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Dennis G Grubb - One of the best experts on this subject based on the ideXlab platform.

  • stabilization of cu contaminated army Firing Range soils using waste oyster shells
    Environmental Geochemistry and Health, 2011
    Co-Authors: Deok Hyun Moon, Kyung Hoon Cheong, Jeehyeong Khim, Dennis G Grubb
    Abstract:

    A stabilization/solidification (S/S) process was used to immobilize Cu in contaminated soils obtained from two army Firing Ranges sites (A and B) with total Cu concentrations of 520 and 380 mg/kg, respectively. Both waste oyster shells (WOS) and pretreated oyster shells (POS) were used to immobilize Cu in the contaminated soils. Waste oyster shells passing the #10 mesh and #20 mesh were used for the Sites A and B, respectively. WOS- and POS-treated soil samples cured for 28 days were evaluated for Cu leaching by the Korean Standard Leaching Test (KSLT) method. Slurry suspensions were prepared to investigate the Cu immobilization mechanism using X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM) energy dispersive X-ray spectroscopy (EDX) analyses. The treatment results showed that the POS treatment was more effective than the WOS treatment of 28 days. For Site A, 10 wt% WOS and 3 wt% POS dosages were required to pass the Korean warning standard of 50 mg/kg, while 10 wt% WOS and 5 wt% POS dosages were required for the Site B treatment. The XRPD and SEM-EDX results showed that Cu immobilization was strongly linked to both CSH/CAH and ettringite. Overall, the POS treatment was effective at immobilizing the Cu in the contaminated soils, very likely due to its CaO content.

  • Phosphate treatment of Firing Range soils: lead fixation or phosphorus release?
    Journal of Environmental Quality, 2008
    Co-Authors: Dimitris Dermatas, Maria Chrysochoou, Dennis G Grubb, Xuanfeng Xu
    Abstract:

    : Phosphate treatment of lead (Pb)-contaminated soils relies on the premise that Pb converts to the thermodynamically stable, insoluble mineral class of pyromorphites. Recent research showed that treatment performance is kinetically controlled and strongly dependent on soil pH; this study employed an acidic phosphate (P) form, monobasic calcium phosphate (MCP), to investigate treatment performance of Pb occurring in an alkaline-buffered and an acidic Firing Range soil. The results of leaching, X-ray powder diffraction (XRPD), and modeling analyses showed that P and Pb dissolution in the alkaline soil and transformation reactions were kinetically controlled, so that: (i) TCLP (toxicity characteristic leaching procedure) and SPLP (synthetic precipitation leaching procedure) results were poor to marginal even at high MCP dosages; (ii) brushite (Ca(HPO(4)).2H(2)O) and cerussite (PbCO(3)) persisted in XRPD patterns; and, (iii) geochemical modeling failed to predict leaching and phase assemblages. In the acidic soil, Pb-P reactions promoted further soil acidification, improved TCLP performance, and generated better agreement with the equilibrium-based model; however, SPLP and modeling results showed that Pb concentrations could not be reduced below 15 microg/L mainly due to the low soil pH. The marginal or inadequate Pb immobilization was observed in both soils despite the elevated MCP dosages, which were well in excess of the pyromorphite stoichiometric ratio (P/Pb = 0.6). Additionally, P leaching concentrations and rates were extremely high (>300 mg/L), under both SPLP and deionized (DI) water extraction conditions, and as predicted by thermodynamic equilibrium. The performance and sustainability of phosphate-based treatment therefore seem questionable.

  • Phosphate application to Firing Range soils for Pb immobilization: The unclear role of phosphate
    Journal of Hazardous Materials, 2007
    Co-Authors: Maria Chrysochoou, Dimitris Dermatas, Dennis G Grubb
    Abstract:

