Final Report: Metals Soil Pollution and Vegetative Remediation

EPA Grant Number: R825549C042
Subproject: this is subproject number 042 , 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: Metals Soil Pollution and Vegetative Remediation
Investigators: Schnoor, J. L. , Erickson, Larry E. , Pierzynski, G. M. , Just, Craig
Institution: University of Iowa
EPA Project Officer: Hahn, Intaek
Project Period: May 1, 1992 through May 1, 1996
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:

The goal of the research is to determine the feasibility and efficacy of vegetative remediation at a variety of sites with heavy metals soil pollution. Poplar trees (Populus spp.) will be utilized in the research because of their potential advantages in growth rates and ease of replanting that has been demonstrated in previous research by investigators in the Hazardous Substances Research Center, EPA Regions 7 and 8. The proposed research is a comparative study that will span three sites: two are mine tailings sites and one is contaminated with metals from atmospheric deposition in an area of severe forest die-back in Central Europe. The hypothesis of the research is that deep-planted poplar trees can be established densely at sites with metals pollution to stabilize soils from wind and water erosion and to decrease the leaching of metals to groundwater via increased evapotranspiration. The specific goals and objectives are: 1) to revegetate and remediate the sites from metals leaching and wind blown dust; 2) to perform mass balance budgets on six metals (Al, Bc, Cd, As, Pb, Zn) for four plots/catchments at three sites: and 3) to monitor vegetation to determine if the uptake of metals into leaves presents a significant problem.

Summary/Accomplishments (Outputs/Outcomes):

The rationale for the research is that 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 and Rocky Mountain Hazardous Substances Research Center. The proposed research is a comparative study at three sites with greatly different problems, so the scope of the research is to expand the applications of the HSRC to determine more broadly the potential of this innovative approach. The New York Times reported recently that mine tailings wastes account for almost half of all hazardous wastes world-wide. 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. In this research, we will attempt to establish vegetation at these sites where it has not already been accomplished.

Metals in Soil:
Extremely high zinc (39,200 +/- 16,200 mg/kg dry soil) and lead (11,600 +/- 6710 mg/kg dry soil) concentrations in surface soils at the Dearing Smelter site, Kansas indicated that the main human health hazard from the site would be by the exposure routes of wind-blown dust and ingestion by children. Arsenic concentrations in surface soils were quite high (993 +/- 127 mg/kg dry soil) at the Whitewood Creek site, South Dakota. The pH values at both sites were relatively well buffered (pH 4.9 - 6.6) suggesting that metal mobilization was not a problem. Even though there were high metals concentration at both sites, accumulation of metals into plants was not large (Hse, 1996).

Growth and Survival:

At the Whitewood Creek site, South Dakota, there were approximately 150 poplar trees still living from a total of 3000 that were planted in 1993 for an overall survival rate of 5%. Due to nutrient deficiencies, arsenic toxicity (Aoki, 1992), harsh and dry climate, and animal browse, growth and survival have been difficult at Whitewood Creek site, South Dakota. One conclusion is that it is difficult to establish vegetation at the Whitewood Creek site given multiple stresses on the trees. A second conclusion is that the original idea of decreasing wind-blown dust and vertical movement of water seems unsuccessful because of the deficient growth of trees and development of roots. Better maintenance of the Whitewood Creek site and replanting of hybrid poplar trees would be needed to ensure successful phytostabilization (Hse, 1996).

At the Dearing Smelter site, Kansas, as of September 1995 there were a total of 400 out of the original 576 trees alive for an overall survival rate of 69.4%. The survival rates were 84% for poplar trees that were planted within soil amendment (with manure) area and 58% for trees that were planted in no soil amendment (without manure) area. Despite much higher levels of cadmium, lead, and zinc at this site, poplar trees grew quite well. One conclusion is that the addition of manure to the trenches (soil amendments) significantly increased growth as measured by increases in height and trunk diameter at the Dearing Smelter site. A second conclusion is that manure addition increased the ability of poplars to accumulate cadmium but decreased the amount of lead and zinc in leaves (Hse, 1996).

Trace Element Uptake:

Metals concentrations in fallen dead, dry leaves at Whitewood Creek site were 36.8 +/- 24.9 mg/kg, 2.55 +/- 0.51 mg/kg, 1.45 +/- 0.46 mg/kg, and 351 +/- 145 mg/kg for As, Cd, Pb, and Zn, respectively. Metal concentrations in leaves at Dearing Smelter site were 6.7 mg/kg, 6.2 mg/kg, and 3000 mg/kg for Cd, Pb, and Zn, respectively. This indicates that the uptake and translocation of metals (As, Cd, and Pb) was not a problem based on EPA 503 rules for biosolids application onto land, although arsenic approached the regulatory guideline. The litter fall from trees poses little human health risk (< 1-in-a-million lifetime cancer risk) based on these guidelines. Zinc in leaves should be considered as phytotoxic to poplars at the Dearing Smelter site based on these guidelines, too (Hse, 1996).

