Toxic Truth: Evidence of leaching ‘confirms’ suspicions

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A DECADE after Pasminco’s lead and zinc smelter closed at Boolaroo and as the land is being prepared for redevelopment, the Newcastle Herald and Macquarie University collected more than 130 soil and  dust samples from homes and public spaces in surrounding suburbs. The analysis revealed alarming levels of contamination remained, despite a government-approved Lead Abatement Scheme.

DANGEROUS metals are leaching into waterways and land across Lake Macquarie from toxic black slag, new Macquarie University research has found.

Lake Macquarie is trying hard to be an environmentally-responsible city, but the legacy of pollution from the Pasminco lead and zinc smelter looms large.

Black slag – which was spread across large areas of Lake Macquarie and other areas in the Hunter over decades – was a serious public health threat, Macquarie University researcher Anthony Morrison said. 

The latest research has heightened concerns about the contamination.

Slag contains high levels of lead, cadmium, arsenic and antimony.

Mr Morrison has worked on a series of core samples of slag, taken from Lake Macquarie to examine the ‘‘leaching characteristics of the heavy metals’’.

Samples were taken from Tredinnick Oval, Speers Point, the reserve alongside Cockle Creek and Eleebana.

‘‘The questions being examined are: how mobile are the heavy metals, how much leaching has already occurred and how much of the available heavy metals are likely to leach out into the future?’’ Mr Morrison said.

‘‘Initial tests have shown evidence that some leaching of heavy metals has already occurred.’’

This confirms what many had suspected and feared for years.

NSW Environment Protection Authority director of contaminated land and environmental health Craig Lamberton agreed that slag could leach.

‘‘Of course it can leach, but in the scheme of things it’s relatively stable compared to fine lead dust [from smelter fallout],’’ Mr Lamberton said.

Mr Morrison said leached heavy metals in a backyard had ‘‘the potential to be taken up in vegetables and chooks and end up in the diet of the occupants’’.

‘‘If the slag is exposed at the surface and handled by children for example, we have previously shown that the heavy metals in the finest particles are highly bioavailable,’’ he said.

This means it can be absorbed into the body, exposing people to health problems.

Large areas of slag contamination close to waterways ‘‘may leach and provide a potential source of continuing contamination for many years to come’’, Mr Morrison said.

‘‘We need to look at the leaching rates and potential methods which would slow or prevent any leaching occurring from the slag.

‘‘It may not be practical to remove it.’’

As a first step, pinpointing the slag pollution was critical, he said.

‘‘Once these sites have been identified, the potential impact can be assessed and mitigation strategies developed and implemented.’’


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