Potemra, T. A., and T. J. Rosenberg. 1973. VLF propagationdisturbances and electron precipitation at mid-latitudes.Journal of Geophysical Research, 78: 1572.

Rosenberg, T. J . , R. A. Helliwell, and J. P. Katsufrakis. 1971.Electron precipitation associated with discrete very-low-fre-quency emissions. Journal of Geophysical Research, 76: 8445.

Atmospheric particulates atSouth Pole Station

JOHN M. ONDOV, ERNEST S. GLADNEY andWILLIAM H. ZOLLER

Department of ChemistryUniversity of Maryland

ROBERT A. DUCE

Graduate School of OceanographyUniversity of Rhode Island

ALUN G. JONES

Shields Warren Radiation LaboratoryHarvard Medical School

Samples of atmospheric particulate matter have beencollected at Pole Station over the past 3 years. Duringthe first year, 1970-1971, samples were collected at bothMcMurdo and Pole Stations for several months. Pre-liminary results of these measurements of the gaseousand particulate halogens and of the metals vanadium,aluminum, and manganese were reported by Duce et al.(1971) and Gladney et al. (1972). The final analysisof these samples has been completed by non-destructiveneutron activation analysis and atomic absorption toyield the atmospheric concentrations of more than 20elements at Pole Station. The interpretation of the par-ticulate and gaseous halogen portion of the data hasbeen reported elsewhere (Duce et al., 1973). Aspreviously stated (Gladney et al., 1972), most of theMcMurdo samples were contaminated by wind-blowndust and, consequently, are of only local interest. ThePole samples originally were collected by 8- by 10-inchDelbag polystyrene filters and both 47-mm and 90-mmMillipore EA filters. The sample-to-blank ratio of theDelbag filters was considerably better than that of theMillipore filters for all elements except zinc and chlo-rine. Owing to the extremely low concentrations en-countered in the polar atmosphere, the blank usually ac-counted for 10 to 90 percent of the total elemental con-centration in the samples when up to 10,000 standardcubic meters of air were filtered by the high-volumepumps.

Interpretation of earlier data was aided by the compu-tation of the ratios of the various atmospheric elemental

concentrations to that of atmospheric aluminum. Theseatmospheric ratios were then compared with similar ra-tios in the earth's crust, as described by Gladney et al.(1972) and Zoller et al. (1973), to determine the crus-tal contribution to the aerosol for the various elements.In this work we have facilitated this comparison by com-puting the enrichment factor, E.F., relative to averagecrustal rock defined as follows:

E.F. - 'V--/Alati,,

crust/Alerustwhere Xatni and Xerugt refer to the concentrations of anelement in the atmosphere and in the crust, respectively.This E.F. is approximately I for elements in atmosphericparticles largely derived from crustal material and isgreater or less than one if the element is enriched or de-pletei with respect to aluminum, relative to the crust.

Based on the mean trace element distribution in theearth's crust as reported by Taylor (1964), our resultsfrom Pole Station fall into three groups as shown in thetable. Except for such clearly marine related elements asNa, Mg, Ca, and K, the sources for the enriched ele-ments, i.e., groups II and III, are unknown. Possiblesources for these elements include volcanism, the ocean,and pollution, particularly sources producing small par-ticles such as oil combustion and motor vehicle operation.

Severe problems with pumps, filter holders, and thelevel of impurities in the filters hampered the first year'swork and caused large analytical uncertainties in themeasurement of certain elements. During the past 2years new pumps, filter holders, and filter materials havebeen evaluated at Pole Station for the intense samplingeffort in 1973-1974. The work has indicated that 4-inchfilters prbvide the optimum sample to blank ratio, whenused with an improved carbon vacuum pump.

Since very low levels of contamination can com-pletely overwhelm the natural level of many trace ele-ments in the samples, clean areas for the collection andhandling of the samples are essential. An 8- by 8- by 12-foot building has been built for sampling at Pole Sta-tion, which is planned to begin again in November 1973.The building is equipped with a clean bench so that fil-ters may be handled without contamination. Air isbrought into the building through an 18-foot-high, 12-inch diameter rvc pipe that connects into a manifoldcapable of handling nine experiments simultaneously. In-line filter holders will be used to collect particles with thepumps exhausting the filtered air directly outside. Otherprograms such as the collection of gaseous mercury,halogens, and chlorinated and non-chlorinated hydro-carbons will be undertaken, partly in cooperation withother research groups. The station will contain a wind di-rectional control system to allow automatic sample col-lection only when the wind is blowing from a prede-termined favorable sector relative to local camp con-tamination sources. A recording condensation nucleus

182 ANTARCTIC JOURNAL

Enrichment factors of South Pole samplesas compared with crustal rock.

