"When large ships use scrubbers to meet international air pollution limits, the treated fuel exhaust gets dumped into the sea along with other contaminants. Researchers say the discharges are packed with metals and organic compounds that threaten marine environments."

"In 2020, an international rule went into effect that sharply reduced the amount of sulfur allowed in ship fuel. The aim was to rein in atmospheric sulfur oxide emissions, which are known to be a threat to public health and the environment.

Most ships have complied with the three-year-old sulfur cap, imposed by the United Nations’ International Maritime Organization, by switching from tar-like heavy fuel oil to cleaner, less polluting fuels. But the IMO also allows the countries where merchant vessels are registered to certify “alternative mechanisms” to comply with the cap.

One is the exhaust gas cleaning system commonly known as a scrubber, which treats the pollution that normally would go into the air—and then dumps it in the sea.

In a new study, researchers report that guidelines created last year by an IMO committee to assess the environmental risk from scrubber discharge are woefully inadequate, resulting in the release of water with multiple pollutants that jeopardize marine environments."

Lydia Larsen reports for Inside Climate News July 17, 2023. [2]