摘要 :
We used semipermeable membrane devices (SPMDs) to sample water, and achieved sub-211 parts-per-quintillion detection limits. We deployed SPMDs during 1997 low-flow 211 conditions and 1998 high-flow conditions at nine main-stem sit...
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We used semipermeable membrane devices (SPMDs) to sample water, and achieved sub-211 parts-per-quintillion detection limits. We deployed SPMDs during 1997 low-flow 211 conditions and 1998 high-flow conditions at nine main-stem sites and seven 211 tributary sites, spanning approximately 700 miles of the Columbia River. We also 211 collected streambed sediment from three sites. SPMD extracts and sediments were 211 analyzed for polychlorinated dibenzo-p-dioxins, polychlorinated dibenzo-furans, 211 polychlorinated biphenyls, organochlorine pesticides and related transformation 211 products, and polycyclic aromatic hydrocarbons.
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The purpose of the workshop was to examine the existing toxicity and exposuredatabase on polychlorinated biphenyls (PCBs) to ascertain the feasibility of developing toxicity equivalency factors (TEFs) for PCB congeners. Given the ...
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The purpose of the workshop was to examine the existing toxicity and exposuredatabase on polychlorinated biphenyls (PCBs) to ascertain the feasibility of developing toxicity equivalency factors (TEFs) for PCB congeners. Given the widespread acceptance and acknowledged utility of the TEF method for assessing risks associated with exposures to complex mixtures of chlorinated dibenzo-p-dioxins and dibenzofurans, some experts have urged development of comparable TEF schemes for other structurally related chemicals, such as PCBs. Information from the workshop will contribute to Risk Assessment Forum recommendations on whether to pursue development of a TEF scheme for PCBs.
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The report gives results of an investigation of the formation of products ofincomplete combustion (PICs) during 'recovered' trichlorofluoromethane (CFC-11) incineration. Tests involved burning the recovered CFC-11 in a propane gas...
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The report gives results of an investigation of the formation of products ofincomplete combustion (PICs) during 'recovered' trichlorofluoromethane (CFC-11) incineration. Tests involved burning the recovered CFC-11 in a propane gas flame. Combustion gas samples were taken and analyzed for volatile organic compounds as well as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF). Test results confirm that incineration can be used to effectively destroy recovered CFC-11; CFC destruction efficiencies of greater than 99.9999 (six nines) were consistently demonstrated for CFC-11-to-propane molar ratios of 0.66-0.6. Additionally, low levels were detected when sampling downstream of the flue gas scrubber. Results of a secondary goal of the study, to determine the fate of chlorine (Cl) and fluroine (F), were inconclusive.
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Certain manufacturing facilities formerly used large quantities of polychlorinated biphenyl (PCB) fluids in heat transfer operations. At many of these locations, operations have also involved PCB-containing electrical equipment. C...
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Certain manufacturing facilities formerly used large quantities of polychlorinated biphenyl (PCB) fluids in heat transfer operations. At many of these locations, operations have also involved PCB-containing electrical equipment. Commonly, over many years of plant operations, spills and leaks have resulted in PCB soil contamination. Dioxins and furans have been associated with PCB contamination in both the technical and popular press. Consequently, the need for analyses for dioxins and furans must be evaluated at locations where soils are contaminated with PCBs. This report presents an evaluation of potential dioxin and furan soil contamination based on heat transfer operations and spills from electrical equipment. The following five scenarios were examined for dioxin and furan contamination: (1) impurities in heat transfer fluids, (2) formation during heat transfer operations, (3) pyrolysis of heat transfer fluids, (4) impurities in dielectric fluids, and (5) pyrolysis of dielectric fluids. The potential contamination with dioxins and furans was calculated and compared with a 20 ppb guideline that has been used by the Centers for Disease Control for dioxin in subsoil. The results demonstrated that dioxins are formed only under pyrolytic conditions and only from the trichlorobenzenes present in dielectric fluids. Furans are found as impurities in PCB fluids but, as with dioxins, are not formed in significant quantities except during pyrolysis. Fortunately, pyrolytic conditions involving PCB fluids and soil contamination are unlikely; therefore, analyses for dioxin and furan contamination in soils will rarely be needed.
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The objective of the report is to provide a summary of the criteria pollutantsand hazardous air pollutants (HAPs) emitted from a variety of gas-fired stationary sources including utility boilers, utility turbines, and turbines use...
