Measurements of lower carbonyls and hydrocarbons at Ny-Alesund, Svalbard (original) (raw)
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Light hydrocarbons in the Norwegian Arctic
Atmospheric Environment (1967), 1989
From late February to mid April 1985 pressurized air samples were collected 3 times per week on weathership M in the North Atlantic and in Ny-Alesund on Svalbard. The samples were analyzed for indi~dual fight hydr~ar~ns C,-C,, and it was found that the average sum of C,-C, hydr~rbons was about 35 ppbC in Ny-Alesund and 31 ppbC on ship M, with the least reactive species ethane and propane as the most abundant ones.
Atmospheric Environment, 2002
Oxygenated hydrocarbons, including for the first time alcohols, in the atmosphere and snow-pack interstitial air were measured at Alert, Nunavut, Canada from 15 February to 5 May 2000. Unexpectedly high concentrations of oxygenated hydrocarbons were observed. Acetone, acetaldehyde and methanol represent about 90% of all oxygenated hydrocarbons measured in this work, and together with formaldehyde their total concentration was higher than the sum of measured NMHCs. During sunlit hours, concentrations in the snow-pack interstitial air were higher than those measured in the gas-phase, implying a positive flux from the snow-pack to the Arctic boundary layer. Fluxes of acetaldehyde, acetone and methanol at that time were estimated to be 26, 7.5 and 3.2 Â 10 8 molecules cm À2 s À1 , respectively. These rates would deplete the local snow of acetaldehyde and acetone in about 2 days if degassing was driving the flux. Additional evidence suggests that photochemical production in the snow-pack could explain these fluxes, especially for acetaldehyde. Diel variations were observed at Alert after polar sunrise in the snow-pack interstitial air and in ambient air. During decreasing O 3 conditions, positive correlation with acetaldehyde was observed which is interpreted as implying local Br driven chemistry, but acetone mixing ratios showed a strong negative correlation. Crown
Atmospheric Environment, 2002
The role of formaldehyde in the atmospheric chemistry of the Arctic marine boundary layer has been studied during both polar day and night at Alert, Nunavut, Canada. Formaldehyde concentrations were determined during two separate field campaigns (PSE 1998 and ALERT2000) from polar night to the light period. The large differences in the predominant chemistry and transport issues in the dark and light periods are examined here. Formaldehyde concentrations during the dark period were found to be dependent on the transport of air masses to the Alert site. Three regimes were identified during the dark period, including background (free-tropospheric) air, transported polluted air from Eurasia, and halogen-processed air transported across the dark Arctic Ocean. In the light period, background formaldehyde levels were compared to a calculation of the steady-state formaldehyde concentrations under background and low-ozone conditions. We found that, for sunlit conditions, the ambient formaldehyde concentrations cannot be reproduced by known gas-phase chemistry. We suggest that snowpack photochemistry contributes to production and emission of formaldehyde in the light period, which could account for the high concentrations observed at Alert. r
Non-methane hydrocarbons in the Arctic atmosphere at Barrow, Alaska
Geophysical Research Letters, 1992
