Microplastics in our fresh water?

Microplastics in water supplies have been identified by the United Nations as a threat similar to climate change – and now research is under way to see if they are present in how New Zealand's fresh water.

This major new study, to investigate the extent of water contamination by microplastics in New Zealand is being led by Institute of Environmental Science and Research (ESR) scientist Dr Olga Pantos and environmental consultant Dr Grant Northcott. More than $12.5 million in government funding has been allocated for research on the impact of microplastics and the threat they pose to New Zealand's ecosystems, animals and people.

Recent overseas studies have shown microplastic particles in drinking water and food, and the United Nations Environment Programme recently likened the issue to climate change, due to its global scale and the magnitude of potential risks it poses to ecosystems and human health.

Dr Kevin Simon, an associate professor in the School of Environment at the University of Auckland, is leading the team concentrating on fresh-water microplastic contamination as part of the ESR study. The researchers will conduct case studies of the Whau River in west Auckland, and the Waimea catchment in the Nelson region.

Looking at the two different environments will enable them to look at microplastic pollution caused by different types of land use, urban and rural.

"Obviously there is a lot of plastic in an urban environment, but there is a lot used in agriculture as well," Simon says. "Microplastics come from all different sources, and we are trying to find out what these plastics are, where they are coming from, their sizes and shapes, and their chemical properties."

The definition of microplastics varies, but this study will look at tiny pieces of 1mm or less.

"Some of these plastics were made this size, such as the microbeads which have now been removed from a lot of products, but much of the material is secondary plastics, where small bits come from larger bits that have broken down over time," says Simon.

"There are also small plastic fibres, which come from clothing such as fleece that has been originally made out of recycled plastic."

Plastics can enter waterways through rubbish disposal, or by being blown or washed there by rainfall. Combined stormwater and sewage systems can also contaminate fresh water with plastic during overflow events, which then flows on to the sea.

"We're trying to identify how much plastic is out there, where's it's coming from, and where it's ending up. We also want to find out if it's making its way into the food web in fresh water systems, so we will be doing some toxicology studies of levels of plastics within organisms."

The study also plans to use scientific modelling to look at the wider Waitemata Harbour and Hauraki Gulf, to ascertain if the majority of microplastic pollution is coming off the land or being carried here from further afield through the ocean; Simon says there are "a lot of unanswered questions".

A separate study is also currently looking into the extent of microplastics pollution in Auckland's waterways and coastlines. Funded by the Government's Waste Minimisation Fund, scientists are analysing sediment samples taken at the high-tide mark from 39 sites across Auckland to identify, quantify and characterise the microplastics found in each location.

Study leader Florian Graichen of Scion Science says the results will be used initially to increase public awareness and to educate relevant industry sectors about the problem and consequences of plastics in our waterways.

"The next stage will be coming up with a plan to remove the dominant sources of these microplastics before they enter the New Zealand environment and, ideally, introducing alternative options, such as biodegradable plastics, into manufacturing applications," he says.

But while industry is responsible for some plastic pollution, there are steps all New Zealanders can take to reduce microplastic pollution.

"The big thing is minimising the use of plastic that you don't need, because unfortunately so much of it just gets disposed of," says Simon. "We're still trying to figure out which of the lots of different types of plastics are the problem, so we can focus on minimising those."

While the scientific community has been aware of and researching plastic pollution in the environment for years, it has only recently come to the forefront of public consciousness with recent headlines involving single use plastic bags, for example.

"When people see images of the swathes of plastic in the Pacific, or news stories about dead whales being found with large amounts of plastic in their stomachs, it makes them more aware and becomes something tangible," says Simon.

"When they go to the market and get offered a plastic bag, people can identify with that and see that it is something they can have an impact on — they can do something about it. Reducing the use of plastic shopping bags is a great first step."