Are microfibres a mega problem?

I sat down with Cordelia Roberts, recent Marine Biology and Oceanography graduate from Plymouth University, to talk about her remarkable research on plastic microfibres in the ocean. The topic of her study is very timely and she is aiming to publish her results in a high ranking journal.

What are microfibres?

“Microfibres are a fibrous division of microplastics, less than 5mm in size. Every time you put a wash on, more than 1900 microfibres per garment can released into the wastewater.”

What clothes produce the most microfibres?

“Depends on what the garment is made of. If it is made up of cotton fibres that go into the environment, it won’t be so bad, because they will degrade eventually over time. But cheap clothes are the worst culprits because they’re not made as well so the fibres come loose really easily. If possible, you should buy long lasting good quality clothes. It is quite easy to a) just buy a cheap item of clothing wear it once and chuck it and also to wear an item once and then just wash it which nine times out of ten isn’t really necessary.”

How do microfibres get into the ocean?

“When fibres come out of a washing machine, they go out of the effluent pipe and into the normal water sewage system. The issue is is that the filters on the washing machine don’t catch the fibres and the filters in the sewage treatment plants aren’t efficient enough either, so they go straight out into the ocean. Studies in Sweden are trying to create filters that would catch the fibres. Essentially its a trade off between whether it is an efficient process and how many microfibres are caught, which is why this is a hard problem to manage.”

Where are microfibres found in the ocean?

“A lot of microfibres and microplastics accumulate in sub-tidal sediments, even at just 10 or 20m offshore. There are studies that show Arenicola marina, commonly known as the lugworm, ingesting the plastic during the bioturbation of the sediment, moving it around, reworking sediments and oxidation layers. So organisms can move the microfibres around, both pushing them in deeper into the sediment, but also bringing them out of the sediment as well. There is also some suggestion of them accumulating in the sea surface layer, which is the top few millimeters of the ocean.”

Would you find microfibres floating in the sea and possibly accumulating inside larger organisms such as fish?

“This is one thing that I’ve been trying to look at because there’s not a lot of accounts of microfibres in the actual water column and which is why I did my study, because I was seeing that there were no reported values in the surface layers. I thought that if they’re not there, where are they?”

What was the thesis of your study?

“The effect of polyamide cotton fibres(a blend of) and the effect of those on the settling velocity of marine snow and the potential implications for carbon transport.”

What is Marine Snow?

“Marine snow is made up of aggregated plankton cells, fecal pellets, and biogenic material that sinks out into the deep sea and it is a source of carbon. It is important because this is the deep sea’s main source of carbon, because obviously there is no light and so there are no plants there. A lot of filter feeders will feed on this before it lands on the seafloor becoming sequestered in the ocean. It is a mechanism for locking carbon into the deep sea.”

What did you think you were going to find?

“Before I did this study, I thought that a higher concentration of microfibres would decrease the settling velocity of marine snow and that it might alter the carbon content too, to what extent, I had no idea.”

What were your main findings?

“I looked at three different concentrations of microfibres, consisting of a control, low, medium and high. The low concentration was similar to levels observed in the Western English Channel, representing a local area, close to shore. The high concentration was representative of the Atlantic Open Ocean. To summarise, I found that a high concentration of microfibres decreases the sinking velocity of marine snow, to an extent where they could even be buoyant. This high concentration also reduced the particulate organic carbon(POC) by 3-fold. As marine snow works its way down through the water column, bacteria feeds on the carbon, only leaving a small percentage of the organic carbon left by around 200 m. The slower sinking rates and decreased carbon content means that even less carbon reaches the sea floor, and whatever even makes it there, is going to take a long time to get there! The slower the marine snow, the more time bacteria have to degrade it, removing further carbon.  If it is not settling out, there is no carbon coming out with it, and that really has the potential to disrupt the efficiency of the biological carbon pump.”

So your results matched your hypothesis?

“Yep but it was to more extent than I thought, which was kind of scary.”

Why are microfibres found in different concentrations in different locations?

“In the summer, people wear less clothes, and I guess people may choose to wear cotton as its a cooler fabric to wear, and therefore people will be washing less material. In the winter, people wear and wash more clothes in winter, as they are wearing more layers, including items like polyester jumpers, a prime candidate for microfibre pollution. The western channel, in this case is a low concentration but it’s localised and is close inshore and so the effluent just goes straight out into the water. You would think the accumulation would be greatest there but actually a lot of oceanographic factors like currents would play a part in taking them away. For the open ocean I would think that the accumulation would be similar to the great ocean garbage patch, carried around by currents.”

So if the microfibres are found in marine snow, are they going all the way down to the deep sea?

“They can sink into the deep sea, if they get there and they can be ingested by organisms . Potentially, they may be picked up by deep sea currents, taken along and then be upwelled somewhere else.”

Are there any known impacts on animals and plants?

“With macrofauna, it’s the fact that they can ingest them and might block their systems as well as the leaching of chemicals into their bodies, which can then accumulate up the food chain. I think there was even a study on crabs which showed them altering their behaviour because of ingestion.”

Are there chemicals attached to microfibres?

“Microfibres from clothes can be very brightly coloured. They are also really good at  absorbing chemicals, so when they are put into the sediments, they are taking those chemicals with them. I think a lot of researchers on heavily concerned about the impact of so called POPs (persistent organic pollutants) and the impacts those might have on marine life ”

Are microfibres everywhere?

“Yes – there are new studies coming out daily, it’s the age old quote of that we know more about the surface of the moon than the oceans. People are exploring parts of the deep sea for the very first time, and are finding microplastics and microfibres, provoking further studies”

Where is further research being directed?

“The impact of microplastics on humans. We’re quite selfish as humans and so when people realise that this is an issue directly affecting them, their shocked and unfortunately only then are they likely to do something about it. Microfibres were seen in the oceans way back in the 1980s but nothing really came of those discoveries. Hopefully, the future will provide a more holistic idea of where the plastics are and mapping that. More research should be done on impacts as wells as applications and how people can stop the plastics from getting into the oceans, through filters etc.”

Cordelia’s Top Tips to reduce plastic usage!

1. I always carry around a metal water bottle – most cafe’s will be happy to refill your bottle with tap water!
2. I carry a ceramic mug for coffee and if I haven’t got it with me, I’ll make sure to ask for my takeaway drink without a plastic lid.
3. I receive Veg Boxes from Riverfords – every Friday I receive seasonal organic locally sourced veg that is packaged using no plastic. The food is extra fresh and helps with a clean conscience.
4. I request for my pizza without the plastic table.
5. NO STRAWS (period).  
6. I always carry reusable plastic bags and if I’m caught out, I never give in to buying a bag and will only buy what I can carry.
7. Girls, get yourself a mooncup!  It’s the best decision I’ve ever made, I’m no longer wasting money every month on sanitary products and no longer inputting into the second most common type of marine pollution!

If you’ve enjoyed reading this interview, then why not follow Cordelia on twitter @polarplasticcod, she’ll happily answer any questions!