Scientists Find Less Mercury in the Arctic Than Expected

For years, researchers have thought that if mercury is high and increasing in fish in the North American and European Arctic, then the same must be true of fish elsewhere in the Arctic. Now, though, scientists have found that this not the case for much of the continental Arctic.

Atmospheric mercury comes largely from mining and ore processing, such as smeltering. Under certain water conditions, though, mercury is converted to a special form that can be absorbed by living organisms through a process called methylation. This methylmercury is highly toxic and can cause a host of problems for marine animals. That's why researchers decided to examine its prevalence in various areas in the Arctic.

The researchers sampled burbot in two Russian rivers, the Lena and the Mezen. These cod-like fish are long-lived, eat other fish and are non-migratory. In addition, they can be found in fresh waters throughout the Arctic. In this case, the scientists sampled the fish using an ice-fishing method in the peak burbot season during November and December.

"The burbot fish was chosen because they are top predators that integrate many bio-geo-chemical processes in the river watersheds," said Leandro Castello, one of the researchers, in a news release. "The fish were collected downstream of the watersheds, so that they would present everything that happened upstream."

So what did they find? It turns out that mercury concentrations from fish in the Mezen River were lower than 10 locations, but higher than eight in North America. Mercury levels in burbot in the Lena River were actually among the lowest.

"Good news since the Lena River is one of the largest watersheds in the world," said Castello in a news release.

The findings reveal that mercury concentrations are not the same throughout the entire Arctic. In addition, these differences could be explained by water quality, geological bedrock formations and proximity to polluting sources.

"More studies are needed in the Russian Arctic if we are to better understand how mercury moves through this type of environment," said Castello in a news release.

The findings are published in the journal Environmental Science & Technology.