    Phosphate treatment has emerged as a widely accepted approach to immobilize Pb in contaminated soils and waste media, relying on the formation of the highly insoluble mineral pyromorphite as solubility-controlling phase for Pb. As such, phosphate treatment has been proposed as a Best Management Practice (BMP) for Firing Ranges where Pb occurs in its metallic forms and several other phases (carbonates, oxides). While pyromorphite thermodynamically has the potential to control Pb solubility at low levels, its formation is kinetically controlled by pH, the solubility of the phosphate source, and the solubility of Pb species. Treatability studies have shown that excess quantities of soluble and acidic phosphate sources, such as phosphoric acid, are necessary for successful in situ treatment. Even under these conditions, Extended X-ray Absorption Fine Structure (EXAFS), the only reliable method to identify and quantify Pb speciation, showed that Pb conversion to pyromorphite in in situ treated soils was less than 45% after 32 months. Furthermore, the use of lime (CaO) to restore soil pH in acidified soil treatments inhibited further conversion. Additionally, phosphate treatment is known to reduce bioavailability through pyromorphite formation in the intestinal tract, and the phytoaccumulation of Pb; both desirable effects for Pb-impacted areas. Given the costs of phosphate treatment, the use of biogenic phosphate sources, such as bone meal, may be a more environmentally sustainable approach toward this end. In the many studies focusing on phosphate treatment, the attendant P leaching and eutrophication have been largely overlooked, along with other issues such as the enhanced leaching of oxyanionic contaminants, such as Se, As and W. The success and sustainability of applying phosphate as a BMP in Firing Range soils therefore remain questionable.

  • Pb speciation versus TCLP release in army Firing Range soils
    Journal of hazardous materials, 2006
    Co-Authors: Dimitris Dermatas, Maria Chrysochoou, Dennis G Grubb, G. Shen, Nektaria Menounou, P. Dutko
    Abstract:

    A series of soil parameter and mineralogical investigative techniques were applied to assess the Pb speciation in four US Army Firing Range soils that presented significantly different Pb leaching regimes and soil characteristics. Soil gradation tests were complemented by total chemical analyses, X-ray powder diffraction (XRPD), Rietveld quantification, optical microscopy and scanning electron microscopy (SEM) analyses. The bulk geotechnical, mineralogical and chemical analyses pointed to two possible Pb retention mechanisms: precipitation as lead carbonate and sorption in the case of fine-grained soils. Lead speciation and mobility was further investigated by the toxicity characteristic leaching procedure (TCLP) and sequential extraction test (SET). As the TCLP Pb concentrations did not necessarily reflect the total Pb analysis of the soils, the Pb leachability ratio (TCLP/total) was found to be controlled by soil mineralogy and its response to changes in system pH. Geochemical modeling, using Visual MINTEQ, was employed to evaluate the mechanisms that controlled the observed TCLP Pb leaching behavior. It was found that lead carbonate precipitation/dissolution reactions controlled Pb TCLP leachability in all soils, while sorptive phenomena did not seem to play a role even in the case of fine-grained soils. More specifically, TCLP Pb leachability was controlled by the pH, the available Pb and the available carbonate in solution. This indicates that geochemical modeling strongly complimented TCLP Pb analyses. Thus, geochemical modeling is an important assessment tool to evaluate the magnitude of site-specific Pb-related environmental problems in Firing Range soils. Carbonation reactions, involving metallic Pb, that occur during the SET obscure its ability to reliably ascertain Pb speciation. More specifically, SET lumps the extractable Pb into predetermined phase categories that may not be truly representative of the actual soil mineralogy or dominant forms of Pb in the soil. A thorough geotechnical, mineralogical and chemical investigation of Firing Range soils, complemented by geochemical modeling, was therefore found to be a more reliable approach to evaluate Pb speciation and TCLP release in Firing Range soils.

Dimitris Dermatas - One of the best experts on this subject based on the ideXlab platform.

  • a quantitative xanes evaluation of the tclp applicability in phosphate induced lead stabilization for Firing Range soils
    Environmental Earth Sciences, 2015
    Co-Authors: Guodong Zheng, G. Shen, Yoshio Takahashi, Dimitris Dermatas
    Abstract:

