The thermal decomposition of ammonium nitrate (AN) laden munitions wastewater and comparable control samples were studied under air and nitrogen environments at pressures from 0.1 MPa to 10 MPa. The decomposition enthalpies, measured... more
The thermal decomposition of ammonium nitrate (AN) laden munitions wastewater and comparable control samples were studied under air and nitrogen environments at pressures from 0.1 MPa to 10 MPa. The decomposition enthalpies, measured using a Differential Scanning Calorimeter (DSC), and gaseous emissions, measured using a Fourier‐Transform Infrared Spectrometer (FTIR), were used to evaluate the quality of decomposition. Experiments demonstrated that higher pressures improved the energy yield and reduced the quantities of harmful from the decomposition of all samples. At 10 MPa, experimentally measured decomposition enthalpy from the munitions wastewater was 1.8 MJ/kg, approximately 45 % of its standard enthalpy of decomposition, and NO and accounted for only 0.7 % and 0.08 % of the nitrogen in the sample, respectively. The emissions stream from the wastewater was found to primarily consist of , , and . An analysis of the heat releases and the emissions showed that higher pressures im...
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Bioavailability is an important consideration in risk assessment of soil contaminants and in the selection of appropriate remediation technologies for polluted sites. The present study examined the bioavailability and biodegradation... more
Bioavailability is an important consideration in risk assessment of soil contaminants and in the selection of appropriate remediation technologies for polluted sites. The present study examined the bioavailability and biodegradation potential of phenanthrene with respect to a pseudomonad in 15 different soils through separate measurements of mineralization, transformation, and desorption to a polymeric infinite sink (Tenax) after 180-d sterile pre-equilibration with phenanthrene. Fractions strongly resistant to desorption and mineralization at long times were evident in all cases. After correcting for bioconversion (moles mineralized per mole transformed) determined in aqueous particle-free soil extracts, a correlation was found between the biotransformation-resistant fraction and the Tenax desorption-resistant fraction. Indices are proposed to assess bioavailability (BAt) and biotransformation potential (BTPt) of a compound in a soil based on parallel desorption and degradation studies over a selected period t. The BAt is the ratio of moles biotransformed to moles desorbed to an infinite sink, and it reflects the biotransformation rate relative to the maximal desorption rate. Values of BA30 (30-d values) ranged from 0.64 (for dark gray silt loam) to 1.12 (Wurtsmith Air Force Base [AFB] 2B, Oscoda, MI, USA). The BTPt is the ratio between moles biotransformed and moles of contaminant remaining sorbed after maximal desorption. The BTPt provides an indication of the maximum extent of biotransformation that may be expected in a system, assuming desorption is a prerequisite for biodegradation. Values of BTP30 ranged between 0.3 (Wurtsmith AFB 1B) and 13 (Mount Pleasant silt loam, NY, USA). The combination of BAt and BTPt provides insights regarding the relationship between physical availability (desorption) and biological processes (biotransformation kinetics, toxicity, other soil factors) that occur during biodegradation and are suggested to represent the remediation potential of the chemical. The BA30 values less than 0.9 and BTP30 values less than five indicate poor potential for site remediation.
