That's why for the next three years Dr Valois will be studying rubbish collected from the Kaiwharawhara catchment in Wellington, every plastic bag, bottle, container, tag and fragment, to study the role of rivers in carrying plastics to the ocean.
"Our hypothesis is that it's in the rivers that the plastics are being broken up into tiny pieces, creating microplastics that are the really dangerous particles harming marine life," she said.
The source of the Kaiwharawhara Stream is near wildlife reserve Zealandia, in Karori. It is a pristine, restored site, but the stream then weaves its way through suburban Wellington, filling with rubbish and contaminants by the time it reaches the harbour.
"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," she said.
"In many ways Wellington is an ideal location for this research because of its windy conditions and steep gullies, which provide plenty of opportunities for plastic to accumulate in waterways."
People were often mystified about how much rubbish ended up on beaches, but it only took a sudden gust of wind for something to blow out of a recycling bin on the side of the road to start the process.
"You don't even know you're responsible for it, and suddenly it's in a gully; the rain pushes it into a river and it ends up on a beach. Because it moves so fast, it's hard to link with individual behaviours. It's seen as someone else's problem because you don't see it or see what you've done," she added.
Dr Valois will also be sorting the plastic to figure out the major sources and types in the hope of coming up with ways of intervening before it reaches waterways.
"There is a plastic bag ban and a microbead ban, but there's no science on why we should ban these over other types of plastics. That's why we need some basic monitoring data, and to try some intervention methods to see what works."
She would be working with community groups and iwi in the first study of its kind, that would also assess the impacts of plastics on Māori cultural values.
"I would love the Kaiwharawhara catchment to become a model catchment for studying plastics from a community perspective, where everyone comes together and makes a plan to reduce it. This is a difficult task at a national level, but working in catchments can effect real change," she said.
And while sifting through plastic rubbish was not going to be glamorous work, she intended to set up a Twitter feed to showcase the amount collected and more unusual finds.
