LOCAL wetlands are turning toxic in some places from soil disturbance. Natural resource management officer Rae McPherson said farmers interested in doing river restoration projects have been discovering that what they thought were saline seeps are acid sulphate soil disturbance. These soils are now being found in wetlands and springs across the landscape around Donnybrook and Kirup.
“If left undisturbed, these soils are not a problem,” Ms McPherson said. “However, if these soils are excavated or stock allowed to walk over and pug up these wetlands, the acid sulphate soils will start to produce sulphuric acid.” This acid would kill off vegetation and leach heavy metals out of the soil into the surrounding wetlands, rivers and creeks, Ms McPherson said.
“This water is a major source of toxic pollution that can harm anything that comes into contact with it including humans, stock, poultry and fish,” she said. “Heavy metals such as arsenic, aluminium, chromium, zinc, copper and cadmium are just some of the toxic elements released into the water at these sites.”
To get expert advice on how to deal with such sites, Ms McPherson invited Steve Appleyard of the Depart-ment of Conservation’s acid sulphate soils branch to do some site visits last week. “Some people think that salinity is bad,” Dr Appleyard said. “But the toxic products released with acid sulphate soil disturbance can be deadly. “The best way to deal with these soils is to not disturb them or drain them.”
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