Exploring plant materials to soak up pollutants

A student-led science inquiry, supported and guided by a parent, explored how natural wetland fibres such as oioi and raupō can absorb oil pollution in an urban stream. After investigating how stormwater carries contaminants into their local waterway, the students designed experiments to test and compare different plant materials.

The project blends environmental monitoring, problem solving and mātauranga-informed thinking, while growing students’ sense of responsibility for protecting the ecosystems and living creatures in their stream.

Questions for discussion

• How did connecting the project with a local stream change the way the students thought about pollution and responsibility?

• In what ways did the investigation combine scientific testing with mātauranga from lived experience and traditional uses of plants?

• Why was it important that the students designed and refined their own methods, even though it involved trial and error?

Transcript

Amelia

Our science fair project was about getting oil out of our waterways and using natural fibres.

Keala

It was about soaking up oil to save our stream.

Luka

The name of it was Nature to the rescue! Wetland fibres versus oil. So we were trying to help all of the animals that were in the stream so then they can stay healthy.

Sam

We called ourselves the Wairākei Warriors because we’re experimenting on specifically the Wairākei Stream.

Elva Conroy

It’s an urban stream, so I know there’s a lot of pressures in terms of discharges into the stream and I know that the kids had carried out some SHMAK monitoring and the eel monitoring last year. I wanted them to shape the project themselves because I wanted them to do something that was of interest to them. So I had provided them with some suggestions, we’d done a bit of a brainstorming session, and that natural curiosity kicked in.

We carried out a visit of the site as well. So we started at the school, had a look at the stormwater gutters and looked at where the drains were. We walked to the stream and saw all of the stormwater drains from the road. And I think for them asking questions. So what happens to all that water that lands on our roof? Where does that go? And where does that water go from the road? And so as we went to the stream and we saw the outlet pipes, it started to solidify for them there’s heaps of these drains heading into the streams. They knew that they wanted to do something around water quality or pollution.

Amelia

The wetlands are home to many different creatures and so how would you feel if someone chucked rubbish or oil into your house?

Sam

I was worried about the fish – the ika – in the stream, and if there was an oil spill, what would we do?

Keala

People are polluting from like cars and stormwater drains.

Elva Conroy

I wanted the kids to realise that carrying out observational monitoring – there are some ways in which they could see and monitor the state of the environment without physical tools. We used our eyes. We looked at the flow of the stream, you know, was it running fast or slow? We looked at what was in the stream. Was it clear or murky? They recorded at multiple sites. What kind of animals could they hear? What kind of plants could they see? And so part of it was actually, even like getting them to realise there’s a lot they can do themselves, you know, as they notice the world around them.

Luka

Before I did this, I thought the environment was just a thing that we lived in. But then once I’ve got into it, we realised that we actually really damage the environment and that we need to look after it.

Elva Conroy

When we were on site and we saw oil in the stream, we’re like, oh, so how, how would people normally soak up oil? The only thing I knew was booms when there were big oil spills. And so we’re trying to think, well, what else could you use?

Sam

So it kind of just like built up. First, we first we were like, we were going to use firefighters’ sponges, but we couldn’t get them, so we had the idea of using natural fibres.

Elva Conroy

And then as we started to look into what other natural materials do people use around the world, they’d find things like, oh, other places have used hair.

Luka

We figured it would be better for the stream if we used fibres that are already in the stream itself.

Elva Conroy

I was sharing with my colleagues, and they would say things like my grandmother used to use raupō to stuff her mattresses. So it’s getting them to realise that those traditional uses were there for a reason, there was like this practical application as to why raupō stalks were used, and then thinking what are some learnings from that traditional knowledge that could guide the way in which we’re doing our project?

Sam

So we would use oioi, raupō stalk and raupō seeds.

Luka

We decided to use oioi because it was a natural plant that grows half in the water and half on the land. So we figured it’s already had experience with the water itself.

Amelia

Raupō seeds are very fluffy, and normally things that have a lot of fluff will soak more than others. And the raupō stalk looked like it had like little holes in it and was kind of sponge-like.

Luka

We wanted to find out if they’d soak up oil.

Elva Conroy

We had a session to kind of test a few ideas of how you can do it. A lot of checking YouTube videos just to work out the different ways in which you could measure how effective was it. What made it a bit tricky though, we had three fibres and they are all in different forms. And so we tried as well as we could to standardise things. But you know, we had a, I guess, we had a tutu is probably the bottom line there. We had a bit of a tutu.

Keala

We put oil and water and we tested the materials and popped it in and see how much it weighed.

Luka

If you mix rice bran oil with cocoa powder, it makes the oil visible in water. So we put our little test substances in a bag and dipped it in to see how much water had gone down and how much oil we could see that was gone and how heavy the actual things that we dipped in were at the end.

Sam

We were measuring the weight difference and the water level difference.

Luka

Our results were that the oioi, with its little leaves that curve upwards, soaked up a little bit of the oil. The raupō stalk was half-half, like it did OK.

Sam

I thought the raupō stalk was actually going to soak up the least but turns out it didn’t. Because it doesn’t look like it’ll soak up. It doesn’t have like, it looks like it’s waterproof and stuff.

Amelia

The raupō seeds soaked up the most. They would be best for soaking up oil.

Luka

Which was a surprise because it’s just this seedy, fluffy things that actually soaked up the most oil.

Acknowledgements

Elva Conroy
Amelia, Keala, Sam and Luka, Pāpāmoa Primary School
Footage of stream being observed by students, Elva Conroy
SHMAK testing; Wairākei stream; stormwater drains and culverts; research worksheet with observation tasks, plant ID chart, raupō and harakeke; oil booms; students working at stream and testing fibres; raupō in seed; student project book with raupō research and experiment design; whiteboard with brainstorming; and aerial footage of Pāpāmoa Primary School, Pāpāmoa Primary School
Hair booms (human and animal hair and fleece), Matter of Trust, San Francisco
Historical still of whānau group in front of a raupō whare by James Hutchings Kinnear (1877–1946). Auckland Libraries Heritage Collections 898-0122