New research has shed more light about where microplastics are accumulating in South Australian waterways — and where the plastic pollution is coming from.
Key points:
- Fibres from synthetic clothing and particles from tyres are among the main sources of plastic in SA waterways
- Researchers used ocean current modelling to predict where plastic particles would congregate
- One says washing machine filters can help cut down the amount of plastic entering the environment
Researchers have found many of the plastics are entering rivers, creeks and the ocean through fibres from synthetic clothing and particles from tyres.
Scientists from Flinders University and the South Australian Research and Development Institute (SARDI) used ocean current modelling to predict where plastic particles are ending up in an effort to better understand the issue.
“We have found a potential accumulation zone off of Myponga … probably about 12 to 15 kilometres offshore where plastics have been accumulating from our modelling predictions from outlets from the Onkaparinga and Torrens River,” Flinders University student Kyle Mitchell said.
The researchers used oceanography to predict currents and place virtual particles into the modelling system to track movement.
They also took physical water samples from the Torrens and Onkaparinga rivers, and in Gulf St Vincent to determine particle numbers.
“We would put 100 points into the model and then the currents will move those 100 points, a day later, we put another 100 points and then eventually you build up this pattern, and we follow those points for 12 months,” SARDI oceanographer, Charles James said.
Flinders University PhD candidate, Elise Tuuri said the research would help inform solutions.
“This information that we’re finding is really beneficial because we have the understanding to know how to implement change from our results,” Ms Tuuri said.
“It’s not so much about cleaning up what’s already out there.
“Stopping what’s entering our ecosystem — that’s a much more achievable task.”
Plastics from tyres and clothing
Some of the microplastics the researchers found were from tyre particles washing into stormwater, while others were from general waste breaking down in the environment.
But the scientists said the vast majority came from synthetic clothing fibres.
“They, on average, made up about 72 per cent of what we were finding,” Ms Tuuri said.
“An easy way to mitigate against that is to use washing machine filters, because then when we’re washing our clothes, that’s not coming out in our wastewater.
“We know how much microplastic is sort of entering our freshwater streams from land use, which means that we can really start targeting policy or efforts to stop that release into our freshwater systems.”
Ms Tuuri said prevention was better than clean-up efforts because, in the process of removing microplastics from water, vital biomass such as zooplankton and phytoplankton were also removed from the ecosystem.
“It’s really about implementing policies that improve what we’re releasing into the environment, and just increasing consumer awareness,” she said.
“But also [important is] having a partnership between industry and researchers so that we can figure out the best solutions going forward.”
A global issue with widespread consequences
Ms Tuuri said scientists were still trying to work out the full extent of the impact of microplastics on the ecosystem.
“They’re finding quite severe consequences — so [they] impact the growth of fish and other marine organisms as well,” she said.
“In terms of human health, we’re still really trying to understand that, we just don’t quite have knowledge of how many microplastics we can consume before it becomes a human health risk to us.”
Mr Mitchell said there was unlikely to be a quick fix.
“Microplastics production is predicted to ramp up in the years ahead, and we’re going to be seeing greater concentrations of plastics in the environment,” he said.
Research to inform policy
The study has now been provided to the government.
“We really want to hear about it and then work together on what we can do to make things better,” SA Environment Minister, Susan Close said.
Ms Close said the state government was working on ways to reduce the amount of plastic in circulation.
“You won’t be able to in a couple of years time get a coffee cup that isn’t biodegradable, you can’t currently get a bowl or a plate that’s easy to throw away, it has to be more durable,” she said.
“We’re getting rid of that single use plastics idea, which will reduce the load on the environment.”
She said she was confident that researchers and policy makers would find a way to solve the issue of plastic pollution.
“The problems are really big, but we keep finding solutions to them … our kids need this earth to be much cleaner and much more sustainable than it is right now, and it’s going to take all of us.”