Melting sea ice.

Melting sea ice.

Plastic pollution in our oceans is no new news. Scientists and researchers are well aware of the accumulation of plastics in large gyres, such as the Great Pacific Garbage Patch, and on coastlines. But in recent years, a study shows a new accumulation of small plastic pieces in a different location: suspended in arctic ice. When the ice melts, a concentration of plastic pieces is released into the water.

New Plastics Sink Discovered

Rachel Obbard, a materials scientist at Dartmouth College, and her colleagues published a study in Earth’s Future in 2014. What surprised Obbard about this plastic discovery was the location – the fact that currents had carried the plastic all the way to the Arctic. “It was such a surprise to me to find them in such a remote region. These particles have come a long way,” says Obbard. Her and her colleagues argue that as arctic water freezes, it locks the suspended plastic particles, trapping them in the ice. This results in hundreds of particles per cubic meter. To put this number in perspective, that’s three times the amount of some counts of plastic in the Great Pacific Garbage Patch. The findings from this study help to bring some clarity to the discrepancy between the increased amount of plastic production and the trends in total plastic particles found in surface waters. Despite this dramatic increase in plastic production and discharges into the environment, data gathered from the surface water of the Atlantic between 1986 and 2008 did not show any increases. Therefore, there must exist substantial sinks of marine debris that have not been discovered. From this study, it is suggested that sea ice is one of these sinks.

The uncovering of this new accumulation of plastic could be the missing answer to the location of deposition of plastic. In the last half-century, industrial plastic production has dramatically increased, even reaching 288 millions tons in 2012 (according to Plastics Europe, an industry association). Although there is documentation accounting for much of the plastic that ends up in gyres and on coastlines, some of the plastic produced has not been accounted for. Obbard’s study proposes that the Arctic ice could be a sink for large amounts of plastic. Obbard and her colleagues noted that in the next decade, with the current melting trends, more than 1 trillion pieces of plastic could be released into the environment.

Obbard’s Study

Obbard and a PhD student take ice cores in Antarctica in 2012

Obbard and her PhD student take ice cores in Antarctica in 2012

The estimates for the next decade were based on sea ice cores that were collected in the Arctic during expeditions in 2005 and 2010. Ironically enough, the cores were not collected for the purpose of estimating plastic counts. Obbard and a Dartmouth student were originally analyzing the cores looking for algae. In order to analyze the core, the team melted parts of the cores and then filtered the water. Once they were left with just the sediment, the plastic pieces jumped out at them. They placed the pieces under a microscope for further analysis, allowing the researchers to sort the pieces by unique shapes and colors. After they were sorted, the researchers used an infrared spectrometer to determine the particles’ chemistry. The most dominant particle found in the core was rayon (54%), however polyester (21%), nylon (16%), and polypropylene (3%) were also present. It would seem that once we had the breakdown of the chemistry of the particles, it would be easy to determine a couple major sources of the plastic waste contributors – however, nothing is ever easy. As Richard Thompson, a marine biologist with the University of Plymouth in the UK, points out, it’s a challenge associating chemical components with specific objects. He uses the example of Rayon, which can be found in clothing, as well as cigarette filters and diapers.

As technology advances further and scientists are able to sift more finely, it’s likely that the estimates for the abundance of plastics in ice will increase. Corrections in human error are likely to yield additional pieces as well. Many of the plastic pieces light tan or brown in color resemble sand grains, making them more easily missed by the human eye.

So what do we make of all this? Although plastic is chemically harmless, it’s no new news the toll it has on ocean life. Overtime, the plastic can absorb organic pollutants and become very highly concentrated with these impurities. Once an animal ingests these plastics, the pollutants may be released, causing harm to the internal system of the animal.



Image Sources:

Melting sea ice:

Arctic core: