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Sr90 and gross β activities were measured on firn sections collected around Base Roi Baudouin, Scott Base, and South Pole Station. The firn layers were dated by stratigraphy and by oxygen isotope variations. The depth distribution of Sr90 and gross β activities revealed three radioactive horizons of potential glaciological application. The deepest horizon occurred at the end of 1953 as a result of the fallout of fission products from the Ivy test series, the second and most important one was formed in early 1955 by the debris of the Castle test series, and a third horizon, defined by a sudden increase in the gross β activity but not in the Sr90 content, was formed at the end of 1962. The rate of Sr90 deposition over Antarctica has been nearly constant since 1956, amounting to 0.2 and 0.1 mc/km2 yr at Base Roi Baudouin and at the South Pole, respectively. The cumulative Sr90 deposition up to January 1963 in the 70–90°S latitude belt is found to lie between 1 and 3 mc/km2.

The concentration of Na, Mg, K, Ca, Cl, and Ni has been measured in firn samples collected in the vicinity of King Baudouin Base (70°S, 24°E) and Amundsen-Scott Station (90°S). The Ni content is of the order of a few ppb at both stations. About 35% of the Ni was probably present in the firn as soluble salts. Arguments are presented in support of an extraterrestrial origin for nearly all the Ni found in the south pole samples. The rate of Ni deposition at the south pole is of the order of 10−8 g/cm²/yr. Under the assumption of a Ni abundance of 1.3% (chondrite average), the influx rate of extraterrestrial matter over the entire earth's surface should lie between 3 and 10 million tons per year depending on the assumption made in the extrapolation.

After a short discussion on the Pb210 dating method, the results of Pb210 measurements on snow and firn samples from four Antarctic stations are reported as well as the experimental procedure used. Pb210 was also measured in the air at ground level, at Base Roi Baudouin, the average Pb210 activity of aerosols in 1958 being 1.3 × 10−3 dpm/kg of air. In samples of surface snow accumulated during the last two to five years, the average Pb210 activity is of the order of 100 dph/kg of snow. This activity seems to be independent of the local rate of accumulation. The variations of Pb210 activity as a function of depth were studied on two vertical firn profiles spanning an interval of more than 200 years, at Base Roi Baudouin (70°S, 24°E) and at Amundsen Scott Station (South Pole). Within experimental errors, the Pb210 activity was found to decrease exponentially with depth at both stations. The most plausible interpretation is that the rate of water accumulation and the initial Pb210 concentration in the snow have remained constant at both places over the last 100 years. The annual rates of water accumulation calculated from the decay curves are 6±1 cm at the South Pole and 45±3 cm at Base Roi Baudouin, in good agreement (to better than 10 percent) with accumulation rates so far obtained by other methods.

210Pb and 90Sr measurements were carried out on firn and ice samples from the Kesselwandferner (Austrian Alps). 90Sr seems to be selectively lost in the firn with respect to the other fission products and to 210Pb. The distribution of the 210Pb 'ages' of the ice samples follows a consistent pattern and is in general agreement with surface velocity measurements. © 1967., SCOPUS: ar.j, info:eu-repo/semantics/published

Sodium, magnesium, potassium, calcium, iron, manganese and nickel were measured in firn samples from Base Roi Baudouin (BRB, 70°S, 24°E), Amundsen-Scott Station (ASS, 90°S) and Plateau Station (PLA, 79°S, 40°E). The rates of snow accumulation at the three stations are respectively, in g.cm-2.yr-1 :40, 6 and 2.8. The analyses were carried out by neutron activation, atomic absorption and isotope dilution. In most cases, Fe, Mn, Ni were measured simultaneously by two or three methods on aliquots of the same sample. The corrections for contamination never exceeded 10%. Average concentrations found at BRB (5 samples, 14 kg total) and at PLA (4 samples, 32 kg) respectively are as follows, in p.p.b. Na 250-30; Mg 29-5; K 29-5; Ca 17-8; Mn 0.1-0.35; Fe 6-7; Ni 0.36-0.08. At AAS (2 samples, 3 kg) :Na 9; Mn 0.2; Ni 0.1. On account of the everpresent possibility of contamination, these values must be considered as upper limits. The following conclusions are drawn from the results: 1. 1), SCOPUS: ar.j, info:eu-repo/semantics/published

