Grantee Research Project Results
Final Report: Innovative Treatment and Bank Stabilization of Metals-Contaminated Soils and Tailings along Whitewood Creek, South Dakota
EPA Grant Number: R825549C036Subproject: this is subproject number 036 , established and managed by the Center Director under grant R825549
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: HSRC (1989) - Great Plains/Rocky Mountain HSRC
Center Director: Erickson, Larry E.
Title: Innovative Treatment and Bank Stabilization of Metals-Contaminated Soils and Tailings along Whitewood Creek, South Dakota
Investigators: Schnoor, J. L. , Licht, Louis A.
Institution: University of Iowa
EPA Project Officer: Hahn, Intaek
Project Period: May 18, 1992 through May 17, 1994
Project Amount: Refer to main center abstract for funding details.
RFA: Hazardous Substance Research Centers - HSRC (1989) RFA Text | Recipients Lists
Research Category: Groundwater, Contaminants, Treatment , Land and Waste Management
Objective:
POPLAR TREE BUFFER REMEDIATION
The first proposed remediation technique was to establish fast-growing hybrid poplar trees along Whitewood Creek to decrease wind and soil erosion of the tailings. The main scientific accomplishment was the successful establishment of a poplar tree buffer strip along a 300 foot stretch of Whitewood Creek in 1993-1994. Leaves have sprouted, indicating viability. However, there has been more than 50% loss of trees due to hail damage, possible toxic inhibition, and heavy deer browsing. We have sampled the vegetation in April and May of 1994 and have analyzed for the uptake of heavy metals. These results have been compared to previous analyses at the site.
PHOTOCHEMICAL REMEDIATION TECHNIQUE
The second proposed remediation technique involved the use of iron rich mine tailings in a remediation process for leachate based on the natural iron cycle. The natural iron cycle involves the photoreductive dissolution of iron(III) (hydr)oxides by naturally occurring ligands to produce soluble iron(II) during the day, and subsequent oxidation and reprecipitation of solid iron(III) (hydr)oxides during the night. The oxidation and reprecipitation of iron would remove such heavy metals as arsenic and cadmium from solution to concentrations less toxic through adsorption and/or coprecipitation. The solid phase precipitate formed would then be more concentrated for a possible metals recovery system. Physiochemical factors that may influence iron(II) photoproduction were investigated and included the pH of the solution, organic matter content of the mine tailings, the presence of amorphous iron oxides, soil surface area, the chemical forms of iron present in the mine tailings, and the cation exchange capacity.
Summary/Accomplishments (Outputs/Outcomes):
Mine tailings and metals pollution of soils is a major problem globally, and it has been identified as a primary research priority area of the Great Plains-Rocky Mountain Hazardous Substance Research Center. The New York Times reported recently that mine tailings wastes account for almost half of all hazardous wastes worldwide. Risk assessments at Superfund sites often reveal that exposure to wind-blown dust by inhalation and ingestion of soil by children is the greatest risk to human health.
POPLAR TREE BUFFER REMEDIATION
Approximately 3100 hybrid poplar trees (Carolina variety) were established in May of 1993. This was done to replace the losses from the planting in 1991 that were more than 50% lost to a killing frost in October of 1991. In March of 1994, a cooperator at the site sent grab samples of poplar leaves, stems, and roots to the University of Iowa for analyses. In April and May of 1994 a systematic resampling and resurvey of the vegetation was conducted by University of Iowa researchers. Metals analyses of the poplar tree sampling are shown in Table 1, in comparison with earlier analyses at the site. Lead analysis were also conducted on some of the vegetation samples at the Whitewood Creek site so that there will be intercomparisons available on two metals (Cd and Pb) between this site and the Dearing site in Kansas. Uptake of lead into the trees appears to be quite small with stem concentrations of 1.1 mg/Kg (dry weight) in a composite sample from the Whitewood Creek site. Uptake in leaves and roots were less than detectable (>1.0 mg/Kg) for lead.
There is an indication from the composite analyses of June 1992 and May 1994 that arsenic and cadmium increased in the stems and cadmium increased in the leaves of poplars as the trees grew. These samples were taken from the original planting established in May of 1991. We must monitor the bioaccumulation of heavy metals for longer periods of time. This can be accomplished through future research on the surviving vegetation at the site. There is also an indication from the March through May 1994 analyses that the newly established trees at the site have taken up higher concentrations of arsenic and cadmium in the stems and leaves than had been analyzed previously. It should be noted that the samples removed from the site in March 1994 were grab samples taken by a cooperator at the site.
