Trace elements in the antarctic atmosphere
Trace elements in the antarctic atmosphere WILLIAM H. ZOLLER, WILLIAM C. CUNNINGHAM; and GARY McG REGOR Department of Chemistry University of Maryland College Park, Maryland 20742
in the figure. The concentrations, which range over five orders of magnitude of both snow and atmospheric aerosols, actually appear to correlate within narrow limits. Even though the samples were collected at different times the agreement between snow and atmospheric concentrations is within a factor of 3 or 4 for the 13 elements determined. These results may indicate that the concentrations of these elements in snow are closely related to atmospheric burdens. There is much more work to be done on snow and aerosol chemical analyses before the correlation can be accurately determined.
ROBERT A. DUCE OOUTn
Graduate School of Oceanography University of Rhode Island Kingston, Rhode Island 02881
This project is designed to ascertain the composition of antarctic aerosols and to determine their source. The results of these studies will be used to evaluate the relationship of atmospheric aerosol burdens and the composition of snow. In line with these goals, several atmospheric particulate samples were collected by Eugene Mroz using the LC-130 aircraft in Antarctica during October 1977. Filter samples were collected for chemical analysis, over the open ocean and over the antarctic ice sheet between McMurdo Sound and the South Pole. The primary mission during the 1977-78 austral summer was the installation of equipment for the collection of atmospheric aerosols in the new clean air facility at Pole Station. William Cunningham and Cary McGregor arrived at Pole in early November to begin assembling equipment for aerosol sampling at the remote 5-kilometer Maryland-Rhode Island site. Sampling was initiated in early January when all equipment was operational and there was a reduced chance of contamination by other groups working in the area. It was initially planned to collect some samples at the remote site to be compared with those from the new clean air facility. This was impossible because of delays in obtaining electrical power in the new facility. During the first week of February most of the equipment was moved from the remote site into the new facility to be operated during the winter by Cary McGregor. Shortly thereafter electrical power was installed, and sampling was initiated on a limited basis. The operation of the new facility is being continued at a reduced level of sampling throughout the 1978 over-winter. We can operate. only a few of our particle collectors because of power limitations. We are concentrating our efforts on the collection of high-volume particle samples for trace metal analysis and on both particulate and gaseous halogen samples. Radon-222 measurements also are being made daily. Samples of snow from the surface and from a shallow 5meter pit were collected, and the results of the chemical analyses will be compared with the atmospheric concentrations of elements we have measured. Since some data on the chemical composition of snow have become available, we have compared our 1974-75 atmospheric data (Maenhaut and Zoller, 1977; Maenhaut et al., in preparation) with that from the snow analyses for the 1973-74 period (Boutron et al., 1977; Delmas and Boutron, 1977). A plot of the absolute concentration of the atmospheric and snow constituents is shown
October 1978
Trace At lor
ID
U)
Ag
ID
100 100 I00
00 KX*)00
Atmospheric Aeroed Concentraton (ng /scm)
Plot of the chemical composition of atmospheric aerosols from the South Pole vs. snow samples.
The results of both Kumi (1976) and Ohtake (1976) indicated that crustal and sea salt aerosol are the most frequent nuclei of ice crystals sampled at the South Pole. Since sulfate dominates the atmospheric aerosol burden, it also must be effectively deposited in the snow, because its concentrations, according to available data, closely reflect the atmospheric levels. Although the correlations shown here are remarkably good, it must be pointed out that precipitation efficiency generally is dependent on particle size (Junge, 1963) and that particles at the South Pole are very uniform in size and, therefore, apparently are all removed with the same overall efficiency. Samples of ice were also collected from the summit of Mount Erebus, where water vapor, possibly containing volatile compounds, is frozen into ice cones. These samples are being analyzed for halogens and other trace species to evaluate the usefulness of these ice cones for recording Erebus emissions. W. Zoller and C. McGregor took additional samples in January 1978 from sulfur deposits in the vicinity of the rim for detailed chemical analysis by W. Zoller. The work on this project was supported by National Science Foundation grant DPP 76-23423.
187
References
Boutron, C., S. Martin, and C. Lorius. Composition of Aerosols Deposited in Snow at the South Pole Time Dependence and Sources, 9th International Conference on Atmospheric Aerosols, Galway, Ireland, September 1977. Delmas, R, and C. Boutron. Sulfate in antarctic Snow: Spatio-Temporal Distribution, International Symposium on Atmospheric Sulfur, Dubrovnik, Yugoslavia, September 1977. Ohtake, T. 1976. Source of nuclei of atmopsheric ice crystals at the South Pole. Antarctic Journal of the US., 11: 148. Kumi, M. 1976. Identification of nuclei and concentrations of chemical species in snow crystals sampled at the South Pole.Journal of Atmospheric Science, 33: 833. Maenhaut, W. R, 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: 637. Maenhaut, W. R, W. H. Zoller, and it A. Duce. In preparation. Concentration and size distribution of particulate trace elements in the South Polar atmosphere (submitted to Journal of Geophysical Research).
