According to a special report by The Guardian, there is a dirty secret in shipping: how the “scrubbers” in the chimneys of ships clean but pollute the sea, says The Guardian.
To reduce air pollution, the shipping industry could have switched to cleaner fuels; instead, many boats turned to special devices that simply dump the toxins into the water.
Despite only accounting for 4% of ships with scrubbers, cruise ships account for 15% of scrubber wash water discharged into ports.
In 2019, Alan Ladd, a marine engineer, was on a cruise ship slowing down to give passengers a better view of Hubbard Glacier, the largest tidewater glacier in North America. Briefly looking away from the harbor seals and killer whales, Ladd noticed a spray of black blubber, with a rainbow sheen, bubbling on the surface of the water.
“The only reason I saw it was because the ship had stopped. Suddenly, I could see this pollutant and this soot,” says Ladd, who works with the Alaska Ocean Ranger program as one of several independent observers of shipping effluents. “What really bothered me more than anything is that they didn’t do anything about it.”
What Ladd saw was the result of a decision by the shipping industry to reduce air pollution at the expense of the ocean.
After the International Maritime Organization (IMO) set out to reduce emissions of sulfur into the atmosphere, which regulators say is harmful to human health, the shipping industry was faced with the option of switching to a cleaner but more expensive or installing a system to clean the exhaust gases. – known as “scrubbers” – which dump chemicals extracted from exhaust gases directly into the sea.
Scrubbers are dirty and very cheap, but as of 2020, more than 4,300 ships worldwide had installed them, up from 732 ships in 2018.
Open & Closed-loop Scrubbers in Ships – DNV“It’s a trade-off: clear the skies but pollute the waters.”
“The writing has been on the wall for many years with scrubbers and their environmental implications,” says Andrew Dumbrille, an advisor to the Clean Arctic Alliance, a coalition of environmental organizations working to protect the polar region from the impact of shipping.
“The problem is that more ships will install scrubbers, so the problems are expected to get worse.”
The race to install debuggers started recently. In January 2020, the IMO, the United Nations body that oversees shipping, announced a new global sulfur limit of 0.5%, down from 3.5%. To meet the target, he urged the global shipping fleet to switch to low-sulfur fuel.
But it also allowed “equivalent” enforcement measures, as long as the ships reduced their emissions.
Scrubbers have proven to be the cheapest way to do this. The cost to buy and install a scrubber is £1.5 million to £5 million, while cleaner fuel is £250 to £400 per tonne. The sewage treatment plant pays for itself in a year, says the Guardian report.
“It has been a loophole for the industry to continue to burn the cheapest and dirtiest fuels,” says Lucy Gilliam of Seas at Risk, an association of European environmental organisations.
Located in ships’ exhaust funnels or stacks, scrubbers use seawater to spray or “wash” sulfur dioxide contaminants from engine exhaust.
Most ships use an open-loop scrubber system, which means that instead of storing the waste in a tank for disposal at dedicated port facilities, the ships dump the acid wash directly, up to 100,000 times. more acidic than seawater, overboard, says Eelco Leemans. an Arctic marine researcher.
According to DNV, open-loop scrubbers use seawater, which is naturally alkaline, to wash SOX from the exhaust. The resulting discharge water must meet the requirements of MARPOL Annex VI before being discharged. This is where the requirements that the IMO should review are found.
Roughly 10 gigatonnes (10,000,000,000 tons) of scrubber wash water are discharged into the oceans annually, according to an International Council on Clean Transport (ICCT) report on global discharge waste, just less than the total weight of the entire cargo transported by ships in a year.
Toxins don’t just go away. In addition to being acidic, scrubbers contain heavy metals that accumulate in marine food chains. The Swedish Environmental Research Institute found that North Sea ship wash water has “serious toxic effects” on zooplankton, which cod, herring, and other species feed on. Meanwhile, a Belgian study found that scrubber discharges contain high concentrations of metals such as nickel, copper, and chromium, which devastate marine ecosystems.
However, it is polycyclic aromatic hydrocarbons (PAHs) that most concern experts. These have been linked to various cancers and reproductive dysfunction in marine mammals, including the southern resident killer whale in the North Pacific and beluga whales.
“A lot of the discharge is toxic and contains all these nasty stuff,” Leemans says, adding, “It’s the whole cocktail that makes it even worse.”
An IMO spokeswoman, Natasha Brown, says the scrubbers were developed as an “equivalent” to meeting air pollution limits and the IMO is now looking at the broader issue in response to concerns.
We could solve the sulfur pollution problem by switching to cleaner fuels. But instead, we are just transferring the problem from one place to another, says Lucy Gilliam, of Seas at Risk.
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