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Letter Report for Characterization of Biochar

Description: On 27 November 2012, a bulk biochar sample was received for characterization of selected physical and chemical properties. The main purpose of the characterization was to help determine the degree to which biochar would be suitable as a soil amendment to aid in growth of plants. Towards this end, analyses to determine specific surface, pH, cation-exchange capacity, water retention, and wettability (i.e. surface tension) were conducted. A second objective was to determine how uniform these properties were in the sample. Towards this end, the sample was separated into fractions based on initial particle size and on whether the material was from the external surface or the internal portion of the particle. Based on the results, the biochar has significant liming potentials, significant cation-retention capacities, and highly variable plant-available moisture retention properties that, under the most favorable circumstances, could be helpful to plants. As a consequence, it would be quite suitable for addition to acidic soils and should enhance the fertility of those soils.
Date: April 9, 2013
Creator: Amonette, James E.
Partner: UNT Libraries Government Documents Department

Multi-Channel Auto-Dilution System for Remote Continuous Monitoring of High Soil-CO2 Fluxes

Description: Geological sequestration has the potential capacity and longevity to significantly decrease the amount of anthropogenic CO2 introduced into the atmosphere by combustion of fossil fuels such as coal. Effective sequestration, however, requires the ability to verify the integrity of the reservoir and ensure that potential leakage rates are kept to a minimum. Moreover, understanding the pathways by which CO2 migrates to the surface is critical to assessing the risks and developing remediation approaches. Field experiments, such as those conducted at the Zero Emissions Research and Technology (ZERT) project test site in Bozeman, Montana, require a flexible CO2 monitoring system that can accurately and continuously measure soil-surface CO2 fluxes for multiple sampling points at concentrations ranging from background levels to several tens of percent. To meet this need, PNNL is developing a multi-port battery-operated system capable of both spatial and temporal monitoring of CO2 at concentrations from ambient to at least 150,000 ppmv. This report describes the system components (sampling chambers, measurement and control system, and power supply) and the results of a field test at the ZERT site during the late summer and fall of 2008. While the system performed well overall during the field test, several improvements to the system are suggested for implementation in FY2009.
Date: April 23, 2009
Creator: Amonette, James E. & Barr, Jonathan L.
Partner: UNT Libraries Government Documents Department

Overcoming Barriers to the Remediation of Carbon Tetrachloride through Manipulation of Competing Reaction Mechanisms--Final Technical Report

Description: The premise of this project was that if we understood the fundamental chemistry that controls the branching among product formation pathways for the degradation of CCl4, we could design remediation strategies that minimize the formation of CHCl3 and thereby provide badly needed alternatives for remediation of the large plumes of CCl4 that contaminate several DOE sites. To this end, we performed a series of coordinated batch, spectroscopic, and modeling experiments, to study the effect of a variety of factors on the yield of CHCl3 from CCl4 during reduction with zero-valent iron (Fe0). The factors studied include those with direct implications for field performance (e.g., the concentration of CCl4 relative to the amount of iron surface area) and others chosen for diagnosis of the reaction mechanism (e.g., incorporation of deuterium into CCl4 reduction products in the presence of D2O). The key mechanistic findings of this study are (i) that CCl3• probably is not an intermediate in the formation of CF, but CCl3− probably is, (ii) the high reductive capacity of the Fe0 core favors the concerted 2e− reduction, and (iii) magnetite on Fe0 favors the benign product formation pathway. The latter conclusion is based on the observation that one type of nano-sized Fe0 that is coated with magnetite shell produces low yields of chloroform (0-40%), whereas others produce the higher yields of chloroform (60-100%) that are typical of most methods for reducing CCl4 (including biodegradation). Since nano-Fe0 can, in principle, be introduced into the deep subsurface by injection, our results would suggest that the right type of nano-Fe0 introduced in the right way might be highly effective at dechlorinating CCl4 with minimal formation of CHCl3 or other undesirable by-products. This conclusion may offer a breakthrough in the search for remediation technologies that are suitable for the deep CCl4-contamination at DOE sites ...
Date: March 7, 2007
Creator: Tratnyek, Paul G.; Amonette, James E. & Bylaska, Eric J.
Partner: UNT Libraries Government Documents Department

