NIWA scientist to collect and study rubbish from Wellington's Kaiwharawhara Stream

Wednesday, 16 January 2019

The Kaiwharawhara Catchment in Wellington could become the country's first to become 'plastic free', a NIWA Scientist says. 

Dr Amanda Valois will study rubbish collected from the catchment during the course of a year - every plastic bag, bottle, container and tag.

'We'll be trying to figure out where the stream is picking up all this plastic from, and what it is doing to this rubbish,' the freshwater scientist said.

In preliminary research, Valois  collected 1500 pieces of plastic from the stream in a 30-metre stretch. 

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 She wants to identify the issues, speak with the community to reduce plastic in the area, and then return to the stream in five years to evaluate the difference. 

The project was the country's first study on plastic pollution from a specific freshwater catchment, she said.  

'There's a lot of interest about the amount of plastics on beaches and in marine animals but the rubbish is coming from the land and it's carried there by rivers.

'Picking it up when it gets to beaches is a very inefficient way to stem this problem.' 

Valois will sort the plastic rubbish to find major sources and types of plastic with the aim to build ways to intervene before the rubbish reaches waterways.

Her hypothesis is that plastics are being broken into tiny pieces in rivers - creating microplastics which harm marine life. 

She hoped the study could be the first of many on pollution in catchments throughout the country. 

The source of Kaiwharawhara Stream is near wildlife reserve Zealandia. It cuts through suburban Wellington and emerges in the harbour.

Valois said the community was behind the project and would be helping to collect rubbish, starting in April. 

 Changes to reduce litter ending up in the catchment would be made at a local level, she said. 

When they returned in five years, it would be great to find no plastic at all, she said. 

'We know that's not reasonable, but we'd like to find significantly less plastic.'