SUMMARY OF THE REMEDIATION TECHNOLOGIES DEVELOPMENT FORUM
IN-PLACE INACTIVATION AND NATURAL ECOLOGICAL RESTORATION
TECHNOLOGIES (IINERT) SOIL-METALS ACTION TEAM
CONFERENCE CALL

April 20, 1998

On Monday, April 20, 1998, the following members of the IINERT Soil-Metals Action met in a conference call:

Bill Berti, DuPont Central Research and Development (Co-chair)
James Ryan, U.S. Environmental Protection Agency (EPA) (Co-chair)
Andrea Austin, Kansas Department of Health and Environment
Sally Brown, U.S. Department of Agriculture (USDA)
Rufus Chaney, USDA
Dean Hesterberg, North Carolina State University
Steve Germani, DuPont
David Mosby, Missouri Department of Natural Resources
Gary Pierzynski, Kansas State University
John Yang, University of Missouri-Columbia

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

COMMENTS ON THE SUMMARY FOR THE PREVIOUS CONFERENCE CALL

Berti stressed that the IINERT Soil-Metals Action Team Web page is an excellent resource. He encouraged conference-call participants to peruse the Web site at their convenience.

SITES

Since the last conference call, one site has been identified through the soil survey. Dean Hesterberg provided it. He and Berti agreed that the new site is a "burning ground" site and falls under the category of "industrial or waste site." With this site, the number of sites identified through the soil survey has climbed to 20. The break-out is:

Berti stressed that he would like to identify additional sites in the categories of industrial or waste, metal disposal, lead paint, and orchard. He asked participants whether they had leads in these areas.

Rufus Chaney is currently pursuing:

• Lead-contaminated sites. Chaney has talked to people working on the “Baltimore, Maryland, and Cambridge, Massachusetts” projects on which he is working but has not yet had a chance to submit information to Berti.
• Orchard sites. Chaney contacted Frank Peryea, a researcher who has identified two to three different soil types with high lead and arsenic contamination. Peryea is willing to give some of the soil to the RTDF team. Chaney noted that only one of Peryea’s sites is a good candidate for a field study. The other sites could provide useful barrel samples, however.

Andrea Austin told the group that she is completing the soil survey for an Army ammunition plant in Kansas and cited two other possible sites, too:

• Fort Riley. A few Fort Riley shooting ranges are under investigation.
• Kansas Army Ammunition Plant at Parsons. At this site, a lead-contaminated area in a firing range lies adjacent to Pond 28.
• At the 700 Area of this site, soluble lead has been discharged to the ground via contaminated waste water. Drainage ditches and a pond are lead-contaminated. (Lead-based detonators and cups were produced at this site.) Austin noted that the wastes have been characterized. (Sludges at the site are categorized as “listed waste,” but the waste water at the site is considered “characteristic waste.”) Extensive soil data have been collected as well. These data indicate high levels of lead and antimony, and lower levels of barium and mercury. Soils near an explosives incinerator, but not in the 700 Area, were tested for dioxins. None were found. According to a reactivity test, the soils are nonreactive.
• The Army Corps of Engineers is currently overseeing the cleanup at this site. Given the results of a treatability study, the Corps plans to solidify and stabilize the waste, follow toxicity characteristic leaching procedure (TCLP), then dispose the waste in a southeastern Kansas landfill. Remediation of the 8,000 cubic yards of contaminated material is expected to cost more than $2 million. Berti noted that, because the Corps is typically very aggressive, the soils at the site could be remediated by the end of the summer. Given this possibility, Berti suggested collecting a bulk sample from this site quickly and using it for laboratory and greenhouse experiments.

CHARACTERIZING SOILS BEFORE COLLECTING A BULK SAMPLE

Conference-call participants noted that it is important for site soils to be well-characterized before collecting a bulk sample. For sites that have not been tested extensively, the Team will likely have to fund screening tests. At other sites, like many Superfund sites, the Team will be able to use the screening data of other groups. Good soil characterization will ensure that the Team:

• Collects the most appropriate sample. Chaney noted that researchers must know the exact locations of contaminants to capture desirable bulk samples. At sites that have not been well- characterized, Chaney thought the RTDF Team should consider collecting samples from a grid to determine the exact location of contaminants. He noted that Sally Brown adopted a similar approach while working in Baltimore, Maryland. (Brown collected several small samples from field plots [although not from a grid], analyzed them separately, then determined where to collect bulk samples.)
• Avoids collecting a waste that will be expensive and difficult to dispose. James Ryan thought soils should be screened fully before the Team considers collecting a bulk sample. He warned that blindly collecting bulk samples of uncharacterized waste could haunt the team members because they would have no place to dispose the waste if it turned out to be “D-listed.” Brown said that the team may not have to worry about disposing soils in all cases. During treatability studies, she noted, site owners typically reaccept wastes after researchers complete testing. Ryan was concerned, however, that the RTDF Team would need to keep the soils for 2 to 3 years. He doubted that all site owners would reaccept the wastes after such a duration. Ryan stressed that it is crucial for the Team to consider the cost of waste disposal before collecting large site samples.