Project Work Plan Carbon Tetrachloride and Chloroform Attenuation Parameter Studies: Heterogeneous Hydrolytic Reactions

Description: Between 1955 and 1973, an estimated 750,000 kg of carbon tetrachloride were discharged to the soil in the 200 West Area of the Hanford Site as part of the plutonium production process. Of this amount, some carbon tetrachloride reached the groundwater more than 70 m below the ground surface and formed a plume of 10 km2. Recent information has shown that the carbon tetrachloride plume extends to a depth of at least 60 m below the water table. Some carbon tetrachloride has been degraded either by the original process or subsequent transformations in the subsurface to form a co-existing chloroform plume. Although current characterization efforts are improving the conceptual model of the source area, more information is needed to effectively assess the fate and transport of carbon tetrachloride and chloroform to support upcoming remediation decisions for the plume. As noted in a simulation study by Truex et al. (2001), parameters describing porosity, sorption, and abiotic degradation have the largest influence on predicted plume behavior. The work proposed herein will improve the ability to predict future plume movement by better quantifying abiotic degradation mechanisms and rates. This effort will help define how much active remediation may be needed and estimate where the plume will eventually stabilize – key factors in determining the most appropriate remedy for the plume.
Date: June 1, 2006
Creator: Amonette, James E.; Truex, Michael J. & Fruchter, Jonathan S.
Partner: UNT Libraries Government Documents Department

Overcoming Barriers to the Remediation of Carbon Tetrachloride through Manipulation of Competing Reaction Mechanisms

Description: Most approaches that have been proposed for the remediation of groundwater contaminated with carbon tetrachloride (CCl4) produce chloroform (CHCl3) as the major product and methylene chloride (CH2Cl2) as a minor product. Both of these products are nearly as persistent and problematic as the parent compound, but competing reaction pathways produce the more desirable products carbon monoxide (CO) and/or formate (HCOO-). Results scattered throughout the chemical and environmental engineering literature show that the branching between these reaction pathways is highly variable, but the controlling factors have not been identified. If we understood the fundamental chemistry that controls the branching among these, and related, product-formation pathways, we could improve the applicability of a host of remediation technologies (both chemical and biological) to the large plumes of CCl4 that contaminate DOE sites across the country. This project will provide the first complete characterization of the mechanisms and kinetics of competing degradation reactions of CCl4 through laboratory experiments in simple model systems closely coordinated with theoretical modeling studies. The results provide strategies for maximizing the yield of desirable products from CCl4 degradation, and the most promising of these will be tested in column model systems using real site waters and matrix materials.
Date: June 1, 2004
Creator: Tratnyek, Paul G.; Amonette, James E. & Bylaska, Eric J. and Szecsody, James E.
Partner: UNT Libraries Government Documents Department

Overcoming Barriers to the Remediation of Carbon Tetrachloride through Manipulation of Competing Reaction Mechanisms

Description: Most approaches that have been proposed for the remediation of groundwater contaminated with carbon tetrachloride (CCl{sub 4}) produce chloroform (CHCl{sub 3}) as the major product and methylene chloride (CH{sub 2}Cl{sub 2}) as a minor product. Both of these products are nearly as persistent and problematic as the parent compound, but competing reaction pathways produce the more desirable products carbon monoxide (CO) and/or formate (HCOO{sup -}). Results scattered throughout the chemical and environmental engineering literature show that the branching between these reaction pathways is highly variable, but the controlling factors have not been identified. If we understood the fundamental chemistry that controls the branching among these, and related, product-formation pathways, we could improve the applicability of a host of remediation technologies (both chemical and biological) to the large plumes of CCl{sub 4} that contaminate DOE sites across the country. This project will provide the first complete characterization of the mechanisms and kinetics of competing degradation reactions of CCl{sub 4} through laboratory experiments in simple model systems closely coordinated with theoretical modeling studies. The results provide strategies for maximizing the yield of desirable products from CCl{sub 4} degradation, and the most promising of these will be tested in column model systems using real site waters and matrix materials.
Date: June 1, 2003
Creator: Tratnyek, Paul G.; Amonette, James E.; Bylaska, Eric J. & Szecsody, James E.
Partner: UNT Libraries Government Documents Department

