Centre for Atmospheric Chemistry
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Browsing Centre for Atmospheric Chemistry by Author "Anlauf, K."
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Item Open Access Atmospheric Concentrations and Temporal Variations of C1-C3 Carbonyl Compounds at Two Rural Sites in Central Ontario(Elsevier, 1991) Shepson, P.B.; Hastie, D.R.; Schiff, H.I.; Polizzi, M.; Bottenheim, J.W.; Anlauf, K.; Mackay, G.I.; Karecki, D.R.Measurements of formaldehyde, acetaldehyde, acetone and propionaldehyde concentrations were made at two rural sites in central Ontario. One site (at Egbert, Ont.) is located ≈60 km northwest of Toronto, while the other site (at Dorset, Ont.) is ≈150 km northeast of the Egbert site. Measurements were made using a modified version of a derivatization technique in which sample air is pumped through Teflon tubes packed with silica gel that is coated with 2,4-dinitrophenylhydrazine (DNPH). The product hydrazones were separated and quantified using HPLC. Quantitative determinations of formaldehyde, acetaldehyde and acetone were made for 49 and 47 samples at the Dorset and Egbert sites, respectively, between 25 July and 30 August 1988. The average concentrations determined at the Dorset site for formaldehyde, acetaldehyde, and acetone were 1.6, 0.46 and 1.8 ppb, respectively, and for the Egbert site the corresponding averages were 1.8, 0.57 and 1.6 ppb. A set of 10 samples from the Egbert site were analysed for propionaldehyde yielding an average concentration of 0.03 ppb. The formaldehyde measurements were compared with measurements made at the same time using Tunable Diode Laser Absorption Spectroscopy. The observed concentrations reported here are compared with previously reported measurements of these species and interpreted in terms of atmospheric variables (e.g. meteorology, concentrations of precursor hydrocarbons) influencing their concentrations.Item Open Access Halogen atom concentrations in the Arctic troposphere derived from hydrocarbon measurements: Impact on the budget of formaldehyde(AGU, 1999) Rudolph, J.; Fu, B.; Thompson, A.; Anlauf, K.; Bottenheim, J.As part of the Polar Sunrise Experiment in 1998 measurements of hydrocarbons were made at the Canadian Arctic station Alert. Halogen atom concentrations play a key role in determining formaldehyde mixing ratios. Formaldehyde mixing ratios observed during ozone depletion episodes agree with those calculated from time integrated halogen atom concentrations. Formaldehyde is the most important loss mechanism for active bromine and at the same time an important source for HOx radicals. Via these reactions formaldehyde will indirectly influence chlorine chemistry and thus feedback mechanisms involving halogen atom concentrations and formaldehyde are likely to play a major role in the development of tropospheric ozone depletion episodes during polar sunrise.Item Open Access Hygroscopicity of particles at two rural, urban influenced sites during Pacific 2001: Comparison with estimates of water uptake from particle composition(Elsevier, 2006) Aklilu, Y.; Mozurkewich, M.; Prenni, A.J.; Kreidenweis, S.M.; Alfarra, M.R.; Allan, J.D.; Anlauf, K.; Brook, J.; Leaitch, W.R.; Sharma, S.; Boudries, H.; Worsnop, D.R.Hygroscopicity of particles was measured at Langley (rural) and Eagle Ridge (semi-rural) as part of the Pacific 2001 field campaign. The measured growth factors at the two sites were comparable. However, differences in particle composition as measured by an Aerosol Mass Spectrometer were evident at these two sites. Sulphate mass concentration was found to be similar at the two sites, while higher nitrate and organic mass were observed at Eagle Ridge. Higher growth factors were observed when the air mass was impacted by SO2 sources, while lower growth factors were observed when the air mass was affected by urban emissions. To examine the hygroscopic role of the different particle components, expected growth factors were calculated from the composition data and compared to measured growth factors. Calculations were done using the Zdanovskii, Stokes and Robinson (ZSR) mixing rule. Sulphate fraction played a dominant role in particle hygroscopicity at both sites. Calculated growth factors were within the uncertainty of the measurements, except when the nitrate fraction was high. The results imply that particulate nitrate takes up much less water than ammonium nitrate, indicating that the ZSR mixing rule fails for nitrate. Small variations of organic growth factors with source regions suggest that secondary organic matter is more hygroscopic than primary organic matter.