    An acidic (pH 5.2) Firing Range soil, FDR26 in New Jersey, with Pb content of 6,017 mg kg−1, was amended by adding 2.5 wt% fish bone grains. The leaching test, toxicity characteristic leaching procedure (TCLP), and spectroscopic technique, non-destructive X-ray absorption near edge structure (LCF-XANES), were employed to determine the leaching behavior and Pb speciation prior to and after the TCLP test. The TCLP-Pb was 209 mg L−1 after the standard 18 h of tumbling and was increased to 288 mg L−1 after an extended tumbling time of 96 h. The XANES of TCLP residue confirmed the existence of extractable Pb species following the 18 h extraction. TCLP-Pb was also reduced to 1.4 mg L−1 after phosphate addition followed by 28 days of curing. LCF-XANES results revealed the transformation of metallic Pb into insoluble pyromorphite precipitates during the leaching test. The acidic extraction solution significantly increased the dissolution of phosphate source and Pb species, and resulted in improved Pb immobilization.

  • Phosphate treatment of Firing Range soils: lead fixation or phosphorus release?
    Journal of Environmental Quality, 2008
    Co-Authors: Dimitris Dermatas, Maria Chrysochoou, Dennis G Grubb, Xuanfeng Xu
    Abstract:

    : Phosphate treatment of lead (Pb)-contaminated soils relies on the premise that Pb converts to the thermodynamically stable, insoluble mineral class of pyromorphites. Recent research showed that treatment performance is kinetically controlled and strongly dependent on soil pH; this study employed an acidic phosphate (P) form, monobasic calcium phosphate (MCP), to investigate treatment performance of Pb occurring in an alkaline-buffered and an acidic Firing Range soil. The results of leaching, X-ray powder diffraction (XRPD), and modeling analyses showed that P and Pb dissolution in the alkaline soil and transformation reactions were kinetically controlled, so that: (i) TCLP (toxicity characteristic leaching procedure) and SPLP (synthetic precipitation leaching procedure) results were poor to marginal even at high MCP dosages; (ii) brushite (Ca(HPO(4)).2H(2)O) and cerussite (PbCO(3)) persisted in XRPD patterns; and, (iii) geochemical modeling failed to predict leaching and phase assemblages. In the acidic soil, Pb-P reactions promoted further soil acidification, improved TCLP performance, and generated better agreement with the equilibrium-based model; however, SPLP and modeling results showed that Pb concentrations could not be reduced below 15 microg/L mainly due to the low soil pH. The marginal or inadequate Pb immobilization was observed in both soils despite the elevated MCP dosages, which were well in excess of the pyromorphite stoichiometric ratio (P/Pb = 0.6). Additionally, P leaching concentrations and rates were extremely high (>300 mg/L), under both SPLP and deionized (DI) water extraction conditions, and as predicted by thermodynamic equilibrium. The performance and sustainability of phosphate-based treatment therefore seem questionable.

  • Phosphate application to Firing Range soils for Pb immobilization: The unclear role of phosphate
    Journal of Hazardous Materials, 2007
    Co-Authors: Maria Chrysochoou, Dimitris Dermatas, Dennis G Grubb
    Abstract:

    Phosphate treatment has emerged as a widely accepted approach to immobilize Pb in contaminated soils and waste media, relying on the formation of the highly insoluble mineral pyromorphite as solubility-controlling phase for Pb. As such, phosphate treatment has been proposed as a Best Management Practice (BMP) for Firing Ranges where Pb occurs in its metallic forms and several other phases (carbonates, oxides). While pyromorphite thermodynamically has the potential to control Pb solubility at low levels, its formation is kinetically controlled by pH, the solubility of the phosphate source, and the solubility of Pb species. Treatability studies have shown that excess quantities of soluble and acidic phosphate sources, such as phosphoric acid, are necessary for successful in situ treatment. Even under these conditions, Extended X-ray Absorption Fine Structure (EXAFS), the only reliable method to identify and quantify Pb speciation, showed that Pb conversion to pyromorphite in in situ treated soils was less than 45% after 32 months. Furthermore, the use of lime (CaO) to restore soil pH in acidified soil treatments inhibited further conversion. Additionally, phosphate treatment is known to reduce bioavailability through pyromorphite formation in the intestinal tract, and the phytoaccumulation of Pb; both desirable effects for Pb-impacted areas. Given the costs of phosphate treatment, the use of biogenic phosphate sources, such as bone meal, may be a more environmentally sustainable approach toward this end. In the many studies focusing on phosphate treatment, the attendant P leaching and eutrophication have been largely overlooked, along with other issues such as the enhanced leaching of oxyanionic contaminants, such as Se, As and W. The success and sustainability of applying phosphate as a BMP in Firing Range soils therefore remain questionable.

