Grantee Research Project Results
2002 Progress Report: Sustainable Remediation
EPA Grant Number: R828770C003Subproject: this is subproject number 003 , established and managed by the Center Director under grant R828770
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: HSRC (2001) - Midwest Hazardous Substance Research Center
Center Director: Banks, M. Katherine
Title: Sustainable Remediation
Investigators: Shann, Jodi R. , Rogstad, Steven
Institution: University of Cincinnati
EPA Project Officer: Aja, Hayley
Project Period: October 1, 2001 through September 30, 2004
Project Period Covered by this Report: October 1, 2001 through September 30, 2002
Project Amount: Refer to main center abstract for funding details.
RFA: Hazardous Substance Research Centers - HSRC (2001) Recipients Lists
Research Category: Hazardous Waste/Remediation , Land and Waste Management
Objective:
The objective of the research project is to determine if the natural process of revegetation and succession is an effective and sustainable means of remediating and restoring historically contaminated sites. The current approach to in situ remediation using plants involves labor-intensive site preparation, planting, and maintenance of the system by replanting, watering, fertilizing, and controlling of pests. Though these activities may be less expensive than many traditional cleanup strategies, they are not necessarily cheap or sustainable over the increased duration needed to achieve acceptable remediation. Without a detailed characterization of the site (prior to planting), success is not guaranteed, as it may rely on the degree to which the species used can tolerate both the contamination present and the local environmental conditions of temperature, light, and moisture. If planted and managed systems do survive, they usually are monocultures or limited mixtures of species, lacking the diversity, complexity, and attributes of natural ecosystems. Revegetation by natural processes would eliminate the planting costs that are part of standard phytoremediation plans, and would better ensure the success of plants because they would only persist in areas that support their growth. Subsequent succession of the plant community across a site would likely lead to a self-sustaining system of increasing compositional, and perhaps functional, biodiversity. If natural revegetation results in effective soil cleanup and leads to a community that looks and functions in a fashion comparable to others in the vicinity, the outcome would be both site remediation and ecological restoration.
The project approach is split into two studies-one focused on remediation, the other on plant succession. Indicators of success under the remediation study include: decreased soil contamination and/or increased stability of contaminants. Stability is measured by this study as decreases in contaminant: (1) mobility within the soil, (2) erosion from the surface, or (3) bioavailability. Ecological restoration is the single success indicator of the succession study. Ecological integrity measures include increased site biodiversity, productivity, and soil quality.
Progress Summary:
Field Design and Sampling Activities
Prior to the actual startup of this funding (summer 2000), the onsite plots were established and the baseline sampling completed. Since then, two full field seasons (2001 and 2002) have been conducted.
Plant data (cover, species diversity, biomass/productivity) were generated in 2000, 2001, and 2002. Soil cores have been directly analyzed for total organic carbon, C/N, pH, texture, water holding capacity, and cation exchange capacity, and were extracted for metal and PAH analysis. The Remediation Technologies Development Forum (RTDF) data for 2000 and 2001 have been acquired; the 2002 data are not yet available.
Remediation. Changes in soil contamination indicate that the rate of contaminant loss from aged soils may be very slow; we have been evaluating our ability to detect real changes over time. It appears that a repeated measures approach provides adequate statistical power, but this would likely be compromised by a high degree of localized heterogeneity. Therefore, a spatial characterization of onsite contamination was conducted in August. Thirty surface cores were removed uniformly across the entire site and their locations mapped by a global positioning system (GPS). Later, 30 more cores were removed, each 1-meter from the locations of the original cores. All cores currently are being analyzed for the same parameters as plot cores. Results should allow determination of contaminant variance at the scales of interest within plots, quadrates, and the whole site. Sampling may need to be adjusted according to these variances. There also is a concern about the potential for somewhat differential sampling and sample handling protocols (between the RTDF study and this one) to invalidate direct comparisons. For this reason, the variance components associated with sampling (RTDF and SR) were calculated this summer. The strategy for this was described in the Quality Assurance Plan submitted for this project.
Increases in Contaminant Stabilization. The issues of detection and sample variance are equally important for two of the stabilization measures, contaminant mobility and bioavailability. Although all of the material has been sampled and processed, statistically sound conclusions cannot yet be drawn from the data. However, the third stabilization measure (surface erosion), can be evaluated from data on cover. Cover for this project is not canopy coverage of the surface, but the actual presence of plant stems growing out of the soil. Cover in 1999, was estimated at 25 percent, all of which was the planted cover species rye. In subsequent years, cover consisted of both rye (no longer planted in) and the local natural vegetation. From 2000 to 2002, cover increased from 32, to 58, to 80 percent. More significantly, the proportion of this cover that was rye has actually decreased over that same period from 27 to less than 20 percent. Therefore, the rapid increase in plant cover is a function of natural revegetation. Cover associated with non-rye species increased from 5 to 68 percent between 2000 and 2002.
