New Zealand researchers have discovered that run-off from the agrichemical DCD may be harmful to some aquatic eco-systems.
The chemical, which has been suspended by its manufacturers after traces were found in milk product samples, was used on pastures to reduce nitrate leaching and greenhouse gas emissions.
A University of
Otago study has found dicyandiamide (DCD) residues in streams in Otago's lower Taieri Plain in concentrations that cause natural nitrogen transformation processes to be disrupted in aquatic ecosystems.
Department of zoology researcher Marc Schallenberg conducted laboratory experiments showing that in a wetland system, the presence of DCD inhibits the processes of nitrification and denitrification - two natural processes that help to purify and detoxify waters.
"While DCD's inhibition of nitrification on land is desirable as it reduces the amount of nitrate entering streams, its similar inhibitory effects within aquatic environments is undesirable, as this could lead to ammonia toxicity in fish and other species, or increased incidences of algal blooms," Dr Schallenberg said.