  • Pb speciation versus TCLP release in army Firing Range soils
    Journal of hazardous materials, 2006
    Co-Authors: Dimitris Dermatas, Maria Chrysochoou, Dennis G Grubb, G. Shen, Nektaria Menounou, P. Dutko
    Abstract:

    A series of soil parameter and mineralogical investigative techniques were applied to assess the Pb speciation in four US Army Firing Range soils that presented significantly different Pb leaching regimes and soil characteristics. Soil gradation tests were complemented by total chemical analyses, X-ray powder diffraction (XRPD), Rietveld quantification, optical microscopy and scanning electron microscopy (SEM) analyses. The bulk geotechnical, mineralogical and chemical analyses pointed to two possible Pb retention mechanisms: precipitation as lead carbonate and sorption in the case of fine-grained soils. Lead speciation and mobility was further investigated by the toxicity characteristic leaching procedure (TCLP) and sequential extraction test (SET). As the TCLP Pb concentrations did not necessarily reflect the total Pb analysis of the soils, the Pb leachability ratio (TCLP/total) was found to be controlled by soil mineralogy and its response to changes in system pH. Geochemical modeling, using Visual MINTEQ, was employed to evaluate the mechanisms that controlled the observed TCLP Pb leaching behavior. It was found that lead carbonate precipitation/dissolution reactions controlled Pb TCLP leachability in all soils, while sorptive phenomena did not seem to play a role even in the case of fine-grained soils. More specifically, TCLP Pb leachability was controlled by the pH, the available Pb and the available carbonate in solution. This indicates that geochemical modeling strongly complimented TCLP Pb analyses. Thus, geochemical modeling is an important assessment tool to evaluate the magnitude of site-specific Pb-related environmental problems in Firing Range soils. Carbonation reactions, involving metallic Pb, that occur during the SET obscure its ability to reliably ascertain Pb speciation. More specifically, SET lumps the extractable Pb into predetermined phase categories that may not be truly representative of the actual soil mineralogy or dominant forms of Pb in the soil. A thorough geotechnical, mineralogical and chemical investigation of Firing Range soils, complemented by geochemical modeling, was therefore found to be a more reliable approach to evaluate Pb speciation and TCLP release in Firing Range soils.

  • Lead Leachability in Firing Range Soils
    Environmental Engineering Science, 2006
    Co-Authors: Dimitris Dermatas, G. Shen, Nektaria Menounou, P. Dutko, M Dadachov, V. Tsaneva
    Abstract:

    This study focuses on investigation of the effects of Pb transformation products (Pb forms in the soil) on Pb leachability by evaluating Toxicity Characteristic Leaching Procedure (TCLP) data from samples taken out of six different Firing Ranges. In all the soils tested, TCLP Pb leachability levels and total Pb concentrations were found to be above the regulatory limits set by the U.S. EPA and state agencies. However, TCLP Pb leachability levels did not always correlate well with total Pb concentrations. Formation of Pb carbonates was found to play an important role in controlling Pb leachability and precipitation was found to be an important Pb immobilization mechanism in all soils tested. The effect of posttumbling TCLP (leaching) pH, soil buffering capacity, grain size, and mineralogy on Pb leachability was also considered. The leaching pH effect was most pronounced in the Range that showed the lowest Pb leachability, and was attributed to the presence of buffering compounds in this soil. Pb leachabili...

Maria Chrysochoou - One of the best experts on this subject based on the ideXlab platform.

