A simple model to estimate atmospheric concentrations of aerosol chemical species based on snow core chemistry at Summit, Greenland (original) (raw)
Related papers
Journal of Geophysical Research, 1995
Experiments were performed during the period May-July of 1993 at Summit, Greenland. Aerosol mass size distributions as well as daily average concentrations of several anionic and cationic species were measured. Dry deposition velocities for SO,:' were estimated using surrogate surfaces (symmetric airfoils) as well as impactor data. Real-time concentrations of particles greater than 0.5 gm and greater than 0.01 gm were measured. Snow and fog samples from nearly all of the events occurring during the field season were collected.
A summer time series of particulate carbon in the air and snow at Summit, Greenland
Journal of Geophysical Research, 2007
1] Carbonaceous particulate matter is ubiquitous in the lower atmosphere, produced by natural and anthropogenic sources and transported to distant regions, including the pristine and climate-sensitive Greenland Ice Sheet. During the summer of 2006, ambient particulate carbonaceous compounds were characterized on the Greenland Ice Sheet, including the measurement of particulate organic (OC) and elemental (EC) carbon, particulate water-soluble organic carbon (WSOC), particulate absorption coefficient (s ap ), and particle size-resolved number concentration (PM 0.1 -1.0 ). Additionally, parallel $50-day time series of water-soluble organic carbon (WSOC), water-insoluble organic carbon (WIOC), and elemental carbon (EC) were quantified at time increments of 4-24 h in the surface snow. Measurement of atmospheric particulate carbon found WSOC (average of 52 ng m À3 ) to constitute a major fraction of particulate OC (average of 56 ng m À3 ), suggesting that atmospheric organic compounds reaching the Greenland Ice Sheet in summer are highly oxidized. Atmospheric EC (average of 7 ng m À3 ) was wellcorrelated with s ap (r = 0.95) and the calculated mass-absorption cross-section (average of 24 m 2 g À1 ) appears to be similar to that measured using identical techniques in an urban environment in the United States. Comparing surface snow to atmospheric particulate matter concentrations, it appears the snow has a much higher OC (WSOC+WIOC) to EC ratio (205:1) than air (10:1), suggesting that snow is additionally influenced by watersoluble gas-phase compounds. Finally, the higher-frequency (every 4-6 h) sampling of snow-phase WSOC revealed significant loss (40-54%) of related organic compounds in surface snow within 8 h of wet deposition.
Particulate and water-soluble carbon measured in recent snow at Summit, Greenland
Geophysical Research Letters, 2007
1] Water-soluble organic carbon (WSOC), waterinsoluble particulate organic carbon (WIOC), and particulate elemental carbon (EC) were measured simultaneously for the first time on the Greenland Ice Sheet in surface snow and in a 3-meter snow pit. Snow pit concentrations reveal that, on average, WSOC makes up the majority (89%) of carbonaceous species, followed by WIOC (10%) and EC (1%). The enhancement of OC relative to EC (ratio 99:1) in Greenland snow suggests that, along with atmospheric particulate matter, gaseous organics contribute to snow-phase OC. Comparison of summer surface snow concentrations in 2006 with past summer snow pit layers (2002 -2005) found a significant depletion in WSOC (20 -82%) and WIOC (46 -65%) relative to EC for 3 of the 4 years. The apparent substantial loss of WSOC and WIOC in aged snow suggests that post-depositional processes, such as photochemical reactions, need to be considered in linking ice core records of organics to atmospheric concentrations. Citation: Hagler, G.
Reactive trace gases measured in the interstitial air of surface snow at Summit, Greenland
Atmospheric Environment, 2004
Concentration measurements of nitric oxide (NO), nitrogen dioxide (NO 2 ), nitrous acid (HONO), nitric acid (HNO 3 ), formaldehyde (HCHO), hydrogen peroxide (H 2 O 2 ), formic acid (HCOOH) and acetic acid (CH 3 COOH) were performed in air filtered through the pore spaces of the surface snowpack (firn air) at Summit, Greenland, in summer 2000. In general, firn air concentrations of NO, NO 2 , HONO, HCHO, HCOOH, and CH 3 COOH were enhanced compared to concentrations in the atmospheric boundary layer above the snow. Only HNO 3 and H 2 O 2 normally exhibited lower concentrations in the firn air. In most cases differences were highest during the day and lowest during nighttime hours. Shading experiments showed a good agreement with a photochemical NO x source in the surface snow. Patterns of H 2 O 2 , CH 3 COOH, and HNO 3 observed within the surface snow-firn air system imply that the number of molecules in the snow greatly exceeded that in the firn air. Deduced partitioning indicates that the largest fractions of the acids were present at the ice grain-air interface. In all cases, the number of molecules located at the interface was significantly higher than the amount in the firn air. Therefore, snow surface area and surface coverage are important parameters, which must be considered for the interpretation of firn air concentrations. r
Local anthropogenic impact on particulate elemental carbon concentrations at Summit, Greenland
Atmospheric Chemistry and Physics, 2008
