A new study by Australia’s national science agency, the CSIRO, has estimated there are 14 million tonnes of microplastics on the seafloor, twice the amount of plastic pollution estimated to be on the ocean’s surface.
Justine Barrett from CSIRO’s Oceans and Atmosphere who led the world-first study, published today, said researchers collected and analysed samples in order to estimate the huge amount of seabed microplastic.
“Plastic pollution that ends up in the ocean deteriorates and breaks down, ending up as microplastics,” Ms Barrett told AAP Newsagency.
“The results show microplastics are indeed sinking to the ocean floor.”
The research is the first global estimate of how much microplastic there is on the seafloor.
AAP reports millions of tonnes of plastic enter the marine environment every year and quantities are expected to increase in coming years despite increased attention on the detrimental impacts of plastic pollution on marine ecosystems, wildlife and human health.
The samples were collected using a robotic submarine in depths to 3000 metres at sites up to 380 kilometres offshore from South Australia.
The amount of microplastics recorded was 25 times higher than estimates in previous deep-sea studies.
Based on the results of deep-sea plastic densities and scaling up to the size of the ocean, the researchers calculated a global estimate.
AAP reports Dr Denise Hardesty, Principal Research Scientist and co-author, said the results showed there was an urgent need to find solutions.
“Our research found that the deep ocean is a sink for microplastics,” Dr Hardesty said.
“We’re finding them hundreds of kilometres offshore and thousands of metres deep, more micro-plastics than has been found by lots of other studies.”
“Micro-plastics come from the same place as plastics,” Dr Hardesty said, adding “micro just means they’re smaller than 5mm”.
“It’s really just small plastic from single-use items, consumer goods, industry or fishing-related goods, cosmetics, micro-beads, agriculture, aquaculture, household waste, everything.”
AAP reports many of these tiny plastics end up in oceans via stormwater drains, sewage systems, sea-based activities, littering, things falling off the backs of trucks, and improper waste management where people intentionally dump rubbish straight into the sea or rivers.
They often end up in the stomachs of marine animals like dolphins or fish, while bigger pieces of plastic can be just as dangerous.
“Face masks that have those little straps can tangle the feet and legs of sea birds and things like that,” Dr Hardesty said.
The number of microplastic fragments on the seafloor was generally higher in areas where there was also more floating rubbish.
“We were surprised to observe high microplastic loads in such a remote location.
“This will help to inform waste management strategies and create behavioral change and opportunities to stop plastic and other rubbish entering our environment, she said.
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