  • Phosphate treatment of Firing Range soils: lead fixation or phosphorus release?
    Journal of Environmental Quality, 2008
    Co-Authors: Dimitris Dermatas, Maria Chrysochoou, Dennis G Grubb, Xuanfeng Xu
    Abstract:

    : Phosphate treatment of lead (Pb)-contaminated soils relies on the premise that Pb converts to the thermodynamically stable, insoluble mineral class of pyromorphites. Recent research showed that treatment performance is kinetically controlled and strongly dependent on soil pH; this study employed an acidic phosphate (P) form, monobasic calcium phosphate (MCP), to investigate treatment performance of Pb occurring in an alkaline-buffered and an acidic Firing Range soil. The results of leaching, X-ray powder diffraction (XRPD), and modeling analyses showed that P and Pb dissolution in the alkaline soil and transformation reactions were kinetically controlled, so that: (i) TCLP (toxicity characteristic leaching procedure) and SPLP (synthetic precipitation leaching procedure) results were poor to marginal even at high MCP dosages; (ii) brushite (Ca(HPO(4)).2H(2)O) and cerussite (PbCO(3)) persisted in XRPD patterns; and, (iii) geochemical modeling failed to predict leaching and phase assemblages. In the acidic soil, Pb-P reactions promoted further soil acidification, improved TCLP performance, and generated better agreement with the equilibrium-based model; however, SPLP and modeling results showed that Pb concentrations could not be reduced below 15 microg/L mainly due to the low soil pH. The marginal or inadequate Pb immobilization was observed in both soils despite the elevated MCP dosages, which were well in excess of the pyromorphite stoichiometric ratio (P/Pb = 0.6). Additionally, P leaching concentrations and rates were extremely high (>300 mg/L), under both SPLP and deionized (DI) water extraction conditions, and as predicted by thermodynamic equilibrium. The performance and sustainability of phosphate-based treatment therefore seem questionable.

  • Phosphate application to Firing Range soils for Pb immobilization: The unclear role of phosphate
    Journal of Hazardous Materials, 2007
    Co-Authors: Maria Chrysochoou, Dimitris Dermatas, Dennis G Grubb
    Abstract:

    Phosphate treatment has emerged as a widely accepted approach to immobilize Pb in contaminated soils and waste media, relying on the formation of the highly insoluble mineral pyromorphite as solubility-controlling phase for Pb. As such, phosphate treatment has been proposed as a Best Management Practice (BMP) for Firing Ranges where Pb occurs in its metallic forms and several other phases (carbonates, oxides). While pyromorphite thermodynamically has the potential to control Pb solubility at low levels, its formation is kinetically controlled by pH, the solubility of the phosphate source, and the solubility of Pb species. Treatability studies have shown that excess quantities of soluble and acidic phosphate sources, such as phosphoric acid, are necessary for successful in situ treatment. Even under these conditions, Extended X-ray Absorption Fine Structure (EXAFS), the only reliable method to identify and quantify Pb speciation, showed that Pb conversion to pyromorphite in in situ treated soils was less than 45% after 32 months. Furthermore, the use of lime (CaO) to restore soil pH in acidified soil treatments inhibited further conversion. Additionally, phosphate treatment is known to reduce bioavailability through pyromorphite formation in the intestinal tract, and the phytoaccumulation of Pb; both desirable effects for Pb-impacted areas. Given the costs of phosphate treatment, the use of biogenic phosphate sources, such as bone meal, may be a more environmentally sustainable approach toward this end. In the many studies focusing on phosphate treatment, the attendant P leaching and eutrophication have been largely overlooked, along with other issues such as the enhanced leaching of oxyanionic contaminants, such as Se, As and W. The success and sustainability of applying phosphate as a BMP in Firing Range soils therefore remain questionable.

  • Pb speciation versus TCLP release in army Firing Range soils
    Journal of hazardous materials, 2006
    Co-Authors: Dimitris Dermatas, Maria Chrysochoou, Dennis G Grubb, G. Shen, Nektaria Menounou, P. Dutko
    Abstract:

