Atmospheric chemistry at South Pole
in 12 hours) from an initially steady condition. These experiments indicate that H increases in magnitude during anticyclonic turning, reaching a maximum and then decaying to a new steady state value consistent with the new wind direction. With cyclonic turning, H is reduced slightly. The period of altered H is the order of the duration of turning plus one day. The magnitude of the enhancement depends on the turning rate; for example, with a turn of 180 degrees in 48 hours, it is twice the steady value. The faster the turning, the greater the magnitude of enhancement. While these results are still preliminary, they appear to be independent of the modeling assumptions. Further work is required to study responses to other forms of variability and to compare these simulations with observations. However, our work to date indicates that the simulations are qualitatively realistic. We therefore conclude that the observed long-term near balance between
R (net radiative losses) and H requires that the boundary layer forcing be unsteady and that the upper snow layer must act as a short-term heat storage medium. For such a layer, the diffusive time scale is about 3.5 days. Therefore, if cloudiness and pressure field vary on time scales of less than 3 days (which observation shows), most of the heat gained at the snow surface is available to be radiated away rather than to be conducted below the first few tens of centimeters. This research work has been supported in part by National Science Foundation grant DPP 77-19362.
Atmospheric chemistry at South Pole
the Pacific to New Zealand and on the trips between New Zealand and Antarctica. We spent several days collecting samples of volcanic deposits from the summit of Mount Erebus volcano on Ross Island. These yellow-white deposits contain some sulfur (approximately 1 percent), but most of the salt appears to consist of complex metal halides condensed either from the volcanic plume or from gases seeping through porous materials on the upper slope of the crater. Some of the deposits obviously have been formed through interactions of acidic volcanic gases with the rocks. Preliminary data from plume samples collected by the LC-130 aircraft and on the rim indicate that Mount Erebus is potentially an important source for volatile species in the pristine antarctic atmosphere. We also did some sampling at a remote site 5 kilometers from main Amundsen-Scott (South Pole) Station during the last portion of December and January. At the end of the austral summer season, we moved the remote site to the station for storage. To keep the clean air quadrant intact, this station will not be used upwind of the South Pole clean air facility (CAF) in the future. Because of the problems of contamination, the clean air quadrant must be off limits to all personnel. The operation of the CAF equipment was then turned over to National Oceanic and Atmospheric Administration (N0AA) personnel currently collecting air filters for our group. This program will continue as a routine part of the NOAA global monitoring program. Additional ice samples were collected from the shallow ice pit for chemical analysis. Byard Mosher managed our operations at the South Pole during the austral summer season, after the departure of Gary McGregor, the winterover scientist. Our studies have indicated that there are four groups of elements found in antarctic aerosols. These groups have been found to relate to sea salt, crustal dust, stratospheric sulfate, and the volatile elements. The volatile elements are found far in excess of what we would expect from either crustal weathering or sea salt and may
ARLENE M. SULEK, WILLIAM C. CUNNINGHAM, DAVID L. ANDERSON, MICHAEL P. FAILEY, and WILLIAM H. ZOLLER Department of Chemistry University of Maryland College Park, Maryland 20742
BYARD MOSHER, CLIFFORD WEISEL, and ROBERT A. DUCE Graduate School of Oceanography University of Rhode Island Kingston, Rhode Island 02881
During the austral summer season of 1978-79, we completed field work on our study of atmospheric chemistry at the South Pole. Over the past several years, we have been collecting atmospheric particulate material at the South Pole for chemical analysis (Duce, Zoller, and Moyers, 1973; Zoller, Gladney, and Duce, 1974; Maenhut and Zoller, 1977; Maenhut, Zoller, and Duce, 1979; Maenhut, Zoller, and Coles, 1979). During this season, our major activities were aircraft sampling, summer sampling at the South Pole, and sampling on Mount Erebus. We performed the aircraft sampling aboard the LC130 Hercules. Clifford Weisel had installed our sampling equipment on the plane at the beginning of the season. We also collected samples on the flight across 194
References Brost, R. A., and J . C. Wyngaard. 1978. A model study of the stably stratified planetary boundary layer. Journal of Atmospheric Science, 35(8): 1427-40. Carroll, J. J., K. L. Coulson, R. Hamilton, and B. Jackson. 1977. Atmospheric processes and energy transfers at the south pole. Antarctic Journal of the United States, 12(4): 164-65.