C2-C8 non-methane hydrocarbons (NMHCs) were detected in the arctic atmosphere at Barrow, Alaska, during seven sampling periods in March 1989. The most prominent NMHCs were ethene, acetylene, etha.ne, propane, and benzene. The concentrations and distribution of these species were similar to those observed at the same location in 1982 and in the Norwegian Arctic in 1983. The distribution of NMHCs in background arctic air during this period was similar to that of aged urban air. These findings provide additional evidence that NMHCs in the arctic atmosphere during spring may originate from industrialized mid-latitude regions and contribute to the arctic haze phenomenon. [Rasmussen et al., 1983; Hovet al., 1984; Blake and Rowland, !986]. Many of these species exhibit maximum concentrations during winter and declining levels during spring and summer [Rasmussen et al., 1983; Khalil and Rasmussen, 1984]. These profiles are similar to those exhibited by aerosol tracers of arctic haze [Rahn and McCaffrey, 1980]. Meteorological investigations indicate that sources of .arctic haze constituents are located in industrialized, mid-latitude regions [Miller, 1981]. Rahn [1981] has suggested that Eurasia may be a more important source than eastern Noah America. Hansen et al. [1989] observed that ratios of aerosol black carbon/CO2 in background arctic air during spring at Barrow, Alaska, were typical of coal or heavy fuel oil combustion in large installations, automobile exhaust, and domestic-scale natural gas combustion. NMHCs are also emitted from these sources. NMHC source profiles have been used in chemical mass balance (CMB) source reconciliation models to examine the origin of NMHCs in ambient air [Aronian et al., 1989]. Chemical alteration of NMHC source profiles during transport must be examined to apply CMB techniques in reconciling sources of NMHCs in background arctic air. The major atmospheric removal processes for NMHCs are gas phase oxidation by OH, nitrate radical (NO3), and ozone [Finlayson-Pitts and Pitts, !986]. The purpose of our investigation was to examine the origins of C2-C10 NMHCs in the springtime arctic atmosphere. Whole air samples were collected in Summa© polished stainless steel canisters on seven occasions during March 1989 at the National Oceanic and Atmospheric Administration's (NOAA) Geophysical Monitoring for Climatic Change (GMCC) observatory in Barrow, Alaska, and analyzed by a cryogenic preconcentration/high-resolution gas chromatography technique. The results of these analyses are discussed in light of the chemical reactivity of these e0rnpounds as they relate to the long-range transport of anthropogenic emissions from mid-latitude regions to the Arctic during early spring.
Carbonyls and nonmethane hydrocarbons at rural European sites from the mediterranean to the arctic
Journal of Atmospheric Chemistry, 1996
Results of regular measurements during 1992-1995 of hydrocarbons and carbonyl compounds for a number of rural European monitoring sites are presented. The measurements are part of the EMEP programme for VOC measurements in Europe. In addition, several years of regular measurements are included from the Norwegian stations Birkenes at the south coast, and Zeppelin Mountain on Spitsbergen in the Arctic. The sampling frequency has been about twice per week throughout the years, implying that a substantial amount of measurement data are available. Almost all the chemical analyses have been performed by one laboratory, the EMEP Chemical Coordinating Centre located at NILU, which avoids problems of intercomparison and intercalibmtion among different laboratories. For the measured concentrations both seasonal and geographical variations are shown and discussed. The diumal cycles of the hydrocarbon concentrations were studied in detail at one site, where the grab samples by EMEP where compared with a parallel continuous sampler, operated by EMPA, Switzerland. Hydrocarbons linked to natural gas and fuel evaporation become well mixed into the Arctic in the winter, whereas combustion products show a latitudinal gradient. The sum of oxygenated species constitutes about 5-15% of the sum of C2-C5 hydrocarbons in winter. In summer they are almost equal in magnitude, consistent with an increasing oxidation of hydrocarbons.
Geophysical Research Letters, 1999
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.