    A series of soil parameter and mineralogical investigative techniques were applied to assess the Pb speciation in four US Army Firing Range soils that presented significantly different Pb leaching regimes and soil characteristics. Soil gradation tests were complemented by total chemical analyses, X-ray powder diffraction (XRPD), Rietveld quantification, optical microscopy and scanning electron microscopy (SEM) analyses. The bulk geotechnical, mineralogical and chemical analyses pointed to two possible Pb retention mechanisms: precipitation as lead carbonate and sorption in the case of fine-grained soils. Lead speciation and mobility was further investigated by the toxicity characteristic leaching procedure (TCLP) and sequential extraction test (SET). As the TCLP Pb concentrations did not necessarily reflect the total Pb analysis of the soils, the Pb leachability ratio (TCLP/total) was found to be controlled by soil mineralogy and its response to changes in system pH. Geochemical modeling, using Visual MINTEQ, was employed to evaluate the mechanisms that controlled the observed TCLP Pb leaching behavior. It was found that lead carbonate precipitation/dissolution reactions controlled Pb TCLP leachability in all soils, while sorptive phenomena did not seem to play a role even in the case of fine-grained soils. More specifically, TCLP Pb leachability was controlled by the pH, the available Pb and the available carbonate in solution. This indicates that geochemical modeling strongly complimented TCLP Pb analyses. Thus, geochemical modeling is an important assessment tool to evaluate the magnitude of site-specific Pb-related environmental problems in Firing Range soils. Carbonation reactions, involving metallic Pb, that occur during the SET obscure its ability to reliably ascertain Pb speciation. More specifically, SET lumps the extractable Pb into predetermined phase categories that may not be truly representative of the actual soil mineralogy or dominant forms of Pb in the soil. A thorough geotechnical, mineralogical and chemical investigation of Firing Range soils, complemented by geochemical modeling, was therefore found to be a more reliable approach to evaluate Pb speciation and TCLP release in Firing Range soils.

Deok Hyun Moon - One of the best experts on this subject based on the ideXlab platform.

  • speciation and phytoavailability of lead and antimony in a small arms Range soil amended with mussel shell cow bone and biochar exafs spectroscopy and chemical extractions
    Chemosphere, 2014
    Co-Authors: Mahtab Ahmad, Deok Hyun Moon, Sang Soo Lee, Jung Eun Lim, Sungeun Lee, Ju Sik Cho, Yohey Hashimoto
    Abstract:

    Mussel shell (MS), cow bone (CB) and biochar (BC) were selected to immobilize metals in an army Firing Range soil. Amendments were applied at 5% (wt) and their efficacies were determined after 175 d. For metal phytoavailability test, maize (Zea mays L.) plants were cultivated for 3weeks. Results showed that all amendments decreased the exchangeable Pb by up to 99% in planted/unplanted soils. Contrarily, exchangeable Sb were increased in the MS- and CB-amended soils. The rise in soil pH (~1 unit) by the amendments affected Pb and Sb mobility in soils. Bioavailability of Pb to maize was reduced by up to 71% in the amended soils. The Sb uptake to maize was decreased by up to 53.44% in the BC-amended soil. Sequential chemical extractions showed the transformation of easily available Pb to stable residual form with the amendment treatments. Scanning electron microscopic elemental dot mapping revealed the Pb association with Al and Si in the MS-amended soil and that with P in the CB- and BC-amended soils. Additionally, the extended X-ray absorption fine structure spectroscopic analysis indicated the transformation of organic bound Pb in unamended control soil to relatively more stable Pb-hydroxide (Ksp=10(-17.1)), chloropyromorphite (Ksp=10(-84.4)) and Pb-phosphate (Ksp=10(-23.8)) in soils amended with MS, CB and BC, respectively. Application of BC was the best in decreasing the phytoavailability of Pb and Sb in the studied army Firing Range soil.

  • Stabilization of lead and copper contaminated Firing Range soil using calcined oyster shells and fly ash
    Environmental Geochemistry and Health, 2013
    Co-Authors: Deok Hyun Moon, Jae Woo Park, Agamemnon Koutsospyros, Kyung Hoon Cheong, Seunghun Hyun, Jeong-hun Park
    Abstract:

