Mercury levels in the Arctic Ocean could be sensitive to climate change

By Tierney Smith

Polar rivers carry large quantities of mercury to the Arctic Ocean during the summer, a process which could prove highly sensitive to climate change, according to new research.

The study published in Nature Geosceince found that the amount of mercury – a toxic element – which ends up in the Arctic Ocean, could be dependant on the climate-induced changes in river flow and permafrost thaw.

The researchers, based at Harvard, warn that this could pose a health concern to indigenous peoples – who rely heavily on marine-based diets.

How does the flow of rivers such as the Ob River in Siberia affect the amount of mercury ending up in the Arctic Ocean? (© Olga Oslina/Creative Commons)

The Arctic is a fairly unique environment. While very remote from the human induced sources of mercury, some of the highest levels of the elements are found in marine animals in the Arctic.

According to the research, Arctic accumulation of mercury is caused by atmospheric forces and the flow of rivers. While the former has been previously widely recognised, the new research points toward river flow as the dominant source of mercury in the Arctic Ocean – a source previously not recognised.

The researchers believe that while it is still unclear how the mercury enters the river systems, climate change may play a large role – with permafrost thaw releasing mercury that was locked in the soil and changes in the hydrological cycle increasing run-off from precipitation that enters the rivers.

Mercury is a naturally occurring element, but has been enriched in the environment by human activities such as coal combustion and mining.

In humans it can be potent – causing long-term developmental delays in exposed children and cardiovascular health problems in adults.

Find the research paper here.

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