Garbage
in, garbage out
A
big test for an innovative approach to remove plastic trash from the
ocean
Alun Anderson
Mon Nov 02 2015
SCIENCE AND
TECHNOLOGY
Engineers and
scientists will take on one of the world’s ugliest problems in 2016
as they test an ambitious method of cleaning the ocean of its tens of
thousands of tonnes of floating plastic rubbish. The project is
thoroughly unconventional. It was started by Boyan Slat, a teenage
Dutch student, funded via Indiegogo, a crowdsourcing site, rather
than by government grants—and at first criticised as impossible.
But in 2016 the
Ocean Cleanup project is on track to build a 2km-long (1.2-mile)
floating boom, claimed to be the longest structure the seas have ever
seen, off the island of Tsushima in Japan. If it can remove floating
junk cost-effectively, then planning will begin for a 100km structure
capable of tackling the ocean’s most junk-ridden spots. Those
include the notorious “great Pacific garbage patch” between
California and Hawaii.
Out at sea, you are
never out of sight of plastic waste which has been thrown from ships,
washed down sewers and rivers, or blown from dumps. Retrieving that
junk has always seemed impractical. It is spread over huge areas, and
proposed solutions (such as towing giant nets behind ships) use
enormous amounts of energy and endanger wildlife. It took a teenager
to think differently.
Boyan Slat was 16
when he encountered seas full of garbage on a diving holiday. He came
up with the idea of mooring a pair of long, floating barriers out at
sea, facing into the prevailing current in a shallow arc. As the sea
brought junk up to the barrier it would bob along the arms and
towards the centre, where it would build up until it could be hauled
out of the water in bulk. The moving water does the work of
concentrating the rubbish and living creatures pass safely under the
boom.
After his 2012 talk
at a TEDx conference went viral, Mr Slat attracted engineers,
oceanographers and donors. Tests of 40-metre-long booms provided
proof of the concept, and a 535-page technical review written by over
100 scientists, engineers and companies muted objections that the
technology could not be scaled up. The big test will come in 2016,
when Mr Slat turns 22 years old, with the 2km boom being readied for
Tsushima, an island which sees some 12,000 cubic metres of junk
washed onto its beaches each year.
The project is
already intensifying the debate over ocean garbage. Some believe that
all effort should go into preventing plastic from getting into the
oceans in the first place, not cleaning it up later. But
long-standing regulations intended to prevent the dumping of plastic
at sea have proved hard to enforce. Could effective rules really be
agreed upon speedily?
The longer action is
delayed, the more ocean plastic slips beyond the reach of even a
project as ambitious as Ocean Cleanup. Recently scientists have
discovered to their horror that floating plastic rapidly breaks up
into ever smaller bits of “microplastic”. A survey in 2014
estimated that at least 5.25 trillion pieces of plastic were
floating in the sea and around 4.8 trillion of them were between
0.33mm and 4.75mm in diameter. Even so, the amount of plastic was far
less than expected, suggesting much of it has broken into even
smaller bits that were too tiny to have been sampled. These may have
been eaten, or colonised by minuscule creatures and sunk into the
depths.
What lies beneath
Visible littering of
the ocean surface may thus be being replaced by an invisible
poisoning, for microplastics both contain chemicals harmful to life
and concentrate them from the surrounding water. Already scientists
know that plastic particles are turning up in mussels and oysters
harvested commercially. There is now a rush to find where the plastic
is going and what the risks are. Landlubbers might wish to think that
the sea is taking care of that vanishing rubbish for them, but they
may be in for an unpleasant surprise.
Alun AndersonScience
journalist and author
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