When we speak about pollution in the Poles, geographically isolated locations, we normally talk about atmospheric or aquatic transportation, or natural sources such as volcanoes. However, there are other ways in which these contaminants can get to the Antarctic continent.
The truth is that seabirds also have their part in bringing several types of contaminants to these isolated locations. Why? Seabirds gather in large groups, called colonies, which results in a big amount of feces being deposited in the soil in the same place. A recent study came to the conclusion that several contaminants, and not only nutrients, accumulate in these birds and are released into the environment through their feces.
This way, to verify which contaminants are being released by these animals, a group of scientists from Brazil and France went to Antarctica and took soil samples from colonies and samples from soils far away from these colonies. When comparing the results from these two types of soils, they concluded that the soils from the colonies have higher concentrations of a few contaminants such as Cadmium (Cd), Mercury (Hg), Arsenic (As) and others.
However, there are many other sources of these elements, and so it is necessary to confirm that these are in fact being released by seabirds, before we can say for sure that seabirds are a source of pollution in the Poles. So, the study used the analysis of stable isotopes of carbon (C) and nitrogen (N) that due to their high resolution can distinguish the different sources. For example, locations with higher amounts of feces showed a high percentage of fractionation of the N15 isotope, with values corresponding to animal-derived nitrogen. Being able to conclude that in fact, there was a large amount of contaminants associated with seabird feces.
Although it seems that seabirds are a source of pollution in Antarctica (which has also been observed in the Arctic), there is still a lot to study! The type of birds, the size of colonies, the health of the birds and many other factors can influence these results!
Source: C.V.Z. Cipro, P. Bustamante, M.V. Petry, R.C. Montone, Seabird colonies as relevant sources of pollutants in Antarctic ecosystems: Part 1 – Trace elements, Chemosphere, Volume 204, 2018, Pages 535-547. DOI: 10.1016/j.chemosphere.2018.02.048
Author: Beatriz Bento