Study says rising mercury levels in fish linked to climate change

mercury levels in fish, mercury pollution
© Vladimir Pisarenko

A new study in Finland found that rising mercury levels in fish can be linked to climate change and increasing land use

In a separate, recent study, an international team of researchers found an increasing accumulation of mercury in the Pacific Ocean. Co-author Ronnie Glud, Professor and Director of the Hadal Centre at the University of Southern Denmark, said at the time: “Ultimately this will improve the accuracy of environmental mercury models and the management of global mercury pollution.”

Globally, mercury pollution remains a distinct health threat when consumed by humans.

In the Amazon, illegal mining increased in frequency during the pandemic. Indigenous sources of water were polluted with mercury, which is part of the gold extraction process currently being conducted by organised crime groups.

Now, a team in Finnish Lapland are examining what level of mercury is in the fish that people eat. Exposure to mercury has always been an issue for people who depend wholly on fish-based diets, but in recent times, scientists point out that this threat has become more existential.

Warmer lakes, higher mercury concentrations

The team, examining lakes across Finnish Lapland, found that the warmer and murkier lakes contained more mercury. The algae in these lakes had a higher concentration, meaning that the fish in those lakes also contained more mercury.

‘Long-range atmospheric deposition’ is responsible

Professor of Environmental Research Kimmo Kahilainen from the University of Helsinki’s Lammi Biological Station, said: “Lapland is an important subject of research, since temperatures, precipitation and nutrient levels grow significantly when we move from the almost pristine lakes in the north towards the southern lakes which are more eutrophic and murkier.

“At the same time, land use in catchment areas is moving from reindeer herding to intensive forestry. Our research area has no direct sources of mercury emissions. Instead, the mercury found in the region originates in long-range atmospheric deposition and leaching from the catchment area soil.

“Global warming and increasing precipitation, together with intensifying land use, increase leaching from catchment areas. In the future, mercury content in Lappish fish can indeed shift closer to the level found in subarctic lakes. As the climate and land use change, mercury concentration in fish and food webs should be increasingly carefully investigated and monitored.”

Read the full study here.


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