Research Interests: Geography, Chemistry, Soil, Kinetics, Environmental Monitoring, and 15 moreEnvironmental Chemistry, Medicine, Adsorption, Biological Sciences, Biodegradation, Environmental Sciences, Pseudomonas, Bioavailability, Desorption, CHEMICAL SCIENCES, Biotransformation, Phenanthrene, Environmental Toxicology and Chemistry, Biological Availability, and Forensic Chemistry and Toxicology
ABSTRACT In order to satisfy its electric energy demand for the next 20 years (440–484 TWh projected demand for year 2020), Turkey has embarked on a series of major investment programs involving energy generation and distribution. A wide... more
ABSTRACT In order to satisfy its electric energy demand for the next 20 years (440–484 TWh projected demand for year 2020), Turkey has embarked on a series of major investment programs involving energy generation and distribution. A wide variety of energy generation projects are being implemented or will be executed in the near future involving nuclear, coal-, and natural gas-fired thermoelectric plants, combined cycle plants, hydroelectric dams, geothermal plants, and wind and solar energy farms. The engineering and scientific communities along with decision makers at the technical, financial, and political level are facing both, huge challenges (e.g., reduce energy dependence, financial feasibility, environmental protection, social acceptance, and resources management) and a once in a lifetime opportunity for improvement of the Turkey’s social welfare and the environment for several generations. This paper presents a view of some of these challenges and opportunities along with a review of the energy–water nexus from a holistic life cycle perspective. Furthermore, it explores different scenarios of technology integration in order to improve the sustainability of the electric energy generation matrix by the sustainable use of available resources and minimization of the carbon and environmental footprint of energy generation.
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2,4-Dinitroanisole (DNAN) is being used as a replacement for 2,4,6-trinitrotoluene (TNT) as a less-sensitive melt-cast medium explosive than TNT. In this paper, we studied the surface-enhanced Raman spectroscopy (SERS) analysis of DNAN... more
2,4-Dinitroanisole (DNAN) is being used as a replacement for 2,4,6-trinitrotoluene (TNT) as a less-sensitive melt-cast medium explosive than TNT. In this paper, we studied the surface-enhanced Raman spectroscopy (SERS) analysis of DNAN using Ag nanoparticles (AgNPs) modified by L-cysteine methyl ester hydrochloride. Due to the formation of a Meisenheimer complex between DNAN and the modifier, the modified AgNPs can detect 20 μg/L (0.2 ng) and 0.1 mg/L (1 ng) DNAN in deionized water and aged tap water, respectively. Three other chemicals (L-cysteine, N-acetyl-L-cysteine, and L-cysteine ethyl ester hydrochloride) were used as AgNPs modifiers to study the mechanism of the SERS of DNAN. It was confirmed that the amino group of L-cysteine methyl ester hydrochloride was the active group and that the methyl ester group significantly contributed to the high SERS sensitivity of DNAN. In order to further test the mechanism of Meisenheimer complex formation, the effect of anions and cations present in natural water on the SERS of DNAN was studied. It was found that CO(3)(2-), Cl(-), and K(+) at 100 mg/L did not negatively affect the SERS of 10 mg/L DNAN, while SO(4)(2-), Na(+), Mg(2+), and Ca(2+) at 100 mg/L significantly quenched the SERS of 10 mg/L DNAN. The negative effect of the bivalent cations could be offset by SO(4)(2-).
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Research Interests: Environmental Engineering, Civil Engineering, Geology, Chemistry, Mass Transfer, and 15 moreKinetics, Environmental Chemistry, Applied Economics, Adsorption, Soil organic matter, Groundwater Quality, Polycyclic Aromatic Hydrocarbon, Desorption, Phenanthrene, Batch Process, Diffusion Model, Naphthalene, Crank Nicolson, Driving force, and Dual mode
Purpose– The purpose of this paper is to assess a comprehensive model that computes a single score in order to evaluate the sustainability of the municipal solid waste management (MSWM) system of a given city. The model was applied to... more
Purpose– The purpose of this paper is to assess a comprehensive model that computes a single score in order to evaluate the sustainability of the municipal solid waste management (MSWM) system of a given city. The model was applied to calculate the sustainability index for the MSWM of Istanbul, Turkey as a case study.Design/methodology/approach– Different sustainability indicators (including environmental, economical, and social parameters) along with exergy analysis were integrated to utilize an analytical hierarchy process (AHP) under a life cycle perspective.Findings– The Istanbul case study helped to verify that AHP is an effective and efficient decision-making tool. According to the analysis, the current MSWM system of Istanbul is sustainable, and the sustainability can be improved only by changing the amounts to be treated by the current system without any new technological investments.Research limitations/implications– The Municipal Solid Waste Management Sustainability Index (MSWMSI) in this study allowed to integrate large amount of information on interrelated parameters and the sustainability indicators in the whole life cycle into one value that is useful for a general or a comparative judgment and helpful in MSWM decision making.Originality/value– The fact that the weighting assigned to each component in the model is dependent on the decision makers’ evaluations enables the model to be tailored to any city of concern. The model allows the user to readily determine the relative contribution of each criterion or sub-criterion to the final MSWM selection. It is convenient to use and the computations can be run utilizing available specialized software as well as computing by hand.
