SUMMARY OF THE REMEDIATION TECHNOLOGIES DEVELOPMENT FORUM

SUMMARY OF THE REMEDIATION TECHNOLOGIES DEVELOPMENT FORUM
PHYTOREMEDIATION ACTION TEAM
TOTAL PETROLEUM HYDROCARBON IN SOIL SUBGROUP
CONFERENCE CALL

February 27, 2001
12:30 p.m.–2:00 p.m.

On February 27, 2001, 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 Corporation (Subgroup Co-Chair)
Steve Geiger, ThermoRetec, Inc.
Peter Kulakow, Kansas State University (KSU)
Kirk O’Reilly, Chevron Corporation
David Tsao, BP Amoco
Duane Wolf, University of Arkansas

UPDATE ON FIELD DEMONSTRATION SITES

The TPH in Soil Subgroup has created a field study program to evaluate how effectively plants degrade petroleum hydrocarbons. Call participants provided updates on sites that are participating in the program.

Site A. Lucinda Jackson said that fertilizer was recently applied at Site A.
Site F. Steve Geiger said that the willows at Site F are healthy and growing tall. He is waiting for the Arthur D. Little Laboratory (ADL) to send results for the time two (T₂) samples.
Site G. Peter Kulakow said that Site G has received significant precipitation this winter.
Site H. David Tsao said that it is still unclear whether a phytoremediation demonstration project will be established at Site H. He asked whether it is too late for the site to be included in the Subgroup’s demonstration program. Kulakow did not think so, noting that results for Site H could be summarized in an addendum to the Subgroup’s final report. Geiger asked whether the Total Petroleum Hydrocarbon Criteria Working Group (TPHCWG) was used to set cleanup levels for this site. Tsao said that a modified version of the methodology was employed, and agreed to ask the site’s regulator whether it could be shared with Subgroup members.
Site I. Tsao said that time zero (T₀) samples have been collected at Site I and sent to ADL.
Site J. Duane Wolf said that samples were collected from Site J six months after the demonstration project was initiated. These samples are being stored at the University of Arkansas but will be sent to ADL soon. The next round of samples, Wolf said, will be collected in March or May 2001. He also noted that root samples have been collected and that information about biomass volume is available. Kulakow expressed interest in visiting Site J, collecting root samples, and comparing his results to those obtained by the University of Arkansas. Wolf said that this could be arranged.
Site K. Kulakow said that samples were collected from Site K in fall 2000. He has received some of the data from this sampling event. (He has data collected from the phytoremediation plots, but not from the natural attenuation plots. The latter, Kulakow said, serve as the control for this site.)

THE SUBGROUP’S ANNUAL REPORT

Kulakow said that he plans to complete the Subgroup’s annual report by June 30, 2001. He hopes to include T₀ data for Site I, T₁ data for Sites B and G, and T₂ data for Sites A and F. In addition, he hopes data will be available for Sites C, D, and E.

Kulakow acknowledged that the Subgroup’s focus is to study hydrocarbons, but asked whether it would be useful to include information about metals in the Subgroup’s annual report. Call participants said that data on metals might be available for Sites A, C, D, E, and J. Jackson agreed to talk to Site A’s manager about the possibility of including data on metals in the Subgroup’s annual report.

PLANT TISSUE ANALYSIS

Regulators have expressed concern about the potential for phytoremediation to create new exposure pathways. The concern, Tsao said, is that contaminants could be introduced to the foodchain when animals eat plant roots and shoots. Call participants agreed that there were three ways in which animals might be exposed:

Exposure to contaminants that have been incorporated into plant tissues. Kulakow said that polycyclic aromatics (PAHs) in soils can be taken up into plant roots and shoots. According to the current literature, however, uptake of PAHs via this route is not expected to be extensive. Any soil contaminant that is incorporated into plant tissues, Kulakow said, is more likely to: (1) accumulate in roots rather than shoots, and (2) represent a low-range rather than a high-range PAH. Kulakow said that PAHs in ambient air can also be absorbed by plants and incorporated into tissues. Jackson confirmed this, noting that plants near roadways have higher PAH concentrations in their tissues than plants located in less developed areas. Kulakow said that the source (i.e., soil versus air) of PAH can be determined by examining PAH fingerprints.
Exposure to soil that adheres to the plant tissues. Call participants noted that soil that adheres to root surfaces will contain PAHs. In addition, contaminated soil dust will blow onto plant shoots.
Exposure to surface soil that surrounds the plants. One call participant said that plants will attract animals to contaminated areas. When these animals sit down to eat, soil will stick to their fur. This soil might be ingested when the animal cleans itself.

