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Some weeds may be bad for allergies, but good for cleaning up the
environment. These plants selectively remove heavy metals such as
lead, zinc and cadmium from contaminated soils. Other plant species
accumulate radioactive isotopes such as uranium or cobalt. Alpine
pennycress--a small perennial herb--has emerged as the best at removing
cadmium and zinc after a three-year study in Maryland and at a Superfund
cleanup site in a Minnesota landfill. Alpine pennycress can hold 30,000
parts per million (ppm) of zinc in its leaves without any loss in growth,
compared to a 500-ppm limit for most plants. Pennycress and other
"hyperaccumulators" can be made into "hay" annually, then burned for
electricity generation. Their ashes can be recycled and marketed
commercially. ARS researchers have finished the Minnesota test and are
continuing lab tests in Maryland on different strains of pennycress. They
have begun a field test at a smelter-contaminated Pennsylvania city park
that has three-percent zinc levels in its soil. The pennycress is
thriving where crops can't survive. The next step is to complete
inheritance studies to find genes for hyperaccumulation from pennycress or
ragweed and move them into common crops that grow larger, faster and are
easier to harvest. Canola grown for hay is a possible candidate.
Environmental
Chemistry Laboratory, Beltsville, MD
Rufus Chaney, (301) 504-8324
Years of searching for the ideal microbe to gobble up herbicides in the
rinsewater from tractor-pulled pesticide tanks has ended. ARS found
the microbe in sewage sludge at a municipal water treatment plant near
Washington, DC. Once the microbe is done feeding, farmers can dump the
water on the ground without fear of contamination. That frees farmers
from having to store several thousand gallons of rinsewater a year while
searching for a way to safely dispose of it. The microbe, Klebsiella
terragena, has a strong preference for the organic nitrogen in
herbicides, but turns up its nose at the inorganic form in fertilizer.
Previously tested microbes ate only fertilizer nitrogen in the rinsewater
and left the pesticides untouched. The new microbe degrades the major
herbicides--atrazine, cyanazine, and simazine--after an initial treatment
with ozone to begin the breakdown process. Other microbes have been
found that degrade alachlor, metolachlor and 2,4-D after ozone treatment.
After feeding, little is left besides water and carbon dioxide. To treat
rinsewater, farmers use two 55-gallon, cone-shaped tanks common on farms.
An ozone generator, the only specialized equipment needed, is attached to
one tank to pump ozone through the rinsewater for 12 hours. Then the
rinsewater is pumped to the second tank where microbes completely degrade
the pesticides in the next 24 hours.
Environmental
Chemistry Laboratory, Beltsville, MD
Cathleen Hapeman/Jeffrey Karns/Daniel Shelton (301) 504-6451
American lakes could be given a new life, free of water pollution from
agricultural runoff. In 1985, ARS scientists began tracking pollution
in Lake Chicot, AR. The lake is surrounded by 577 square miles of cotton,
soybeans and rice. Lakes in such large agricultural drainage areas often
have poor water quality because agrichemicals, soil and other pollutants
wash into them. The study examined how suspended sediments and other
contaminants can harm lake water quality and productivity. Based on the
study, researchers came up with a viable solution--divert storm water
around the lake and channel cleaner water into it. That practice improved
the lake's water quality, lowered sediment and rejuvenated recreation and
fish.
National
Sedimentation Laboratory, Oxford, MS
Charlie Cooper, (601) 232-2935
Gypsum from coal-burning electric plants could be a low-cost, widely
available soil enhancer. In tests with corn and pasture grasses, ARS
scientists are finding that gypsum not only reduces the effects of soil
acidity, but also supplies essential calcium, sulfur and boron. This
allows plant roots to "explore" more soil in searching for water. Gypsum
is one of many byproducts currently produced by scrubbers and other
pollution control technology mandated by the Clean Air Act. ARS
scientists are rating various byproducts to see which ones have a future
as niche-market soil additives.
Appalachian Soil and Water
Conservation Research Laboratory, Beckley, WV
Virupax C. Baligar, (304) 252-6426
Capillary electrophoresis (CE) helps keep the environment healthy while
pinpointing mycotoxins in corn. CE, which separates compounds based
on their electrical charges, can be used to detect levels of mycotoxins
produced by fungi that infect grain. When ARS researchers used CE
analysis to check 20 corn samples, 99 percent less hazardous waste was
generated than with high performance liquid chromatography, a standard
analytical technique for detecting carcinogens. Researchers are working
on ways to reduce the cost of CE so that more scientists will use it, thus
reducing chemical waste.
Mycotoxin Research, Peoria, IL
Chris Maragos, (309) 681-6266
Mixing composts in high-lead soil may reduce by two-thirds the amount of
lead that gets into the bloodstream of children who eat the soil.
These were the results in rats given diets containing five-percent
soil--similar to the amount eaten by young children who have an abnormal
craving for soil. Such abnormal behavior is called pica. Soil fed to the
rats came from inner city New Orleans and had lead levels of 1,600 parts
per million (ppm). Urban soils commonly contain 1,000 to 10,000 ppm or
more. Researchers measured lead in the rats' thigh bone because bone
accumulates lead over time. Lead levels averaged 60 ppm in the bones of
rats fed the soil without compost. That's compared to 20 ppm for rats fed
soil with 10-percent compost. The compost binds the lead in the soil as
it moves through the intestines. As a result, more lead is eliminated
from the body rather than absorbed into the bloodstream.
Environmental
Chemistry Laboratory, Beltsville, MD
Rufus Chaney, (301) 504-8324
What do you do with more than 100,000 gallons of insecticidal dip after
tick-proofing cattle at the U.S. border? Turn it into harmless waste.
ARS scientists and USDA tick eradicators found that microbes living in the
dip help convert the liquid waste into harmless substances. The dip
cleaned itself in a week or two when researchers added iron, magnesium
salts and other nutrients, and monitored the dip's temperature, pH and
oxygen. Soils contaminated with dumped waste dip can be cleaned in a
similar manner. Over two years, it takes more than 100,000 gallons of dip
to tick-proof American cattle before they leave a quarantine zone in south
Texas. It takes even more anti-tick bath to dip Mexican cattle before
allowing them into the United States. That's to prevent them from
carrying cattle fever into the United States. The disease cost the U.S.
livestock industry over $1 billion a year before the culprit tick was
eradicated.
Soil-Microbial Systems
Laboratory, Beltsville, MD
Walter Mulbry/Jeffrey Karns/Daniel Shelton, (301) 504-6417
Last updated: November 15, 1996
Return to: Quarterly Report
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