about 14 minutes, and the vertical error bars, which are the one-sigma estimate. The dew point curve is dashed for the first 3 degrees of latitude, because the sensor appears to have become saturated while at surface level at the Pole and the data are questionable. The correlations among potential temperature, humidity, and HTO mixing ratio are quite striking. The warming trend proceeding away from the Pole is generally correlated with higher dewpoint and is not evidence Qf stratospheric air intrusion. The appearance of stratospheric air is marked by a sudden lowering of dew point and a dramatic increase of HTO mixing ratio. SAMPLE TRAPS
TO
OUTSIDE AIR INTAKE
PS G__F^^4
RV PS FC ST
IC
IC
TV
TV
Relief V.1w Pressure S a fety S w it c h Fl,,, Co n tr o l Sl.,oid Val v e
MT Ms Fl,.,t,,
Antarctic tritium measurements
MT()) UT(S)
S V
TV Toggle Iva NV N ee dle V&l +
ALLEN S. MASON and H. GOTE OSTLUND
Figure 1. Flow diagram of atmospheric HT/HTO/CH3T sampler.
Rosenstiel School of Marine and Atmospheric Science University of Miami Miami, Florida 33149
The 1977-78 austral summer marked the commencement of the University of Miami Tritium Laboratory's atmospheric work in the Antarctic. The objectives of the program are to determine the global atmospheric baseline mixing ratios of tritium gas (Hi') and tritiated hydrocarbons by analysis o: biweekly samples from Amundsen-Scott South Pole Station to study the transport of H 20 and tritiated water vapor (HT() in the polar region by sampling UTO and surface snow at th Pole, and to study further the transport processes by quasi synoptic atmospheric sampling of HT and HTO from aircraft. During the field season, a sampler of the type described b Ostlund and Mason (1974), with an additional catalytic corn bustion stage for hydrocarbon sampling, was installed in tb clean-air facility at the Pole. The flow diagram of this devic is shown as figure 1. At the time this report was prepared, n samples had been analyzed. An LC-130 aircraft was equipped with a sampler for HI and HTO, and 47 samples of each species were obtained in i series of flights in and around Antarctica. The sampler is shown in figure 2. Its design is similar to that shown in fIgur 1, except that the hydrocarbon sampling feature and th pump are omitted. In this case, the aircraft bleed air manifold is used as the air source. These samples have been analyzed: preliminary interpretation of the data follows. Figure 3 shows the results of a sampling flight on 10 November 1977 from the South Pole to McMurdo Sound. The tritium data are represented by the horizontal bars, which denote the latitudes spanned by the sampling times of
• 0
a-e
C
t
188
I.
• •
•
Figure 2. Atmospheric IIT/HTO sampler for aircraft use.
ANTARCTIC JOURNAL
in the figure. The concentrations, which range over five orders of magnitude of both snow and atmospheric aerosols, actually appear to correlate within narrow limits. Even though the samples were collected at different times the agreement between snow and atmospheric concentrations is within a factor of 3 or 4 for the 13 elements determined. These results may indicate that the concentrations of these elements in snow are closely related to atmospheric burdens. There is much more work to be done on snow and aerosol chemical analyses before the correlation can be accurately determined.
ROBERT A. DUCE OOUTn
Graduate School of Oceanography University of Rhode Island Kingston, Rhode Island 02881
This project is designed to ascertain the composition of antarctic aerosols and to determine their source. The results of these studies will be used to evaluate the relationship of atmospheric aerosol burdens and the composition of snow. In line with these goals, several atmospheric particulate samples were collected by Eugene Mroz using the LC-130 aircraft in Antarctica during October 1977. Filter samples were collected for chemical analysis, over the open ocean and over the antarctic ice sheet between McMurdo Sound and the South Pole. The primary mission during the 1977-78 austral summer was the installation of equipment for the collection of atmospheric aerosols in the new clean air facility at Pole Station. William Cunningham and Cary McGregor arrived at Pole in early November to begin assembling equipment for aerosol sampling at the remote 5-kilometer Maryland-Rhode Island site. Sampling was initiated in early January when all equipment was operational and there was a reduced chance of contamination by other groups working in the area. It was initially planned to collect some samples at the remote site to be compared with those from the new clean air facility. This was impossible because of delays in obtaining electrical power in the new facility. During the first week of February most of the equipment was moved from the remote site into the new facility to be operated during the winter by Cary McGregor. Shortly thereafter electrical power was installed, and sampling was initiated on a limited basis. The operation of the new facility is being continued at a reduced level of sampling throughout the 1978 over-winter. We can operate. only a few of our particle collectors because of power limitations. We are concentrating our efforts on the collection of high-volume particle samples for trace metal analysis and on both particulate and gaseous halogen samples. Radon-222 measurements also are being made daily. Samples of snow from the surface and from a shallow 5meter pit were collected, and the results of the chemical analyses will be compared with the atmospheric concentrations of elements we have measured. Since some data on the chemical composition of snow have become available, we have compared our 1974-75 atmospheric data (Maenhaut and Zoller, 1977; Maenhaut et al., in preparation) with that from the snow analyses for the 1973-74 period (Boutron et al., 1977; Delmas and Boutron, 1977). A plot of the absolute concentration of the atmospheric and snow constituents is shown
October 1978
Trace At lor
ID
U)
Ag
ID
100 100 I00
00 KX*)00
Atmospheric Aeroed Concentraton (ng /scm)
Plot of the chemical composition of atmospheric aerosols from the South Pole vs. snow samples.