Investigation of the role of the snowpack on atmospheric formaldehyde chemistry at Summit, Greenland
Journal of Geophysical Research, 2002
1] Ambient gas-phase and snow-phase measurements of formaldehyde (HCHO) were conducted at Summit, Greenland, during several summers, in order to understand the role of air-snow exchange on remote tropospheric HCHO and factors that determine snowpack HCHO. To investigate the impact of the known snowpack emission of HCHO, a gas-phase model was developed that includes known chemistry relevant to Summit and that is constrained by data from the 1999 and 2000 field campaigns. This gas-phase-only model does not account for the high ambient levels of HCHO observed at Summit for several previous measurement campaigns, predicting approximately 150 ppt from predominantly CH 4 chemistry, which is $25-50% of the observed concentrations for several years. Simulations were conducted that included a snowpack flux of HCHO based on HCHO flux measurements from 2000 and 1996. Using the fluxes obtained for 2000, the snowpack does not appear to be a substantial source of gas-phase HCHO in summer. The 1996 flux estimates predict much higher HCHO concentrations, but with a strong diel cycle that does not match the observations. Thus, we conclude that, although the flux of HCHO from the surface likely has a significant impact on atmospheric HCHO above the snowpack, the time-dependent fluxes need to be better understood and quantified. It is also necessary to identify the HCHO precursors so we can better understand the nature and importance of snowpack photochemistry. INDEX TERMS: 0322 Atmospheric Composition and Structure: Constituent sources and sinks; 0365 Atmospheric Composition and Structure: Tropospherecomposition and chemistry; 1863 Hydrology: Snow and ice (1827); 3367 Meteorolgy and Atmospheric Dynamics: Theoretical modeling Citation: Dassau, T. M., et al., Investigation of the role of the snowpack on atmospheric formaldehyde chemistry at Summit, Greenland,
Journal of Geophysical Research, 1994
Variations of selected volatile organic compounds (11 halocarbons, 3 hydrocarbons, and acetone) in Arctic air were measured with an automated GC/MS at Alert, Canada, as a part of the 1992 Polar Sunrise Experiment. During the springtime ozone depletion, several volatile organic compounds (VOCs) correlated significantly with ozone. In particular, trichloroethylene had a strong positive correlation (R = 0.90), while bromoform (R =-0.87) and acetone (R =-0.90) were negatively correlated. Isopentane (R = 0.77), n-butane (R = 0.77), and tetrachloroethylene (R = 0.66) were also positively correlated with ozone. These findings suggest that the ozone depletion at Alert, including its small-scale fluctuations, is caused by the advection of air masses in which reactions by C1 and Br atoms rapidly consumed chloroethylenes and alkanes concurrently and destroyed ozone while the air was over the ocean. In winter, however, slightly negative correlations of ozone with trichloroethylene (R =-0.51) and tetrachloroethylene (R =-0.40) were found, which may be caused by the vertical mixing of surface and free tropospheric air. Introduction Springtime ground level ozone depletion in the Arctic at Alert, Canada, has been attributed to the transport of air masses off the Arctic Ocean boundary layer in which chemical destruction of ozone has occurred [Barrie et al., 1988; Bottenheim et al., 1990]. A strong relationship between ozone depletion and increase of filterable bromine found by Barrie et al. [1988] suggested the involvement of bromine chemistry in Arctic ozone destruction. This has been confirmed by Barrie et al. [this issue] during Polar Sunrise Experiment 1992. Recently, a positive correlation of ozone with ethylene and acetylene and a negative correlation with bromoform have been observed in the daily sampling data from the Polar Sunrise Experiment 1988 [Bottenheim et al., 1990]. Although the chemical impact of bromoform on the ozone destruction process has been unclear, the negative correlation between ozone and bromoform (a marine-derived brominated compound) has been explained by the accumulation of bromoform in stable boundary layer air over the Arctic Ocean that is depleted in ozone as it diffuses through the crack-ridden ice cover. On the other hand, decreases of ethylene and acetylene concurrent with ozone depletion suggest that these compounds are related to ozone-consuming reactions. This 1National Institute for Environmental Studies, Tsukuba, Ibaraki, Ja!•an.
Atmospheric Environment, 2002
Experiments were conducted during the ALERT 2000 field campaign aimed at understanding the role of air-snow interactions in carbonyl compound chemistry and the associated ozone depletion in the atmospheric boundary layer. Under sunlit conditions, we find that formaldehyde, acetaldehyde and acetone exhibit a significant diel cycle with average ambient air concentrations of 166, 53 and 385 ppt, respectively. A box model of Arctic surface layer chemistry was used to understand the diel behavior of carbonyl compound concentrations at Alert, Nunavut, Canada, with a focus on the chemical and physical processes that affect carbonyl compounds. Results of the study showed that the measured carbonyl compound concentrations can only be simulated when a radiation-dependent snowpack source term (possibly photochemistry) and a temperature-dependent sink (physical uptake on snow grains) of carbonyl compounds were added to the model. We are able to simulate the concentration and amplitude of the observed diel cycle, but not the phase of the cycle. These results help confirm the importance of snowpack chemistry and physical processes with respect to carbonyl compound concentrations in the Arctic surface boundary layer, and reveal weakness in the details of our understanding.