Table 1. Chemical composition of snow layers: South Pole (ng/g) Element O Soluble Species-
S 4 Na
Winter Biocka Coresb 102 ± 33 72 ± 18 93 ± 18 13.0 ± 5.3 6.9 ± 1.4 13.0 ± 3.6
Boutron, Summer Delmasc Vostersc 132 ± 24 138 ± 15
50-100
-
7.5 ± 0.9 23.0 ± 2.3 7.7 ± 0.14 12
Particulate Speciese
Na Fe Mn (x103) Th (x103)
0.59 ± 0.17 0.40 ± 0.21 1.5 ± 0.1 1.9 ± 0.4 2.2 ± 1.7 10.8 ± 0.1 0.76 ± 0.09 4.1 31±8 32±14 150±34 18±5 84 0.59±0.11 04±flnQ One sample collected from each layer in large block sample representing three winter and two summer seasons. b Samples taken from 12 core samples representing winter seasons. Levels represent total elemental concentration. d From 310 12 samples collected from each layer and analyzed independently. Error shown is standard deviation of results of chemical analysis. • Results are averages of 2 to 12 samples analyzed. Error shown is standard deviation of results of chemical analysis. be either from natural or anthropogenic sources (Duce et al., 1975). Our chemical analyses suggest that there is a difference in the chemical composition of the summer and winter snow layers. In the accompanying table, we have given the averages for sodium, sulfate, and some particulate elements in the snow layers from different seasons. It is evident that, in the summer snow layers, there is a significant increase in the quantity of the particulate species and a slight, but significant, increase in the sulfate. The soluble sodium is more erratic in its behavior, and this may reflect real variability between different seasons or contamination of the samples. From previous studies of the chemistry of atmospheric aerosols at the South Pole (Zoller, Gladney, and Duce, 1974; Maenhaut, Zoller and Duce, 1979; Maenhaut, Zoller, and Coles, 1979) we believe that the sodium comes predominantly from sea salt and that most of the sulfate is apparently transported through the lower stratosphere to the interior of Antarctica. Most of the insoluble particulate species listed come from crustal weathering and have an abundance identical to that of average crustal material. The higher summer values may be attributable to the greater abundance of aerosols during the summer sea son (Hogan, 1975), to more effective aerosol removal mechanisms, or to a mechanism of concentrating the impurities by sublimation of the surface snow. The sublimation of surface snow resulting from intense sunlight and low relative humidity is easily observable during the warmest portion of the summer seasons; in fact, these summer layers can be used to visually locate yearly deposition layers in the snow near the surface. In collecting snow samples, therefore, it is very important to be sure to know the areas where a sample is taken. For example, the bulk concentration observed will appear considerably higher for some of the elements, especially those of crustal origin, if the sample contains two summer layers and one winter layer than if it contains only winter snow.
Some of the scatter in the measured concentrations as reported by Boutron and Lorius (1979), Delmas and Boutron (1978), and Vosters (1971) may indeed be related to the collection of several summer layers with the clean winter snow. This work has been supported by National Science Foundation grant DPP 76-23423. References Boutron, C., and C. Lorius. 1979. Trace metals in antarctic snows since 1914. Nature, 277: 551-54. Delmas, R., and C. Boutron. 1978. Sulfate in antarctic snow: spatio-temporal, distribution. Atmospheric Environment, 12: 723-28. Duce, R. A., G. L. Hoffman, and W. H. Zoller. 1975. Atmospheric trace metals at remote northern and southern hem isphere sites: pollution or natural? Science, 187: 59-61. Duce, R. A., W. H. Zoller, and J . L. Moyers. 1973. Particulate and gaseous halogens in the antarctic atmosphere. Journal of Geophysical Research, 78: 7802-11. Hogan, A. W. 1975. Aerosol observations over the ice caps. Antarctic Journal of the United States, vol. 10. (Unpublished data.) Maenhaut, W., and W. H. Zoller. 1977. Determination of the chemical composition of the South Pole aerosol by instrumental neutron activation analysis. Journal of Radioanalytical Chemistry, 37: 673-50. Maenhaut, W. R., W. H. Zoller, and D. G. Coles. 1979. Radionuclides in the South Polar atmosphere. Journal of Geophysical Research, Maenhaut, W. R., W. H. Zoller, and R. A. Duce. 1979. Concentration and size distribution of particulate trace elements in the South Polar atmosphere. Journal of Geophysical Research, vol. 84. Vosters, M. 1971. Contribution a la chimie des Neiges Antarctiques. Composition et Origine des aerosols Atmosphériques. Thesis. Brussels, Belgium: Free University of Brussels. Zoller, W. H., E. S. Gladney, and R. A. Duce. 1974. Atmospheric concentrations and sources of trace metals at the South Pole. Science, 183: 198-200. 195
R (net radiative losses) and H requires that the boundary layer forcing be unsteady and that the upper snow layer must act as a short-term heat storage medium. For such a layer, the diffusive time scale is about 3.5 days. Therefore, if cloudiness and pressure field vary on time scales of less than 3 days (which observation shows), most of the heat gained at the snow surface is available to be radiated away rather than to be conducted below the first few tens of centimeters. This research work has been supported in part by National Science Foundation grant DPP 77-19362.