Overcoming Barriers to the Remediation of Carbon Tetrachloride through Manipulation of Competing Reaction Mechanisms

Description: Most approaches that have been proposed for the remediation of groundwater contaminated with carbon tetrachloride (CCl{sub 4}) produce chloroform (CHCl{sub 3}) as the major product and methylene chloride (CH{sub 2}Cl{sub 2}) as a minor product. Both of these products are nearly as persistent and problematic as the parent compound, but competing reaction pathways produce the more desirable products carbon monoxide (CO) and/or formate (HCOO{sup -}). Results scattered throughout the chemical and environmental engineering literature show that the branching between these reaction pathways is highly variable, but the controlling factors have not been identified. If we understood the fundamental chemistry that controls the branching among these, and related, product-formation pathways, we could improve the applicability of a host of remediation technologies (both chemical and biological) to the large plumes of CCl{sub 4} that contaminate DOE sites across the country. This project will provide the first complete characterization of the mechanisms and kinetics of competing degradation reactions of CCl{sub 4} through laboratory experiments in simple model systems closely coordinated with theoretical modeling studies. The results provide strategies for maximizing the yield of desirable products from CCl{sub 4} degradation, and the most promising of these will be tested in column model systems using real site waters and matrix materials.
Date: June 15, 2004
Creator: Tratnyek, Paul G.; Amonette, James E.; Bylaska, Eric J. & Szecsody, James E.
Partner: UNT Libraries Government Documents Department

Interfacial Reduction-Oxidation Mechanisms Governing Fate and Transport of Contaminants in the Vadose Zone

Description: Immobilization of toxic and radioactive metals (e.g., Cr, Tc, and U) in the vadose zone by the In Situ Gaseous Reduction (ISGR) using hydrogen sulfide (H2S) is a promising technology for soil remediation. Earlier laboratory studies have shown that Cr(VI) in soil samples can be effectively immobilized by treatment with dilute gaseous H2S. A field test completed in 1999 at White Sand Missile Range, New Mexico, has shown a 70% immobilization of Cr(VI). The objective of this EMSP project is to characterize the interactions among H2S, the metal contaminants, and soil components. Understanding these interactions is needed to optimize the remediation system and to assess the long-term effectiveness of the technology. Proposed research tasks included: (A) Evaluation of the potential catalytic effect of mineral surfaces on the rate of Cr(VI) reduction by H2S and the rate of H2S oxidation by air; (B) Identification of the reactions of soil minerals with H2S and determination of associated reaction rates; (C) Evaluation of the role of soil water chemistry on the reduction of Cr(VI) by H2S; (D) Assessment of the reductive buffering capacity of H2S-reduced soil and the potential for emplacement of long-term vadose zone reactive barriers; and (E) Evaluation of the potential for immobilization of Tc and U in the vadose zone by reduction and an assessment of the potential for remobilization by subsequent reoxidation.
Date: June 1, 2003
Creator: Deng, Baolin; Thornton, Edward C.; Cantrell, Kirk J.; Olsen, Khris B. & Amonette, James E.
Partner: UNT Libraries Government Documents Department

Abiotic Degradation Rates for Carbon Tetrachloride and Chloroform: Progress in FY2009

Description: This report documents the progress made through FY 2009 on a project initiated in FY 2006 to help address uncertainties related to the rates of hydrolysis in groundwater for carbon tetrachloride (CT) and chloroform (CF). The study seeks also to explore the possible effects of contact with minerals and sediment (i.e., heterogeneous hydrolysis) on these rates. In previous years the work was funded as two separate projects by various sponsors, all of whom received their funding from the U.S. Department of Energy (DOE). In FY2009, the projects were combined and funded by CH2MHill Plateau Remediation Corporation (CHPRC). Work in FY2009 was performed by staff at the Pacific Northwest National Laboratory (PNNL). Staff from the State University of New York at Cortland (SUNY–Cortland) contributed in previous years.
Date: March 2010
Creator: Amonette, James E.; Jeffers, Peter M.; Qafoku, Odeta; Russell, Colleen K.; Wietsma, Thomas W. & Truex, Michael J.
Partner: UNT Libraries Government Documents Department

Abiotic degradation rates for carbon tetrachloride and chloroform: Final report.

