization (IMO) adopted
regulations to control air pollution from ships, stipulating a progressive reduction in the emissions of sulphur oxide until 1 January 2020, when a maximum 0.50%
of emissions could comprise sulphur oxide
To comply with these limits, ships should switch to
a fuel with lower sulphur content or install an exhaust gas cleaning system,
also known as a scrubber.
The price difference between heavy fuel oil and low sulphur
fuels has meant that an increasing number of ships have opted to install
installation of a scrubber allows for the continued use of lower cost fuels
that have higher sulphur content. Within the scrubber, the exhaust gas passes
through a fine spray of alkaline water which readily dissolves sulphur oxides so that levels are sufficiently reduced
in air emissions. Nitrogen oxides, and other contaminants are also washed out. However, the resulting scrubber discharge water is a chemical
cocktail of acidifying, eutrophying, and contaminating substances and elements. The impacts of scrubber discharge water can be completely avoided through
the use of alternative fuels, such as distilled low sulphur fuels. Distilled fuels
have the added benefit that they remove the threat of heavy fuel oil spills
from shipping activities.
had taken place within the IMO to emphasize that air pollution was not just transferred to the marine environment.
However, while the number of ships with installed scrubber systems is increasing, scrubber
discharge water remains poorly regulated.
It is in response to the lagging legislation that
ICES releases our latest Viewpoint. This has been developed by a collaboration
between members of our expert groups on Shipping Impacts in the Marine
Environment (WGSHIP), Marine Chemistry (MCWG),
Biological Effects of Contaminants (WGBEC), and Marine Sediments in Relation to
A background report details the consequences and
impacts of scrubber discharge water, including immediate mortality in plankton,
negative synergistic effects, and further impacts through bioaccumulation,
acidification and eutrophication in the marine environment.
Ida-Maja Hassellöv, co-chair of WGSHIP also thinks that the Viewpoint on scrubbers
reflects the timely startup of her group, which had its first meeting in November
2019. "Worldwide, there is an increasing awareness and interest regarding the
impact from shipping on the marine environment. WGSHIP gathers researchers
working on this topic in 13 different countries and in addition we have a broad
network within ICES, which facilitated interaction with other relevant expert
groups. To assess the environmental impact of scrubber discharge water, competence
within many different marine disciplines is required, and I am happy that we
managed to have such a good collaboration within the group."
that if the use
of alternative fuels is not adopted, and scrubbers continue to be considered an
equivalent method to meet the sulphur emissions limits, then there is urgent
need for significant investment in technological advances and port reception
facilities to allow zero discharge closed loop scrubber systems, improved
protocols and standards for measuring, monitoring and reporting on scrubber
discharge water acidity and pollutants, and evidence-based regulations on
scrubber water discharge limits that consider the full suite of contaminants.
An initial response from the IMO to the background
report was that, “it provides helpful input to the
discussion on exhaust gas cleaning
systems discharge water”.
Dickey-Collas, Chair of ICES Advisory Committee will formally present this
viewpoint to the IMO in 2021. Noting the importance of the translation of science
into advice Dickey-Collas states, “ICES viewpoints enable scientists to highlight the
evidence that impacts important societal issues. We use viewpoints to
comment and advise on human impacts on and services from the marine
environment. This viewpoint on scrubbers is very timely as we propose to submit
it to the
IMO in the spring of 2021.”
VIEWPOINT: Scrubber discharge water from ships – risks to the marine environment
and recommendations to reduce impacts and the
supporting report, ICES Viewpoint background document: Impact from exhaust gas cleaning systems (scrubbers) on the marine environment, are now available
on ICES website.
Incorporating innovation is a priority area for
ICES Advisory Plan. Supporting the translation of
mature science into Viewpoints incorporates new knowledge into
the advisory process to contribute effectively to the creation of advice on
meeting conservation, management, and sustainability goals. Read more about ICES advice priority
areas in ICES Advisory Plan.
The background document for this viewpoint was developed by
Ida-Maja Hassellöv (Chalmers University of Technology), Marja
Koski (DTU Aqua), Katja
Broeg (German Federal Maritime and Hydrographic
Agency), Octavio Marin-Enriquez (German Federal Maritime and Hydrographic Agency),
Jacek Tronczynski (Ifremer), Valérie
Dulière (Royal Belgian Institute of Natural
Sciences), Cathryn Murray (Fisheries and Oceans Canada), Sarah Bailey (Fisheries and Oceans Canada), Jessica
Cabot Center for Ocean Life), Karen de Jong (Institute of Marine Research, Norway), Emmanuel
Ponzevera (Ifremer), Maria
Jesus Belzunce-Segarra (AZTI), Claire
Mason (Cefas), Josephine
C. Iacarella (Fisheries
and Oceans Canada), Brett Lyons (Cefas), Jose A.
Fernandes (AZTI) and Koen Parmentier(Royal Belgian Institute of Natural
Discharge of scrubber water his a growing concern worldwide.