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ABSTRACT Detailed knowledge about the fate and transport of tungsten in soils is critical to understanding and effectively addressing tungsten behavior in the environment. Recent studies have shown that tungsten anions may polymerize... more
ABSTRACT Detailed knowledge about the fate and transport of tungsten in soils is critical to understanding and effectively addressing tungsten behavior in the environment. Recent studies have shown that tungsten anions may polymerize (depending upon concentration, pH, and aquatic geochemistry) in aquatic and soil systems. However, to date, of all soluble tungstate species only monotungstates have been scrutinized to a fair extent in adsorption studies. There is a lack of information evaluating adsorption mechanisms of mono- and polytungstates onto clay minerals. The objective of this work is to investigate the adsorption behavior of monotungstates (sodium tungstate, Na2WO4) and polytungstates (sodium metatungstate, 3Na2WO4·9WO3) onto different types of clay minerals (montmorillonite, kaolinite, illite) and an organic adsorbent (Pahokee peat). Batch equilibrium experiments as a function of concentration (adsorption isotherms) and pH (adsorption envelopes) were performed to provide information about mono- and polytungstate adsorption onto clays and Pahokee peat. Adsorption equilibrium data for mono- and polytungstates onto different types of clay minerals and Pahokee peat were modeled with Freundlich and Langmuir isotherms. The adsorption affinity of clays and Pahokee peat for monotungstates follows the order: Pahokee peat>kaolinite>montmorillonite>illite; for polytungstates, the order is as follows: kaolinite>Pahokee peat>montmorillonite>illite. Results of this study suggest that the charges of the clay mineral surface, tungsten species, and solution pH are the main factors controlling tungsten adsorption. Moreover, polymeric tungsten species (i.e., metatungstate) appear to be more mobile in the environment than monomeric tungstate.
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Research Interests: Environmental Engineering, Civil Engineering, Environmental Science, Geology, Mass Transfer, and 15 moreWater resources, Applied Economics, Diffusion, Porous Media, THERMAL DIFFUSIVITY, Particle Size, Porous Medium, Tortuosity, Diffusion Model, Water Masses, Empirical Model, Mass Transfer Coefficient, Secondary Air Injection, Sparging, and Unsaturated Zone
Research Interests: Engineering, Chemistry, Physical Chemistry, Mass Transfer, Environmental Pollution, and 15 moreMedicine, Correlation, Porous Media, Ground Water, Hazardous Materials, Particle Size, Organic carbon, Decontamination, Empirical Model, Organic Chemicals, Mass Transfer Coefficient, Soil Pollutants, Sparging, Airflow, and Volatilization
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Research Interests: Chemistry, Physical Chemistry, Kinetics, Medicine, Multidisciplinary, and 15 moreEnvironmental science and technology, Diffusion, THERMAL DIFFUSIVITY, Absorption, Sorption, Solubility, Polycyclic aromatic hydrocarbons (PAHs), Theoretical Models, Science Technology, Environmental Pollutants, Phenanthrene, Biological Availability, Soil Water, Geologic Sediments, and Soil Pollutants
... Environmental Chemistry. Fate of adsorbable organic halides from bleached laundering in septic tank systems. Washington Braida 1 ,; Say Kee Ong 1,* ,; William L. Smith 2 ,; James W. McCabe 2. Article first published online: 26 OCT... more
... Environmental Chemistry. Fate of adsorbable organic halides from bleached laundering in septic tank systems. Washington Braida 1 ,; Say Kee Ong 1,* ,; William L. Smith 2 ,; James W. McCabe 2. Article first published online: 26 OCT 2009. DOI: 10.1002/etc.5620170308. ...