Average enrichment bGroup Elements factor

I(Al), Ka, Caa, Sc, V, Mn, 0.8-2.2Fe, La, Sm, Eu, Th

IIMga, Cr, Co, Ce 4.4-7.0IIINaa, Cu, Zn, Se, Bra, Sb, Ph49-43,000

a Each of these elements has some contribution from oceanicaerosols, possibly explaining the observed enrichment factor.

b All enrichments were computed relative to Al.

counter will monitor the number of particles in the air.In the next few years other collection programs will beadded to the building as new techniques and equipmentare developed.

This project was supported in part by the NationalScience Foundation grants GV-33335 and GA-200I0.Computer time was supported in part by National Aero-nautics and Space Administration grant NSG-398 tothe computer science center of the University of Mary-land.

References

Duce, R. A., W. H. Zoller, and A. G. Jones. 1971. Atmosphericparticle and gas sampling at McMurdo and South PoleStations. Antarctic Journal of the (Jotted States, VI (4)133-134.

Duce, A. R., 'X'. H. Zoller, and J . L. Moyers. In preparation.Particulate and gaseous halogens in the antarctic atmosphere.

Gladney, E. S., W. H. Zoller, R. A. Duce, and A. G. Jones.1972. Vanadium, aluminum, and manganese in atmosphericparticulates from McMurdo and South Pole Stations. Ant-arctic Journal of the United States, VII (5): 171-173.

Taylor, S. R. 1964. Abundance of chemical elements in thecontinental crust: a new table, Geochirnica et CosmochimicaAcia, 28, 1273-1285.

Zoller, W. H., G. E. Gordon, E. S. Gladney, and A. G. Jones.In press. The sources and distributions of vanadium in theatmosphere. Adi ances in Chemistry Series.

Aerosols in the south polar stratosphere

D. J . HOFMANN, R. G. PINNICK, J . M. ROSEN

Department of Physics and A stroti o mjUniversity of lJ''yoming

In 1971, the University of 'Wyoming's atmosphericphysics group began monitoring stratospheric aerosol(submicron particulates) globally. Recent interest inthe properties of the stratospheric aerosol, generatedmainly through environmental concern in connection

with the use of supersonic transports, has motivatedthese studies. Using balloon soundings, over 40 meas-urements of submicron particulates from 85 0N. to 90°S.have been recorded to date. Among these measure-ments are three soundings from the antarctic continent.The first of these was flown from South Pole Stationon January 24, 1972, while the other two were flownfrom McMurdo Station on January 12, 1973, and fromSouth Pole Station on January 16, 1973. Thus, in ad-dition to being vital links in the global chain of mças-urements, the new data constitute a comparison ofthe stratospheric aerosol at the center and on the Out-skirts of the weak summer vortex of the polar circu-lation system and, when combined with the originalmeasurement, allow one to investigate the time variationof the stratospheric aerosol at the South Pole over aperiod of 1 year.

The instruments used to detect the aerosol utilize thelight-scattering characteristics of individual particles andare constructed and calibrated at the University ofWyoming. In its present version the instrument weighsabout 9 kilograms and is lofted to an altitude of about30 kilometers by either a large rubber balloon or aplastic balloon having a fully inflated diameter of about15 meters. Fig. 1 shows one of the plastic balloonsduring preparation for launch at McMurdo. Duringascent, at about 0.3 kilometers per minute, a continuousair sample is pumped through an illuminated region ofthe instrument. Photomultiplier tubes detect light scat-tered by particles in the air sample. From Pulse heightlevel discrimination, particles in two size ranges—over0.3 micrometers and over 0.5 micrometers diameter—are counted. Data also are collected during parachutedescent following the balloon's arrival at ceiling al-titude. Shortly after launch, the detector package islowered 100 meters below the balloon by a reel device,so that contamination from the balloon and turbulencefrom the balloon wake will have a minimum effect onthe results.

In addition to aerosol measurements, ozone, watervapor, and temperature were measured. The presentdiscussion is limited to the aerosol results.

Fig. 2 compares the vertical distribution of theconcentration of particles having diameters over 0.3micrometers at McMurdo and Pole Stations. Arrows.inthe diagrams mark the observed position of the tropo-pause. The smooth curves are lines of constant mixingratio in units of particles per milligram of air. Thethin layer of high concentration, observed on the SouthPole flight at an altitude of about 3 kilometers, wascaused by a cloud layer lying low over the 2.8-kilometer-thick polar ice cap. Although the profiles are notidentical, the total integrated aerosol above the tropo-pause is essentially the same at the two stations. Thusthe presence of the polar vortex appears to have littleeffect in creating any spatial nonuniformities of the

July-August 1973 183