Redefining the Arctic Ocean Mercury C ycle: New Insights into Mercury Loading and Burial Processes

While global efforts are undertaken to mitigate anthropogenic emissions of Hg, thawing permafrost and melting glaciers threatens to mobilize large amounts of Mercury (Hg) into the Arctic Ocean (AO). Future risks of wildlife and human mercury exposure, however, remain highly uncertain. This, as there are still critical uncertainties in our understanding of the AO Hg cycle to address.

From a mapping study of Hg burial rates in AO surface sediments, we conclude that burial of Hg in shelf sediments plays a much larger role in the AO Hg cycling than what was previously thought and that these sediments may store valuable information that may help us to redefine the AO Hg cycle.

Here, we will explore this by i) identifying and mapping sources of Hg in AO sediments and ii) generating a better understanding of Hg burial processes.

To identify the sources of Hg, we will determine and evaluate natural isotopic signatures of Hg in surface sediment collected from AO’s different shelf seas and terrestrial endmembers.

We will then quantify these sources by evaluating the distribution of Hg source proportions along with already generated maps of Hg burial rates.

To generate a better understanding of Hg burial processes, we will evaluate the circumarctic distribution of Hg source proportions together with existing maps of organic carbon sources.

Through these actions, we will be able to address critical uncertainties that currently prevent us from understanding future risks of Arctic Hg.