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Ultrafiltration (UF) studies were conducted on latex and ink rinse wastewaters to assess the potential of concentrating the wastewater and recovering the permeate for reuse and recycling purposes. The physicochemical characteristics of... more
Ultrafiltration (UF) studies were conducted on latex and ink rinse wastewaters to assess the potential of concentrating the wastewater and recovering the permeate for reuse and recycling purposes. The physicochemical characteristics of the ink and latex wastewater suggested ...
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Shop ASCE; MyASCE; Donate Now; Contact Us; About Civil Engineering; About ASCE. ASCE Join Now. Knowledge & Learning: Books & Journals; CE Body of Knowledge; Certification; Codes & Standards; Conferences; Continuing ...
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Microalgal biofilms have attracted a good deal of attention as highly beneficial systems capable of reducing the cost of dewatering operations, the costliest component of suspended-growth systems. The support material is a key factor for... more
Microalgal biofilms have attracted a good deal of attention as highly beneficial systems capable of reducing the cost of dewatering operations, the costliest component of suspended-growth systems. The support material is a key factor for algal biofilms generating high solids biomass slurries. This study presents results from screening experiments for algae biofilm support materials in a stationary flood-and-drain system (FDS) and a rotating biological contactor (RBC). Areal biomass productivity served as the selection criterion for attachment while nutrient removal performance was also monitored. Batch experiments tested the attachment capability of Scenedesmus obliquus ATCC®11,477 on the surface of several materials, (e.g., cotton duck, PVC foam, ceramic et.) with BG11 as growth medium. The highest average biomass productivity of 3.4±0.7 g·m− 2·d− 1 was recorded in the FDS using cotton duck as a support material. Comparable total nitrogen (TN) uptake rates of 3.51 and 3.14 mg L− 1d− 1were obtained under low P conditions (N:P = 35:1) in the FDS and RBC, respectively. Under high P conditions (N:P = 5:1), the TN uptake rate and removal efficiency increased to 16.04 mg L− 1d− 1 and 99.8%, respectively. In addition, nitrate removal experiments were carried out in a continuous flow microalgal biofilm reactor (MABR) with cotton duck support material operating at steady state and high effluent recirculation rates. The reactor was modeled using first order nitrate uptake kinetics in a completely mixed regime. The applied model fitted the experimental data adequately and allowed for determination of the nitrate uptake rate constant (K = 58.1 d− 1) via linear regression (R2 = 0.967). • Attached algal biomass support materials are evaluated in FDS and RBC systems. • Among all materials tested, cotton duck supports the highest biomass productivity. • Nitrogen uptake in MABR is adequately described by first order kinetics.
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Microalgae as a substrate for anaerobic digestion (AD) offer promising outcomes over other conventional feedstocks. In this work, the generation of biofuel in the form of biogas via AD using wastewater‐grown microalgae was investigated.... more
Microalgae as a substrate for anaerobic digestion (AD) offer promising outcomes over other conventional feedstocks. In this work, the generation of biofuel in the form of biogas via AD using wastewater‐grown microalgae was investigated. In particular, batch screening of different microalga strains and co‐substrates, culminated into the evaluation of biomethane potential (BMP) from AD of Scenedesmus obliquus grown in energetic‐laden wastewater through benchtop‐scale semi‐continuous reactor. Effectiveness of AD was evaluated for biogas yield, volatile solids (VS) removal, and kinetics for various microalga strains as potential substrate candidates. High carbon content co‐digestants were also investigated including return activated sludge and waste office pulped paper. At semi‐continuous scale, the specific BMPs associated with of 15, 20, and 30 days hydraulic residence times (HRT) were determined as 67.0, 86.6, and 86.3 ml CH4/g VS (added) with average methane content of 70%. In addit...