Description: This report documents the objectives, technical approach, and progress made through FY 2012 on a project initiated in FY 2006 to help address uncertainties related to the rates of hydrolysis in groundwater for carbon tetrachloride (CT) and chloroform (CF). The project also sought to explore the possible effects of contact with minerals and sediment (i.e., heterogeneous hydrolysis) on these rates. We conducted 114 hydrolysis rate experiments in sealed vessels across a temperature range of 20-93 °C for periods as long as 6 years, and used the Arrhenius equation to estimate activation energies and calculate half-lives for typical Hanford groundwater conditions (temperature of 16 °C and pH of 7.75). We calculated a half-life of 630 years for hydrolysis for CT under these conditions and found that CT hydrolysis was unaffected by contact with sterilized, oxidized minerals or Hanford sediment within the sensitivity of our experiments. In contrast to CT, hydrolysis of CF was generally slower and very sensitive to pH due to the presence of both neutral and base-catalyzed hydrolysis pathways. We calculated a half-life of 3400 years for hydrolysis of CF in homogeneous solution at 16 °C and pH 7.75. Experiments in suspensions of Hanford sediment or smectite, the dominant clay mineral in Hanford sediment, equilibrated to an initial pH of 7.2, yielded calculated half-lives of 1700 years and 190 years, respectively, at 16 °C. Experiments with three other mineral phases at the same pH (muscovite mica, albite feldspar, and kaolinite) showed no change from the homogeneous solution results (i.e., a half-life of 3400 years). The strong influence of Hanford sediment on CF hydrolysis was attributed to the presence of smectite and its ability to adsorb protons, thereby buffering the solution pH at a higher level than would otherwise occur. The project also determined liquid-vapor partition coefficients for CT under ...
Date: December 1, 2012
Creator: Amonette, James E.; Jeffers, Peter M.; Qafoku, Odeta; Russell, Colleen K.; Humphrys, Daniel R.; Wietsma, Thomas W. et al.
Partner: UNT Libraries Government Documents Department

Abiotic Degradation Rates for Carbon Tetrachloride: and Chloroform: Progress in FY 2008

Description: This is a letter report summarizing work performed in FY2008 to determine the rates of carbon tetrachloride hydrolysis at temperatures close to actual groundwater temperatures. The report describes the project, the methodology, and the results obtained since the project's inception in FY2006. Measurements of hydrolysis rates in homogeneous solution have been completed for temperaturs of 70 C through 40 C, with additional data available at 30 C and 20 C. These results show no difference between the rates in deionized H2O and in filter-sterilized Hanford-Site groundwater. Moreover, the rates measured are 2-3 times slower than predicted from the open literature. Measurements of rates involving sterile suspensions of Hanford-Site sediment in Hanford-Site groundwater, however, show faster hydrolysis at temperatures below 40 C. Extrapolation of the current data available suggests a six-fold increase in rate would be expected at groundwater temperature of 16 C due to the presence of the sediment. This result translates into a 78-year half-life, rather than the 470-680 year half-life that would be predicted from rate determinations in homogeneous solution. The hydrolysis rate data at 20 C, in contrast to those at higher temperatures, are preliminary and have low statistical power. While significant (p < 0.05) differences between the heterogeneous and homogeneous systems are seen at 30 C, the results at 20 C are not statistically significant at this level due to limited data and the very slow nature of the reaction. More time is needed to collect data at these low temperatures to improve the statistical power of our observation. Given the critical need for hydrolysis rate data at temperatures relevant to groundwater systems, we have three recommendations for future work. First, we recommend a continuation of the sampling and analysis of the remaining long-term sealed-ampule experiments described in this report. These are primarily 20 C and ...
Date: October 31, 2008
Creator: Amonette, James E.; Jeffers, Peter M.; Qafoku, Odeta; Russell, Colleen K.; Wietsma, Thomas W. & Truex, Michael J.
Partner: UNT Libraries Government Documents Department

Abiotic Degradation Rates for Carbon Tetrachloride and Chloroform: Progress in FY 2010