Atmospheric chemistry at South Pole
the Pacific to New Zealand and on the trips between New Zealand and Antarctica. We spent several days collecting samples of volcanic deposits from the summit of Mount Erebus volcano on Ross Island. These yellow-white deposits contain some sulfur (approximately 1 percent), but most of the salt appears to consist of complex metal halides condensed either from the volcanic plume or from gases seeping through porous materials on the upper slope of the crater. Some of the deposits obviously have been formed through interactions of acidic volcanic gases with the rocks. Preliminary data from plume samples collected by the LC-130 aircraft and on the rim indicate that Mount Erebus is potentially an important source for volatile species in the pristine antarctic atmosphere. We also did some sampling at a remote site 5 kilometers from main Amundsen-Scott (South Pole) Station during the last portion of December and January. At the end of the austral summer season, we moved the remote site to the station for storage. To keep the clean air quadrant intact, this station will not be used upwind of the South Pole clean air facility (CAF) in the future. Because of the problems of contamination, the clean air quadrant must be off limits to all personnel. The operation of the CAF equipment was then turned over to National Oceanic and Atmospheric Administration (N0AA) personnel currently collecting air filters for our group. This program will continue as a routine part of the NOAA global monitoring program. Additional ice samples were collected from the shallow ice pit for chemical analysis. Byard Mosher managed our operations at the South Pole during the austral summer season, after the departure of Gary McGregor, the winterover scientist. Our studies have indicated that there are four groups of elements found in antarctic aerosols. These groups have been found to relate to sea salt, crustal dust, stratospheric sulfate, and the volatile elements. The volatile elements are found far in excess of what we would expect from either crustal weathering or sea salt and may
ARLENE M. SULEK, WILLIAM C. CUNNINGHAM, DAVID L. ANDERSON, MICHAEL P. FAILEY, and WILLIAM H. ZOLLER Department of Chemistry University of Maryland College Park, Maryland 20742
BYARD MOSHER, CLIFFORD WEISEL, and ROBERT A. DUCE Graduate School of Oceanography University of Rhode Island Kingston, Rhode Island 02881
During the austral summer season of 1978-79, we completed field work on our study of atmospheric chemistry at the South Pole. Over the past several years, we have been collecting atmospheric particulate material at the South Pole for chemical analysis (Duce, Zoller, and Moyers, 1973; Zoller, Gladney, and Duce, 1974; Maenhut and Zoller, 1977; Maenhut, Zoller, and Duce, 1979; Maenhut, Zoller, and Coles, 1979). During this season, our major activities were aircraft sampling, summer sampling at the South Pole, and sampling on Mount Erebus. We performed the aircraft sampling aboard the LC130 Hercules. Clifford Weisel had installed our sampling equipment on the plane at the beginning of the season. We also collected samples on the flight across 194
References Brost, R. A., and J . C. Wyngaard. 1978. A model study of the stably stratified planetary boundary layer. Journal of Atmospheric Science, 35(8): 1427-40. Carroll, J. J., K. L. Coulson, R. Hamilton, and B. Jackson. 1977. Atmospheric processes and energy transfers at the south pole. Antarctic Journal of the United States, 12(4): 164-65.