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The objective of the report is to provide a summary of the criteria pollutantsand hazardous air pollutants (HAPs) emitted from a variety of gas-fired stationary sources including utility boilers, utility turbines, and turbines used for natural gas transmission. The report provides emission factors for each compound measured as a function of load to support general use during the preparation of Title V permit applications.
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The paper discusses the mechanistic implications of polychlorinated dibenzodioxinand dibenzofuran (PCDD and PCDF) homologue profiles from municipal waste and coal co-combustion. Variation in PCDD and PCDF homologue profiles from a...
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The paper discusses the mechanistic implications of polychlorinated dibenzodioxinand dibenzofuran (PCDD and PCDF) homologue profiles from municipal waste and coal co-combustion. Variation in PCDD and PCDF homologue profiles from a pilot-scale, co-fired-fuel combustion program was used to provide insights into postcombustion
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This decision document presents the selected remedial action for the Ritari Postand Pole Site in Meadow Township. Wadena County, Minnesota. The selected remedial action for the Ritari Post and Pole Site addresses the source of the...
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This decision document presents the selected remedial action for the Ritari Postand Pole Site in Meadow Township. Wadena County, Minnesota. The selected remedial action for the Ritari Post and Pole Site addresses the source of the contamination by remediation of soil. Excavation of the contaminated soils will reduce the potential for contaminants to move into the underlying ground water. The contaminant concentrations should be greatly reduced after the source (the contaminated soil) is removed. Long-term ground water monitoring will provide information about the natural reduction of the ground water contaminants. The expanded monitoring well network will be used to monitor and confirm this.
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This Explanation of Significant Differences (ESD) for the Idaho Pole Company211 Superfund Site to explain modifications to the remedy at the Site contained in 211 the Record of Decision (ROD) issued on September 28, 1992 (PB93-964...
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This Explanation of Significant Differences (ESD) for the Idaho Pole Company211 Superfund Site to explain modifications to the remedy at the Site contained in 211 the Record of Decision (ROD) issued on September 28, 1992 (PB93-964406). The 211 significant difference between the remedy described in the 1992 ROD and in this 211 ESD is that the plant structures included concrete pads, piping, vaults, etc., 211 preventing access to contaminated soil will be demolished and disposed of in 211 accordance with State of Montana and EPA requirements and that contaminated soils 211 underlying these areas will be excavated and treated like the accessible plant 211 soils have been to date.
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The report gives results of the collection of combustion emissioncharacterization data from chlorofluorocarbon (CFC) incineration. A bench scale test program to provide emission characterization data from CFC incineration was deve...
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The report gives results of the collection of combustion emissioncharacterization data from chlorofluorocarbon (CFC) incineration. A bench scale test program to provide emission characterization data from CFC incineration was developed and performed, with emphasis on the formation of products of incomplete combustion (PICs). Tests involved separate metering of CFC-11 and -12 into a propane gas primary flame. Propane also fueled an afterburner. Simultaneous combustion gas samples were taken upstream and downstream of the afterburner. The gas samples were analyzed for the CFCs to determine the destruction efficiencies of the CFCs and for the major PICs from each CFC. Sampling was performed on time to screen for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polycyclic aromatic hydrocarbons (PAHs) while incinerating CFC-12. Toluene and xylene were the two most frequently occurring PICs in the study. Most of the PICs identified were non-halogenated. PIC concentrations were independent of the concentration of CFC in the fuel. Flammability limits were 39 volume % CFC-11 and 58 volume % CFC-12 in propane. Destruction efficiencies of at least 99.999% can be repeatedly attained for both CFC-11 and -12 even from relatively low temperature flames.
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The paper reports results from tests that were designated to examine some of thefactors influencing the emissions of polychlorinated-p-dioxins and polychlorinated dibenzofurans (PCDDs/Fs) from burn barrels. Based on the wide varia...
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The paper reports results from tests that were designated to examine some of thefactors influencing the emissions of polychlorinated-p-dioxins and polychlorinated dibenzofurans (PCDDs/Fs) from burn barrels. Based on the wide variability of emissions within duplicate-run sets, in spite of all efforts to replicate run conditions and the large number of interacting variables that can account for this variability, it is suggested that a probability-based scheme using Monte Carlo simulations may be useful for developing emissions inventory estimates for this source.
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