Dagmar R. Cronn

Chemical characterization of plywood veneer dryer emissions

Abstract The chemical composition of the plywood veneer dryer emissions from eight steam- or gas-heated mills in the U.S. were analyzed by flame ionization detection gas chromatography and gas chromatography-mass spectrometry. The feed stocks examined consisted of three Pacific Northwestern species and three Southern yellow pines. The composition and the amount of emissions have changed since a 1972 study. The bulk of emissions was gaseous, and 40–95 % of total emissions consisted of ten terpenes. Of 28 components in the condensable portion of the emissions, 13 were identified by name and 4 by functional group. Isopimaric, dehydroabietic and oleic acids were most common. Some emissions were contaminants present in the air before entry into the dryers. Gaseous dryer emissions are similar to the foliage emissions and the cortical oleoresin content of living trees. Non-gaseous emissions are similar to biogenic components in rural aerosols and in wood extracts.

Rapid Determination of Methyl Chloride in Ambient Air Samples by GC-MS

Abstract The methyl chloride concentration distribution in the atmosphere is of importance to the discussion of potential ozone destruction by chlorine-catalyzed reactions in the stratosphere. A gas chromatographic-mass spectrometric technique for rapid measurement of methyl chloride in air samples is described. The procedure provides both better sensitivity and better precision than previously reported determinations of methyl chloride in air. Some representative data are presented to illustrate the use of the method.

Determination of Atmospheric Halocarbon Concentrations by Gas Chromatography-Mass Spectrometry

Abstract GC-MS methods have been developed which provide either analysis of eleven halocarbons in ambient air samples or only rapid analyses of CH3CI and CH2CI2, two species for which GC-ECD is particularly insensitive. Detection limits and precision of analysis for the remaining species are generally not as good as with GC-ECD, but the methods provide separate checks for more certain identification of the particular species of interest. In addition, the methods exhibit more uniform sensitivity for all of the halocarbons, and the GC oven can be temperature-

Expanded list of halogenated hydrocarbons measurable in ambient air

To date, halogenated hydrocarbons containing bromine or iodine have received very little attention in atmospheric research and measurement studies. As early as 1975, however, an article was published warning of possible depletion of stratospheric ozone due to bromine-catalyzed reactions. The widespread use of methyl bromide as an agricultural fumigant, and the discovery that bromine is a more effective catalyst for recombination of ozone than either chlorine or nitric oxide will lead to expanded programs for bromine and iodine-containing hydrocarbons in the atmosphere. Reported here are additional halocarbon compounds which can be measured in ambient air samples using the freezeout concentration method. The original list of compounds measurable by use of this method, and additional halocarbon compounds which were not originally labeled or did not appear in the rural air sample are presented in a table. Retention times and approximate detection limits using a 500 ml sample are also presented. The method employs a gas chromatograph equipped with an electron capture detector operated at 350/sup 0/C. Chemical storage must be carefully controlled in the vicinity of the analytical laboratory to avoid trace halocarbon contamination.

Tropospheric latitudinal distributions of CF2Cl2, CFCl3, N2O, CH3CCl3 and CCl4 over the remote Pacific Ocean