Table 1. Chemical composition of snow layers: South Pole (ng/g) Element O Soluble Species-
S 4 Na
Winter Biocka Coresb 102 ± 33 72 ± 18 93 ± 18 13.0 ± 5.3 6.9 ± 1.4 13.0 ± 3.6
Boutron, Summer Delmasc Vostersc 132 ± 24 138 ± 15
50-100
-
7.5 ± 0.9 23.0 ± 2.3 7.7 ± 0.14 12
Particulate Speciese
Na Fe Mn (x103) Th (x103)
0.59 ± 0.17 0.40 ± 0.21 1.5 ± 0.1 1.9 ± 0.4 2.2 ± 1.7 10.8 ± 0.1 0.76 ± 0.09 4.1 31±8 32±14 150±34 18±5 84 0.59±0.11 04±flnQ One sample collected from each layer in large block sample representing three winter and two summer seasons. b Samples taken from 12 core samples representing winter seasons. Levels represent total elemental concentration. d From 310 12 samples collected from each layer and analyzed independently. Error shown is standard deviation of results of chemical analysis. • Results are averages of 2 to 12 samples analyzed. Error shown is standard deviation of results of chemical analysis. be either from natural or anthropogenic sources (Duce et al., 1975). Our chemical analyses suggest that there is a difference in the chemical composition of the summer and winter snow layers. In the accompanying table, we have given the averages for sodium, sulfate, and some particulate elements in the snow layers from different seasons. It is evident that, in the summer snow layers, there is a significant increase in the quantity of the particulate species and a slight, but significant, increase in the sulfate. The soluble sodium is more erratic in its behavior, and this may reflect real variability between different seasons or contamination of the samples. From previous studies of the chemistry of atmospheric aerosols at the South Pole (Zoller, Gladney, and Duce, 1974; Maenhaut, Zoller and Duce, 1979; Maenhaut, Zoller, and Coles, 1979) we believe that the sodium comes predominantly from sea salt and that most of the sulfate is apparently transported through the lower stratosphere to the interior of Antarctica. Most of the insoluble particulate species listed come from crustal weathering and have an abundance identical to that of average crustal material. The higher summer values may be attributable to the greater abundance of aerosols during the summer sea son (Hogan, 1975), to more effective aerosol removal mechanisms, or to a mechanism of concentrating the impurities by sublimation of the surface snow. The sublimation of surface snow resulting from intense sunlight and low relative humidity is easily observable during the warmest portion of the summer seasons; in fact, these summer layers can be used to visually locate yearly deposition layers in the snow near the surface. In collecting snow samples, therefore, it is very important to be sure to know the areas where a sample is taken. For example, the bulk concentration observed will appear considerably higher for some of the elements, especially those of crustal origin, if the sample contains two summer layers and one winter layer than if it contains only winter snow.
Some of the scatter in the measured concentrations as reported by Boutron and Lorius (1979), Delmas and Boutron (1978), and Vosters (1971) may indeed be related to the collection of several summer layers with the clean winter snow. This work has been supported by National Science Foundation grant DPP 76-23423. References Boutron, C., and C. Lorius. 1979. Trace metals in antarctic snows since 1914. Nature, 277: 551-54. Delmas, R., and C. Boutron. 1978. Sulfate in antarctic snow: spatio-temporal, distribution. Atmospheric Environment, 12: 723-28. Duce, R. A., G. L. Hoffman, and W. H. Zoller. 1975. Atmospheric trace metals at remote northern and southern hem isphere sites: pollution or natural? Science, 187: 59-61. Duce, R. A., W. H. Zoller, and J . L. Moyers. 1973. Particulate and gaseous halogens in the antarctic atmosphere. Journal of Geophysical Research, 78: 7802-11. Hogan, A. W. 1975. Aerosol observations over the ice caps. Antarctic Journal of the United States, vol. 10. (Unpublished data.) Maenhaut, W., and W. H. Zoller. 1977. Determination of the chemical composition of the South Pole aerosol by instrumental neutron activation analysis. Journal of Radioanalytical Chemistry, 37: 673-50. Maenhaut, W. R., W. H. Zoller, and D. G. Coles. 1979. Radionuclides in the South Polar atmosphere. Journal of Geophysical Research, Maenhaut, W. R., W. H. Zoller, and R. A. Duce. 1979. Concentration and size distribution of particulate trace elements in the South Polar atmosphere. Journal of Geophysical Research, vol. 84. Vosters, M. 1971. Contribution a la chimie des Neiges Antarctiques. Composition et Origine des aerosols Atmosphériques. Thesis. Brussels, Belgium: Free University of Brussels. Zoller, W. H., E. S. Gladney, and R. A. Duce. 1974. Atmospheric concentrations and sources of trace metals at the South Pole. Science, 183: 198-200. 195