PHOTOCHEMICAL REMEDIATION TECHNIQUE
Four mine tailing samples were collected from near Whitewood Creek and were identified as SST, SS1-2, SS2, and ORG. Laboratory synthesized ferrihydrite (5Fe2O3. 9H2O) used in comparison studies was also prepared. Laboratory photolysis experiments were conducted in a photochemical reactor using a 450 watt medium pressure mercury vapor lamp with a water cooled jacket. Experiments of unphotolyzed soil suspensions, used as controls, were conducted in a 1 L Erlenmeyer flask completely enclosed in aluminum foil to avoid exposure to light. Mine tailing suspensions were agitated and the pH adjusted initially to pH 2.2. Cadmium and arsenic spikes were added to the suspensions. If the effects of a ligand were to be studied, then either sodium oxalate, sodium citrate, or sodium ascorbate were also added. A sample aliquot was removed from the suspensions, filtered, and measured for iron(II), arsenic and cadmium. The suspensions in the photochemical reactor were irradiated for 6 hours while the control was kept in the dark. After 6 hours, another aliquot was removed from both suspensions, filtered, and analyzed for the same three analyses. With continued agitation, the pH was adjusted to greater than pH 7 and another aliquot was removed from both suspensions, filtered, and analyzed. After approximately 24 hours,;a final sample was removed, filtered, and the analysis repeated.
A sequential extraction procedure for iron speciation to remove ion exchangeable, sorbable, organic, chelate extractable, and acid digestible iron phases was performed on all samples and synthesized ferrihydrite. The ion exchangeable and sorbable extraction steps remove iron that is weakly, electrostatically bound to the surface of the soil particles. The organic extraction step removes iron associated to organic compounds within the soil. The chelate extractable extraction removes iron that forms polydentate ligands. The acid digestible extraction removes the remaining forms of iron in the soil and includes sulfides and carbonates. A selective extraction procedure for the concentration of iron as amorphous iron oxides was also performed on all samples and the ferrihydrite. Reductive and nonreductive dissolution of iron oxides are controlled by surface processes. Amorphous iron oxides are significantly less crystalline that other iron oxides and are characterized by large surface areas. Large surface areas thus increase the number of available iron(III) reactive surface sites and can potentially enhance both iron(II) and iron(III) dissolution. The mine tailing samples were also characterized for metals content, nutrients, pH, percentage organic matter, cation exchange capacity (CEC), and BET soil surface area.
Laboratory photolysis experiments using mine tailings resulted in reductive dissolution of iron after 6 hours at pH 2.2 and iron reprecipitation upon pH adjustment to pH>7. Irradiation enhanced the photoreductive dissolution of iron from samples as compared to the dark controls with varying degrees of iron photoreactivity among the samples. Iron(II) measured in control solutions was likely due to proton promoted dissolution of surface bound iron(II) while iron(II) measured in irradiated samples could be due to both surface bound iron(II) dissolution as well as photoreduction of iron(III) by naturally occurring reductants. Naturally occurring ligands and reductants can accelerate and enhance the reductive and nonreductive dissolution of iron from iron(III) (hydr)oxides. Soil microorganisms degrade organic matter producing ligand byproducts. Ligands can also be released in exudation products from the roots of plants and trees and include oxalate, citrate, and diphenols. Biological acids such as maleic, acetic, succinnic, tartaric, and ketogluconic acids have also been found in soils. The addition of oxalate, citrate, and ascorbate in laboratory experiments effectively enhanced iron reduction in samples but only ascorbate effectively enhanced iron reduction in dark controls. Photolysis of laboratory synthesized ferrihydrite indicated significant iron photoreactivity relative to the mine tailings.
Measured soil characteristics suggested that ion exchangeable iron, sorbable iron, organic iron, and amorphous iron oxides strongly correlated to the amount of soluble iron(II) produced in photolyzed mine tailing solutions. Each form of iron exhibited a positive correlation to iron(II) photoproduction and may be a potential source of iron available for photoreduction. Measured soil characteristics suggested that the concentration of organic matter present in the tailings plays a determining role in iron photoreduction with a positive correlation to iron(II) photoproduction. Organic matter may be indicative of naturally occurring ligands that may act as reductants and facilitate in the reductive and nonreductive dissolution of iron. Measured soil characteristics suggested that acid digestible iron may also infiuence the amount of iron(II) produced during photolysis. These forms of iron may inhibit photoreduction with a negative correlation observed for iron(II) photoproduction. Measured soil characteristics such as chelate extractable iron, cation exchange capacity, readily extractable iron, and soil surface area did not correlate significantly with iron(II) photoproduction from the mine tailings.
