Each year, several tonnes of mercury end up in the Arctic Ocean. This mercury is transported from more southerly latitudes with the help of the wind and originate from, for example, the burning of fossil fuels and small-scale gold extraction. In the Arctic environment, mercury is converted into methyl mercury, the most hazardous form of mercury, and is absorbed by algae and microorganisms that are eaten by small fish and crustaceans, which in turn become food for larger fish and mammals.

Mercury is one of the most hazardous environmental toxins on earth. Humans and marine animals that live in the Arctic have high levels of mercury in their bodies. This is a major problem because high levels of mercury have an impact on reproductive capacity and on the cardiovascular and nervous systems. If pregnant women eat contaminated fish, methyl mercury can be transferred to the child through the mother’s placenta and this can cause mild developmental disorders and damage to the foetal nervous system.

Plastic microparticles are also a global problem and constitute a potential threat to marine organisms. We do not currently known exactly what quantity of microparticles there is in the Arctic, but studies at other latitudes show that the plastic microparticles are ingested by animals in the oceans and end up in the food chain.

potential plastic microparticles

Images of potential plastic microparticles from continuous sampling of sea water through Oden’s bow water system. Photo: La Daana Kanhai

Attempting to find out what the impact of climate change is on environmental toxins in the Arctic

During the expedition, we performed continuous measurements in the surface water and air in order to see how much and what type of mercury and microparticles there are in these areas. We also charted depth profiles of the sea water and studied ice cores, snow profiles and the water that lies just under the ice floe. These measurements are important in helping us understand the impact of melting sea ice and other phenomena caused by climate change on the transport and transformation mechanisms of environmental toxins in the Arctic. The measurements are also important to help us understand whether these toxins interact, and if so, how; for example if plastic microparticles also function as transporters of mercury and other toxins in the Arctic food web.

Gaseous mercury can evaporate from the ocean surface and investigations from the summer expedition indicate that the concentrations are generally lower in the Arctic than in the seas around Antarctica. We were also able to see that the sea ice partly prevents mercury from evaporating from the sea surface and also that the ice acts as a barrier that prevents mercury in the air from ending up in the sea water. Under the surface of the sea however, we saw that there is a lot of organic mercury being formed and there is thus a risk of this being absorbed by the fauna.  Our visual inspection of samples showed that there are plastic microparticles in several places in the Arctic Ocean in the area around the North Pole.