Six years ago, the 5 Gyres Institute formed to answer a question the world had put in its too hard box. Marcus Eriksen, PhD, director of research for the 5 Gyres Institute, explained, “The 5 Gyres Institute’s work began six years ago. “When The 5 Gyres Institute formed in 2008, we set out to answer a basic question: How much plastic is out there? There was no data from the Southern Hemisphere, Western Pacific, or Eastern Atlantic. After six long years and a wide-reaching collaboration, we have completed the most comprehensive plastic pollution study to date. We’ve found microplastic ocean pollution, in varying concentrations, everywhere in the world.”
The first global estimate of plastic pollution of both micro- and macroplastic floating in every ocean on earth had led researchers to conclude that the smallest and most insidious particles are present throughout the world’s oceans. Previous reports, though, had only looked at one size class and thus reported much lower plastic densities in the world’s oceans.
The 5 Gyres Institute’s pelagic plastics research covered 50,000 nautical miles in 24 expeditions (2007-2013) across all five sub-tropical gyres, coastal Australia, Bay of Bengal and the Mediterranean Sea. Microplastics were collected with nets. Floating macroplastics were counted by systematic observations. An oceanographic model of floating debris dispersal was calibrated by the data, and corrected for wind-driven vertical mixing. On 10 December 2014, the results of its exploration were published.
The report is, of course, shocking. But there is intriguing news as well. The is a curious loss of microplastic from the sea surface in the garbage patches of the five subtropical gyres, the large areas of rotating currents where the fragments tend to accumulate. “When comparing between four size classes, two microplastic 4.75mm, a tremendous loss of microplastics is observed from the sea surface compared to expected rates of fragmentation, suggesting there are mechanisms at play that remove
The study also found a wide distribution of the smallest microplastics in remote regions of the ocean. Plastics occur nearly everywhere, often far outside of the garbage patches. The smallest microplastics are present in remote regions like the subpolar gyres.
“Our findings show that that the garbage patches in the middle of the five subtropical gyres are not final resting places for floating plastic trash. Unfortunately, the endgame for microplastic is dangerous interaction with entire ocean ecosystems. We should begin to see the garbage patches as shredders, not stagnant repositories,” Eriksen explained.
How does this occur? While large fragments accumulate in gyres, these expanses are functioning not as repositories but as shredders and redistributors. Quantities of large plastic pieces are degraded by sunlight and oxidation, become brittle, are broken up by waves and fragmented by grazing fish. Mechanisms such as subsurface currents, foraging and filter-feeding by marine organisms, help to disperse what are now microplastics.
The new research categorised plastic into four size classes - roughly equivalent to a grain of sand, to a grain of rice, to a water bottle, and anything larger. The researchers expected to find more small particles than larger ones.
Martin Thiel, a co-author of the report noted, “One would expect an exponential increase in the number of plastic particles due to fragmentation. But this was not the case. Although the two smallest sizes combined accounted for more than 90% of the total count, there were more than 100 times fewer of the smallest particles than expected.”
A worldwide distribution of microplastic is, in fact, a problem of great magnitude. This is because smaller particles have a greater surface for the absorption of pollutants than larger pieces. Plastics act like sponges, absorbing toxins such as PCBs, DDT and other pesticides, flame retardants, and other persistent organic pollutants found in our oceans. Some marine organisms, including seabirds and fish, ingest these toxic plastics and excrete them.
“The garbage patches could be a frightfully efficient mechanism for corrupting our food chain with toxic microplastics,” Eriksen observed.
The study was carried out to do more than merely measure. “Knowing that plastic pollution becomes hazardous waste in the ocean, it is essential that innovative products and packaging designed for recovery replace the single-use, throwaway culture of the past. It’s time to focus our mitigation strategies upstream from production to disposal. The status quo is not acceptable. Our goal is to vanquish the idea that oceans can bear our waste and to usher in an age of restoration and responsibility,” Eriksen concluded.
