On June 27, 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:
Marcos Alvarez, Environment Canada
Steve Geiger, ThermoRetec, Inc.
Peter Kulakow, Kansas State University (KSU)
Steve Rock, U.S. Environmental Protection Agency (EPA)
David Tsao, BP America
Christine Hartnett of Eastern Research Group, Inc., (ERG) was also present.
The TPH in Soil Subgroup has created a field study program to evaluate how effectively plants degrade petroleum hydrocarbons. Call participants provided information about the following:
Sites B, I, and J. Peter Kulakow said that samples have been collected from these three sites and sent to the Arthur D. Little Laboratory (ADL) for analysis. Analyses for Sites B and J are scheduled to be completed in July. Kulakow did not indicate when ADL expects to complete analysis of Site I's samples.
Sites C, D, and E. Kulakow said that Mike Reynolds presented data for these sites at a recent meeting. Call participants expressed strong interest in gaining access to these data.
Site L. Seeds were planted at this site on June 5, 2002; the plants are just starting to emerge. Kulakow said that two types of controls are being used: (1) nonvegetated/unfertilized and (2) nonvegetated/fertilized. He also provided a brief description of the site, noting that the contaminated materials being used for the phytoremediation demonstration project were excavated from an onsite flare pit. The soils, which contain a mixture of hydrocarbons, have high clay content and high salt concentrations.
Site M. Kulakow said that site managers hope to establish plants at this site in fall 2002.
Call participants discussed two issues that relate to data interpretation and analysis:
Statistical analysis. Steve Geiger said that Jessica Patino is analyzing Site F's data. As part of this process, Geiger said, Patino is trying to determine the best way to perform a meaningful statistical analysis. Kulakow said that one of KSU's graduate students is doing the same for Site G. Kulakow and Geiger agreed that it would be useful to hold a conference call to discuss the merit of different statistical analysis approaches. David Tsao said that he would like someone from his company to participate in this call. Steve Rock suggested inviting an EPA Quality Assurance (QA) Officer as well.
Nondetects. During a previous conference call, Kulakow said, the following question was asked: should ADL's "nondetects" be substituted with zeros? Kulakow said that he has not been using zeros. Instead, he substitutes nondetects with a value that is one-twentieth ADL's minimum reporting limit. (He said that ADL's detection limit is about one-tenth of the minimum reporting limit. Kulakow divides the detection limit by half to obtain the value he substitutes for nondetect readings.) Kulakow said that EPA's QA Officers appear to find this approach acceptable, at least in the interim. Kulakow said that he would like other Subgroup members to think about this issue and to comment on the approach he is using.
Kulakow said that EPA's Al Venosa recommended including chromatograms in the Subgroup's annual report. Prior to this conference call, Kulakow sent Subgroup members a file presenting chromatograms for Site G's time zero (T0), time one (T1), and time two (T2) samples. (All three curves were displayed on one graph. In order to make this possible, data had to be normalized to account for the fact that analytical instruments behave differently each time they are used.) Kulakow asked whether the chromatograms presented for Site G are useful. Tsao said that they are, noting that the chromatograms provide a compelling visual image of the changes occurring at the site. For example, a quick glance at them shows that hydrocarbons, especially those on the lighter end, decreased dramatically between T0 and T1. Kulakow said that it could be a challenge to determine how many chromatograms to include in the Subgroup's annual report. One call participant recommended including chromatograms for one vegetated and one nonvegetated plot from each Subgroup site. Tsao suggested providing data for two time periods rather than all of the time periods. That is, he recommended presenting curves that represent (1) the T0 data and (2) the most recent sampling event. Kulakow asked Subgroup members to contact him if other suggestions come to mind.
Marcos Alvarez and Kulakow went to the University of Saskatchewan to participate in the June 2002 Canadian Society of Microbiologists meeting, as well as a phytoremediation workshop that was held in conjunction with the meeting. They summarized the proceedings, highlighting the following points of interest:
Academic researchers are interested in performing analyses on Subgroup field site soil. Kulakow said that David Crowley, a professor from the University of California at Riverside, is investigating phytoremediation processes. Crowley might ask Subgroup members to provide soil for his experiments. (Crowley is analyzing plants for their surfactant-producing capabilities and trying to determine whether plants produce exudates that increase contaminant bioavailability and mobility.)