The results of both Kumi (1976) and Ohtake (1976) indicated that crustal and sea salt aerosol are the most frequent nuclei of ice crystals sampled at the South Pole. Since sulfate dominates the atmospheric aerosol burden, it also must be effectively deposited in the snow, because its concentrations, according to available data, closely reflect the atmospheric levels. Although the correlations shown here are remarkably good, it must be pointed out that precipitation efficiency generally is dependent on particle size (Junge, 1963) and that particles at the South Pole are very uniform in size and, therefore, apparently are all removed with the same overall efficiency. Samples of ice were also collected from the summit of Mount Erebus, where water vapor, possibly containing volatile compounds, is frozen into ice cones. These samples are being analyzed for halogens and other trace species to evaluate the usefulness of these ice cones for recording Erebus emissions. W. Zoller and C. McGregor took additional samples in January 1978 from sulfur deposits in the vicinity of the rim for detailed chemical analysis by W. Zoller. The work on this project was supported by National Science Foundation grant DPP 76-23423.
187
References
Boutron, C., S. Martin, and C. Lorius. Composition of Aerosols Deposited in Snow at the South Pole Time Dependence and Sources, 9th International Conference on Atmospheric Aerosols, Galway, Ireland, September 1977. Delmas, R, and C. Boutron. Sulfate in antarctic Snow: Spatio-Temporal Distribution, International Symposium on Atmospheric Sulfur, Dubrovnik, Yugoslavia, September 1977. Ohtake, T. 1976. Source of nuclei of atmopsheric ice crystals at the South Pole. Antarctic Journal of the US., 11: 148. Kumi, M. 1976. Identification of nuclei and concentrations of chemical species in snow crystals sampled at the South Pole.Journal of Atmospheric Science, 33: 833. Maenhaut, W. R, 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: 637. Maenhaut, W. R, W. H. Zoller, and it A. Duce. In preparation. Concentration and size distribution of particulate trace elements in the South Polar atmosphere (submitted to Journal of Geophysical Research).
about 14 minutes, and the vertical error bars, which are the one-sigma estimate. The dew point curve is dashed for the first 3 degrees of latitude, because the sensor appears to have become saturated while at surface level at the Pole and the data are questionable. The correlations among potential temperature, humidity, and HTO mixing ratio are quite striking. The warming trend proceeding away from the Pole is generally correlated with higher dewpoint and is not evidence Qf stratospheric air intrusion. The appearance of stratospheric air is marked by a sudden lowering of dew point and a dramatic increase of HTO mixing ratio. SAMPLE TRAPS
TO
OUTSIDE AIR INTAKE
PS G__F^^4
RV PS FC ST
IC
IC
TV
TV
Relief V.1w Pressure S a fety S w it c h Fl,,, Co n tr o l Sl.,oid Val v e
MT Ms Fl,.,t,,
Antarctic tritium measurements
MT()) UT(S)
S V
TV Toggle Iva NV N ee dle V&l +
ALLEN S. MASON and H. GOTE OSTLUND
Figure 1. Flow diagram of atmospheric HT/HTO/CH3T sampler.
Rosenstiel School of Marine and Atmospheric Science University of Miami Miami, Florida 33149
The 1977-78 austral summer marked the commencement of the University of Miami Tritium Laboratory's atmospheric work in the Antarctic. The objectives of the program are to determine the global atmospheric baseline mixing ratios of tritium gas (Hi') and tritiated hydrocarbons by analysis o: biweekly samples from Amundsen-Scott South Pole Station to study the transport of H 20 and tritiated water vapor (HT() in the polar region by sampling UTO and surface snow at th Pole, and to study further the transport processes by quasi synoptic atmospheric sampling of HT and HTO from aircraft. During the field season, a sampler of the type described b Ostlund and Mason (1974), with an additional catalytic corn bustion stage for hydrocarbon sampling, was installed in tb clean-air facility at the Pole. The flow diagram of this devic is shown as figure 1. At the time this report was prepared, n samples had been analyzed. An LC-130 aircraft was equipped with a sampler for HI and HTO, and 47 samples of each species were obtained in i series of flights in and around Antarctica. The sampler is shown in figure 2. Its design is similar to that shown in fIgur 1, except that the hydrocarbon sampling feature and th pump are omitted. In this case, the aircraft bleed air manifold is used as the air source. These samples have been analyzed: preliminary interpretation of the data follows. Figure 3 shows the results of a sampling flight on 10 November 1977 from the South Pole to McMurdo Sound. The tritium data are represented by the horizontal bars, which denote the latitudes spanned by the sampling times of
• 0
a-e
C
t
188
I.
• •
•
Figure 2. Atmospheric IIT/HTO sampler for aircraft use.
ANTARCTIC JOURNAL
