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Phytoremediation - Terry Lab UCB |
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1/22/2003 - Berkeleyan "Wetlands Clean Selenium from Agricultural Runoff" Researchers at Berkeley have found a natural “detox program” for selenium-contaminated farm runoff, in the form of wetland vegetation and microbes. Results from a two-year study by Berkeley researchers show that man-made wetlands in the San Joaquin Valley were able to remove an average of 69.2 percent of the selenium in agricultural drainage water. More significantly, some plant populations showed remarkable promise at converting selenium into a harmless gas consisting primarily of dimethyl selenide (...) 1/4/2003 - Oakland Tribune "Marshes can Clean Pollutant from Farm Runoff" Wetlands are a great place to scrub selenium from contaminated farm runoff, two scientists reported this week after a two-year study in the Central Valley -- a finding that challenges the notion that agricultural runoff and wetlands just don't mix. The study, published Wednesday in the online edition of Environmental Science and Technology, found that plants and microbes can send into the atmosphere close to 50 percent of the selenium found in drainage water from the San Joaquin Valley's selenium-rich west side. "The upshot is that wetlands are a very efficient and affordable solution to ridding polluted water of a toxic chemical," said Norman Terry, a University of California, Berkeley, professor of plant biology and the study's principal investigator 1/2/2003 - UC Berkeley Campus News "Nature's filter: Wetlands clean selenium from agricultural runoff" BERKELEY - Researchers from the University of California have found a natural detox program for selenium-contaminated farm runoff in the form of wetland vegetation and microbes. Results from a two-year study by UC Berkeley researchers show that man-made wetlands in the state's San Joaquin Valley were able to remove an average of 69.2 percent of the selenium in agricultural drainage water. More significantly, some plant populations showed remarkable promise at converting selenium into a harmless gas consisting primarily of dimethyl selenide. That means less of the selenium would end up in sediment or plant tissue. The new study, published online Wednesday, Jan. 1, in the journal Environmental Science and Technology, follows previous research at the Chevron oil refinery in Richmond, Calif. The researchers found that wetland ponds built in Richmond could take out as much as 89 percent of the selenium from millions of gallons a day of refinery discharge, preventing it from reaching San Francisco Bay. "We thought that if wetlands could filter selenium from oil refinery wastewater, then they could probably be used for agricultural runoff," said Norman Terry, professor of plant biology at UC Berkeley's College of Natural Resources and principal investigator of the study. "We're basically learning that some of the best, most efficient filters for pollutants can be found in nature." (...) 4/22/1995 - West County Times "Biologist: Solution to selenium is marshes" BERKELEY - Bay Area oil refineries have spent millions of dollars searching for a solution to the problem of selenium pollution, but the answer may be as simple as building marshes full of plants. This is the conclusion of UC Berkeley biologist Norman Terry, who will deliver a paper on his research today in Columbia, Mo., during a conference on the use of plants to clean up toxic contamination. (...) 4/22/1995 - Oakland Tribune "Plants found to detoxify selenium in wastewater" 5/8/1995 - Business Week "Plants that clean a mess of messes" (...) Chevron Corp., for instance, is using cattails to soak up selenium discharged from its Point Richmond (Calif.) oil refinery. Some of the selenium is expelled into the air in nontoxic quantities. Cattails containing selenium can be reaped and spread over soil that's deficient in the metal. That should cost a fraction of the hundreds of million of dollars that would be required to dredge and bury or burn the sediments, according to University of California at Berkeley plant biologist Norman Terry. (...) 5/17/1995 - Berkeleyan "Nature tackles a Cleanup" June/1995 - Estuary "Brocolli Cure-All" Broccoli may help clean up selenium-contaminated soil, according to U.C. plant biology professor Norman Terry. Terry has found that several common crop plants - especially broccoli, rice , and cabbage - have the ability to "volatize" selenium by absorbing the substance and their root systems and converting it to a gas which is then dispersed into the atmosphere. (...) 6/2/1995 - Express "Revolutionary New Selenium Treatment" (...) Terry, a professor of plant biology at UC Berkeley, is one of a growing number of scholars working in what he calls the "exploding field" of phytoremediation - the sciencs of using plants to clean up the environment. Earlier this spring, Terry presented some of his findings at the first conference ever held for phytoremediation research. The size of the conference, which was held in Columbia, Nissouri, is an indication of the burgeoning interest in the field, he says - over 300 scientists from the US, Australia, and Europe attended/ June/1995 - Environtech "Applying Phytoremediation to Selenium" 21/7/1995 - Science "Plants Proving their worth in Toxic Metal Cleanup" (...) "Interest in phytoremediation has exploded in the last few years," says Norman Terry, a plant biologist at the University