A representative from Imperial Oil is skeptical about the cost-efficacy of phytoremediation. Kulakow and Alvarez noted that a panel of industry representatives presented information during the phytoremediation workshop. During this session, a representative from Imperial Oil (a Canadian company) made negative statements regarding phytoremediation's ability to degrade petroleum contaminants: she concluded that the results achieved with phytoremediation are at best only incrementally greater than those realized with more "traditional bioremediation" approaches. Call participants asked what was meant by "traditional bioremediation." Neither Alvarez or Kulakow were sure, noting that the Imperial Oil representative was vague regarding this matter. Alvarez said that the Imperial Oil representative also indicated that phytoremediation requires too much maintenance. Call participants felt that this was a common misconception, noting that some people think that watering, regular mowing, and repetitive fertilization are an integral part of any phytoremediation project. This is not the case. Call participants expressed some surprise about the negative conclusions the Imperial Oil representative offered, and expressed interest in learning more about the foundations of her argument. Alvarez said that he would ask Terry McIntyre (of Environment Canada) whether he had additional information, since McIntyre has spoken to the Imperial Oil representative at greater length. If McIntyre is unable to shed light on the issue, one call participant suggested, it would be useful to contact the Imperial Oil representative directly for additional information. Before closing the discussion on this topic, Kulakow and Alvarez made it clear that Imperial Oil is not rejecting plant-based technologies outright. While the company appears to have little faith in phytoremediation as a technology for petroleum spill cleanup, phytoextraction research is being undertaken to identify plants that can remove salt from saline soils. Company representatives are hopeful that chloride and sodium can be harvested from the plants. Kulakow and Alvarez also felt it was necessary to point out that Imperial Oil's opinion does not reflect the opinions of all oil companies in Canada. In fact, several Canadian companies have expressed enthusiasm for the University of Saskatchewan's interest in phytoremediation; these companies regard phytoremediation as a promising remedial strategy that has the potential to be cost-effective and useful at remote sites.
Rock said that he hopes to hold a large Phytoremediation State of the Science conference in spring 2003. This would be a followup, he noted, to a phytoremediation meeting held in May 2000 in Boston, Massachusetts. Rock said that he will try to obtain funds to support the meeting and will start pulling together a planning committee. (Kulakow said that KSU would be interested in participating in the committee.) Rock said that he does not have a location in mind yet, but noted that it would be wise to hold the meeting near the Canada—United States border. Alvarez will ask McIntyre for suggested locations. Call participants agreed that it would be useful to hold a TPH in Soil Subgroup meeting in conjunction with the large Phytoremediation State of the Science conference.
The following miscellaneous topics were discussed during the call:
Arctic and Marine Oilspill Program (AMOP) meeting. ADL's Henry Camp presented information about the TPH in Soil Subgroup at a recent AMOP meeting. Kulakow said that a paper on Site A was submitted as well.
Genetically engineered plants. Rock said that a workshop will be held in Seattle, Washington, in January 2003 to discuss the possibility of using transgenic plants to enhance phytoremediation.
A conference call will be held in August 2002 to discuss statistical analysis methodology. Subgroup members should send ERG the names of those who will participate in the call. ERG will contact these people to find out which dates are acceptable for a call. Proposed dates include August 5-9 and August 13-16. Once a date has been set, ERG will set up the conference call and alert participants of the call's date, time, phone number, and access code.
Kulakow asked call participants to let him know if they have suggestions regarding how much chromatogram data should be included in the Subgroup's annual report.
Subgroup members expressed interest in obtaining copies of the presentations that were offered at the Canadian Society of Microbiologists meeting. Kulakow agreed to find out whether the presentations are available.
A representative from Imperial Oil expressed negative conclusions about phytoremediation. Call participants were interested in learning more about the foundations of her argument. Alvarez said that he would ask McIntyre whether he had additional information. If McIntyre is unable to shed light on the issue, one call participant suggested, it would be useful to contact the Imperial Oil representative directly for additional information.
Rock will try to obtain funds to support a Phytoremediation State of the Science meeting. Alvarez will ask McIntyre for suggested locations.
Kulakow said that he sent data to EPA's QA Officers for review. Rock agreed to contact them to find out whether the review has been conducted yet.
Alvarez said that the Canadian Council of Ministers of the Environment has established national criteria for hydrocarbons. He will send Kulakow an e-mail that explains where these values can be found.