Succession. Soil quality measures also are dependent on detection and sample variance, and are therefore not discussed in this report. However, the data on plant diversity and productivity are statistically robust. Biodiversity of the plant community is increasing significantly, which is typical of early stage succession. In terms of species richness, 28 species were found on the site (within plots) in 2000. In 2001, 42 were identified. In this last field season, 60 plant species were counted in plot sub-samples. Ecosystem productivity (measured as biomass per unit area) actually decreased between 2000 and 2002. This is a function of the decrease in rye and the increase in the natural species. Rye forms heavy clumps even if the cover is less. This complicating factor is being addressed by the separation of the biomass produced by the natural species and that produced by the rye. It is anticipated that the biomass of successional vegetation will then appear to increase each year. In addition to above-ground productivity, below-ground biomass (for individual species) was determined for the most recent field season. These data will serve as baseline for comparison to subsequent years.
Future Activities:
The field season generated an enormous data matrix, plant samples, and two different sets of soil samples. During the next few months, the samples will be processed and all the data will be entered into the project spreadsheets. By spring, it will be possible to statistically separate and collectively analyze the data from this and previous years. Beyond the needed activities for the two primary studies, some additional work has begun and is described below.
The collaboration with Dr. Nedunuri began this summer. He and one of his students spent the month of August collecting environmental data across the site, as well as the uniform samples of soil for determination of spatial heterogeneity. In addition to the spatial heterogeneity calculation, these data will be used to: (1) map whole site surface (root zone) contamination, and (2) map whole site environmental conditions. Coordinates from these "maps" will be used in GIS models to answer the question: On an aged site like this, what else influences plant establishment and ecological succession-soil contamination or the standard environmental conditions of light, moisture, and elevation? The answer to this question is beyond what was originally proposed, but will make a major contribution to our ability to predict the success of natural revegetation.
In 2002, we made assessments of plant tolerance. Seedlings of plants commonly identified on the site (e.g., goldenrod sp.) were removed to evaluate their growth, metal tolerance, and metal uptake under controlled conditions. These species now are being used in soil treatability studies. In the near future, the effect of root exudates from these same species will be applied to site soils to determine if the response of LTU soil microorganisms (to the natural vegetation) differs from the response to the planted rye. Higher increases in PAH degradation following natural plant exudate enrichment may indicate the potential for continued soil remediation (i.e., contaminate loss).
Journal Articles:
No journal articles submitted with this report: View all 14 publications for this subprojectSupplemental Keywords:
remediation, phytoremediation, polycyclic aromatic hydrocarbon, PAH, metals, waste, water, contaminated sediments, ecology, ecosystem, hazardous, hazardous waste, chemical transport, community succession, contaminant transport, contaminated soil, ecological impacts, extraction of metals, hazardous waste treatment, heavy metal contamination, heavy metals, metal contamination, metal wastes, revegetation, sustainable remediation., RFA, Scientific Discipline, Waste, Water, Contaminated Sediments, Remediation, Environmental Chemistry, Hazardous Waste, Ecology and Ecosystems, Hazardous, hazardous waste treatment, revegitation, contaminant transport, revegetation, contaminated sediment, chemical transport, contaminated soil, PAH, ecological impacts, treatment, community succession, phytoremediation, metal wastes, extraction of metals, heavy metal contamination, sustainable remediation, heavy metals, metal contaminationRelevant Websites:
http://bridge.ecn.purdue.edu/~mhsrc/ Exit
Progress and Final Reports:
Original AbstractMain Center Abstract and Reports:
R828770 HSRC (2001) - Midwest Hazardous Substance Research Center Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R828770C001 Technical Outreach Services for Communities
R828770C002 Technical Outreach Services for Native American Communities
R828770C003 Sustainable Remediation
R828770C004 Incorporating Natural Attenuation Into Design and Management
Strategies For Contaminated Sites
R828770C005 Metals Removal by Constructed Wetlands
R828770C006 Adaptation of Subsurface Microbial Biofilm Communities in Response to Chemical Stressors
R828770C007 Dewatering, Remediation, and Evaluation of Dredged Sediments
R828770C008 Interaction of Various Plant Species with Microbial PCB-Degraders
in Contaminated Soils
R828770C009 Microbial Indicators of Bioremediation Potential and Success
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.
Project Research Results
Main Center: R828770
108 publications for this center
14 journal articles for this center