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

November 14, 2000
12:30–2:00 p.m.

On November 14, 2000, 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:

Phil Sayre, U.S. Environmental Protection Agency (EPA) (Subgroup Co-Chair)
Steve Geiger, ThermoRetec, Inc.
Peter Kulakow, Kansas State University
Kirk O’Reilly, Chevron Corporation
David Tsao, BP Amoco
Duane Wolf, University of Arkansas

Also present was Christine Hartnett of Eastern Research Group, Inc. (ERG).

ADDITIONAL AVENUES OF RESEARCH AT THE SUBGROUP FIELD SITES

Phil Sayre announced that EPA’s Office of Research and Development (ORD) has issued a request for proposals for phytoremediation research projects. Proposals, Sayre said, are due in January 2001. Grants will be awarded to non-profit or academic institutions located in the United States.

Conference call members said it would be useful if ORD grants could be used to perform additional research at the TPH in Soil Subgroup’s field sites. Duane Wolf said that he thought the sites made an ideal choice for additional research, since so much background information has already been collected on them. Call participants identified the following as areas that would be of particular interest to pursue:

Microbial community structure. Wolf expressed interest in researching whether phytoremediation induces changes in microbial community structures. He said that it would be informative to compare microbial community structures across a number of sites. Several call participants expressed enthusiasm for this idea. Steve Geiger noted that Microbial Insights, Inc., a company that uses molecular-based approaches to characterize microbial communities, might be able to assist in the effort.

Bioavailability issues. Sayre said that the relationship between bioavailability and risk is of great interest to EPA. Many representatives from the industrial sector and some from the government sector argue that a contaminant is not of concern if it is not bioavailable. If such a stance is adopted at the large scale, Sayre said, this would obviously have significant ramifications for regulatory frameworks. If this stance were adopted, Sayre continued, scientists would have to address the following question: Could changing site conditions cause a non-bioavailable contaminant to become bioavailable? For example, scientists would need to determine whether changes in soil pH impact bioavailability. Kirk O’Reilly said that it would be very interesting to learn more about the bioavailability of hydrocarbons at the Subgroup’s sites and to determine what impact plants have on bioavailability. He did, however, question whether such a research effort is feasible at this point. He said that the Petroleum Environmental Research Forum (PERF) recently used a variety of extraction methods to study bioavailability at sites employing bioremediation technologies. PERF’s report, O’Reilly said, concluded that it is difficult to assess bioavailability. Accordingly, he questioned whether research methodologies are sufficiently developed to detect how plant systems affect bioavailability. Call participants agreed that there is not currently a universally accepted methodology, but did note that several new protocols are emerging. For example, Geiger said, the Gas Research Institute is performing work in this area, a researcher in Texas is exploring different techniques, a researcher in Oklahoma recently released a review article on surrogate tests, and the National Environmental Policy Institute plans to release a white paper that addresses bioavailability. Sayre also said that the National Science Foundation (NSF) is evaluating bioavailability, noting that NSF dedicated a meeting to this topic a few months ago.

Sayre said that some researchers attribute changes in the bioavailability of contaminants in soil to interactions with microbes and plant exudates. He asked whether call participants had a hunch about which of the two has a more dramatic impact on bioavailability. Geiger believes microbes are the major player, but he recommended against trying to elucidate the exact contribution of microbes and plant exudates. Doing so would be very costly, he said; at this point, more could be gained by obtaining crude measurements of bioavailability. O’Reilly asked whether evaluating plant uptake makes it easier to assess bioavailability issues, and asked whether the Subgroup’s current field test protocol includes such evaluations. It does, said Peter Kulakow and Geiger.

Fundamental hypotheses that underpin the concept of phytoremediation. O’Reilly said that scientists have developed several hypotheses to explain why phytoremediation enhances degradation. He suggested researching some of these basic hypotheses. Call participants agreed that it would be useful to evaluate some of the fundamental mechanisms that have been proposed. Sayre said that efforts could be initiated to evaluate the interactions between microorganisms, plants, chemicals, soils, and sediments. Wolf expressed interest in learning more about the roles that different types of microbes play in degradation processes. While researchers have exhibited much interest in studying bacteria, he said, very few have focused effort on evaluating microrhizal fungi. He said that fungi might play a large role in the degradation process at hot and dry sites. Another conference call participant noted that just knowing that plants increase total bacterial numbers does not provide enough evidence that phytoremediation is working. Researchers need to hone in on the subset of bacteria that are responsible for the degradation and determine how their numbers are impacted by phytoremediation systems.

Sayre asked whether it would be possible to dovetail the microbial community analysis and the bioavailability efforts together. Call participants expressed interest in this suggestion. They agreed that the Subgroup’s site owners would be amenable to having the above-listed research efforts initiated at their sites. Kulakow and Wolf, both of whom are affiliated with universities, said that they would discuss some of these issues in greater depth and consider drafting proposals for the ORD grants. They will discuss the matter in further detail on November 20, 2000. Assuming that the decision is made to go forth with a proposal, Wolf said, a draft version will be completed before the next Subgroup conference call.

Call participants asked whether anyone outside of the RTDF Subgroup has expressed interest in performing field work at the Subgroup field sites. Sayre said that someone contacted Ernie Lory asking about opportunities. David Tsao said that he knew of some researchers in Scotland and the United Kingdom who are interested. Wolf said that researchers in Canada might also be interested.

ACTION ITEMS

O’Reilly agreed to fax Kulakow the bibliography from the PERF report. He also agreed to mail a hard copy.

Sayre agreed to send Subgroup members information that he recently received from NSF.

ERG agreed to set up the next TPH in Soil Subgroup conference call for Monday, December 4, 2000, between 12:30 and 2:00 Eastern Standard Time.

Kulakow and Wolf will discuss the possibility of writing proposals for the ORD grants.