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Research Interests: Chemistry, Kinetics, Environmental Chemistry, Medicine, Adsorption, and 15 moreHysteresis, Biological Sciences, Environmental Sciences, Diffusion, Sorption, Bioavailability, Desorption, CHEMICAL SCIENCES, Pollutant, Phenanthrene, Environmental Toxicology and Chemistry, Environmental, Biological Availability, Soil Water, and Soil Pollutants
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This paper describes the development of a system dynamics framework toward a dynamic risk assessment while taking into consideration the mass depletion processes in a natural attenuated environment. The development of this framework,... more
This paper describes the development of a system dynamics framework toward a dynamic risk assessment while taking into consideration the mass depletion processes in a natural attenuated environment. The development of this framework, assumes that natural attenuation is a complex system that evolves over time. Through the cause and effects loops, this deterministic frameword, relates the contaminants mass depletion processes, physical and biological, with the different potential risk, water ingestion and air inhalation. In order to test the proposed framework, a conceptual model of a leaking Underground Storage Tank containing pure benzene in a vadoze zone has been analyzed. Geological site specifications and chemical characteristics of benzenes are considered along with fate and transport mechanisms that contribute source mass depletion, including volatilization, biodegradation, and groundwater recharge due to water infiltration processess.
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1. Sci Total Environ. 2007 Sep 20;383(1-3):241-2; author reply 243-5. Epub 2007 Jun 14. Re: "release of copper from sintered tungsten-bronze shot under different pH conditions and its potential toxicity to aquatic organisms". ...
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Research Interests: Engineering, Environmental Toxicology, Environmental Monitoring, Heavy metal monitoring and analysis, Environmental Chemistry, and 15 morePublic Health, Humans, Toxicity, Animals, Drinking Water, Hazardous Materials, LD, Environmental Pollutants, NTP, PPM, Dimensionless, DOM, Acute Lymphocytic Leukemia, Pel, and All
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Tungsten is a metal with many industrial and military applications, including manufacturing of commercial and military ammunition. Despite its widespread use, the potential environmental effects of tungsten are essentially unknown. This... more
Tungsten is a metal with many industrial and military applications, including manufacturing of commercial and military ammunition. Despite its widespread use, the potential environmental effects of tungsten are essentially unknown. This study addresses environmental effects of particulate and soluble forms of tungsten, and to a minor extent certain tungsten alloy components, present in some munitions formulations. Dissolution of tungsten powder significantly acidifies soils. Tungsten powder mixed with soils at rates higher than 1% on a mass basis, trigger changes in soil microbial communities resulting in the death of a substantial portion of the bacterial component and an increase of the fungal biomass. It also induces the death of red worms and plants. These effects appear to be related with the soil acidification occurring during tungsten dissolution. Dissolved tungsten species significantly decrease microbial yields by as much as 38% for a tungsten media concentration of 89 mg l(-1). Soluble tungsten concentrations as low as 10(-5) mg l(-1), cause a decrease in biomass production by 8% which is possibly related to production of stress proteins. Plants and worms take up tungsten ions from soil in significant amounts while an enrichment of tungsten in the plant rhizosphere is observed. These results provide an indication that tungsten compounds may be introduced into the food chain and suggest the possibility of development of phytoremediation-based technologies for the cleanup of tungsten contaminated sites.
