Mercury in the Southern Ocean

Mercury is one of the most hazardous elements all over the world. During centuries, mercury was used on medicine, as preservative and anti-bacterial agent, and also largely used in industry. However, the problems associated to its use were only recognized on the 20th century (e.g.: Minamata disease; 1971 Iraq poison grain disaster). We may have thought that being the Antarctic a remote and isolated continent that it would be “free” of anthropogenic pollutants, but through atmospheric and oceanic currents they are carried from the sources to the Southern Ocean.

The distinctive Antarctic atmosphere and Ocean with the characteristic sea ice, create a particular combination that can explain why does the remote Antarctic Ocean have some of the highest concentrations of methylmercury [1] in open waters. The presence of halogens in the atmosphere promotes deposition of atmospheric mercury in the ocean or on the snow (that will later melt to the ocean); Phytoplankton absorbs mercury in the water and thus this contaminant enters the food web.

Mercury is a really concerning issue mainly on the top predators (e.g.: Albatrosses, Penguins, Seals, Orcas) due to its high bio accumulation and bio magnification. Wandering albatrosses are one of the marine birds with higher concentrations of mercury in the world. What may be an extra stress in a species that is already facing conservation problems. We can’t forget that what it happens on our backyard as a global effect, mercury is one of many examples of the impact of global anthropogenic pollution.

[1] Methylmercury – a highly bioaccumulative organic form of Mercury, that is formed from inorganic mercury by the action of microbes that live in aquatic systems. Learn more about Mercury here.

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Sources:

Bargagli, R. (2008). Environmental contamination in Antarctic ecosystems. Science of the Total Environment, the, 400(1-3), 212–226. doi: 10.1016/j.scitotenv.2008.06.062

Cossa, D., Heimbürger, L.-E., Lannuzel, D., Rintoul, S. R., Butler, E. C. V., Bowie, A. R., et al. (2011). Mercury in the Southern Ocean. Geochimica Et Cosmochimica Acta, 75(14), 4037–4052. doi: 10.1016/j.gca.2011.05.001

Tavares, S., Xavier, J. C., Phillips, R. A., Pereira, M. E., & Pardal, M. A. (2013). Influence of age, sex and breeding status on mercury accumulation patterns in the wandering albatross Diomedea exulans. Environmental Pollution, 181, 315–320. doi: 10.1016/j.envpol.2013.06.032

Author: José Seco

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