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New Zealand Science Teacher

Science Education & Society

Our plastic oceans

We use plastic every day, but this addiction is creating an unholy continent of sludge in the ocean, writes MELISSA WASTNEY.

This article first appeared in last year's New Zealand Science Teacher print journal. To download an e-copy of the journal, please click on the link to the right. --->

The Great Pacific Garbage Patch, sometimes known as the Pacific trash vortex, is thought be to six times the size of France. It’s a swirling mass of discarded plastic bags and bottles; a thick soup of plastic gloop in the north east of the Pacific Ocean. It’s the world’s biggest landfill, and it is ever increasing in size.

Because it’s confined within the North Pacific gyre, which is made up of large, slowly rotating ocean currents, it rotates around an area between Hawaii and the North America mainland.

The area is an oceanic desert, filled with tiny phytoplankton but few big fish or mammals. Due to its lack of large fish, gentle breezes and lack of currents, fishermen and sailors rarely travel through the gyre.

The debris can eventually escape. As wave action and ultraviolet light break it down into smaller pieces, it becomes weighted down with microbial biofilms and sinks. Once it’s in deeper waters, it can be transported by deep currents out of the gyre and away from the patch. While the Great Pacific Garbage Patch has garnered worldwide attention via the media, it’s not the only trash vortex on Earth.

In all, there are thought to be five major oceanic gyres, complete with swirling plastic: The Indian Ocean, The North Pacific, North Atlantic, South Atlantic, and the South Pacific gyre. (Visit www.5gyres.org for a good breakdown of these.) This video, of Maximenko’s plastic pollution growth model, describes the plastic pollution spread http://vimeo.com/8350606

How bad is this problem, and what can we do about it?

While some kinds of plastic degrade over time, none of it ever completely breaks down. Some of the plastic items in the ocean end up in the bodies of marine wildlife, who mistake them for food. Turtles, for example, occasionally mistake plastic bags for their food staple of jellyfish and suffocate. Dead albatrosses have been found in Hawaii with bellies full of cigarette lighters and bottle caps. Plastic items are considered to cause more marine animals deaths than oil spills, heavy metals, or other toxic materials.

As plastic particles circulate through the sea, they become ‘sponges’ for waterborne contaminants such as PCBs, DDT, other pesticides, PAHs, and many other hydrocarbons. These toxin pollutants, known as ‘POPs’ (persistent organic pollutants), are absorbed in high concentration by plastic pollution in the marine environment. These toxins then enter the marine food chain, with potentially dire consequences for all living things.

A scientific study conducted in 2012 revealed that the Great Pacific Garbage Patch is also a breeding ground for a water parasite called Halobates sericeus. Not only has the mass of plastic increased by 100 times over in the past 40 years, but it has led to changes in the natural habitat of animals such as the marine insect Halobates sericeus. These ‘sea skaters’ or ‘water striders’ – relatives of pond water skaters – inhabit water surfaces and lay their eggs on fingernail sized pieces of plastic.

These insects may be a food source for crabs and sea-birds, but they’re also a predator in their own right, feeding on plankton and fish eggs, and they threaten to upset the fine balance of the ocean’s ecosystem.

Above: plastic beads found on a NZ coastline Image: Sustainable Coastlines NZ.

Plastic does degrade into small pieces until it’s no longer visible to the human eye. This happens very slowly in the ocean, because of the cold and dark conditions. But most plastic does not mineralise. We call the small pieces of broken-down plastic ‘microplastics’ if they are smaller than 5mm long.

The answer to this can be found in the chemical make-up of plastic. Most plastic is manufactured from petroleum, which is itself the end product of once-living organisms, but a crucial manufacturing step turns this biomaterial into something unrecognised by the organisms that normally break organic matter down.

When propylene is heated up in the presence of a catalyst, individual chemical units of the material link together by forming strong carbon-carbon bonds with each other. These polymer chains are called polypropylene. Organisms that decompose organic matter have evolved over billions of years to attack certain types of bonds that are common in nature, but have no metabolic pathways to break down carbon-carbon bonds.

While it is possible to make plastic from different bonds such as peptides, which link carbon to nitrogen, and are commonly found in nature, these alternative types of plastic have a very short shelf life, or are not as strong and stable as the carbon-carbon types of plastic.


Common types of plastic:


Acronym Full name Common example
PET (PETE) Polyethylene terephthalate soft drink bottles
PES Polyester (yes, it’s actually a plastic!) synthetic clothing
PE Polyethylene plastic bags
HDPE High-density polyethylene detergent bottles
PVC Polyvinyl chloride plumbing pipes
PP Polypropylene drinking straws


Polyamide (aka nylon)



takeaway food containers


A personal encounter with the Great Pacific Garbage patch

As someone who works to clean up Auckland harbour, Hayden Smith has seen first-hand the effects of plastic ocean pollution. Hayden’s company, Hayden’s Harbour Clean Ltd, is a contractor to the Auckland Council’s Watercare Harbour Clean Up Trust, which removes debris from local waterways.