The Subgroup’s protocol recommends analyzing plant tissue samples from each site after the third growing season. By performing these analyses, call participants said, the Subgroup will be able to determine whether significant uptake of contaminants occurred. Kulakow said that he has started drafting a protocol for the tissue analysis. In summary, he plans to recommend:

Collect plant material. Kulakow said that two root samples and two shoot samples should be collected from each of the Subgroup’s sites. One set of root and shoot samples should be collected from areas planted with the standard grass mix treatment, he said, and the other set should be collected from areas planted with the site-specific plant mix. Noting that each site has several replicates of each treatment type, Kulakow recommended collecting samples from the plots with the highest contaminant concentrations. Each of the samples, he said, should represent a composite from the chosen plot. He said that the Subgroup will need to talk about the percentage of old and new plant material to include in the sample. The former would probably be more heavily impacted by air deposition than the latter.
Dry the plant material. Kulakow said that plant tissues should be dried before they are analyzed. Enough material should be collected to generate 50 grams of dried material.
Wash the roots and shoots. Kulakow said that roots and shoots will need to be washed with a surfactant to remove soils adhered to roots and dust settled on shoots. That way, researchers will be able to distinguish between contaminants that have been incorporated into the plant from those that just adhere to the plant. If investigators want to know what risk adhering soils and dust cause, Tsao said, the wash material could be analyzed for contaminants.
Send samples to a laboratory for analysis. Kulakow said that ADL has created a protocol for plant tissue analysis, noting that ADL performed the analytical work for the Craney Island site. Kulakow said that EPA has also generated a protocol and that he plans to forward this to ADL. Kulakow said that many judgment calls are associated with plant tissue analysis. Thus, he recommended setting up a conference call so that ADL and Subgroup members could discuss the protocol.

Kulakow said that he would distribute a draft protocol to Subgroup members and EPA regulators for comment. Tsao agreed to show the draft to representatives from the Interstate Technology and Regulatory Cooperation (ITRC) Work Group.

Kulakow said that it might be useful to run the plant tissue analysis for all of the sites at the same time. That way, results would be comparable. Call participants agreed that this was an interesting idea, but noted that not all of the sites will be ready for sampling at the same time. Kirk O’Reilly did not think that holding times would be an issue with plant material. If this is true, materials collected from one site could be placed in storage until the samples from other sites are available. As an alternative, another call participant suggested setting one date for plant sampling. If this approach were taken, all the samples would be collected at the same time even though the sites would be at different stages. Thus, while tissues being analyzed at one site might have been collected after the third growing season, tissues collected at another may have been pulled after just one growing season. Jackson did not think this was a good idea; she feared using this approach would confound results. Nevertheless, the question did prompt call participants to note that it would be wise to re-evaluate why the end of the third growing season was chosen as the most appropriate sampling time.

NEXT FACE-TO-FACE MEETING

Subgroup members agreed that it would be useful to hold a meeting in fall 2001. They identified two options for their meeting:

Hold a Subgroup meeting in conjunction with the October 22–25, 2001, Contaminated Soils Conference in Amherst, Massachusetts. Kulakow said that he submitted an abstract for this conference, asking for permission to speak about the RTDF’s activities. In addition, he told the conference planners that the TPH in Soil Subgroup might be interested in holding a meeting in conjunction with the conference. The meeting planners were amenable to this idea.
Hold a stand-alone RTDF Phytoremediation Action Team meeting. Jackson said that it might be useful to hold a stand-alone RTDF meeting, involving all three Phytoremediation Action Team subgroups, rather than piggybacking with another conference. Kulakow and Tsao said that they would talk to Steve Rock about this option and find out whether he has suggestions for meeting location. Kulakow identified two locations that might serve as good candidates: (1) KSU in Manhattan, Kansas, and (2) Purdue University in West Lafayette, Indiana. Kulakow was quite sure that KSU would be interested in hosting a meeting, and said that he would contact representatives from Purdue University to determine whether they had any interest in doing so.