Research Interests: Chemistry, Environmental Toxicology, Ecotoxicology, Biomass, Fungi, and 15 moreFate and Transport of Emerging Contaminants, Mortality, Medicine, Multidisciplinary, Growth, Heavy Metal Pollution, Animals, Plant, Bacteria, Environmental Effect, Oligochaeta, Environmental Impact, Biomass production, Food Chain, and Microbial community
Research Interests: Chemistry, Physical Chemistry, Kinetics, Medicine, Multidisciplinary, and 10 moreEnvironmental science and technology, Absorption, Solubility, Polycyclic aromatic hydrocarbons (PAHs), Theoretical Models, Science Technology, Environmental Pollutants, Biological Availability, Geologic Sediments, and Soil Pollutants
Abstract The energetic compounds 1-methoxy-2,4-dinitrobenzene (DNAN), nitroguanidine (NQ), 3-nitro-1,2,4-triazole-5-one (NTO) and 1,3,5-trinitro-1,3,5-triazinane (Research Department Explosive, RDX) are widely used for explosive... more
Abstract The energetic compounds 1-methoxy-2,4-dinitrobenzene (DNAN), nitroguanidine (NQ), 3-nitro-1,2,4-triazole-5-one (NTO) and 1,3,5-trinitro-1,3,5-triazinane (Research Department Explosive, RDX) are widely used for explosive formulations production. Wastewater streams from industrial munition facilities are rich in nitrogen and contain considerable amounts of residual energetic compounds and metals such as zinc, nickel and copper. As such, these wastewater streams require physicochemical and/or biological treatment to meet regulatory discharge limits. The high nitrogen content of these streams makes them an attractive nutrient source for growing biomass such as microalgae. In previous studies we have identified some wastewater streams suitable for microalgal growth with minimal or no prior treatment, while others have shown moderate to high growth inhibition. The current study aims to elucidate the toxicity response of microalgae by performing growth-inhibition assays using solutions of single compounds and mixtures of energetic compounds and heavy metals. Using the freshwater green microalga Scenedesmus obliquus (S. obliquus) (ATCC® 11477) as a model organism, a microwell-plate growth-inhibition test procedure was performed to assess potential growth inhibition effects by DNAN, NQ, NTO, RDX, Zn, Ni and Cu. For the three metals tested, the order of growth rate inhibition effect on S. obliquus was Ni > Cu > Zn. The EC50s of Ni, Cu and Zn for S. obliquus were 0.08 mg/L, 0.26 mg/L and 10.13 mg/L, respectively. The effective concentrations for 50% growth inhibition (EC50) were 4.86 mg/L for DNAN and 8,700 mg/L for NTO. Conversely, RDX exhibited no toxicity below its solubility limit, and NQ had a mild toxic effect on S. obliquus with an EC20 of 303.3 mg/L.
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Electrodeposition of Mo/MoOx Thin Film on Nickel Substrate From Dimethyl-Sulfoxide: Assessing Electrolytic Bath Characteristics Akbar Dauletbay, Washington Braida, MihailNauryzbaev, Leila Kudreeva a al-Farabi Kazakh National University,... more
Electrodeposition of Mo/MoOx Thin Film on Nickel Substrate From Dimethyl-Sulfoxide: Assessing Electrolytic Bath Characteristics Akbar Dauletbay, Washington Braida, MihailNauryzbaev, Leila Kudreeva a al-Farabi Kazakh National University, Chemical and Chemical Technology Department, alFarabi 71, 050040, Almaty, Kazakhstan. b Stevens Institute of Technology, Center for Environmental System, Hoboken, NJ 07030, USA
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<p>Molybdenum (Mo) is a refractory metal used principally as an alloying... more
<p>Molybdenum (Mo) is a refractory metal used principally as an alloying agent in steels, cast irons, and super alloys to enhance hardness, strength, toughness, wear and corrosion resistance and it is also widely used in catalytic applications, lubricants and pigments. The single electrodeposition of Mo from aqueous solutions cannot be achieved but Mo it can be co-deposited as an alloy with iron group metals (induced co-deposition). In this study, the electrodeposition of Mo/MoO<sub>x</sub> from dimethyl sulfoxide solutions on a copper substrate has been investigated. Different experimental electrodeposition parameters have been assessed (i.e., supporting electrolyte concentration and small amounts of water to the electrolytic bath) to analyze their influence on mechanism of induced Mo/MoO<sub>x</sub> deposition. Linear scan voltammetry has been used to follow up the electrodeposition of Mo/MoO<sub>x</sub> films. Film morphology has been characterized using scanning electron microscopy (SEM), compositional analysis was performed using X-ray photoelectron spectroscopy. Mo bearing films were also chemically characterized by ICP-OES analysis. An electrodeposition mechanism was developed and discussed.</p>
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Batch leaching tests were conducted to assess the stabilization of cupper (Cu), lead (Pb) and tungsten (W) in six representative contaminated firing range soils in the United States using nine different amendments. The amendments included... more
Batch leaching tests were conducted to assess the stabilization of cupper (Cu), lead (Pb) and tungsten (W) in six representative contaminated firing range soils in the United States using nine different amendments. The amendments included Granulated Ferric Oxide (GFO), ...
