Adelaide rivers dump microplastics in sea

Fast-fashion victims shed microplastic particles with every step and it could help explain why Adelaide's rivers and creeks are loaded with them.

Flinders University researchers have just completed the first baseline study on microplastic loads in metropolitan Adelaide's freshwater streams.

Unfortunately, they found plenty and the vast majority - 72 per cent - were textile fibres.

PhD student Elise Tuuri is an author of the study and says fast fashion could have a lot to do with that.

She says fast fashion - cheap clothes made from synthetic, non-biodegradable plastic materials such as polyester and spandex - is a major source of micro plastics.

The pollution particles can enter waterways in a range of ways, such as through treated wastewater that has been used to wash clothes, but also in dust carried on the wind.

"If you look at dust, it generally has a lot of textile fibres in it because we are constantly releasing these fibres from our clothes," she says.

"Whenever you go for a walk you're going to shed fibres."

Other synthetic textiles, such as rope and braided fishing line, could be contributing to the problem.

The study found microplastics at eight sites, spanning seven catchments, including the Torrens, Onkaparinga, Field and Sturt rivers - water that ultimately winds up in the Gulf of St Vincent, where it can enter the marine food chain.

Flinders University Professor Sophie Leterme, who also worked on the study, says up to 80 per cent of all marine plastic pollution comes from land-based sources.

It can enter freshwater and marine ecosystems in numerous ways, including via stormwater runoff, discharge from wastewater treatment plants and by being transported in the atmosphere.

Yet, the study notes, waste management facilities are located within 1km of the Pedler, Onkaparinga, Christie, Brownhill and Magazine waterways.

"This study provides a baseline understanding of the microplastic load entering the Gulf St Vincent, and hopefully this will be a beneficial step in the process to understand the impacts microplastics are having in the marine waters of our state," Ms Tuuri says.

The second most commonly detected type of microplastic was fragments (17 per cent), small particles that have broken away from degraded plastic objects.

The third most common was cosmetic beads (8 per cent).