Summit, Greenland is a remote Arctic research station allowing for field measurements at the highest point of the Greenland Ice Sheet. Due to the current reliance on diesel generators for electricity at Summit, unavoidable local emissions are a potential contamination threat to the measurement of combustion-related species in the air and snow. The effect of fossil-fuel combustion on particulate elemental carbon (EC) is assessed by a combination of ambient measurements (∼1 km from the main camp), a series of snow pits, and Gaussian plume modeling. Ambient measurements indicate that the air directly downwind of the research station generators experiences particulate absorption coefficient (closely related to EC) values that are up to a factor of 200 higher than the summer 2006 non-camp-impacted ambient average. Local anthropogenic influence on snow EC content is also evident. The average EC concentration in 1-m snow pits in the "clean air" sector of Summit Camp are a factor of 1.8-2.4 higher than in snow pits located 10 km and 20 km to the north ("downwind") and south ("upwind") of the research site. Gaussian plume modeling performed using meteorological data from years 2003-2006 suggests a strong angular dependence of anthropogenic impact, with highest risk to the northwest of Summit Camp and lowest to the southeast. Along a transect to the southeast (5 degree angle bin), the modeled frequency of significant camp contribution to atmospheric EC (i.e. camp-produced EC>summer 2006 average
Polar Science, 2016
The central Arctic is within the range of air pollution transported from industrial areas of Eurasia and North America. A poor network of weather stations means that there is limited information available about air quality and contaminant deposition in the Arctic environment. For this reason seasonal snow cover is an important source of information. Chemical properties of precipitation, snow cover and fresh snow were monitored at the Hornsund Polish Polar Station (Spitsbergen) and in the altitude profile of the Hans Glacier. Meteorological data from the coast and the glacier helped to examine in detail the impact of atmospheric processes on snow cover contamination. The episode with extremely acidic precipitation was recognized in snow cover analysed in spring 2006. The source area of pollution and type of synoptic situation which enhanced transfer of pollution to the European Arctic were identified. Changes in snow chemistry in the altitude profile demonstrated the impact of the atmospheric boundary layer on chemical properties of precipitation and snow cover. Non-sea salt SO 2 emissions and the role of nitrate in acidification should be considered a serious threat to the Arctic environment.
Chemical composition of snowfall in the high Arctic: 1990–1994
Atmospheric Environment, 2002
From 1990 to 1994 at Alert, Nunavut, Canada, weekly snow samples were collected under low wind conditions to avoid contamination by blowing snow. They were analysed for major ions, Br À , and the organic ions methylsulphonate, formate, acetate and propionate. In the Arctic, where annual precipitation is low and blowing snow is common, these observations are unique. On an equivalent weight basis, acids and sea salt in snowfall are mixed approximately equally from December to January but from March to May acids dominate. The acidity of snowfall increases progressively throughout the winter to a May peak of B16 meq l À1 . SO 4 2À , Br À , and the organic acids acetate, and propionate peak in snowfall after polar sunrise indicate the influence of enhanced photochemical reactions. The greater enrichment of halides relative to sea salt Na + in snow compared to aerosols indicates that gaseous uptake by snowflakes is important in the removal of these substances from the atmosphere and their deposition on to the Earth's surface. There is a marked difference between the seasonal variation of enrichment of Cl À and Br À in snow. The latter show a marked increase after polar sunrise while the former does not. These results provide valuable baseline information on the ionic content of fresh snowfall to be used in understanding the results of snowpack chemistry and post-depositional process studies conducted in the high Arctic. Crown
Annals of Glaciology
Atmospheric particles originate from a variety of natural and anthropogenic sources. Estimates of man’s contribution to the total particle mass loading of the atmosphere range from 5 to 48%. Much of this is initially in the form of gases (SO2, NO2, hydrocarbons) that convert to particles while being transported to glacial receptors where they are incorporated into snow. The complex physical and chemical processes involved in the deposition of atmospheric particles to glaciers are reviewed. Both wet and dry deposition contribute to the pollutant loading of a snowfield. However, except in the case of low snowfall (<60 kg m−2 a−1) or exceptionally large particle sizes, such as might be released by volcanoes or when unrimed snowfall predominates, wet deposition is dominant. Estimates of the relative importance of wet and dry deposition based on scavenging ratios for rimed snowfall and dry deposition velocities agree well with observations in southern Greenland.
Five years of air chemistry observations in the Canadian Arctic
Atmospheric Environment (1967), 1985
Arctic air chemistry observations made in Canada between 1979 and 1984 are discussed. The weekly average concentration of 25 aerosol constituents has been measured routinely at three locations. Anthropogenic pollution typified by SO:-and V has a persistent seasonal cycle. SO:-concentrations are similar at all three locations, although they tend to be. somewhat higher at Alert than at Mould Bay and Igloolik. The seasonal variation of an aerosol constituent depends on its source. There are four distinctive seasonal variations for: (i) anthropogenic constituents Cr. Cu, Mn, Ni, Pb, Sr, V, Zn, H+ , NHf , SO: -, NO;, (ii) halogens (excepting Cl) Br, I, F, (iii) sea salt elements Na, Mg, Cl and (iv) soil constituents Al, Ba, Ca, Fe and Ti. In the Arctic winter, the mean concentrations ofanthropogenic aerosol constituents, except SO:-, are 2-4 times lower than annual mean concentrations in southern Sweden near a major source. region. SOiconcentrations are only 30% lower mainly because of production from SO*. Light scattering (b,,) and