SUMMARY OF THE REMEDIATION TECHNOLOGIES DEVELOPMENT FORUM
PHYTOREMEDIATION ACTION TEAM
TOTAL PETROLEUM HYDROCARBON IN SOIL SUBGROUP
CONFERENCE CALL
April 16, 2002
12:30 p.m.-2:00 p.m.
On April 16, 2002, the following members of the Remediation Technologies Development Forum's (RTDF's) Phytoremediation Action Team, Total Petroleum Hydrocarbon (TPH) in Soil Subgroup, met in a conference call:
Lucinda Jackson, Chevron Texaco (Subgroup Co-Chair)
Phil Sayre, U.S. Environmental Protection Agency (EPA) (Subgroup Co-Chair)
Marcos Alvarez, Environment Canada
Jim Brown, Lockheed Martin
Henry Camp, Arthur D. Little Laboratory
Steve Geiger, ThermoRetec, Inc.
Peter Kulakow, Kansas State University
Kirk O'Reilly, Chevron Texaco
Steve Rock, EPA
Greg Thoma, University of Arkansas
Michelle Arbogast of Eastern Research Group, Inc., (ERG) was also present.
UPDATE ON SAMPLE ANALYSIS
The TPH in Soil Subgroup has created a field study program to evaluate how effectively plants degrade petroleum hydrocarbons. Samples have been collected from several sites and sent to the Arthur D. Little Laboratory (ADL) for analysis. Peter Kulakow said that some puzzling results have been reported at Site G. For example, TPH concentrations were shown to increase between time 1 (T1) and time 2 (T2). Also, data collected for the standard reference sample show TPH concentrations as increasing over time. The call participants spent a significant portion of the call discussing the data, analytical techniques, sampling techniques, and variabilities associated with analytical processes.
STATUS OF THE SUBGROUP'S PROGRESS
When the field demonstration project started, Subgroup members agreed to collect data for 3 years. Some sites have reached this milestone, and another group of sites will do so shortly. Phil Sayre asked whether the study program will be extended at any of these sites. Steve Geiger said that sampling will continue at Site F, and that funding is being sought for another 3 years of study. Additional samples will not be collected, however, from Sites A, C, D, E, or K. Sampling might continue at Site B, but it is not clear yet. Funding for Kulakow's support is secured through September 2003.
Call participants talked about the findings that have emerged from the Subgroup's field study so far. At Site A, Kirk O'Reilly said, phytoremediation did not offer dramatic improvements. Contaminants at this particular site, he said, were highly weathered before the pilot project began. He questioned whether phytoremediation is effective in such an environment. Steve Rock said that the results collected thus far suggest that phytoremediation may offer an advantage over bioremediation and land farming by improving the rate of cleanup and addressing deeper soil layers. Jim Brown said that he was not sure that plants enhance cleanup rates: for example, at one non-Subgroup site, the rate of contaminant degradation has been more rapid in nonvegetated fertilized plots than it has been in vegetated fertilized plots. (Brown said that microbial activity might be greater in the nonvegetated plot because soil temperatures were higher there--it was exposed to direct sunlight.)
Call participants said that a broader set of criteria should be used to determine whether phytoremediation is a success. Contaminant reduction rates, although important, are just one way to measure benefits. For example, Brown said, phytoremediation also stabilizes soil, helps reduce erosion, and initiates site restoration processes. Geiger said that some groups believe that phytoremediation may be able to reduce contaminant bioavailability. The plants may not eliminate contaminants, he said, but they may be able to convert them into forms that do not harm humans or the ecosystem. (Geiger said that researchers at the Lawrence Berkeley National Laboratory have submitted a proposal to perform bioavailability research at established phytoremediation sites. He asked Subgroup members to consider letting the researchers perform studies at Subgroup sites.)
Call participants did note that phytoremediation does have a potential downside. Concerns have been expressed about the potential for contaminants to concentrate in plants and to enter the ecological food chain via this pathway. The Subgroup is performing analyses to determine whether contaminants have accumulated in plants. Thus far, there is no evidence of uptake. Nevertheless, Lucinda Jackson noted, there is some evidence in the scientific literature about PAHs accumulating in plant tissues. Call participants said that they would like to explore the "ecorisk" question further. Brown said that he knew of some experts on the topic; he will forward their names to Kulakow.
NEXT TPH IN SOIL SUBGROUP MEETING
Call participants agreed that there was no need for a face-to-face meeting this year. Rock asked Subgroup members to e-mail him with suggestions for the date and location for a 2003 meeting. Participants agreed that it should not be held before June; Kulakow suggested waiting until the fall. Rock suggested bringing together all three Phytoremediation Action Team Subgroups at the meeting.
PRESENTATION IN ROME, ITALY
Rock said that he is going to present information about the Subgroup at a meeting in Rome, Italy, in May 2002. Rock plans to focus his talk on the Subgroup's protocol and the collaborative approach used to conduct field studies. He will also describe the data that have been collected, and tell participants about some of the challenges the Subgroup has faced.
ACTION ITEMS