Phytoremediation of organics moving rapidly into field trials Several chemical and petroleum companies are contemplating an offer by EPA's Technology Innovation Office (TIO) to form partnerships between the public and the private sector to exploit emerging phytoremediation technologies of organics and hydrocarbons. Surface planting is already in use for remediation of metal contaminants, and methods for the removal of organics—until now the domain of microbial bioremediation—are passing greenhouse and laboratory tests. The partnerships would evaluate their effectiveness in the field. Some researchers, however, are hesitant about such field trials. University of Oklahoma researcher John Fletcher believes that phytoremediation requires the right plant species for the job, and failures of large studies that use the wrong plants could dampen phytoremediation in the eyes of regulators. "[Failures using] species that were never looked at closely enough in the laboratory could be a fatal blow to phytoremediation " said Fletcher. Phytoremediation of nonhydrophobic contaminants, including chlorinated solvents and some petroleum hydrocarbons, has produced encouraging results in the field; but hydrophobic contaminants such as polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), which bind tightly to soil and resist uptake by plants, continue to elude efforts at phytoremediation. At an EPA-sponsored workshop on phytoremediation of organics in Fort Worth, Tex., in December, Fletcher outiined his research approach. He studied the root-associated microbial community nurtured by carbon sources emitted from the plants. According to the team's findings, PCB and PAH-degrading bacteria favor coumarins and flavonoids as carbon sources, and these compounds are released by the root structures of apple, mulberry, and Osage orange trees. Fletcher suspects that these trees alter the microbial environment favoring the microbes that feed primarily on the counicirins a.nd
Eastern cottonwood trees are being used by the U.S. Air Force at a phytoremediation demonstration in Fort Worth, Tex., to remediate TCE-contaminated groundwater. Site manager Olen Long measures growth after five months. (Photo courtesy Steve Rock, EPA, Cincinnati)
flavonoids and, evidence suggests, the structurally similar PCBs and PAHs. Plants also extract water-soluble compounds from the soil and store, metabolize, or release them into the air; their roots may hem in contaminated groundwater, preventing it from seeping into surrounding areas. Sheldon Nelson presented data on a Chevron project in which
the company planted one- or two-year-old poplar trees over a site with gasoline-contaminated groundwater. Calculations suggested that each plant pumped about 1.5 gallons of groundwater per day, and the water level dropped one to two inches. To satisfactorily control the groundwater, Nelson believes that each tree would have to pump 8.5 gallons per day. In unrelated research, a 5-year-old poplar has been shown to pump as much as 40 gallons per day. Most researchers agree that many basic pathways and mechanisms of phytoremediation are still poorly understood, and uncovering these should be a high priority. "I think phytoremediation has leap-frogged over basic research," says Fletcher. TIO director Walt Kovalick agrees and expects the trend to continue because of the pressure to clean up sites. "We're seeing a readyfire-aim approach. These proso benign and forgiving that [companies] are out in the field experimenting." —JAMES KLING
EPA audits its peer reviews, begins agency-wide training program Starting this spring, EPA will conduct a training program to improve the quality of the peer review process in all agency program and regional offices. The training will be customized to meet the needs of each office, according to Nancy Wentworth, director of EPA's Office of Research and Development (ORD) Quality Assurance Division, who is helping organize the effort. The training program follows on the heels of an internal audit of peer review practices in more than 30 and regional offices, which began in January. Driving the examination is a critical General Accounting Office (GAO) report, released in October 1996, that concluded that EPA's implementation of its 1994 directive to improve the peer review process was "uneven." In some cases, the report found confusion among EPA offices over what quali-
fies as a peer review. For instance, in some regional and program offices, public comment was confused with peer review. GAO noted, however, that ORD was more experienced and successful in conducting adequate peer reviews than were program or regional offices {ES&T, ,ec. 1996, p. 522A)A Consequentiy, according to a Jan. 14 memo from EPA Deputy Administrator Fred Hansen to agency upper management, ORD will establish and oversee the overall audit and review process. The agency expects to review about 150 "products" that call for peer review. Wentworth said EPA may turn to trainers outside ORD or in programs or regions to run the training programs. According to Hansen's memo, EPA expects to begin the training programs in May. —JEFF JOHNSON
VOL.31, NO. 3, 1997/ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 1 2 9 A
