King penguin colony exudes nitrous oxide | Polarjournal
One of the largest king penguin colonies in the world is located in St. Andrews Bay on South Georgia island. Around 300 – 400,000 animals live here all year round, thanks to the long breeding cycle of the penguins. Photo: Michael Wenger

One of the highlights for Antarctic travelers is the huge colonies of king penguins on South Georgia or other sub-Antarctic islands. Time and again it is pointed out how this sight puts a smile on the faces of the visitors as they stand for hours in front of the majestic animals. But perhaps it is not the sight, but an invisible gas that is responsible for the smile. Danish researchers have found that significant amounts of nitrous oxide N2O are produced in the colonies.

The research team, led by lead author Peiyan Wang and study leader Professor Bo Elberling from the University of Copenhagen, concluded in an environmental study in South Georgia that in places with increased penguin activity, the N2O concentration is massively higher than in places without penguins. “The maximum output is up to 100 times higher than in a freshly fertilized Danish field,” explains Professor Elberling, Head of the Department of Geosciences and Natural Resource Management at the University. “That’s really high, especially considering that nitrous oxide is a greenhouse gas 300 times stronger than CO2.”

According to the study, the amount of nitrous oxide is not harmful to the climate. However, a longer stay during the field study often led to headaches, mild nausea due to the various gases that arise from the degradation of the penguin guano. Image. Michael Wenger

Asked whether the amount of N2O released could have an impact on the climate, Professor Elberling said: “It is not enough in this case to have an impact on the earth’s overall energy budget. But our results show how penguin colonies have an impact on their environment. This is very interesting, as some of the colonies continue to grow.” What the amounts of nitrous oxide certainly have an influence on, however, is the health of people around a colony. “When you’re nosing around the guano for hours, you get really crazy. You can feel mild nausea and headache (…) from the combination of nitrous oxide, hydrogen sulphide and other gases,” continues Bo Elberling. The odor intensity at a colony of hundreds of thousands of king penguins is often perceived as very unpleasant, despite the cold and distance that visitors have to keep. Whether the penguins are affected by the amounts of nitrous oxide has not been investigated.

The research area, St. Andrews-Bay on South Georgia. In the background, Heany Glacier is visible, the penguin colony itself extends further to the left in the picture. The recording was made in November, when the colony is only about half its total size. Photo: Michael Wenger

Using the example of the colony of St. Andrews Bay in South Georgia, where about 300,000 – 400,000 animals live, the research team studied how the combination of glacial retreat and the simultaneous colonization of the released soil influence greenhouse gas emissions. The scientists found that the age of soil release plays an important role in the formation of CO2 due to soil respiration and the fixation of methane. But the longer and more penguins were present, the stronger the effects were eliminated. On the other hand, the production of nitrous oxide increased significantly. The gas forms when soil bacteria break down the penguins’ feces and the nitrogen enters the soil, where it is converted into nitrous oxide by other bacteria and then escapes again. Professor Elberling is also convinced that important findings for domestic agriculture can be drawn from the results. “Something we can learn from this is, for example, how and when to fertilize, contrary to the optimal conditions for bacteria to produce nitrous oxide.”

Source: University of Copenhagen / Wang et al (2020) Sci Tot Env 718

Link to ther original article: https://www.sciencedirect.com/science/article/pii/S0048969719352477?via%3Dihub

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