The test will detect whether heavy metals
are 'locked' in soil or can get into food and
water supplies,
Image: iStockphoto
A team of international scientists has developed a world-first technique that identifies the danger heavy metals in soil pose to humans and the environment.
Professor Steve McGrath of Rothamsted Research in the UK will discuss the model, which has the potential to save millions of dollars and improve human health, today in Adelaide at the CleanUp 09 Conference’s Chemical Bioavailability Workshop.
Heavy metals left in our soil from industry or agriculture can result in the loss of useable land, and when contaminants enter our food and water supplies they have been linked to cancer and degenerative diseases. It is estimated there are around 100,000 potentially contaminated sites in Australia alone.
Scientists can currently detect heavy metal levels at these sites, but this costly process does not reveal whether toxins are stored safely in the soil or are ‘available’ to plants and organisms, which could result in the contamination of our food and water sources. This inaccurate measurement system leads to millions of wasted dollars and can put human health at risk.
“Unless we have a proper understanding of bioavailability we may remediate sites which do not need it, or conversely, not remediate or control the use of pollutants where this is actually necessary,” said Professor McGrath.
According to Professor McGrath, it is not just the concentration of heavy metals but also the condition of the soil that determines whether or not dangerous contaminants can enter our food chain. The new model takes soil type, as well as heavy metal concentrations, into account in order to predict whether contaminated land is ‘safe’ for reuse.
To calibrate their model, the researchers took soil samples from all over Europe and measured the concentrations at which zinc, copper, nickel and cobalt became available to invertebrates, plants and microbes. They then determined the properties of soil that ‘locked in’ the heavy metals.
The model has allowed the researchers to accurately set ‘safe’ levels of these heavy metals, acting as a first tier of assessment which will help to protect society and vulnerable ecosystems from contamination by identifying the sites that most need to be cleaned up. It will also ensure policies are created that will properly regulate industry’s use of toxins. The model is already being used in Europe to create soil protection guidelines.
“The penalties of inappropriate measures for control entail huge costs, ultimately borne by all of us. Examples are the reduction in land values if there is contamination, the huge costs of remediation ($M per hectare), and the change in industry viability and employment if inappropriate controls or bans on materials are applied,” said Professor McGrath.
The model currently assesses the threat of copper, zinc, nickel and cobalt, but in the future it may be able to identify ‘safe’ levels of toxic metals, such as arsenic, which threatens the health of over 100 million people worldwide.
“The prime importance is to protect the health of the ecosystem and humans in the long term,” said Prof McGrath.
|
