Meet two winners of the 2023 Prime Ministers Science Prizes. In the wake of the 2019 Whakaari eruption, Professor Ben Kennedy engaged communities with the science of volcano hazards - mahi that earns him the 2023 Science Communication Prize. Meanwhile, Future Scientist prizewinner 17-year-old Sunny Perry has developed a helpful soil map.

When Sunny Perry decided to make a map identifying locations of corrosive soil around Northland, she didn't foresee the extra benefits.

Winning the 2023 Prime Minister's Future Scientist Prize was a big one. Heaps of driving practice with her dad - which helped her pass her driving test - was another.

But there were downsides too: 5am starts, turning her bedroom into a chemistry lab, and having to let her dad pick the road trip tunes. "There were some very questionable choices sometimes," Sunny says.

Road tripping for soil samples

In total, the duo visited 20 sites across Northland: from north of Kaitaia, all the way south to Mangawhai, and across to the west coast.

At each site, Sunny took triplicate soil samples at different depths which she then brought back to her makeshift chemistry lab to test for the presence of a certain type of soil - one that has the potential to cause damage to the environment and infrastructure if disturbed.

An aggressive soil

You may not have heard the term "acid sulphate soil", but Whangārei District Council certainly has. This soil was the culprit behind corrosion of concrete pipes in the Marsden City development at Ruakākā, which cost ratepayers $5 million. Auckland Airport is aware too, since it had to add eight tonnes of lime to a stream on its property in 2016, after plants started to die around it.

These acid sulphate soils can form in waterlogged areas devoid of oxygen and rich in organic matter. They contain crystals of pyrite - iron sulphide minerals. When they lie undisturbed, they are safe and harmless.

But, if they are dug up or drained, and exposed to oxygen, the pyrite in the soil reacts with the oxygen, producing sulphuric acid. The acid lowers the pH of the soil, which can cause damage to plants, creatures, and infrastructure.

Where are these soils found?

To avoid disturbing these soils, you need to know where they are likely to be.

That's what Sunny set out to determine. Using knowledge of the conditions needed for these soils to form, mapping skills developed throughout the project, and her soil sample testing, she has created a map of Northland which shows where these acid sulphate soils might be.

Sunny hopes it can be used to make good decisions about land management across Northland. …

Go to this episode on rnz.co.nz for more details