Irradiation of mine tailings resulted in increased removals of arsenic from solution relative to the controls. However, as increased concentrations of iron(II) were photoproduced in solution, generally concentrations of arsenic removed decreased. Photoreductive dissolution of iron competed with arsenic adsorption/coprecipitation processes. Irradiation of mine tailings did not result in significant differences in cadmium removal behavior. Dark controls and photolyzed samples had relatively similar percent removals of cadmium with slight enhancement observed in the controls. As with arsenic, as increased concentrations of iron(II) were photoproduced in solution, generally concentrations of cadmium removed decreased. One possible explanation may be due to the formation of soluble arsenic and cadmium complexes. Oxidized and unoxidized soluble organic compounds may form complexes with arsenic and cadmium and inhibit adsorption. Other ions released in solution during photolysis may also exhibit site competition. Thus, coupling iron photoreduction and oxidative reprecipitation with arsenic and cadmium removal was not very feasible.
The results have been presented at professional meeting and communicated to other interested parties.
Journal Articles:
No journal articles submitted with this report: View all 5 publications for this subprojectSupplemental Keywords:
poplar trees, immobilization, metal stabilization, arsenic, Scientific Discipline, Waste, Water, Ecosystem Protection/Environmental Exposure & Risk, Contaminated Sediments, Environmental Chemistry, Geochemistry, Remediation, Analytical Chemistry, Fate & Transport, Bioremediation, Ecology and Ecosystems, fate and transport, contaminant transport, Poplar trees, biodegradation, acid mine drainage, contaminated sediment, pesticides, metals recovery, contaminated soil, bioremediation of soils, biotechnology, contaminants in soil, chemical kinetics, acid rock drainage (ARD), mining waste, phytoremediation, heavy metal contamination, contaminated soils, heavy metalsRelevant Websites:
http://www.engg.ksu.edu/HSRC Exit
Progress and Final Reports:
Original AbstractMain Center Abstract and Reports:
R825549 HSRC (1989) - Great Plains/Rocky Mountain HSRC Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R825549C006 Fate of Trichloroethylene (TCE) in Plant/Soil Systems
R825549C007 Experimental Study of Stabilization/Solidification of Hazardous Wastes
R825549C008 Modeling Dissolved Oxygen, Nitrate and Pesticide Contamination in the Subsurface Environment
R825549C009 Vadose Zone Decontamination by Air Venting
R825549C010 Thermochemical Treatment of Hazardous Wastes
R825549C011 Development, Characterization and Evaluation of Adsorbent Regeneration Processes for Treament of Hazardous Waste
R825549C012 Computer Method to Estimate Safe Level Water Quality Concentrations for Organic Chemicals
R825549C013 Removal of Nitrogenous Pesticides from Rural Well-Water Supplies by Enzymatic Ozonation Process
R825549C014 The Characterization and Treatment of Hazardous Materials from Metal/Mineral Processing Wastes
R825549C015 Adsorption of Hazardous Substances onto Soil Constituents
R825549C016 Reclamation of Metal and Mining Contaminated Superfund Sites using Sewage Sludge/Fly Ash Amendment
R825549C017 Metal Recovery and Reuse Using an Integrated Vermiculite Ion Exchange - Acid Recovery System
R825549C018 Removal of Heavy Metals from Hazardous Wastes by Protein Complexation for their Ultimate Recovery and Reuse
R825549C019 Development of In-situ Biodegradation Technology
R825549C020 Migration and Biodegradation of Pentachlorophenol in Soil Environment
R825549C021 Deep-Rooted Poplar Trees as an Innovative Treatment Technology for Pesticide and Toxic Organics Removal from Soil and Groundwater
R825549C022 In-situ Soil and Aquifer Decontaminaiton using Hydrogen Peroxide and Fenton's Reagent
R825549C023 Simulation of Three-Dimensional Transport of Hazardous Chemicals in Heterogeneous Soil Cores Using X-ray Computed Tomography
R825549C024 The Response of Natural Groundwater Bacteria to Groundwater Contamination by Gasoline in a Karst Region