of California, Berkeley. (...) But Terry says "lots of sites" need phytoremediation to remove metals, so business is booming, even for this single application. (...) Also, Berkeley's Terry has found that selenium can be volatized as nontoxic dimethyl selenide by plants, including broccoli and cabbage. December/1995 - Environmental Health Perspectives "Absorbing Possibilities: Phytoremediation" (...) In the United States, Norman Terry, professor of plant biology at the University of California at Berkeley is exploring the possibility of using Indian mustard to remove naturally ocurring selenium from soil. A necessary nutrient, selenium can leach into water. In high amounts, this metal can poison wildlife and livestock. In laboratory research, Terry has found that Indian mustard not only takes up selenium but converts it into dimethyl selenide, a gas which he describes as relatively nontoxic. January 1996 - Environment Update "EPRI Research to Optimize Constructed Wetlands Design" (...) Another new project, at the University of California, Berkeley, will indentify approaches for maximizing trace metal removal by wetland biota. This research will involve pilot field studies at the APS site, as well as laboratory experiments at a constructed wetland adjacent to San Francisco bay employed by Chevron Oil Corp. to remediate oil refinery wastes, and at constructed wetlands used by Tennessee Valley Authority(TVA) to treat acid drainage from reclaimed coa mines and coal ash piles. Currently, Berkeley scientists are screening plant species to identify those that absorb toxic trace elements at the fastest rate. In future work, the potential of biological volatilization as a removal mechanism will be quantified. Also, contaminant cycles will be monitored to determine the proportion retained in sediments or water versus that immobilized in plant tissues or volatilized. June 1996 - Compressed Air "Stemming the Toxic Tide" (...) Not all plants sequester metals in their roots. Some are able to convert toxic metals into gas. Broccoli, cabbage, rice, and other plants can accumulate selenium in their roots and convert it to a nontoxic gas that the plants easily disperse, reports Dr. Norman Terry, professor of plant biology at the University of California at Berkeley. That gas is dimethylselenide, which is 500 to 700 times less toxic major contaminant in agricultural runoff and industrial waste in the western half of the United States. In a three-year test conducted by the U.S. Department of Agriculture, plants were able to remove 40 perent of the selenium in a toxic test plot. (...) Chevron Oil Company's constructed wetland in Point Richmond, CA, removed more than 70 percent of the selenium from wastewater. Only half of the missing selenium was found in the sediments, water, or plant tissue. The rest was transformed into a nontoxic gas and released into the atmosphere. (...) And eight days is just enough time because "Water [typically] stays in wetlands seven to 10 days before coming out the other end," says Terry of UC Berkeley. If the wetland is full and cannot provide the necessary time for plants to absorb the contaminants, water can diverted into a different area for further remediation before being discharged from the wetland. July 20, 1996 - Science News "Botanical Cleanup Crews" (...) Soil in parts of the western United States has a natural abundance of selenium, an important nutrient for animals and humans that in high doses is toxic. Drainage water from agricultural fields often becomes rich in selenium. Growers then send the water to their evaporation ponds, where the selenium reaches even higher concentrations, which are deadly to wildlife. Plants, however, "are very effective at removing selenium from contaminated soils," asserts Norman Terry of the University of California, Berkeley. They not only absorbthe chemical, they also turn some of it into the less toxic dimethyl selenide gas. Selenate, the common form of selenium in soil, in about 600 times more toxic than dimethyl selenide gas. In june, Terry and his colleagues completed construction of 10 experimental quarter-acre wetlands in Corcoran, Calif. They want to see if these wetlands reduce selenium concentrations in agricultural runoff to less than 2 ppb before it reaches the evaporation ponds. Grasses, such as cattails, bulrushes, and Spatina, grow in the wet lands. The researchers are aso investigating how much of the selenium in wetands stays in sediments and plant tisseues rather than being volatillized and dispersing into the atmosphere. Plants with large amounts of selenium could sicken birds and insects that eat them, the scientists fear. Studies from the late 1980s suggested that plants volatilize about 30 percent of the selenium entering a wetland. Terry's recent laboratory studies, however, show that volatilization rates differ from plant to plant and depend on the concentration of selenium in the soil. Terry expects to have more information on volatilization later this summer, after analyzing data on the selenium stored in plantsin a 90-acre wetland in Point Richmond, Calif., that Chevron Corp. built in 1988. The company originally constructed the wetand, which features cattais and bulrushes, for its beauty. Now the wetand is removing 70 to 75 percent of the selenium from the 10 million liters of wastewater that the company pumps throughit every day, says Terry. Department of Plant and Microbial
Biology
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