The Groundwater team works on a variety of science projects, mainly focused on characterising the bio-physical properties of New Zealand groundwater systems and studying how contaminants of concern move in the subsurface. The work provides science-based knowledge that can be incorporated into models applied for freshwater resource management decision-making and inform policies on protection of the environment and public health.
“Much of our groundwater research is targeted directly at answering a question or providing some scientific solution to a groundwater pollution issue, such as nitrate contamination from intensified farming or microbial contamination from land-based effluent disposal practices,” Lee says.
“We work closely with regional councils and public health authorities on matters that are of concern to them, and our scientific investigations might vary in physical scale from small in vitro tests performed in the lab, to a full-blown field-scale investigation of a particular groundwater system.”
Nitrate pollution is a topic where much of Lee’s research is focused. He currently leads several field projects that are testing whether woodchip denitrifying bioreactors are a feasible nitrate-mitigation option for the agricultural sector and water management in the Canterbury region.
“To address to the problem of farming within freshwater quality limits, we are exploring ways to enhance natural attenuation of nitrate in groundwater. Our work is targeted at reducing nitrate in gravel aquifer systems, since gravel aquifers contain much of New Zealand’s usable groundwater and are particularly vulnerable to nitrogen contamination.”
A goal of the Groundwater Nitrate Mitigations project Lee is working on is to tailor denitrification wall technology to gravel aquifer settings.
“This project is exciting because it represents the first time a woodchip denitrification wall has been trialled in a gravel aquifer setting. It presents a number of engineering and science challenges, and the science is diverse, for it encompasses the topics of hydrogeology, chemistry, microbiology and social science. Hydro-geophysical methods that have not previously been applied in New Zealand are being used in the Groundwater Nitrate Mitigations project, to both inform design and evaluate the hydraulic performance of the denitrification wall. The project also provides an opportunity to examine how the change in chemical state of the shallow groundwater system impacts on the groundwater ecology, including stygofauna that inhabit New Zealand’s gravel aquifers.”