The production rates of 7Be from 16O by cosmic rays were measured at three locations of different latitudes and altitudes. From the altitude dependence of the production rates, the attenuation length of L =165 ± 30g/cm2 was obtained. This value falls in the range of the reported values obtained by physical methods for the atmospheric neutrons. The experimental value at the sea level of the geomagnetic latitude, λ = 25°N, was in good agreement with the value calculated from the generally accepted atmospheric neutron spectrum and the best estimated excitation function. The latitude effect on the production rate is also discussed.
Method of chemical separation for nitrogen compounds in soils established by BREMNER (1965) was checked and modified to apply for the measurement of the natural variation in isotopic ratios of nitrogen compounds in sediments. Separation of nitrogen compounds which exist in different occurrences i.e., (a) in interstitial water, (b) in the exchangeable site on the surface of solid, and (c) in solid, was also studied, and the optimum conditions for the separation were determined.
On the basis of the vertical distribution of 3H observed at the Geosecs station (1969) in the Northeast Pacific, the vertical eddy diffusivity in the thermocline was evaluated to be O.16cm2/sec. By using this value and dissolved oxygen profile, the consumption rate of oxygen in the thermocline was estimated to be 3.9 × 10-2 ml/kg/y on an average.
The steam, water and dissolved sulphate in the discharges from the Otake geothermal bores have been isotopically analyzed. The results show that the Otake geothermal water is derived from local meteoric water with 18O shift of a few per mill. From the oxygen isotopic fractionation between dissolved sulphate and water, assuming equilibrium conditions, isotopic equilibrium temperature has been estimated for each bore. Estimated temperatures range from 180 to 280°C, and they are consistent with the measured and chemically estimated temperatures.
Abundances of the rare-earth elements (REE) in nine pelagic sediments from the Pacific Ocean floor were determined. Gross features of the REE patterns for the studied samples are similar to those of the North American shale composite (HASKIN et al., 1966), but rather small but clear differences from this shale composite can be discerned. Namely, the North American shale composite appears to have no europium anomaly, whereas all of the studied samples show negative europium anomaly. Besides, there appears to be a difference in the position of the break of the curve between the shale composite in question and the Pacific pelagic sediments. A sample from. near the equator shows the highest REE content. A fact that, despite the considerable difference in longitude, three samples from latitudes of 38-44°N show almost the same REE contents, is considered to reflect ocean current and westerly wind being parallel with the latitude for this belt. The REE contents of these three samples are similar to those in a Japanese granodiorite (JG-1). In addition to REE abundances, the major chemical constituents are also presented for each sample.
As one of the steps that lead to understanding limestone formation, the geochemical behavior of chemical species during limestone formation from corals was discussed by calculating values of concentration factors for chemical species between limestones and corals. During the limestone formation, iron, silicon, aluminum, manganese and phosphorus are enriched in limestones, while sodium, chloride and sulfate ions are removed to river waters from corals. Aluminum seems to be the least mobile element in the processes. The chemical composition of river waters in the limestone areas of the Ryukyu Islands is interpreted to be a result of addition of sulfate, sodium, calcium and bicarbonate from corals and limestones through dissolution and of supply of chloride and sodium from dry fallout and precipitation of sea salt.
Chemical composition and molecular weight of dissolved organic matter were determined by employing chemical analysis and Sephadex Gel filtration method with respect to bacterial degradation products of green algae. The chemical composition is as follows; pigment materials 15%, lipid and organic acid materials 30%, proteinous materials 26% and carbohydrate materials 8%. The molecular weight of the dissolved organic matter is distributed in wide ranges. Organic matter with high molecular weight (> 50, 000) consists mainly of proteinous and carbohydrate materials, intermediate one (1, 500-50, 000) consists of pigment and lipid materials. The composition of lower molecular weight matter is not yet known. The dissolved organic matter produced by bacterial degradation of green algal cells is characterized by yellow colouring, which originates in pigments (in main chlorophyll pigments), and high molecular weight organic substances, which consist almost of proteinous substances with lesser amounts of carbohydrate substances. Although there is a considerable difference between the dissolved organic matter of bacterial degradation products and that in natural water, the former is suggested to be an important source of the latter.