New study aims to understand how our waterways generate greenhouse gases

This is the focus of a unique Southern Cross University research project to be conducted over the next three years where the outcomes will provide new information for effectively monitoring Australia’s freshwater resources, which are under increasing threat from both pollution and climate change.

Freshwater streams are disproportionately large producers of greenhouse gases and the study will identify how changing rainfall patterns and human pollution contribute to that equation.

“Global estimates of greenhouse gas emissions from rivers and streams are poorly constrained because they don’t include 50% of the streams that run dry for part of the year, including many in Australia,” said Professor Bradley Eyre, Director of the University’s Centre for Coastal Biogeochemistry and Project Lead Chief Investigator.

“We have a new laser-based instrument* that will let us measure the isotopes on one of our target greenhouse gasses, nitrous oxide. This will enable us to figure out whether this gas is produced the same way in all the streams over time.”

The project is jointly funded by the Australian Research Council Linkage program LP190100271 ($359,260) and the local environmental engineering company GeoLINK ($120,000) and will focus on coastal waterways between Ballina and Coffs Harbour on the NSW North Coast. The project also involves two PhD candidates who will be based at Southern Cross University.

According to Dr Naomi Wells, Co Project Investigator, councils spend millions of dollars every year measuring a suite of water quality parameters, but can struggle to connect parameters to environmental health while being forced to overlook the 70% of Australian waterways that seasonally run dry.

“Even in this relatively wet part of Australia we know our streams actually run dry for at least a few months every year. These periods of ‘drying’ and then ‘rewetting’ will dramatically alter the biology and chemistry in the stream. This study is designed to ‘capture’ what happens in these intervals when streams don’t look like streams,” said Dr Wells.

The devastating 2019/2020 summer bushfires will also come under the microscope to determine the effect of fire charcoal on water quality.

“We’re going to be using continuous field loggers to measure how each of the stream sites ‘breath’ - consuming and producing oxygen and carbon dioxide,” said Dr Judith Rosentreter, Co Project Investigator.

It’s hoped the project’s findings will improve waterways management as decreased rain and increasing temperatures drive demand for vanishing freshwater resources.

*The laser based instrument is funded by an Australian Research Council Linkage Infrastructure Equipment and Facilities program LE200100156 ($896,000).