Chaney and Ryan talked about the most cost-effective way to characterize the soils so that both of the preceding objectives could be met. They agreed that it is impractical to run full screening tests on multiple-grid samples. (Some full tests cost up to $1,000.) Chaney noted that the most logical approach would be to (1) test the grid samples for desired properties only, (2) use the data collected from the grid samples to determine the most appropriate location for a bulk sample, and (3) collect a small composite sample from the designated area and subject it to full screening.

Participants discussed whether dioxin testing would be a required part of the screening tests. One participant noted that dioxins are not an issue at orchard sites. Other participants disagreed, noting that dioxins may appear to be absent from orchards sites simply because researchers never analyzed for them. On a related note, one participant noted that dioxin contamination had been reported recently in steel- mill fume waste. Before this finding, no one had reported a link between dioxin contamination and steel- mill fume waste.

SHIPPING AND WAREHOUSING COLLECTED SOILS

Conference-call participants acknowledged that they must gather additional information about how to ship hazardous waste samples. Austin said that she would contact an Army ammunition plant in Nebraska for suggestions.

Ryan said that he had identified a place in which the Team can store collected soils. Brown asked whether the Team could start sending soils to him. Ryan said they could as long as the soils were screened fully.

Berti asked how long collected soils can be stored. Ryan noted that soils labeled “samples” can be stored indefinitely. Soils earmarked for treatability studies, however, must be used more quickly.

UPDATE ON ACTIVITIES AT THE JOPLIN TEST SITE

Conference-call participants provided the following information about ongoing activities at the Joplin test site:

• Results from swine study. David Mosby was waiting to hear from Stan Casteel about the latest results obtained from the swine dosing studies. (The pigs were fed soils that had been treated on site.)
• Results from rat feeding studies. Chaney noted that the concentrations for rat feedings were being analyzed. He expected the data to be available by the next conference call.
• Mine reclamation project. Mosby was working on a mine reclamation project. He planned to conduct some phosphate treatment on mine waste. His efforts had been delayed due to difficulties with his water pollution control program.
• Collection of additional plant data. Mosby hoped to get more plant data from smelter soils and mine soils. He asked Brown about her involvement in the collection of additional plant data. Brown responded that she collected plant data in September 1997 and was still working with them. Using the data, she had conducted: (1) “total lead per plot” analyses, (2) in vitro per plot analyses (using the new Ruby et al. method), and (3) plant data per plot analyses. She said she soon planned to release a report summarizing her findings. In addition to her work on this data set, Brown planned to collect additional plant shoot samples during the week of May 17, 1998.

PLANT ROOT SAMPLES

Mosby asked the group whether anyone planned to collect plant root samples. He said that he had become more interested in root studies because of an impending need to address soil biology in the rhizosphere. An ecological risk assessment, which had been released recently, stated that certain metals (e.g., lead and zinc) are toxic to soil invertebrates (e.g., earthworms). Mosby said he wanted to learn more about root interactions at the rhizosphere and phosphate influence on lead and zinc toxicity.

The USDA team (i.e., Brown and Chaney) cited two information sources they thought might prove useful to Mosby:

• Data from the Bunker Hill site. Brown noted that researchers at this site are looking at microbial functionality for amended and below-amended soil.
• Studies of the white clover rhizobium. Chaney noted that studies of white clover rhizobium could interest Mosby. He warned, however, that such studies offer conflicting results. Researchers from the United States and Sweden obtained similar results, but a researcher from the United Kingdom generated conflicting ones.

Chaney agreed to send Mosby a reference for the Bunker Hill work as well as an annotated bibliography for earthworms and soil microbes.

Brown noted that Mosby might find it useful to analyze roots to see if pyromorphite can be found on or near the root. Researchers from Ohio State (i.e., Valerie and Trainer) conducted one such study. They found that, while lead-phosphate compounds (e.g., pyromorphite) form on the root surface and that there is no real reduction in lead-tissue concentrations in root systems, there is such a reduction in the above- ground tissue. Brown noted that it might be worthwhile to try to confirm these results by testing soil from the Joplin site. She noted that the root materials could be provided but that she would not be able to perform the experiments.

Mosby asked whether anyone else in the group thought it would be helpful to search for the formation of pyromorphites on root surfaces. Participants agreed that it would. Berti asked participants why pyromorphite on root surfaces is more desirable than in the soil. Ryan noted that both the lead solution and phosphorus concentration are high on the root surface. As a result, the root surface is the most likely place for a reaction to occur.