    A stabilization/solidification treatment scheme was devised to stabilize Pb and Cu contaminated soil from a Firing Range using renewable waste resources as additives, namely waste oyster shells (WOS) and fly ash (FA). The WOS, serving as the primary stabilizing agent, was pre-treated at a high temperature to activate quicklime from calcite. Class C FA was used as a secondary additive along with the calcined oyster shells (COS). The effectiveness of the treatment was evaluated by means of the toxicity characteristic leaching procedure (TCLP) and the 0.1 M HCl extraction tests following a curing period of 28 days. The combined treatment with 10 wt% COS and 5 wt% FA cause a significant reduction in Pb (>98 %) and Cu (>96 %) leachability which was indicated by the results from both extraction tests (TCLP and 0.1 M HCl). Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDX) analyses are used to investigate the mechanism responsible for Pb and Cu stabilization. SEM–EDX results indicate that effective Pb and Cu immobilization using the combined COS–FA treatment is most probably associated with ettringite and pozzolanic reaction products. The treatment results suggest that the combined COS–FA treatment is a cost effective method for the stabilization of Firing Range soil.

  • Immobilization of lead in contaminated Firing Range soil using biochar
    Environmental science and pollution research international, 2013
    Co-Authors: Deok Hyun Moon, Jae Woo Park, Yoon Young Chang, Sang Soo Lee, Mahtab Ahmad, Agamemnon Koutsospyros, Jeong-hun Park, Kitae Baek
    Abstract:

    Soybean stover-derived biochar was used to immobilize lead (Pb) in military Firing Range soil at a mass application rate of 0 to 20 wt.% and a curing period of 7 days. The toxicity characteristic leaching procedure (TCLP) was performed to evaluate the effectiveness of the treatment. The mechanism responsible for Pb immobilization in military Firing Range soil was evaluated by scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX) and x-ray absorption fine structure (XAFS) spectroscopy analyses. The treatment results showed that TCLP Pb leachability decreased with increasing biochar content. A reduction of over 90 % in Pb leachability was achieved upon treatment with 20 wt.% soybean stover-derived biochar. SEM-EDX, elemental dot mapping and XAFS results in conjunction with TCLP leachability revealed that effective Pb immobilization was probably associated with the pozzolanic reaction products, chloropyromorphite and Pb-phosphate. The results of this study demonstrated that soybean stover-derived biochar was effective in immobilizing Pb in contaminated Firing Range soil.

  • Stabilization of Pb2+ and Cu2+ contaminated Firing Range soil using calcined oyster shells and waste cow bones
    Chemosphere, 2013
    Co-Authors: Deok Hyun Moon, Jeong-hun Park, Kyung Hoon Cheong, Seunghun Hyun, Jeehyeong Khim, Mahmoud Wazne, Yoon Young Chang
    Abstract:

    Abstract Pb 2+ and Cu 2+ contamination at army Firing Ranges poses serious environmental and health risks to nearby communities necessitating an immediate and prompt remedial action. In this study, a novel mixture of calcined oyster shells (COSs) and waste cow bones (WCBs) was utilized to immobilize Pb 2+ and Cu 2+ in army Firing Range soils. The effectiveness of the treatment was evaluated based on the Korean Standard leaching test. The treatment results showed that Pb 2+ and Cu 2+ immobilization in the army Firing Range soil was effective in significantly reducing Pb 2+ and Cu 2+ leachability upon the combined treatment with COS and WCB. A drastic reduction in Pb 2+ (99%) and Cu 2+ leachability (95%) was obtained as compared to the control sample, upon treatment with 5 wt.% COS and 5 wt.% WCB. The combination treatment of COS and WCB was more effective for Pb immobilization, than the treatment with COS or WCB alone. The 5 wt.% COS alone treatment resulted in 95% reduction in Cu 2+ leachability. The SEM-EDX results suggested that Pb 2+ and Cu 2+ immobilization was most probably associated with the formation of ettringite, pozzolanic reaction products and pyromorphite-like phases at the same time.

