Plastics will pollute oceans for hundreds of years

Even if we stopped putting plastic into our oceans today, giant garbage patches would continue to grow for hundreds of years. Regardless of where plastic waste enters our oceans, it can end up in any of the five ocean basins.

These are just two of the sobering discoveries that came from research by the Australian Research Council Centre of Excellence for Climate System Science that looked at how these giant ocean garbage patches - some of which are the size of NSW - form as a result of ocean currents.

“There are five known garbage patches in the subtropical oceans between each of the continents,” said lead author Erik Van Sebille, a Research Fellow at the UNSW-based centre. “Each contains so much plastic that if you were to drag a net through these areas you would pull up more plastic than biomass.

“Interestingly, our research suggests a smaller sixth garbage patch may form within the Arctic Circle in the Barents Sea, although we don’t expect that to appear for another 50 years.”

Giant oceanic eddies of up to 50 km across can shift plastics between garbage patches thousands of kilometres apart in entirely different oceans, the researchers found.

“This means that garbage from any country can end up in any one of these garbage patches. This tells us that no single country is responsible. Ocean garbage is an international problem that requires an international solution,” said Dr Van Sebille.

The researchers released drifter buoys into the ocean to determine the movement of surface ocean currents as part of the Global Drifter Program. The buoys send out regular 140-character messages about their location and environmental conditions. Dr Van Sebille describes it as being like Twitter from the ocean.

The data was used to determine how garbage moves across oceans and into areas where currents and winds converge. These areas, known as gyres, are where the massive garbage patches form.

“If you sail through these areas you will not see big lumps of plastics or rubber duckies or things like that,” Dr Van Sebille said. “The sun and interaction with the ocean breaks the plastics down into very small pellets that are almost invisible to the naked eye.

“However, these plastics even at this small size do affect ecosystems - fish and albatross swallow these plastics while phytoplankton can use the floating pellets to stay buoyant and float near the surface where they grow best. Plastic is also the canary in the coal mine: poisonous chemicals, that are much more hazardous to the ecology, ride the currents in the same way and are actually absorbed by the plastic pellets.”

The next stage of research will examine what happens to plastics closer to the coast.