[Phytonet] Alpine Pennycress and cadmium

[Alan Johnson]

Dear List,

I thought this might be of interest to those too busy to readthe news:-):
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Acidifying Soil Helps Plant Remove Cadmium, Zinc Metals

By Sharon Durham
June 14, 2005

Acidifying cadmium-contaminated soil can help a plant called alpine
pennycress to remove even more cadmium and zinc from contaminated soil,
Agricultural Research Service (ARS) and cooperating scientists report.

ARS agronomist Rufus Chaney and University of Maryland colleagues Shengchun
Wang and Scott Angle have found lowering the soil pH—increasing its
acidity—can maximize the ability of alpine pennycress (Thlaspi caerulescens)
to remove cadmium and zinc metals from soil.

The scientists used a particular strain of alpine pennycress from southern
France in their research. In the study, they increased the acidity of two
soils collected at different fields near a zinc smelter at Palmerton, Pa.
The pH of the soils was lowered from a neutral level of 7 to an acidic level
of about 4.7 by using sulfur.

Alpine pennycress was grown on these soils for six months and then analyzed.
As the pH was lowered, concentration of cadmium in the plant shoots rose.
But if the pH was lowered below 6, the soils were so acidic that the alpine
pennycress yields were reduced.

Alpine pennycress can concentrate cadmium in its leaves up to about 8,000
parts per million. Harvesting the above-ground vegetation annually makes it
possible to gradually reduce the soil concentration of cadmium to safe
levels. The cost of this remediation method, called phytoextraction, costs
about $250 to $1,000 per acre per year, according to Chaney. He's based at
the ARS Animal Manure and By-Products Laboratory in Beltsville, Md.

The alternative clean-up method—removal and replacement with clean
soil—costs about $1 million per acre. Most highly contaminated soils can be
deemed safe after three to 10 years of phytoextraction, an effective
clean-up at far lower cost. The technology will be especially useful in
cleaning up rice paddy soils in Asia, where mine waste contamination is
causing human health effects from cadmium accumulated in rice grain.

In 2000, a patent was filed by the University of Maryland on the use of
alpine pennycress for the phytoextraction of cadmium from soil, and a patent
has been granted in Australia. No other similar technologies currently exist
for remediation of cadmium contaminated soils using plants.

ARS is the U.S. Department of Agriculture's chief in-house scientific
research agency.
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Or go follow this link to read the original:

http://www.ars.usda.gov/is/pr/2005/050614.htm

Regards

--
Alan Johnson, Geotr at ns
www.geotrans-online.de
German-English, Geosciences/Technical
http://geotransblog.blogspot.com/
Terminus Est