Clever new models to help tackle nitrogen pollution around the corner

Ransome Road Reserve 


Getting technical: how the natural filter system works

Nitrogen removal occurs via two major processes: denitrification and anammox. In denitrification, bacteria break down nitrate, a form of nitrogen which occurs naturally in soil and is a major component of many fertilisers, into nitrogen gas. Anammox bacteria remove nitrogen through a different reaction which converts ammonia nitrogen from sewage and industrial wastewater into nitrogen gas and water. Coastal wetlands have high denitrification rates, making them hotspots for nitrogen removal, but so far little is known about the role of anammox in these systems.

Nitrogen = life (…but too much not a good thing)

In the right quantity, nitrogen is an essential nutrient for coastal ecosystems, supporting the growth and vitality of aquatic plants and algae, which in turn provides vital habitat and food sources for other marine life. However, too much nitrogen can be detrimental. It can cause toxic algal blooms and plant overgrowth which depletes oxygen supply in the water and can result in habitat dead zones and fish kills.

Cutting-edge new models are being built which are set to significantly increase understanding of how coastal zones naturally remove nitrogen from waterways, as it is carried downstream, before being passed out into the ocean.

The coastal zone, which includes tidal wetlands and estuaries, effectively acts as a giant natural filter system by absorbing nitrogen. However, developing best practice to optimise management of these systems has been hampered by a global lack of knowledge about their nitrogen removal capacity and pathways.

In the quest to improve understanding and management of these natural filter systems, clever researchers from Southern Cross University and the University of Western Australia are teaming up with Healthy Land and Water to build a models which will show how nitrogen is removed from water as it travels downstream through the catchment to the ocean.

The project has been made possible thanks to vital funding through the Australian Research Council’s (ARC) Linkage Projects scheme.

The smart new models will help put significant additional information at the fingertips of environmental managers, equipping them with the knowledge and tools to help maximise nitrogen removal. It will not only help inform best practice going forward but will also assist in monitoring the effectiveness of waterway management actions in the future.

Effective intervention to reduce nitrogen loads will reduce harmful downstream impacts and minimise the production of nitrous oxide, a potent greenhouse gas.

This is growing issue, with nitrogen pollution on the rise due to growing populations and the associated development that brings. Some of the contributing factors include stormwater runoff, suboptimal wastewater treatment and the use of nitrogen fertilisers and fossil fuels.

The three-year project is expected to start in late 2021.


The project is a large scale collaborative effort, being delivered in partnership with Southern Cross University and the University of Western Australia and supported by the Australian Research Council’s (ARC) Linkage Projects scheme. Healthy Land and Water is providing cash and in-kind contributions over three years. Healthy Land and Water’s Jack Coates-Marnane is acting as Partner Investigator scientist on the project.

Healthy Land and Water has collaborated with Southern Cross University on two previous Linkage-funded projects, ‘Unravelling the drivers of greenhouse gas emissions in estuaries’ and ‘The Impact of Trawling on Nitrogen Removal through Sediment Denitrification in Western Moreton Bay’.

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