Media Release
18 October 2001
Taking the petals to the metals
The human response to stress is to fight or flee, but modern medical sciences counsel us to choose a middle option and
flow. Using relaxation techniques when it’s not sensible to fight or flee is a great option, and one that is also being
applied to the world of plants.
Instead of deciding whether contaminated land must be fought - capped or bulldozed - or just fled from, we can use
plants to let it flow. The proper name for this is phytoremediation, from the Greek phyto, meaning plant. Remember it by
thinking “Fight or mediate.” It’s an active and targeted way of achieving something that might otherwise happen, but
haphazardly: with the emphasis on ‘hazard’.
A demonstration of how this works occurred in 1999 when HortResearch was asked by Fletcher Challenge Forests to assist
them in the clean up of a five hectare disused sawdust pile. The sawdust was contaminated by a cocktail of heavy metals
as well as an organic timber preservative. One plan was to cap and contain the site because its toxins were leaching
into surrounding waterways – a typical fight-back reaction.
HortResearch scientists were able to offer a better, and cheaper, solution. The site was planted in poplar and willow
varieties that have been specially selected and bred for such work. As the trees grow, they are consuming large amounts
of water as well as toxins, which means substantially less is leaching.
More dramatically, the collapse of a dam containing mine tailings caused damage to 4,000 hectares of farmland in Spain,
a problem to which our scientist Dr Brett Robinson helped offer a similar solution. Cleaning up the disaster will take a
very long time, but interim gains in timber harvest will bring something positive out of the vast sea of metallic mud.
This connection between plants and mines is an interesting twist to an old piece of knowledge. Certain metal-loving
plants were once looked for to identify places where those metals could be mined. Now we are more likely to be taking
the plants to the metals. Any scenic features or spring blossoms will be an added bonus.
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For further information please contact
Dr Brent Clothier, HortResearch
Private Bag 11 030, Palmerston North, New Zealand
BClothier@hortresearch.co.nz
Tel +64-6-356 8080 ext 7733
Photo available as JPG, please contact
MEder@hortresearch.co.nz
Tel +64-6-351 7000 ext 7728