Several mercury assessments carried out by different teams indicate that there is a net export of mercury from the Arctic to the Atlantic, via the 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 depths of the Arctic Ocean (https://www.insu.cnrs.fr/fr/cnrsinfo/flux-dexport-du-mercure-en-arctique…), scientists1 led by the Mediterranean Institute of Oceanography (MIO) have been looking into this issue.
Thanks to the 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 the 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 mercury were transported to the Arctic Ocean, while 54 ± 13 tonnes/year were exported to the Atlantic Ocean. This new assessment therefore shows that the Arctic Ocean exports around 18 tonnes/year of mercury to the Atlantic Ocean, including 40 % in the form of methyl mercury.
1. The French laboratories involved in this study are as follows: Institut méditerranéen d'océanographie (MIO/PYTHÉAS, CNRS / Université de Toulon / IRD / AMU), Géosciences environnement Toulouse (GET/OMP, UPS / CNRS / IRD / CNES) and Centre européen de recherche et d'enseignement de géosciences de l'environnement (CEREGE/PYTHÉAS, CNRS / Université Aix-Marseille (AMU) / IRD / Collège de France).
Contact
Lars-Éric Heimbürger-Boavida
MIO/PHYTHEAS
04 86 09 06 14
lars-eric.heimburger@mio.osupytheas.fr