After researching different options, Kulakow and Tsao will distribute information about potential meeting locations and solicit feedback from Subgroup members.

COST ESTIMATES

A spreadsheet, available at www.rtdf.org, has been prepared to track the costs of the Subgroup’s demonstration project. Kulakow said that he still needs data for Sites A, C, D, E, G, and I. Once data are filled in for these sites, Geiger said, Subgroup members will need to hold a conference call to talk about extrapolating the costs to obtain estimates for full-scale application costs. The model applied at the Craney Island site, Geiger said, might be a useful tool to use for the extrapolation exercise. The unit cost ($ per cubic foot) for full-scale applications is expected to be lower than that calculated for field scale applications. This is because: (1) there are likely to be economies of scale, and (2) sampling activities are not likely to be as intense. Call participants agreed that it would be useful to present the costs by volume as well as by unit area; using a volume measurement will help engineers compare the costs associated with phytoremediation with those incurred by other remediation technologies.

MISCELLANEOUS TOPICS

Call participants talked about the following miscellaneous topics:

Funding for KSU. For the last couple years, Kulakow said, KSU has been supporting the Subgroup by processing raw data, tracking the progress of Subgroup field sites, performing site visits and plant assessments, and writing annual reports. KSU recently submitted a proposal to EPA’s Technology Innovation Office (TIO) asking for funds to continue this support.
Grants. Kulakow noted that EPA’s Office of Research and Development issued a request for proposals for phytoremediation research projects. He said that he and Wolf submitted proposals.
New documents and databases. Tsao said that the ITRC recently completed a technical and regulatory guidance document that addresses phytoremediation. Kulakow said that a new database, called Phytorem, is available on CD-Rom. This database lists plants that accumulate, tolerate, or hyperaccumulate metals. Tsao said that Terry McIntyre has agreed to send 25 copies of the CD to Rock or Phil Sayre.
Nitrogen sources. Wolf said that he plans to evaluate plant uptake of nitrogen. Before initiating his studies, he must decide upon an appropriate nitrogen source to use. He said that the literature indicates that urea is not as good to use as ammonium nitrate or ammonium sulfate. Wolf asked whether call participants had experimented with different nitrogen sources, and if they had, whether they had noticed differences in nitrogen availability rates between the different sources. O’Reilly said that he had not noticed differences.
Media attention. Jackson said that much interest has been expressed in phytoremediation lately, noting that reporters from Forbes and The New York Times recently contacted her with questions about phytoremediation. Call participants also noted that Lena Ma’s article on phytoremediation appeared in a recent edition of Nature. Wolf said that he and Kathy Banks provided some information about phytoremediation to a reporter from ABCNews.com.
Habitat restoration. Tsao said that the Wildlife Habitat Council has expressed interest in using phytoremediation to restore certain areas near Houston and Texas City. Wolf said that he has been contacted by people who are also interested in using phytoremediation for habitat restoration, but that he is a bit reluctant to pursue this avenue until more is known about the link between phytoremediation and potential ecological risks.

ACTION ITEMS

Tsao agreed to let the regulators associated with Site H know that it is not too late to become involved with the Subgroup’s demonstration program. He will also ask them whether the modified TPHCWG methodology can be shared with Subgroup members.
Kulakow agreed to contact Mike Reynolds to determine whether new data are available for Sites C, D, and E.
Jackson agreed to talk to Site A’s manager about the possibility of including data on metals in the Subgroup’s annual report.
Kulakow agreed to send EPA’s plant tissue analysis protocol to ADL.
Kulakow agreed to distribute a draft plant tissue analysis protocol to Subgroup members and EPA regulators. Tsao agreed to show the draft to representatives from ITRC.
Kulakow and Tsao agreed to talk to Rock about the next face-to-face meeting. In addition, Kulakow will determine whether Purdue University has any interest in hosting a meeting. After researching different options, Kulakow and Tsao will distribute information about potential meeting locations and solicit feedback from Subgroup members.
Call participants will send Kulakow cost data.
ERG will set up the next TPH in Soil Subgroup conference call for April 19, 2001, between 12:30 and 2:00 p.m. Eastern Standard Time.