He’s seen what happens to plastic that travels further, too. In 2009, Hayden chartered a Billabong sea plane and flew to the Great Pacific Garbage Patch from Hawaii. The trip was a personal expedition. He says the plan was to fly into the middle of the patch, then board a marine research vessel and meet the man who is said to have discovered the patch, Charles Moore (see box).

That never happened "because of the confused swells, the plane touched down on the patch but didn’t stop," says Hayden. Nevertheless, the extent of the pollution was made clear, and in retrospect, Hayden says the trip was a success because he was able to really explore the environment of the patch.

“We saw huge convergence zones, which bring any ocean debris towards the surface, stretch from horizon to horizon, and these zones were lined up one after another after another. With the plane, we were able to fly along the convergence zones with the sun behind us, which gave us an amazing outlook.”

From what he saw, Hayden estimates there were 70 pieces of plastic per square metre – "and that’s not counting all the pieces smaller than 5mm to 10mm. There were many photodegraded bits of plastic, which were breaking down into smaller and smaller pieces.

Particular pieces of plastic he remembers include a green plastic coat hanger and a yellow clamshell burger container.

“Most of the plastic had broken down and was therefore more difficult to recognise, but those two pieces were very memorable because they hadn’t broken down at all.

“From my experience working in the harbour, there are definitely some types of plastic that don’t break down as readily as other types. Sometimes if you try to pick up a plastic bottle or a bag, it just crumbles into a thousand little pieces, but they never really go away.”

Hayden says the black bases of Coke bottles that were in circulation around 25–30 years ago are still being found in the harbour in good condition, highlighting their long life. He says the main purpose of his journey to the Great Pacific Garbage Patch was to witness the extent of the pollution in the area but also to highlight the work he and his team are doing closer to home.

“We’re cleaning it up ‘at source’. If you believe cities are the place where the most pollution is happening. Obviously, you could pinpoint the oil wells where the plastic material first comes from, but basically what’s feeding the gyres is plastic littering from towns and cities.”

Starting locally

It’s not just the Pacific Garbage Patch that contains plastic litter. A year-long study of Auckland’s storm-water discharges found that each day 28,000 pieces of litter, much of it plastic, ended up in the Waitematā Harbour.

Since its inception in December 2002, the Watercare Harbour Clean Up Trust has removed more than 1.9 million litres of waste.

The trust estimates that approximately 80 to 90 per cent of the litter that its contractors remove is plastic – mainly bottles and their lids and bags. This litter creates a significant hazard for birds and marine and freshwater fish species and causes direct damage to the environment through leaching and degradation of habitats.

Polystyrene from construction sites is also a problem. This usually comes from commercial and industrial sites near waterways or from unsecured rubbish loads on trucks and other vehicles. Hayden says even the machine-dispensed parking tickets in cities have a plastic coating, and many of these can be found in the harbour.

“It’s often the little things you don’t think about. A driver might wind their window down and the ticket will be swept from the dashboard – eventually it ends up in the waterways,” he says. Whether it’s an old tyre or a lolly wrapper, everything makes its way to the sea eventually, says Hayden (you can hear Capt. Charles Moore talking about this in detail on youtube.)

As well as careless litter disposal, Hayden says animals ripping open rubbish bags and loads not being securely fastened on vehicles can all contribute to the problem. Since its formation, the Trust’s contractors have removed over 25 million pieces of litter from Auckland’s waterways (this is an estimate based on an average of eight individual pieces of litter per litre collected).

Hope on the horizon

Hayden says that since he’s been operating there has been a huge shift in peoples’ awareness. Over the past ten years, many more New Zealanders are taking cloth bags to the supermarket and reusing other products. School education programmes and initiatives like ‘litter-free lunches’, whereby children bring their unwrapped food to school, are helping to create awareness of the issue.

“We’ve also seen a huge increase in volunteers wanting to help us out. People email me every day wanting to help us in our work.”

Another group working hard to clean up the coast is Sustainable Coastlines. This non-profit organisation consists of four staff and a network of passionate volunteers who coordinate and support large-scale coastal clean-up events.

Left: New Zealand school children help with a coast clean-up project. Image: Sustainable Coastlines NZ.

The group also facilitates educational and public awareness campaigns and conducts riparian planting projects in addition to supporting communities to organise their own clean-up events.

Sustainable Coastline’s Sam Judd says his work spans all sectors of New Zealand society. “We’ve had two-year-olds helping us collect litter, and we’ve had 85-year-olds help us, too,” he laughs.

“But most of our effort is focused on schools because they’re well-organised and we can effect the most behavioural change through young people.” In addition, the organisation works with offenders through the Department of Corrections, and it’s this work that has produced a remarkable set of data about coastline pollution, that you can view on their website.

“The offenders are the ones who classify and record the data, so we can really see what’s going on out there,” says Sam. “The goal is to produce really good educational resources from the data we’ve collected. We want them to be as comprehensive and useful as possible.”

Sam points out there are positive things about plastic as a material. It’s economical, it’s light, mouldable, and strong – but it's also the main thing polluting the ocean. We need to be smarter about how we use it, he says. He highlights a metal water bottle with a hard plastic lid, which can be used thousands of times, as opposed to a clear plastic bottle that invariably ends up in landfill or the waterways.