R825549C025 An Electrochemical Method for Acid Mine Drainage Remediation and Metals Recovery
R825549C026 Sulfide Size and Morphology Identificaiton for Remediation of Acid Producing Mine Wastes
R825549C027 Heavy Metals Removal from Dilute Aqueous Solutions using Biopolymers
R825549C028 Neutron Activation Analysis for Heavy Metal Contaminants in the Environment
R825549C029 Reducing Heavy Metal Availability to Perennial Grasses and Row-Crops Grown on Contaminated Soils and Mine Spoils
R825549C030 Alachlor and Atrazine Losses from Runoff and Erosion in the Blue River Basin
R825549C031 Biodetoxification of Mixed Solid and Hazardous Wastes by Staged Anaerobic Fermentation Conducted at Separate Redox and pH Environments
R825549C032 Time Dependent Movement of Dioxin and Related Compounds in Soil
R825549C033 Impact of Soil Microflora on Revegetation Efforts in Southeast Kansas
R825549C034 Modeling the use of Plants in Remediation of Soil and Groundwater Contaminated by Hazardous Organic Substances
R825549C035 Development of Electrochemical Processes for Improved Treatment of Lead Wastes
R825549C036 Innovative Treatment and Bank Stabilization of Metals-Contaminated Soils and Tailings along Whitewood Creek, South Dakota
R825549C037 Formation and Transformation of Pesticide Degradation Products Under Various Electron Acceptor Conditions
R825549C038 The Effect of Redox Conditions on Transformations of Carbon Tetrachloride
R825549C039 Remediation of Soil Contaminated with an Organic Phase
R825549C040 Intelligent Process Design and Control for the Minimization of Waste Production and Treatment of Hazardous Waste
R825549C041 Heavy Metals Removal from Contaminated Water Solutions
R825549C042 Metals Soil Pollution and Vegetative Remediation
R825549C043 Fate and Transport of Munitions Residues in Contaminated Soil
R825549C044 The Role of Metallic Iron in the Biotransformation of Chlorinated Xenobiotics
R825549C045 Use of Vegetation to Enhance Bioremediation of Surface Soils Contaminated with Pesticide Wastes
R825549C046 Fate and Transport of Heavy Metals and Radionuclides in Soil: The Impacts of Vegetation
R825549C047 Vegetative Interceptor Zones for Containment of Heavy Metal Pollutants
R825549C048 Acid-Producing Metalliferous Waste Reclamation by Material Reprocessing and Vegetative Stabilization
R825549C049 Laboratory and Field Evaluation of Upward Mobilization and Photodegradation of Polychlorinated Dibenzo-P-Dioxins and Furans in Soil
R825549C050 Evaluation of Biosparging Performance and Process Fundamentals for Site Remediation
R825549C051 Field Scale Bioremediation: Relationship of Parent Compound Disappearance to Humification, Mineralization, Leaching, Volatilization of Transformaiton Intermediates
R825549C052 Chelating Extraction of Heavy Metals from Contaminated Soils
R825549C053 Application of Anaerobic and Multiple-Electron-Acceptor Bioremediation to Chlorinated Aliphatic Subsurface Contamination
R825549C054 Application of PGNAA Remote Sensing Methods to Real-Time, Non-Intrusive Determination of Contaminant Profiles in Soils
R825549C055 Design and Development of an Innovative Industrial Scale Process to Economically Treat Waste Zinc Residues
R825549C056 Remediation of Soils Contaminated with Wood-Treatment Chemicals (PCP and Creosote)
R825549C057 Effects of Surfactants on the Bioavailability and Biodegradation of Contaminants in Soils
R825549C058 Contaminant Binding to the Humin Fraction of Soil Organic Matter
R825549C059 Identifying Ground-Water Threats from Improperly Abandoned Boreholes
R825549C060 Uptake of BTEX Compounds by Hybrid Poplar Trees in Hazardous Waste Remediation
R825549C061 Biofilm Barriers for Waste Containment
R825549C062 Plant Assisted Remediation of Soil and Groundwater Contaminated by Hazardous Organic Substances: Experimental and Modeling Studies
R825549C063 Extension of Laboratory Validated Treatment and Remediation Technologies to Field Problems in Aquifer Soil and Water Contamination by Organic Waste Chemicals
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: R825549
904 publications for this center
182 journal articles for this center