O18/O16 ratios have been measured along a firn profile extending from the surface to a depth of 16 meters in the shelf ice of King Baudouin station (East Antarctica, 70°26′S, 24°19′E). Periodical variations are found which are believed to reflect the seasonal variations in the O18/O10 ratio of precipitations. They allow the identification of annual layers following the method suggested by Epstein and Sharp. The oxygen isotope variations are compared with the stratigraphic features of the same profile. The notion ‘winter’ or ‘summer’ layers is shown to be meaningless when the layers are derived from stratigraphie criteria only. Very often the fine-grained unmetamorphosed layers (generally called ‘winter’ layers) are made up of snow with high O18 content which must represent summer precipitation. On the other hand, the coarse-grained recrystallized layers (‘summer’ layers) often display a minimum O18 content and are composed of snow that fell in the winter. Identification of annual layers involves a similar degree of uncertainty from personal interpretation in the stratigraphic method as well as in the isotope ratio method, but the two methods are complementary, being affected differently by natural circumstances. A good agreement is found between the average accumulation rates deduced from both methods.

Climatological records from the Amundsen-Scott Station, South Pole, show the summer 1957-1958 to be characterized by periods of exceptionally warm air temperature and above normal snow accumulation. The firn layer deposited during this summer displays an exceptionally high oxygen-18 content, as revealed by 18O/16O ratio profiles obtained by Epstein et al. [6,7] and by us in five pits dug along-side accumulation stakes. © 1966., SCOPUS: ar.j, info:eu-repo/semantics/published

The reasons why 53Mn (a cosmogenic radionuclide with a half-life of 3.7 × 106 y) appears as one of the best indicators of the presence of interplanetary dust are summarized. This paper reports the detection of 53Mn in pre-1952 snow samples collected on the Eastern Antarctic Plateau in the vicinity of Plateau Station. The measurements were carried out by neutron activation and X-ray spectrometry on three samples weighing a few hundred kg and covering each the time interval 1935-1950. The specific activity of 53Mn was found to be (0.82 ± 0.17) disint.min-1/103 tons of snow, corresponding to a deposition rate at Plateau Station of (2.2 ± 0.5) × 10-5 disint. min-1 m-2 y-1. The mean global deposition rate would be three times higher if 53Mn were assumed to behave in the same way as stratospheric 90Sr. By comparing this figure with existing data on the meteorite flux reaching the earth and with the galactic and solar production rates of 53Mn, it is concluded that the bulk of the 53Mn found at Plateau Station is associated with interplanetary dust in which it had been produced by the action of solar protons on iron. The deposition rate of extra-terrestrial dust-borne iron must be between 1.3 × 10-5 and 1.3 × 10-4 g m-2 y-1 at Plateau Station. These results support jointly with other studies the concept of an interplanetary zodiacal cloud of dust with a chemical composition and density not essentially different from chondritic meteorites, with a relatively 'flat' grain size distribution and a mass influx to the earth of the order of 105 tons/y. © 1974., SCOPUS: ar.j, info:eu-repo/semantics/published

In the area around King Baudouin Station (70°S, 24°E), it is shown that a reference horizon, easy to identify, was formed by the stratospheric fallout of radioactive debris from thermonuclear bomb tests. Gross β activity and Sreo have been measured in snow and firn samples from 1935 to 1960. The samples were dated by stratigraphy and by oxygen isotope-ratio measurements. The contribution of natural radionuclides is negligible, and the gross β activity can be taken as a measure of the fission products concentration. The following average values were found: from 1955 to 1960, 14 dpm/kg of snow; beginning of 1955, 22 dpm/kg (Sr90 = 4.5); 1953 and 1954, 2 dpm/kg; and from 1935 to 1952: 0.5 dpm/kg (Sr90

Total beta measurements have been made on melt water samples from a stratigraphically dated firn core profile from the inland Greenland ice sheet (77°10′N, 61°08′W). A marked increase in radioactivity is found in the 1953 firn layer which corresponds to the first important fallout from nuclear test bombs. The pre-1953 natural beta activity is 5 d.p.m./kg. The influx of artificial debris from the Ivy tests in 1953 is noted by a sharp rise in beta activity to 10 d.p.m./kg. Total 90Sr deposit to June 1964 is 9.3 ± 1.5 millicuries/km 2 (24 ± 4 mC/mi 2). Average 210Pb activity at time of deposit is 3.9 ± 0.4 d.p.m./kg. © 1966., SCOPUS: ar.j, info:eu-repo/semantics/published