“Single-use plastic would have to be the main problem. Most of what we find on the coastline is this kind of plastic food packaging, and it almost always can be replaced by another product. If we’re going to use something that lasts forever, let’s use it in smart ways.”

Hayden Smith says that while vast patches of ocean trash can horrify and fascinate, the focus must remain on what can be done here, in our daily lives. “It has to come back to what we do with our plastic waste here. We just really need to dispose of rubbish properly – it’s all of our responsibility to solve this problem.” 


Ideas for student/teacher/parent projects


Join a ‘coast clean-up’: http://www.sirpeterblaketrust.org/get-involved/care-for-our-coast/

Take care of a local stream: http://www.mfe.govt.nz/issues/oceans/kids/reducing-pollution.html#4

‘Adopt-a-stream’: http://www.watercare.co.nz/community/water-in-schools/adopt-a-stream/Pages/default.aspx

Think about the plastic you use and how this can be reduced as much as possible: http://www.mfe.govt.nz/issues/oceans/kids/reducing-pollution.html

Make sure only rain goes down the stormwater drain: http://www.mfe.govt.nz/issues/oceans/kids/reducing-pollution.html#3

Befriend your native fish species: http://www.gw.govt.nz/befriending-native-fish/

Get involved in the next Sea Week: http://www.doc.govt.nz/getting-involved/events-and-awards/seaweek/


Interesting further reading:


http://5gyres.org/  5 gyres is a site that give good background information on the problem.

This Greenpeace site gives a good summary of this problem. The site has a good animation of the Pacific gyre currents showing the rotating currents. http://www.greenpeace.org/international/en/campaigns/oceans/pollution/trash-vortex/

This Wikipedia site talks about the catamaran that is made completely out of recycled plastic bottles. http://en.wikipedia.org/wiki/Plastiki

Rubber ducks in the ocean: This is a fascinating story about rubber ducks, and other plastic toys, that fell off a boat into the sea near Taiwan but ended up being washed up on beaches from South America to Scotland! http://www.nzscienceteacher.co.nz/curriculum-literacy/planet-earth-and-beyond/rubber-ducks-in-the-ocean/#.UgF67vLXrxU

http://seacleaners.com/ Seacleaners are trying to remove plastic rubbish from around the Waitemata Harbour.

Sustainable Coastlines are also trying to clean up the New Zealand coast and nearby ocean.http://sustainablecoastlines.org/about/impact/

Plastics NZ tell you everything you wanted to know about plastics, including the recycling of them. http://www.plastics.org.nz/factsandresources/schoolsresources/wasteandrecyclingfacts/


Possible questions to use in the classroom:


●     When you discard plastic, where does it go?

●     Can you think of other places where you’ve seen waste plastic?

●     Does plastic ever really ‘go away’?

●     Describe how your household deals with rubbish and plastic waste.

●     What steps can we take to use less plastic in our everyday lives?


Special terms


gyre A ring-like system of ocean currents that rotate clockwise in the Northern Hemisphere and counter-clockwise in the Southern Hemisphere. Many of the biggest, most persistent gyres have become collection sites for floating long-lived trash – especially plastic.

biofilm A gooey community of different types of microbes that essentially glues itself to some solid surface. Living in a biofilm is one way microbes protect themselves from stressful agents (such as poisons) in their environment.

degrade The way some plastics break down with exposure to natural conditions, such as light, water, etc.

mineralisation This term refers to full degradation into carbon dioxide, water and inorganic molecules.


Captain Charles Moore


Charles J. Moore is an oceanographer and roving boat captain who first brought the Great Pacific Garbage Patch to international attention. He was sailing to southern California in 1997 when he first caught sight of plastic rubbish floating in the North Pacific Gyre. Since then, he has written articles about the extent of ocean pollution, and its effect on sea life.

Charles Moore is the founder of the Algalita Marine Research Foundation in Long Beach, California. This non-profit organisation works to conduct thorough research on ocean pollution, and facilitates a wide variety of education programmes.


What about recycling?


- What do the numbers on the bottom of plastic containers mean? This is a good overview: http://bit.ly/1arXJSS

- How is plastic recycled in New Zealand? Read about what happens to the different types here: http://bit.ly/17R02OR

- In some countries, waste plastics are burned to recover the energy from them as an alternative fuel source. Because plastic is derived from natural gas and petroleum refining processes, they can be a valuable fuel source in some countries.

- Is there any legislation to regulate the use of plastic packaging in NZ? There is nothing official, but in 2004, a Packaging Accord was established between industry and central government, which is in turn endorsed by local government, with the aim of reducing packaging waste. There is also a Code of Practice for Consumer Goods Packaging and an independent system for performance monitoring and handling complaints procedures.

- A voluntary industry plan is the NZ Plastics Sustainability Initiative. This has a focus on sustainability in the NZ plastic sector.

- Read about Dunedin woman Ann Dennison, who has eliminated plastic from her everyday life http://bit.ly/16Yq42D

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