The Arctic Ocean exports mercury to the Atlantic Ocean

Several mercury assessments carried out by different teams indicate that there would be a net export of mercury from the Arctic to the Atlantic, via Fram Strait, the only deep link between these two oceans. However, these estimates were too approximate because they were not based on observations.

Following their previous study on the export of mercury to the deep Arctic Ocean (, scientists1 led by the Mediterranean Institute of Oceanography (MIO) have been working on this issue.

Thanks to new data acquired during the two GEOTRACES oceanographic campaigns in 2015 and 2016, they were able to establish a new mercury balance. They estimated that mercury concentrations were higher in waters leaving the Arctic via the East Greenland Current than in those entering via the West Spitsbergen Current. They calculated that 43 ± 9 tonnes/year of Hg were transported to the Arctic Ocean, while 54 ± 13 tonnes/year were exported to the Atlantic Ocean. This new balance sheet therefore shows that the Arctic Ocean exports about 18 tonnes/year of mercury to the Atlantic Ocean, 40% of which is in the form of methyl mercury.

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