Description: This report documents the progress made through FY 2010 on a project initiated in FY 2006 to help address uncertainties related to the rates of hydrolysis in groundwater at the Hanford Site for carbon tetrachloride (CT) and chloroform (CF). The study also explores the possible effects of contact with minerals and sediment (i.e., heterogeneous hydrolysis) on these rates. The research was initiated to decrease the uncertainties in abiotic degradation rates of CT and chloroform CF associated with temperature and possible heterogeneous effects. After 2 years of data collection, the first evidence for heterogeneous effects was identified for hydrolysis of CT, and preliminary evidence for the effects of different mineral types on CF hydrolysis rates also was reported. The CT data showed no difference among mineral types, whereas significant differences were seen in the CF results, perhaps due to the fact that CF hydrolyzes by both neutral and base-catalyzed mechanisms whereas CT follows only the neutral hydrolysis path. In this report, we review the project objectives, organization, and technical approaches taken, update the status and results of the hydrolysis-rate experiments after 4 years of experimentation (i.e., through FY 2010), and provide a brief discussion of how these results add to scientific understanding of the behavior of the CT/CF plume at the Hanford Site.
Date: December 8, 2010
Creator: Amonette, James E.; Jeffers, Peter M.; Qafoku, Odeta; Russell, Colleen K.; Humphrys, Daniel R.; Wietsma, Thomas W. et al.
Partner: UNT Libraries Government Documents Department

Interfacial Reduction-Oxidation Mechanisms Governing Fate and Transport of Contaminants in the Vadose Zone

Description: Immobilization of toxic and radioactive metals (e.g., Cr, Tc, and U) in the vadose zone by in situ gaseous reduction using hydrogen sulfide (H2S) is a promising technology the U.S. Department of Energy (DOE) is developing for soil remediation. Earlier laboratory studies have shown that Cr(VI) in a number of soil samples can be effectively immobilized by treatment with dilute gaseous H2S. A field test has also been completed that resulted in 70% immobilization of Cr(VI). The objective of this project is to characterize the interactions among H2S, the metal contaminants, and soil components. Understanding these interactions is needed to assess the long-term effectiveness of the technology and to optimize the remediation system.
Date: June 1, 2001
Creator: Deng, B.; Thornton, Edward C.; Olsen, Khris B.; Cantrell, Kirk J. & Amonette, James E.
Partner: UNT Libraries Government Documents Department

Interfacial Reduction-Oxidation Mechanisms Governing Fate and Transport of Contaminants in the Vadose Zone

Description: Immobilization of toxic and radioactive metals (e.g., Cr, Tc, and U) in the vadose zone by In Situ Gaseous Reduction (ISGR) using hydrogen sulfide (H2S) is a promising technology for soil remediation. Earlier laboratory and field studies have shown that Cr(VI) can be effectively immobilized by treatment with dilute gaseous H2S. The objective of this project is to characterize the interactions among H2S, the metal contaminants, and soil components. Understanding these interactions is needed to assess the long-term effectiveness of the technology and to optimize the remediation system. Proposed research tasks include: (A) Evaluation of the potential catalytic effect of mineral surfaces on the rate of Cr(VI) reduction by H2S and the rate of H2S oxidation by air; (B) Identification of the reactions of soil minerals with H2S and determination of associated reaction rates; (C) Evaluation of the role of soil water chemistry on the reduction of Cr(VI) by H2S; (D) Assessment of the reductive buffering capacity of H2S reduced soil and the potential for emplacement of long-term vadose zone reactive barriers; (E) Evaluation of the potential for immobilization of Tc and U in the vadose zone by reduction and an assessment of the potential for remobilization by subsequent reoxidation. Through a collaborative effort in the last three years, Tasks A, B, C, and E have been completed, resulting in a much improved understanding of reaction kinetics and mechanisms involved in the Cr(VI)-H2S-O2-Soil System and the treatability for Tc and U. Research on Task C will continue in the one-year period of no-cost extension granted to this project. The result will be submitted to the Department of Energy by October 2003 as a supplement to this report.
Date: June 1, 2002
Creator: Deng, Baolin; Thornton, Edward C.; Cantrell, Kirk J.; Olsen, Khris B. & Amonette, James E.
Partner: UNT Libraries Government Documents Department