Burning Less Coal Means Less Mercury In Your Sushi


Katy Evans

Katy is Managing Editor at IFLScience where she oversees editorial content from News articles to Features, and even occasionally writes some.

Managing Editor

A reduction in coal-burning emmisions has resulted in a 19 percent drop in mercury in Atlantic bluefin tuna. kps123/Shutterstock

If the idea of climate change is too overwhelming and it feels like we are already fighting a losing battle, it helps to be able to see actual progress, results that prove that changing our ways is actually doing something.

A new study by researchers from Stony Brook University, New York, shows that the reduction in burning coal between 2004 and 2012 resulted in a 19 percent reduction in the amount of mercury found in Atlantic bluefin tuna – a surprising drop in a relatively short period of time.


Mercury (Hg), a toxic heavy metal, enters the ocean through carbon emissions from coal-burning power plants. Atlantic bluefin tuna, which can reach around 2 meters (6.5 feet) in length and weigh on average 250 kilograms (550 pounds), are at the top of the food chain, so their high consumption of smaller fish means they tend to have a high mercury concentration.

Although mercury was once considered medicinal, health officials have been warning people for decades that tuna can carry enough mercury to be a health risk for humans, as it poisons the kidneys and nervous system. Mercury exposure is especially risky for vulnerable people like young children and pregnant women, as it can interfere with brain development. The US Environmental Protection Agency puts the figure at around 75,000 babies born each year with a greater risk of learning disabilities because of their mothers’ exposure to mercury.

According to the study, published in Environmental Science and Technology, the decrease in mercury concentration levels in Atlantic bluefin tuna over the eight-year period mirrored the reduction in anthropogenic Hg emissions measured over the same period. Therefore, they propose this is “the first evidence to suggest that emission reduction efforts have resulted in lower Hg concentrations in large, long-lived fish.”

“We found it striking that this decline in tissue concentrations of mercury was nearly identical to declines reported for mercury emissions from North America over the same time period as well as declines in mercury concentrations in North Atlantic air and in seawater,” senior author Nicholas Fisher said.


What they also found interesting was the level of mercury found in much older tuna (which had higher levels) fell at the same rate as the level of mercury found in the seawater, meaning the link is quite clear and reducing Hg emissions could lead to reduced mercury concentrations in fish much faster than expected.

The important message that we can take away from this study is that yes, as humans we have had a huge impact on the environment but it is also possible to reverse some of these impacts, and if we act fast, we can actually see results much sooner than we had thought.  

[H:T Ecowatch]


  • tag
  • mercury,

  • environment,

  • bluefin tuna,

  • mercury emissions,

  • Hg emissions,

  • coal emissions