Citation: Cunningham, E. M., Ehlers, S. M., Dick, J. T., Sigwart, J. D., Linse, K., Dick, J. J., & Kiriakoulakis, K. (2020). High abundances of microplastic pollution in deep-sea sediments: evidence from Antarctica and the Southern Ocean. Environmental Science & Technology.
Antarctica is known to be one of the most remote places on the planet. Despite its remoteness though, people around the world impact it on a daily basis. One of these impacts is in the form of pollution. Since the 1980’s plastic pollution has been documented in Antarctica and has only increased over more recent years. For example, between 2000 and 2001 over 6000 pieces of plastic washed ashore on the sub-Antarctic islands. In one region of the Southern Ocean, over 350 kg of plastic debris was recorded from 1989 to 2019. So why does it matter that plastic makes its way to Antarctica? While remote to people, Antarctica is home to a lot of wildlife which can be harmed by plastic pollution. For example, Antarctic fur seals have been found entangled in plastic debris and plastic has been found in the stomachs of breeding petrels, which are a species of sea bird.
In addition to these dangers, plastic debris breaks down over time into microplastics, which is a threat to many marine species.. In fact, microplastics have been ingested by species ranging from invertebrates to penguins. In addition to the dangers associated with being ingested, microplastics are also known for containing persistent organic pollutants, which are toxic chemicals. Given the dangers of microplastics to marine life, a lot of research has been done to understand where they come from and their impacts. However, only a very small amount of this research has focused on Antarctica, so our knowledge of the extent of the problem there is lacking. Because of this and the fact that the Arctic, which is a similar remote environment, is known to have a lot of microplastic pollution, a team of researchers from northern Ireland wanted to conduct a study to determine the abundance of microplastics in the deep sea in Antarctica.
Microplastics, many of them denser than water, sink and settle in the sediment at the bottom of the ocean. To find out how much microplastic is present in Antarctica, the researchers took samples of the sediment from 30 sites within three different regions of the Southern Ocean: the Antarctica Peninsula, South Georgia, and the South Sandwich Islands. The purpose of collecting from individual sites from different regions was to see if the abundance of microplastic varied not only from site to site, but also between regions. They also collected samples from different depths and examined the sediments’ overall composition to learn more about the processes that lead to sediment and microplastic deposition. Through chemical analysis and visual examination, the researchers were able to determine the concentration and composition of microplastics in each sample.
Overall, the researchers found that microplastics were present in 93% of their samples, or 28 of the 30. They also identified a total of 147 microplastic particles. Most of the plastics were fragments that had broken off of larger pieces of plastic, but some were also from fibers and films. The high levels of microplastics that the researchers found in Antarctica resembles the results from research that has been conducted in the Arctic, as well as in Canada and other locations globally. Given larger human populations elsewhere, it would be expected that sediment in Antarctica would have fewer microplastics, which was not the case. In sum, these results indicate that high levels of microplastic can accumulate in Antarctic sediment despite its remoteness.
So now that we know there are high levels of microplastics in Antarctica and that they are dangerous to the species that inadvertently ingest them, the next question to investigate is where are these plastics coming from? This will help use reduce plastic pollution. All three regions that were sampled had very similar levels of microplastics, which was unexpected since the Antarctic Peninsula has more human presence than the other regions studied. Microplastics can be transported to other regions biologically when they are consumed by an animal, but that would not explain the high levels seen in Antarctica. Given this, the researchers hypothesized that the plastics are from a combination of visiting ships and people, as well as long range transport from other parts of the world. This means that plastic pollution from thousands of miles away can ultimately end up in Antarctica because ocean and atmospheric currents carry them there. This shows that we can all play a role in reducing plastic pollution in remote areas. By reducing the amount of plastic we allow to enter the environment, we can reduce the amount that is transported around the globe and therefore reduce the impacts on wildlife.