Abstract Latitudinal measurements of CF 2 Cl 2 , CFCl 3 , CH 3 CCl 3 , CCl 4 and N 2 O were made over the remote Pacific Ocean by six separate aircraft flights between mid-1976 and late 1980 and one oceanographic cruise during fall 1983. These trace gas latitudinal distributions were used to calculate Northern (NH) and Southern (SH) Hemisphere mean concentrations, annual time trends, total atmospheric burdens, and lifetimes. The October–November 1980 mean hemispheric concentrations for each trace gas were 290.5 ±3.4 pptv (NH) and 279.0 ± 3.1 pptv (SH) for CF 2 Cl 2 (F-12); 181.1 ± 1.9 pptv (NH) and 173.3 ± 2.2 pptv (SH) for CFCl 3 (F-11); 125.0±4.9 pptv (NH) and 108.8 ± 2.9 pptv (SH) for CH 3 CCl 3 ; 140.7±2.5 pptv (NH) and 137.9 ±2.7 pptv (SH) for CCl 4 ; and 302.15±2.13 ppbv (NH) and 300.99± 1.94 ppbv (SH) for N 2 O. The mid-1976-late 1983 trace gas mean hemispheric concentrations increased annually at: 17.4± 1.2 pptv (NH) and 16.7 ± 0.8 pptv (SH) for CF 2 Cl 2 ; 11.4±0.3 pptv (NH) and 10.8±0.3 pptv (SH) for CFCl 3 ; 10.5 ±1.9 pptv (NH) and 10.4±0.9 pptv (SH) for CH 3 CCl 3 ; 5.7±0.6 pptv (NH) and 4.5 ± 0.3 pptv (SH) for CCl 4 ; and 0.99 ±0.10 ppbv (NH) and 0.82 ±0.21 ppbv (SH) for N 2 O. Normalizing these hemispheric annual time trends with the October–November 1980 mean hemispheric concentrations shows CH 3 CCl 3 mean hemispheric concentrations increased the fastest at ~9% yr −1 , while N 2 O increased the slowest at ~0.3% yr −1 . The October–November 1980 trace gas total atmospheric burdens were: 5.81 Mton for CF 2 Cl 2 ; 3.95 Mton for CFCl 3 ; 2.47 Mton for CH 3 CCl 3 ; 3.50 Mton for CCl 4 ; and 2283 Mton for N 2 O. The atmospheric lifetimes of CF 2 Cl 2 , CFCl 3 and CH 3 CCl 3 were estimated using annual growth rates (% yr −1 ), total atmospheric burdens, and cumulative emissions data. The atmospheric lifetimes obtained for CF 2 Cl 2 , CFCl 3 and CH 3 CCl 3 were 174 ±89, 202 ± 149 and 14.5 ± 2.2 yr, respectively.

Volcanic gases in the april 1979 soufriere eruption

Six gas samples from the 17 April 1979 Soufriere eruption plume were analyzed for carbonyl sulfide, carbon disulfide, carbon monoxide, carbon dioxide, methane, nitrous oxide, fluorocarbon-11, fluorocarbon-12, methyl chloroform, and carbon tetrachloride. Only carbon monoxide, carbon dioxide, carbonyl sulfide, and carbon disulfide were found to have increased mixing ratios as compared with those in clean tropospheric air, but the increases were not sufficient to contribute greatly to the global budgets of these four components.

Fume hood exhaust re-entry into a chemistry building.

The rooftop air intakes are in close proximity to the fume hood exhaust vents on the roof of the attached chemistry buildings (Fulmer Hall and Fulmer Annex) at Washington State University. Complaints resulted from the apparent re-entry of hazardous and odorous exhaust vapors and gases returning into the building fresh air supplies. An atmospheric tracer study of the flow patterns and exhaust gas dilution rates determined the suitability of other potential air intake locations. Isopleth maps showed concentration patterns for tests conducted during the different wind regimes (southwest prevailing winds and substantial wintertime southeast periods). As expected, the observed dilution rates were greater than the conservative minimum dilution rates calculated from models. Tracer gas concentrations indicated large areas over which odor thresholds would exceeded for vapors resulting from typical evaporation rates of solvents. Tracer gas concentrations at the building air intakes were about the same as inside building concentrations because little dilution occurred between the intakes and building interiors. Significant infiltration was observed due to negative building pressure relative to outside. The recommendation to move the intakes down the south building walls is being followed since roof-level concentrations are typically a factor of ten or more higher than below-roof levels.

A modified commercial electrostatic aerosol analyzer for size distribution measurements of condensing aerosols in hot, wet stack gases

Abstract Modifications to a commercially-available electrical aerosol mobility analyzer are described which allowed particle size distribution measurements in hot (180°C) stack plumes with high water vapor content. Modifications described include physical rearrangement of components, flow system changes and electronic wiring and circuit alterations. Field measurement techniques for use of the modified instrument are described and examples are given of successful field trial measurements in plywood veneer dryer stack plumes.