  • application of waste resources for the stabilization of heavy metals pb cu in Firing Range soils
    Journal of Korean Society of Environmental Engineers, 2011
    Co-Authors: Keunyoung Lee, Deok Hyun Moon, Kyung Hoon Cheong, Jeehyeong Khim, Kyoungwoong Kim, Taesung Kim, Kyoungran Moon, Subin Choi
    Abstract:

    In this study, a heavy metal stabilization treatment using waste resource stabilizing agents was utilized on army Firing Range soil contaminated with Pb and Cu. Both calcined oyster shells (COS; 5% w/w) and waste cow bone (WCB; 3% w/w) were applied for a wet-curing duration of 28 days. Following the stabilization treatment, the process efficiency was evaluated by various extraction methods for Pb and Cu. Neutral and weak acid extraction methods, such as water soluble extraction and SPLP, did not show positive results for heavy metal stabilization with very low leachability. On the other hand, TCLP and 0.1 N HCl extraction showed that the stabilizing agents significantly reduced the amount of the heavy metals leached from the soil, which strongly supports that the treatment efficiency is positively evaluated in acidic leaching conditions. Specifically, in the 0.1 N HCl extraction, the reduction efficiencies of Pb and Cu leaching were 99.9% and 83.9%, respectively. From the sequential extraction results, a difference between Pb and Cu stabilization was observed, which supports that Pb stabilization is more effective due to the formation of insoluble Pb complexes. This study demonstrates that the application of waste resources for the stabilization of heavy metals is feasible.

Daniel Zytnicki - One of the best experts on this subject based on the ideXlab platform.

  • Mixed Mode Oscillations in Mouse Spinal Motoneurons Arise from a Low Excitability State
    Journal of Neuroscience, 2011
    Co-Authors: Caroline Iglesias, Marin Manuel, Claude Meunier, Yulia Timofeeva, Nicolas Delestrée, Daniel Zytnicki
    Abstract:

    We explain the mechanism that elicits the mixed mode oscillations (MMOs) and the subprimary Firing Range that we recently discovered in mouse spinal motoneurons. In this Firing regime, high-frequency subthreshold oscillations appear a few millivolts below the spike voltage threshold and precede the Firing of a full blown spike. By combining intracellular recordings in vivo (including dynamic clamp experiments) in mouse spinal motoneurons and modeling, we show that the subthreshold oscillations are due to the spike currents and that MMOs appear each time the membrane is in a low excitability state. Slow kinetic processes largely contribute to this low excitability. The clockwise hysteresis in the IF relationship, frequently observed in mouse motoneurons, is mainly due to a substantial slow inacti-vation of the sodium current. As a consequence, less sodium current is available for spiking. This explains why a large subprimary Range with numerous oscillations is present in motoneurons displaying a clockwise hysteresis. In motoneurons whose IF curve exhibits a counterclockwise hysteresis, it is likely that the slow inactivation operates on a shorter time scale and is substantially reduced by the de-inactivating effect of the afterhyperpolarization (AHP) current, thus resulting in a more excitable state. This accounts for the short subprimary Firing Range with only a few MMOs seen in these motoneurons. Our study reveals a new role for the AHP current that sets the membrane excitability level by counteracting the slow inactivation of the sodium current and allows or precludes the appearance of MMOs.

  • Fast Kinetics, High-Frequency Oscillations, and Subprimary Firing Range in Adult Mouse Spinal Motoneurons
    Journal of Neuroscience, 2009
    Co-Authors: Marin Manuel, Caroline Iglesias, Maud Donnet, Félix Leroy, C. Heckman, Daniel Zytnicki
    Abstract:

    The fast contraction time of mouse motor units creates a unique situation where motoneurons have to fire at low frequencies to produce small forces but also at very high frequency (much higher than in cat or rat motoneurons) to reach the fusion frequency of their motor units. To understand how this problem is solved, we performed intracellular recordings of adult mouse spinal motoneurons and investigated systematically their sub-threshold properties and their discharge pattern. We show that mouse motoneurons have a much wider Range of Firing frequencies than cat and rat motoneurons because of three salient features. First, they have a short membrane time constant. This results in a higher cut off frequency and a higher resonance frequency, which allow mouse motoneurons to integrate inputs at higher frequencies. Second, their AHP is faster allowing the motoneurons to discharge at a higher rate. Third, motoneurons display high frequency (100–150 Hz) sub-threshold oscillations during the interspike intervals. The fast membrane kinetics greatly favors the appearance of these oscillations, creating a "sub-primary Range" of Firing. In this Range, which has never been reported in cat and in rat spinal motoneurons, the oscillations follow the AHP and trigger spiking after a variable delay, allowing a discharge at low frequency but at the expense of an irregular rate.