Hunting for plastic with #exxpeditionroundbritain

We have four missions on Sea Dragon: raising awareness about pollution, empowering women, creating strong networks and champions for environmental advocacy – and of course collecting data about plastic in our waters.

There are several research institutes and universities for whom we are sampling, mostly in America and Europe; eXXpedition is well networked with ocean scientists trying to piece together the jigsaw of what is going on out there. And of course it is a changing and evolving situation. Many people have now heard of the Pacific Garbage Patch, but that’s really a bit of a misleading image. Yes, there are places where ocean plastic gathers. There are five gyres in the world’s oceans, areas where currents swirl in ways which allow stuff to gather – materials such as weed, plankton, timber and – of course – plastic. But when you go and look at them, there’s less big, visible chunks of plastic than you’d expect.

This discovery led to the work of trawling for smaller pieces. Plastic – a range of complex compounds – does not decompose in that it does not break down into its chemical components. On the contrary it breaks up, retaining its molecular integrity but in smaller and smaller bits. Right down to fragments smaller than plankton, mixed in with the plankton at such a scale that even under a microscope it is hard to see. Of course, the fish can’t tell the difference, which is a key way the stuff enters the food chain. That’s our human food chain, by the way. 

This non-disintegration also means that plastic bits can travel all over the world, and indeed up and down the water column, at different depths. A plastic soup is now spreading across our oceans. But we do not know much about how thick it is, where is strongest or how tides and currents affect its dispersion. Our mission is helping to fill in a few of the gaps.
So on this mission, we are looking for plastic pollutants at different scales. We record larger bits using an app called the Marine Debris Tracker which collects data from all over and which we can use to say whether it is a bottle cap, or a toothbrush or whatever. We also put out trawls which capture materials down to 1/3 of a millimetre in diameter. That’s pretty small. Those samples get bottled up and labelled and sent off to various places, along with tests of salinity, ph and turbidity (light in the water). On the metal frame over the aft hatch sits our air pollution monitor, measuring particulates along our route. Our bodies also carry pollutants and betray our exposure. We’ve all provided hair samples for testing for mercury which will be fascinating,

Not all our tests can happen every day.  The manta trawl needs the sea to be flat enough to get the spinnaker pole rigged at 90degrees for the mast and then the trawl to ride alongside the boat, skimming off the top 10cm or so of water into its trailing net. It spend half an hour out there while we poodle along at 2 knots and then we bring it all in again. In contrast the phytoplankton trawl, a little torpedo that trails off our stern is much easier to put out and retrieve, and we can travel at 6kts while it is in the water.  But that doesn’t go out in the sort of weather we’ve seen at sea since Our trawl just outside Belfast harbour.

But whenever we can, we put the trawls out. This morning, in Loch Lochy, were perfect flat conditions monitoring for plastic in the stunning waters and hills of the Great Glen. 

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About Sarah Tanburn

I'm a writer, a sailor and a strategic adviser to public organisations. Visit my websites to find out more.
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