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Final Report: The Response of Natural Groundwater Bacteria to Groundwater Contamination by Gasoline in a Karst Region
EPA Grant Number: R825549C024Subproject: this is subproject number 024 , 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: The Response of Natural Groundwater Bacteria to Groundwater Contamination by Gasoline in a Karst Region
Investigators: OConner, John T. , Brazos, Blaise J.
Institution: University of Missouri - Columbia
EPA Project Officer: Manty, Dale
Project Period: February 22, 1990 through February 21, 1992
Project Amount: Refer to main center abstract for funding details.
RFA: Hazardous Substance Research Centers - HSRC (1989)
Research Category: Organic Chemical Contamination of Soil/Water
Description:
Objective:Because of the timeliness, scale and prominent locale of this particular spill, the authors feel that there is a unique opportunity for investigations coordinated with a state regulatory agency and its contractor relative to the spread and natural bioremediation of the components of gasoline in a Karst region. Summary/Accomplishments (Outputs/Outcomes):
The Karst geology provides an unusual bioreactor in which calcium carbonate saturation, high alkalinity and neutral-to-alkaline pH is maintained despite microbial production of carbon dioxide. In addition, dissolved oxygen concentrations may be maintained for prolonged periods, owing to the lack of organic carbon concentrations which are generally less than 0.5 mg/L and often, as low as 0.2 to 0.3 mg/L as carbon. The unique feature of the study derives from the dolomitic limestone surface in contact with the migrating water. This surface would be expected to serve as a favorable substrate for the attachment of periphytic bacteria and for the formation of a biological film capable of oxidizing the organic contaminants.
The fact that contaminated water moves relatively rapidly through the large pores and solution channels of the Karst may, in fact, be beneficial for natural bioremediation if the attached film is spread over an extensive area. This would be analogous to a lowered food to microorganism ratio (BOD/contact surface area) in the treatment of wastewater by trickling filtration. The important aspect of this hypothesis is that, if the kinetics of biodegradation by microbial films attached to dolomite is favorable, additional remedial options may be available in Karst regions. For example, withdrawing and recharging (recirculation) or vertical water table modulation (surging to enhance surface contact with attached films) may be acceptable alternatives to water extraction and treatment at the surface.
The proposed study was conducted in two phases. The first phase was directed at obtaining field data to determine the characteristics of the subsurface material, the persistence of the contaminant and its effect on observed natural microbial populations in water samples taken from affected wells. The data obtained yield the rate of overall contaminant depletion as influenced by well operation, dilution, volatilization, adsorption, abiotic and biotic degradation.
The second phase, conducted simultaneously with the field survey, was directed at determining the extent of microbial degradation of contaminants in laboratory studies. Contaminated water was applied to columns packed with Lake of the Ozarks dolomitic limestone.
The natural decrease in contaminant concentration was observed in a longitudinal study where well water samples were collected and analyzed monthly for specific constituents of gasoline (benzene, etc.) by gas chromatography in accordance with Standard Methods (17). In addition, the microbial community were monitored monthly by epifluorescent microscopy (acridine orange direct count, AODC) (18) to determine the total number and by heterotrophic plate count (HPC) by pour plate and spread plate at 35?C and 20?C, respectively (17). Each of the contaminated well waters was characterized initially by measurements of total organic carbon, mineral composition, oxygen concentration and temperature. In conjunction with observed changes in organic contaminant concentrations, changes in the indices of microbial ecology (biomass, activity, diversity and number) were monitored to determine whether the biodegradation of the contaminants was related to changes in the planktonic microbial community. The in-situ groundwater conditions were preserved by collection of samples with minimal exposure to the atmosphere.
The assessment of changes in the microbial ecology resulting from organic contamination of groundwater was the pivotal feature of the study. If readily discernible ecological changes accompany contamination and recovery of well water quality, then biodegradation was a factor in contaminant dissipation.
In recent years an extensive list of sophisticated methods have been developed within the discipline of microbial ecology for the determination of biomass, activity, diversity and number. The following methods were chosen to quantitate the four components of the groundwater microbial ecology based upon both the author's experience with the methods and the suitability of the method to this study.
The diversity was determined both by direct microscopic examination and by calculation of a diversity index, such as the ratio of HPC to total bacteria. The authors have previously shown that the natural assemblages of microorganisms in 83 Missouri groundwaters are exceptionally low (104 to 105 total bacteria/mL). The numbers of microorganisms were enumerated by both direct count and culture by plate count. The biomass was calculated from direct measurement of cell size. This was accomplished by measurement of cell volumes from projected micrographs, and conversion of cell volume to biomass. Since groundwater planktonic populations were hypothesized as being relatively inactive, increases in their relative activity due to petroleum degradation was readily discernible. Five methods for estimating organism activity were evaluated for this application. These included: INT reduction with AODC, microautoradiography with AODC, frequency of dividing cells by AODC, thymidine incorporation, and heterotrophic potential.
