Can oceans be cleared of plastic?

Scientists are investigating ways of dealing with the millions of tonnes of floating plastic rubbish that is accumulating in our oceans.

They are a quirk of ocean currents – a naturally created vortex known as a gyre – where floating rubbish tends to accumulate.

The largest is in the North Pacific and covers an area twice the size of France. Others have since been discovered in the North Atlantic and most recently the South Atlantic.

Scientists now fear the same process is probably taking place in the South Pacific and Indian Ocean.

As well as damaging coasts and killing marine life who mistake the plastic for food, contaminants in the water, which attach to the plastic debris, are transporting waste chemicals across the world’s oceans.

‘Plastic munching’

At the UK’s University of Sheffield, scientists are investigating how they could accelerate the speed at which the plastic breaks down by looking at micro-organisms already found in the sea that naturally feed on plastic.\Promising results have already been seen in finding out which microbes are attaching themselves to plastic in coastal waters around the UK.

The next stage will be to analyse how these enzymes work in the natural environment and how they might work in controlled environments where plastic would be the prominent carbon source.

But the researchers emphasise that even if they can narrow down the microbes and encourage their proliferation in an area like the plastic waste patch just found in the South Atlantic, this would be a very slow process.

“It’s a bit like imagining how long it would take us to eat something the size of Canary Wharf,” says the university’s Dr Mark Osborn.

“If you have hundreds of thousands or millions of organisms colonising one piece of plastic then you can imagine the potential for scale up in terms of the rates of potential degradation.”

Biological intervention to restore the ocean environment, otherwise known as bioremediation, is a relatively new field and would require careful assessment of any potential consequences.

And most current work is based on stopping plastic getting into the oceans in the first place.

‘Diesel’ plasticRecycling and prevention

The challenge is to prevent it reaching landfill in the first place.

Our plastic lifestyle is at the heart of the problem according to Richard Thompson, professor of marine biology at the University of Plymouth.

Varying colours of plastic and different components such as sports caps which are made of different plastic types, make them harder to recycle compared to clear and strong plastic.

Despite campaigns to improve recycling, many plastics – such as food packaging packaging – are still not recyclable.