This paper presents a table of abundances of the elements in the various major units of the Earth's lithic crust with a documentation of the sources and a discussion of the choice of units and data.

Distribution of the Elements in Some Major Units of the Earth's Crust

From the time that detailed oxygen isotope records derived from foraminifera living in the constant-temperature environment of the abyssal ocean became available, there has been a discrepancy between the ice volume record that these records imply, and that derived from the altitude of dated coral terraces around the world. Here, we re-examine the data and conclude that the temperature of the abyssal ocean has been an actively varying component of the climate system.

Oxygen isotopes and sea level

An oxygen and carbon isotopic history based on analyses of benthonic and planktonic foraminifera in three overlapping subantarctic sections is presented for the last 55 m.y. with a sampling interval ofless than 1 m.y. Surface temperature at Site 277, on the Campbell Plateau, was about 19°C in the early Eocene, about 13°C in the middle Eocene, about 11°C in the late Eocene, and about 7°C in the Oligocene. Declines in temperature appear to have been rather rapid and are separated by episodes of relative temperature stability. Bottom temperature at Site 277 was about 1°C below surface temperature in the Paleocene and about 2°C below surface temperature in the Oligocene. Site 279, on the Macquarie Ridge, records an early Miocene warming of over 2°C followed by a cooling and a second similar temperature rise in the middle Miocene. Bottom temperature at this somewhat deeper site was about 3°C below surface temperature and was probably as low as 4°C during part of the early Miocene. Comparisons between Sites 277 and 279 suggest that from the early Oligocene temperatures of deep water were low like the present day, implying that the mean annual temperature in high southern latitudes was near freezing by the beginning of the Oligocene (but certainly no earlier). From this time glaciers would have descended to sea level, and there would have been sea-ice production. If an ice sheet were present, it could not have been more than a small fraction of its present-day size. Site 281, on the South Tasman Rise, extends the record into the middle and late Miocene during which time the major East Antarctic ice sheet accumulated. A significant rise in surface temperature during the late Miocene did not cause the melting of this ice sheet, demonstrating that by this time it had already achieved its present invulnerability to climatic change. Since temperatures during much of the Miocene were significantly above any Pleistocene values, it is extremely unlikely that any climatic change in the geologically near future will significantly affect the stability of the East Antarctic ice sheet.

Paleotemperature history of the Cenozoic and the initiation of Antarctic glaciation : Oxygen and carbon isotope analyses in DSDP Sites 277,279, and 281

238U234U230Th232Th systematics and the precise measurement of time over the past 500,000 years

Human activities have already modified the chemical composition of the natural atmosphere even in very remote regions of the world. The study of chemical parameters stored in solid precipitation and accumulated on polar ice sheets over the last several hundred thousand years provides a unique tool for obtaining information on the composition of the preindustrial atmosphere and its natural variability over the past. This paper deals with the chemistry of polar ice focused on the soluble mineral (Na+, NH4+, K+, Ca++, Mg++, H+, F−, Cl−, NO3−, SO4−−, and H2O2) and organic (methanesulfonate (CH3SO3−), formate (HCOO−), acetate (CH3COO−), and formaldehyde (HCHO)) species and their interpretation in terms of past atmospheric composition (aerosols and water soluble gaseous species). We discuss ice core dating, the difficulties connected with trace measurements, and the significance of the ionic composition of snow. We examine temporal (from the last decades back to the last climatic cycle) and spatial (including examples from coastal as well as central areas of Greenland and Antarctica) variations in the ionic budget of the precipitation and evaluate ice core studies in terms of the chemical composition of our past atmosphere. We review (1) how Greenland and Antarctic ice cores that span the last few centuries have provided information on the impact of human activities and (2) how the chemistry of deep ice cores provides information on various past natural phenomena such as climatic variations (glacial-interglacial changes, El Nino), volcanic eruptions, and large boreal forest fires.

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Glaciochemistry of polar ice cores: A review

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<0.1). The sharp tenfold increase in the β activity at the beginning of 1955 is attributed to the sudden release in the antarctic troposphere of fission products from the Castle thermonuclear tests series (March 1954). The previous and first thermonuclear test (Ivy, November 1952) is less marked. The β activity before 1952 is essentially due to Pb210 and K40. There are indications that this radio-active horizon has been formed at the same time over the whole ice cap, but direct checks are needed on more, well-dated firn profiles.

/pdf/fission-products-in-antarctic-snow-a-reference-level-for-3mqpvuvlw0.pdf

Fission products in Antarctic snow, a reference level for measuring accumulation

MEASUREMENTS carried out in the Oceanographical Institute, Goteborg, on the radium content in deep-sea cores by H. Pettersson, Traude Bernert, V. Kroll1 et al. showed the vertical distribution of radium to be highly complicated. We were therefore asked to develop a method for direct measurement of the ionium content in samples of sediment from the Swedish Deep-Sea Expedition.

Ionium determination in Deep-sea sediments

Mesure des isotopes du thorium dans l'eau de mer

The rate of snow accumulation has been measured at the USSR station situated at the Pole of Relative Inaccessibility (eastern Antarctic plateau) Five independent methods were used The results, expressed in g cm−2 year−1, are as follows: (1) Accumulation-stake measurements show an accumulation of 3·1±0·5 in 1965 A maximum value of 3·6 for the 6–year interval 1959–65 is derived from snow-thickness measurements (2) Firn stratigraphy was found difficult to interpret in terms of annual layers An upper limit of 12 g cm−2 year−1 is suggested (3) 18O/16O ratios were measured along the upper 235 cm Assuming that each maximum in the isotope profile corresponds to a summer season, the accumulation would be 8·6±0·9 (4) Gross β radioactivity as a function of depth was measured on three firn sections The 1955 radioactive fall-out horizon is clearly marked, enabling the derivation of an average accumulation of 3·0±0·3 (5) The average accumulation over the last 80 years, derived from the 210Pb distribution with depth, is 3·1±0·3 A multi-annual average accumulation rate of (3·0±0·3) is thus firmly established, as well as the validity of both the 210Pb method and the 1955 radioactive fall-out horizon method Stratigraphie studies lead to uncertain results Oxygen isotope variations give accumulation values which are too high by a factor of two at least Accumulation values of the same order of magnitude (2·8±0·2) were derived from radioactive fall-out measurements at the US “Plateau” station

/pdf/determination-of-the-rate-of-snow-accumulation-at-the-pole-2c9w7x3qg5.pdf

Determination of the rate of snow accumulation at the pole of relative inaccessibility, eastern Antarctica: a comparison of glaciological and isotopic methods

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.

/pdf/strontium-90-fallout-in-antarctica-3sg7lrr1aw.pdf

S. Wilgain

Papers

Fission products in Antarctic snow, a reference level for measuring accumulation

Ionium determination in Deep-sea sediments

Mesure des isotopes du thorium dans l'eau de mer

Determination of the rate of snow accumulation at the pole of relative inaccessibility, eastern Antarctica: a comparison of glaciological and isotopic methods

Strontium 90 fallout in Antarctica