Plastic pollution is becoming more common, and now scientists have just made the most detailed estimate ever of the amount of plastic in the global ocean.
Marcus Eriksen of Five Gyres Institute, an organization aimed at reducing the amount of plastic in Earth's ocean, led the study. The team determined there is currently around 5.25 trillion pieces of plastic in oceans, weighing a total of 250,000 tons, floating on the water's surface.
Researchers investigated data collected from 24 expeditions carried out across sub-tropic regions, from 2007 to 2013. The team utilized the information in a computer model of the global ocean, which accounted for mixing driven by wind.
Previously, environmentalists were able to detect plastic pollution at several spots around the world, in various concentrations. The amount of plastic present in Earth's oceans, however, remained a question unanswered until now.
Larger pieces of plastic were found to be more common near coastlines, while smaller samples migrated to more remote regions of the world's oceans. Much of the plastic collects in gyres, areas where water circulates like a gentle whirlpool. The floating garbage is driven to those areas due to the actions of water and wind currents. Because smaller samples are found in these regions than in coastal regions, it is possible gyres act like shredders, tearing the garbage into tiny pieces, which are then spread throughout the ocean.
"Our findings show that the garbage patches in the middle of the five subtropical gyres are not the final resting places for the world's floating plastic trash. The endgame for micro-plastic is interactions with entire ocean ecosystems," Marcus Eriksen, director of research for Five Gyres Institute, said.
Most plastic pollution occurs in the northern hemisphere, yet the study found concentrations of the materials were just as high in the south of the equator. This suggests that pollution may move between gyres more easily than once believed. Another possibility is that microplastics - those less than 0.19 inches across - may sink into the water more quickly in the north than the south.
Plastics in oceans can break down not just from the action of water in gyres, but are also broken down by ultraviolet light, and some of the pollutants are consumed by animals. This can cause additional problems with wildlife around the globe.
"We figured if we are going to try to solve the problem, we first must know how big the problem is. Well, we've done that," Five Gyres officials stated.
Development of the new estimate of quantities of plastic polluting oceans around the world was detailed in the online journal PLOS One.
