Microscopic Rubbish Threatening Our Seas

EADT.co.uk: Microscopic Rubbish Threatening Our SeasThomas Maes and Peter Kershaw are analysing data on the prevalence of marine litter in the oceans – particularly the build up of what has become known as micro-plastics.

These are tiny particles of plastic – invisible to the human eye – now to be found in huge volumes in the North Sea and elsewhere and, after being ingested by fish, are entering the human body with so far unknown consequences.

Maes and Kershaw work at the laboratories run by the Centre for Environment, Fisheries and Aquaculture Science (Cefas), a Government agency which occupies Lowestoft’s former Grand Hotel, an imposing sea-front building which was in its commercial heyday in the late 19th and early 20th centuries.

Cefas scientists design and implement ecosystem monitoring programmes, carry out formal environmental assessments and report their results directly to the Department of Environment (Defra) to help meet a range of global and European policy needs.

The agency has pioneered the use of “real time” instruments left at sea – attached to buoys.

Thomas Maes, 30, is one of the world’s leading experts in marine litter and I met him in a ground floor room at the Cefas laboratories.

He told me that the agency has been collecting marine litter data since 1992, on the back of fisheries research cruises, and he has been analysing the figures to assess the size of the problem.

The work has been expanded recently with trawls by a “manta” device which skims off particles floating on the surface of the sea.

“The initial results suggest widespread distribution of marine litter in the North Sea, dominated by plastics,” Thomas said.

“The data shows detailed distribution and accumulation patterns in north European waters. There is considerable variation in geographical abundance. Plastic, mainly bags and bottles, accounted for a very high percentage, more than 70%.”

“Remarkably, the available trend data seems to indicate that quantities of marine litter remain relatively stable over the past two decades,” he added.

Thomas is also developing methods of collecting marine litter data in the future so that the information collected throughout the world, can be reliable and the basis for effective action.

The much maligned plastic bag is, as the scientist’s study suggests, the source of much marine pollution, either being wind-blown into the oceans or discharged in pieces via the sewage outlet.

Life-cycle analysis shows that plastic single-use shopping bags can have a lower environmental impact than paper ones, in terms of energy and resource use.

But while a paper bag will disintegrate rapidly in seawater, the plastic bag will remain intact for much longer and will pose a threat to sea life.

There are many reported examples of turtles, seals and whales dying as a result of ingesting plastic bags, perhaps mistaking them for jelly fish or another food.

Bio-degradable plastics, whose use is growing, can appear to be “greener” — but the claims can be misleading.

In many cases, the plastic will not truly degrade (i.e. reduce to carbon dioxide, methane and water) unless it is subject to the temperature and chemical conditions found in an industrial composting plant.

Some ‘degradable’ plastic bags are designed to disintegrate into smaller pieces, which will be just as persistent. Bio-plastic produced from crops, once polymerised, can have the same durable properties as material made from petrochemicals.

And promoting so-called ‘biodegradable’ plastics may cause people to show even less willingness to improve waste management. Clear labelling and applying proper testing standards are critical.

According to Maes and Kershaw, much discarded plastic ends up on the seabed but there are increasing reports of mid-ocean “garbage patches” and “floating islands” of plastic debris, some as big as Texas or twice the size of France.

Most of this debris consists of micro-plastics distributed through the upper few metres of the ocean, concentrated in regions known as convergence zones.

About 70 per cent of the surface of our planet is ocean. We depend on it to regulate the climate, as a source of food, for transport, and as a place to enjoy, especially along the coast.

We have also tended to regard it as a convenient place to dispose of our unwanted waste.

The scientists say that the type of waste we produce, and the way in which we dispose of it, reflect a combination of technological advances, the increasing demands of a growing population, economic growth and attitudes towards stewardship of the environment.

The acute impacts of such marine pollution such as discarded fishing lines caught in the mouths of fish and birds - are relatively easy to demonstrate, but longer-term or more chronic effects - such as those caused by micro-plastic particles and the contaminants they may carry - can be very difficult to identify and quantify.

Plastics began being produced at an increasingly industrial scale midway through the 20th century, and scientists began reporting the spread of plastic debris in the oceans from the early 1970s.

Many plastics are buoyant and very durable, and their debris is commonly seen on coastlines worldwide.

Several assessments by the United Nations Environment Programme - and many local and international beach ‘cleanup’ campaigns - have helped raise awareness of the problem and reduced local impacts, for a time.

It is generally assumed that the problem is increasing, but there is a lack of reliable estimates of the material’s sources, quantities, distribution, fate and effects.

Some of the most comprehensive studies have indicated no change in the quantities of debris in the ocean surface, but scientists are largely ignorant of the eventual fate of what enters the ocean every year.

Micro-plastics - defined as any plastic particle less than 5mm in diameter, which can readily be ingested by an organism - mostly arise from the breakdown of larger fragments.

Others consist of plastic resin pellets — used as a raw material in the plastics industry, and sometimes referred to as ‘Mermaid’s Tears’ when found on the beach.

The particles reach the ocean through poor waste management and accidental losses in transport. Industry moves to reduce these have been partially successful, but the pellets already released will persist for many years to come.

A third, more recent, source arises from the use of micro plastic particles in such products as toothpaste and hand cleaners, which are not retained by wastewater treatment so end up in the ocean.

Particles may damage or block an animal’s digestive tract or other organs, depending on its lifestyle and the quantities involved.

Even more worryingly, plastics can absorb persistent organic pollutants and, possibly, enter the human food chain. The impact of this is surrounded by uncertainty which is why the accumulation of accurate data is so important.

Maes and Kershaw say developed countries generally have the technical know-how to manage waste effectively, but there is often a lack of coordination or willingness in local government and industry to bring this about.

The performance is very patchy, with several European countries recycling or re-using more than 80 per cent of waste plastic while in others the figure is less than 25 per cent.

In developing countries, infrastructure is often lacking and managing plastic waste has to compete with other demands for limited resources.

Maes and Kershaw say that plastic pollution may gradually become less of a problem if waste is considered a valuable resource — for recycling, reuse or energy generation — and if people accept more personal responsibility for the waste they generate. This would require political commitment and investment — and an integrated approach from politicians, the plastics industry, major users of plastics, retailers, user groups and the general public.