Page 499. EFFECT OF SOLUTE CONCENTRATION ON SORPTION AND DESORPTION KINETICS FOR POLYCYCLIC AROMATIC HYDROCARBONS IN SOIL JASON C. WHITE, WASHINGTON J. BRAIDA, FRANCIS J. FERRANDINO ...
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Tungsten is a metal with many industrial and military applications, including manufacturing of commercial and military ammunition. Despite its widespread use, the potential environmental effects of tungsten are essentially unknown. This... more
Tungsten is a metal with many industrial and military applications, including manufacturing of commercial and military ammunition. Despite its widespread use, the potential environmental effects of tungsten are essentially unknown. This study addresses environmental effects of particulate and soluble forms of tungsten, and to a minor extent certain tungsten alloy components, present in some munitions formulations. Dissolution of tungsten powder significantly acid-ifies soils. Tungsten powder mixed with soils at rates higher than 1% on a mass basis, trigger changes in soil microbial communities resulting in the death of a substantial portion of the bacterial component and an increase of the fungal biomass. It also induces the death of red worms and plants. These effects appear to be related with the soil acidification occurring during tungsten dissolution. Dissolved tungsten species significantly decrease microbial yields by as much as 38% for a tungsten media concentration of 89 mg l À1. Soluble tungsten concentrations as low as 10 À5 mg l À1 , cause a decrease in biomass production by 8% which is possibly related to production of stress proteins. Plants and worms take up tungsten ions from soil in significant amounts while an enrichment of tungsten in the plant rhizosphere is observed. These results provide an indication that tungsten compounds may be introduced into the food chain and suggest the possibility of development of phytoremediation-based technologies for the cleanup of tungsten contaminated sites.
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Biodegradation and plant uptake suggest possible entry of CL-20 into food chain. Abstract CL-20 is a relatively new energetic compound with applications in explosive and propellant formulations. Currently, information about the fate of... more
Biodegradation and plant uptake suggest possible entry of CL-20 into food chain. Abstract CL-20 is a relatively new energetic compound with applications in explosive and propellant formulations. Currently, information about the fate of CL-20 in ecological systems is scarce. The aim of this study is to evaluate the biodegradability of CL-20 in soil environments. Four soils were used where initial CL-20 concentrations (above water solubility) ranged from 125 to 1500 mg of CL-20 per kg dry soil (corresponding to the concentrations derived from unexploded ordnance, low order detonation, or manufacturing spills). CL-20 appears to be biodegradable in soil under anaerobic conditions, and additions of organic substrates can substantially accelerate this process. However, CL-20 is not degraded in soil under aerobic conditions kept in the dark at temperatures up to 30 C without organic amendments. Additions of starch or cellulose promote the biodegradation of CL-20 under aerobic conditions. Soil microbial community mediated biodegradation and plant uptake appears to enhance CL-20 biodegradation, the latter suggesting a possible route for CL-20 to entry in the food chain.
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Air sparging is a remediation technology currently being applied for the restoration of sites contaminated with volatile organic compounds (VOCs). Attempts have been made by various researchers to model the fate of VOCs in the gas and... more
Air sparging is a remediation technology currently being applied for the restoration of sites contaminated with volatile organic compounds (VOCs). Attempts have been made by various researchers to model the fate of VOCs in the gas and liquid phase during air sparging. In this study, a ...