Participants talked about how an experiment could be conducted to search for pyromorphites on root surfaces. They relied on the Laperche, Logan, Gaddam, and Traina, 1997 paper (reference: ES&T, Volume 31, 1997, page 2745) for guidance. In this study, roots were collected from (1) a contaminated soil set and (2) a sand culture set. No special precautions were taken when collecting the root samples. The roots were simply removed, and the root and adhering soil materials were stored in plastic bags at room temperature. The samples were subjected to scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. (The SEM analysis was conducted 1 year after the samples were collected.) The results indicated that pyromorphite formed in both soil sets.

One participant recommended looking at Janet Cotter-Howells’ sampling and analysis approach, claiming that her approach does a better job at ascribing root changes (Cotter-Howells’e-mail address is j.cotter-howells@abdn.ac.uk or the following Internet address may be accessed: http://www.abdn.ac.uk/ pss/staff.htm#anchor106749). John Yang offered to talk to people who have handled biological samples to see if they could offer insight into ways to preserve biological samples.

Berti noted that it would probably be a good idea to collect limited root samples and subject them to SEM and XRD. He said that the experimental station at DuPont might be able to do some of this work. One participant noted that root samples from Joplin would not be amenable to XRD analyses due to particle size.

EXPOSURES TO INVERTEBRATES VIA PLANT ROOT INGESTION

Mosby had been focusing on identifying invertebrates that might eat plant roots. Berti asked whether lead becomes more concentrated in root systems than in the bulk soil surrounding the root systems. One participant said that the edible root has lower lead concentrations than bulk soils. The participant acknowledged that lead can accumulate in roots when it is soluble but not when it is insoluble.

PLANT SPECIES’ EFFECT ON THE TRANSFORMATION OF SOIL-LEAD TO PYROMORPHITE

Participants noted that no one has analyzed whether different plant species can hasten the transformation of soil-lead to pyromorphite. Mosby noted that he was thinking about initiating a study to determine whether planting Brassica sp. leads to a more aggressive hyperaccumulation of lead. Brown doubted that any hyperaccumulation would be detected unless ethylenediaminetetraacetic acid was added.

Participants noted that certain plants are better than others at accumulating phosphorus. Participants were unsure whether it is more desirable to use plants that are “phosphorus pigs” over those that do not capture phosphorus as readily. Berti asked participants whether it would be a good idea to identify plants at either end of the spectrum and to grow them at Joplin. The question was not resolved.

RESULTS FROM KANSAS STATE UNIVERSITY’S ACTIVITIES

Gary Pierzynski and a Ph.D. graduate student have been working together on some studies. The graduate student collected soil samples in fall 1997 at 20% gravimetric water content. (Pierzynski said that collecting samples under these conditions is a little more realistic than collecting in the slurry system.

Using these samples, Pierzynski and the graduate student are (1) looking at the effects of acidification, (2) trying to determine whether the preacidification step is useful, and (3) trying to determine how different acids affect the system. (For example, is it better to use hydrochloric acid to form chloro- pyromorphite or a different acid that forms hydroxy-pyromorphite?) For their experiments, the pair used 2,500 parts per million (ppm) of phosphorus, the molar basis of which far exceeds the lead in the soils. Pierzynski and the student acidified the sample but raised the pH back to 7.5 before starting the in vitro test.

Pierzynski said he has been surprised by the results reported to date. After 1 week of incubation with the in vitro test, no difference in extractable lead has been detected between the treated and the control sample. These results were confirmed in three different samples, one of which was collected from Joplin. These results differ from those recorded by other research teams. Pierzynski noted that the unusual results may be attributed to low moisture content or to a too-short incubation period. He asked whether the group had any comments.

Participants were surprised by the results, because all other studies have found reductions in bioaccessibility. For example, Yang’s team found that the bioavailability of lead decreased from 15.1 to 12.0 over 5 days. Like Pierzynski,Yang used 2,500 ppm of phosphorus. Unlike Pierzynski, Yang did not raise the pH back to a neutral level before extracting it for the in vitro test.

MISCELLANEOUS

Brown noted that she would be in St. Louis May 17 to 19, 1998, to attend a conference on mine problems and revegetation. Berti asked her to send him information on the meeting. Brown agreed to do so.

Mosby wanted the group to know that he had recently gotten an e-mail address (nmosbd@mail.dnr.state.mo.us).

NEXT CONFERENCE CALL

The next conference call was originally set for May 18, 1998, but the group agreed to change it to May 26 at 3:00 p.m. Berti said he would notify the group of the chosen date.