Microplastics a new threat to quality of major waterways Reply

By Alexander Salenko


Research into use of microplastics suggests important waterways like Sydney Harbour are again under threat of pollution. Photograph by Peter Dowley used under Creative Commons licence

Every time you wash your face or your fleece jacket, you may be releasing small plastic pieces into the water cycle. The contamination in Sydney Harbour is extraordinarily high. Vivian Sim, a young scientist at the University of NSW, presented the results of her research into our use of microplastics at a public event at the Mosman Art Gallery recently.

When you stand in front of a toiletries shelf in a supermarket, you see many different bottles, jars, cans and tubes. The contents are of various colours and consistencies. In some, there are air bubbles and in others, small colourful beads. These beads can be found in shampoo, body soap, toothpaste and in almost all face scrubs. They serve as abrasives for cleansing purposes and in many cases they are made of polyethylene, a material usually used to make bottles, bags or clothes. Every time you clean your face or wash your teeth with these products, microplastic beans get into the water cycle.

Vivian Sim has been working on the dispersion of microplastics in the harbour for three years. She has discovered that in certain hotspots, 100 milligrams of sediment can contain up to 100 particles of microplastics. This amount is much higher than in other comparable harbours. Ms Sim’s report, which was released for the first time last August by the Sydney Institute of Marine Science, has caused a great stir. Rob Stokes, the NSW Minister for the Environment, has promised to support a national ban on the production of microplastics by 2016.

But toiletries are not the only source of microplastics. Ms Sim says plastic particles in the form of threads are common. They may come from plastic ropes used by mariners, or from clothing. The clothing industry is suspected as a big source of microplastic particles. Each year Australians spend about $10 billion on synthetic clothing and shoes. A single fleece jacket can release nearly 2000 plastic fibres directly into the sewage system every time it is washed.

According to Ms Sim, the size of the smallest particle is about 0.36 mm. The majority of wastewater processing plants are not able to do anything about it. Tertiary wastewater plants in Sydney can actually filter particles up to 0.001 millimeter, but these plants treat less than 10 per cent of Sydney’s wastewater. The contaminants from the remaining water pass almost unhindered into the ocean.

Vivian Sim emphasises that the research on microplastics is a new field. Further investigations on the concentration, sources and impacts of microplastics in Sydney Harbour would probably take another four years. It is generally agreed that pollution caused by microplastics jeopardises the wildlife, but the exact ecological effects are still uncertain, she says. Some cosmetics manufacturers such as Unilever and Beiersdorf have already stopped the production of products containing plastic beads, and others will follow in the next few years.


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