In Phase two, laboratory studies were conducted to simulate contaminated groundwater flow through the dolomitic, limestone present in the Lake of the Ozarks Karst. Groundwater was circulated through three separate glass columns, 6 feet long and 8 inches in diameter, with teflon seals and stainless steel caps. These columns were filled with limestone fragments derived from well coring and flows were adjusted to simulate three different rates of water migration. The total surface area of limestone in each column was measured and the appropriate recirculation flow was adjusted to achieve a range of contact surface area to water volume ratios. The appropriate range was estimated from hydrologic data accumulated by the State Geological Survey. However, the empty bed contact times are on the order of one week, one day and three hours, respectively, in order to alter A/V ratios by seven to eight times between columns. The columns were stored in a temperature - controlled, dark room at actual site groundwater temperatures (approx. 12?C) and samples were collected weekly for analysis of the specific organic contaminants and planktonic organism population. Each month, smooth limestone fragments or glass slides were removed from glass ports located in the lower portion of each column. These surfaces were scraped to recover the attached organisms. As in the case of the planktonic community, the periphytic organism numbers, biomass, diversity and activity were measured by the methods cited previously. Peristaltic pumps were used to recirculate the water stored in glass tanks. Each of the three storage tanks were covered with a collapsible polyethylene "bladder" to maintain the in-situ groundwater conditions and minimize volatilization as samples were withdrawn throughout the study. A static control was used for comparison with the recirculating systems.
The results of these studies indicated the relative effect of the accumulated periphytic community under various flow conditions on the biodegradation of the specific contaminants. They also indicated qualitatively whether there were significant potential benefits from improved contact between the contaminated water and the confining media.
These results indicated the rate at which native microorganisms were acting to reduce degradable constituents. They also indicated the organism populations achieved in groundwater relative to the amount of organic substrate present. This served as a monitoring index of continuing biodegradation.
Both the Missouri Department of Natural Resources and Riedel Environmental Services have evaluated the contamination site. They have constructed three monitoring wells in addition to five private wells which are now contaminated to evaluate the spread of the contaminant. The private wells are all approximately 150 feet deep and are cased to 120 feet. The monitoring wells are 38 feet deep and located down gradient of the contaminant site. In addition, two corings have been drilled to determine the subsurface strata.
The coring have shown that the area consists of fractured dolomite down to the lower Gasconade Formation. The dolomite in addition to being highly fractured also contains vugs which are non-contiguous. The monitoring wells have shown that the gasoline is spreading due to changes in the lake level of the Lake of the Ozarks and downgradient pumping activities by one landowner. Originally the gasoline was resting on top of the water table and was 14 feet deep. It has now spread over an area 500 feet long by 400 feet wide and is now 8 feet deep at the center of the plume.
The Department of Natural Resources has been monitoring the levels of benzene, toluene, xylene and ethylbenzene in seven drinking water wells in the affected area. The total BTXE levels have increased to 5000 ppb. Well owners have utilized granular activated carbon filters to remove the contaminants.
Riedel Environmental Services has conducted a Recovery Feasibility Study. They conducted pumping tests using both dyes and ions. In addition, a vapor recovery test has been performed on these wells. Their recommendations, which have not been approved by MDNR indicate that the initial recovery will be by liquid separation followed by GAC adsorption on the surface. The only in situ treatment may be air stripping as necessary to remove volatile components trapped in pockets.
Three columns for the laboratory study have been constructed. They are large (200 mm) diameter to accommodate limestone and have heavy glass walls which will help maintain a constant temperature of 12 ?C in the recirculating system.
The results have been presented at professional meetings and shared with other interested parties.
Journal Articles:No journal articles submitted with this report: View all 1 publications for this subproject
Supplemental Keywords:Karst region, bacteria, biodegradation, fate. , Ecosystem Protection/Environmental Exposure & Risk, Geographic Area, Scientific Discipline, Waste, RFA, Remediation, Analytical Chemistry, Hazardous Waste, EPA Region, Fate & Transport, Environmental Chemistry, Hazardous, Ecology and Ecosystems, Geochemistry, Bioremediation, gasoline, aquatic ecosystem, biodegradation, fate and transport, microbial degradation, phytoremediation, fate and transport , chemical transport, groundwater, contaminated aquifers, chemical kinetics, hazardous wate, Region 8, contaminated sediments, contaminated soil, well water, contaminated groundwater, groundwater remediation, Region 7, aerobic degradation
Relevant Websites:
Progress and Final Reports:
Original Abstract
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