The Plant Accumulation Factor values (PAF, ratio of concentration in plant: concentration in soil) at Whitewoad Creek site, South Dakota for arsenic were 0.0371, 0.0267, 0.0087, and 0.0190 in dead leaves, fresh leaves, dead stems, and fresh stems, respectively. These PAF values were the lowest values among the other three elements (cadmium, lead, and zinc). It is concluded that the relative amount of plant available arsenic is very small (Hse, 1996).

At the Whitewood Creek site, the PAF values for cadmium were 15.0, 6.5, 4.6, and 7.6 in dead leaves, fresh leaves, dead stems, and fresh stems, respectively. These PAF values for cadmium were the highest values compared to the other three elements (arsenic, lead, and zinc). At the Dearing Smelter site, the PAF values for cadmium were 0.064, 0.083, and 0.046 in leaves from an average of four different cultivars, from leaves within the manure treatment area, and from leaves outside of the soil amendment area, respectively. For Cd, 100 mg/kg in leaf dry matter is set as the concentration representing Cd hyperaccumulating plants (Baker, 1995). Therefore, poplar trees can not be considered a hyperaccumulating plant because the Cd concentration in poplar leaf was only 1.1 - 8.6 mg/kg (Hse, 1996).

At the Whitewood Creek site, the PAF values for lead were 0.313, 0.088, 0.060, and 0.084 in dead leaves, fresh leaves, dead stems, and fresh stems, respectively. At the Dearing Smelter site, the PAF values for lead were 0.00053, 0.00032, and 0.00075 in leaves from an average of four different cultivars, from leaves within the manure treatment area, and from leaves outside of the soil amendment area, respectively. These PAF values were low and poplar trees can be considered as metal "excluders". This lack of uptake most often is due to low plant availability and nearly irreversible binding of lead to soil exchange surfaces (Hse, 1996).

A simple chemical equilibrium model with sorption of Pb+2 to inorganic and organic sites indicated that lead would not become available until pHsoil < 5, and 99.9% of Pb(II) is adsorbed by inorganic and organic complexes surface sites which is probably unavailable for plant uptake and mobilization (Hse, 1996).

At the Whitewood Creek site, the PAF values for zinc were 0.47, 0.29, 0.12, and 0.19 in dead leaves, fresh leaves, dead stems, and fresh stems, respectively. Zinc concentration in leaves was high ( 350.75 mg/kg) indicating that poplars can uptake and translocate zinc into deciduous leaves, and it is a plant nutrient. At the Dearing Smelter site, the PAF values for zinc were 0.077, 0.071, and 0.082 in leaves from an average of four different cultivars, from leaves within the manure treatment area, and from leaves outside of the soil amendment area, respectively. Zinc concentration in leaves was relative high ( 3000 mg/kg) indicating that poplars can uptake and translocate zinc into deciduous leaves, and it is phytotoxic. However, to be considered a hyperaccumulating plant for zinc, a concentration threshold of 10,000 mg/kg in tissue has been used. Therefore, poplar trees can not be considered a hyperaccumulator for zinc (Hse, 1996).

Uptake of metals into the leaves and stems of poplar trees at the sites was not considered hazardous to humans. However, establishing a healthy stand of trees for phytostabilization is difficult. Planting poplar trees at sites such as these can only be accomplished with the addition of soil amendments such as manure and phosphate at the Dearing Smelter site (Hse, 1996).

Results from this project have been disseminated in many ways. Results have been presented at many of the Beneficial Effects of Vegetation workshops sponsored by the HSRC and at the HSRC Annual Conferences. Dr. Pierzynski is also currently using results from this work to assist state agencies from Kansas and Missouri on determining natural resource damage estimates as part of ongoing Superfund activities. Dr. Pierzynski has also been assisting the Jasper County Superfund Site Coalition from Joplin, MO as a technical expert. This is a group of citizens that represent the interests of the citizens in remediation activities in Jasper County, MO. The results have been communicated to these with environmental responsibility for these sites.

Journal Articles:

No journal articles submitted with this report: View all 5 publications for this subproject

Supplemental Keywords:

metals, soil, pollution, remediation, poplar trees, Scientific Discipline, Waste, Water, Contaminated Sediments, Remediation, Environmental Chemistry, Geochemistry, Analytical Chemistry, Ecology and Ecosystems, contaminant transport, contaminated sediment, Poplar trees, hazardous waste, chelating extraction, soil washing, contaminated soil, mining waste, heavy metal contamination, phytoremediation

Relevant Websites:


http://www.engg.ksu.edu/HSRC Exit

Progress and Final Reports:

Original Abstract
  • 1992
  • 1993
  • 1994

  • Main 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