Digging in deep to help Reef
FARMERS in the Tully-Johnstone region are leading the way in trialling bioreactors in an effort to treat nitrogen flowing to the Great Barrier Reef.
A denitrification bioreactor has been installed on a cane farm as part of the Wet Tropics Major Integrated Project.
Bioreactors are trenches filled with woodchips that work by converting excess dissolved inorganic nitrogen (DIN) in groundwater into nitrogen gas.
Proven internationally but untested in the Wet Tropics, they are among initiatives being trialled to reduce nutrient, sediment and pesticide loads flowing to the Reef.
The $15 million reef water quality initiative is funded by the Queensland Government through the Queensland Reef Water Quality Program.
Wet Tropics Major Integrated Project catchment repair officer Suzette Argent said it was estimated the first bioreactor would remove up to 400kg of nitrogen feeding into the reef lagoon each year.
“This bioreactor is treating groundwater draining from a 5ha paddock,’’ she said.
“It follows months of community engagement, rigorous site assessments, topographical surveys, soil tests and design works.”
Excess amounts of dissolved inorganic nitrogen in the reef lagoon impact water quality and reduce reef resilience. They have also been linked to increased outbreaks of the coral-eating Crown of Thorns starfish.
Basin co-ordinator Sandra Henrich said if the trail proved successful, the bioreactors could be implemented across the landscape as smallscale groundwater treatment systems.