Dr Adam Hartland is planning to establish what the environmental impact of the heavy metal cadmium is on New Zealand’s agricultural and aquatic systems.
The Waikato Regional Council estimates that around 8.3 tonnes of cadmium is currently applied to Waikato soils each year, with the largest single source being superphosphate fertiliser. Cadmium is a naturally occurring, toxic, non-essential and biologically cumulative heavy metal. Dr Hartland has been award a Ministry of Business Innovation and Enterprise Smart Ideas grant to get a better grasp of its impact on the country.
If cadmium builds up to high enough levels in soils, land has to be classified as contaminated and can’t be used for growing food. Dr Hartland says there is currently evidence to suggest cadmium accumulation is slowing or plateauing in certain areas. “If we’re still applying fertilizer loaded with cadmium, if it is not accumulating in the soil, it is going somewhere else. So we’re looking at how much of a problem it is, monitoring [cadmium] levels in groundwater and lakes, but also doing controlled experiments to see if it can leach out of the soils depending on what land practices you use - like whether you irrigate, or spread effluent on your land.”
The research will use isotope ratio analysis, which gives more certainty about whether the cadmium is from fertilisers or is natural. Dr Hartland says the research can help inform the debate about cadmium’s environmental impact. “We’ll be able to advise regulators about whether it is a problem or not. MPI runs a Cadmium Working Group, so we can directly inform policy through that mechanism. We’re also looking at the Te Aroha Lakes to see whether cadmium is making it that far, and whether it’s accumulating in fish, which is of value to the local community and iwi.”
The two year project will include experiments on soil samples from three different parts of the country, and a range of ground and fresh water monitoring. It will also look at the accumulation of organisms in lakes, by sampling different aquatic organisms like fish and eels.
