The ²³⁹Pu/²³⁸U ratios are reexamined in volcanic ashes and rock, uranium mineral and other contemporary terrestrial samples and also in the atmospheric samples. This ratio in rain samples collected at Fayetteville (36°N, 94°W), Arkansas, reaches up to 10^-5 (atom/atom), which is about 2 orders of magnitude higher than those of volcanic ashes and rock and about five or six orders of magnitude higher than the ²³⁹Pu/²³⁸U ratio of 10^-12 (atom/atom) typical of uranium minerals. The data obtained from our measurements indicate that the high ²³⁹Pu/²³⁸U ratios observed in this contemporary terrestrial samples are due to fallout contaminations.

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Isotopic composition of nitrogen in soil organic matters from subalpine forest areas, upland, and paddy fields in Japan was investigated. In the forest areas, ¹⁵N abundance in soil organic nitrogen increased with depth irrespective of soil types such as alpine brown forest soil and podzolic soil. Biological nitrogen fixation appear as the main source of soil nitrogen. Higher plants seem to promote the above vertical trend even in a cultivated field. ¹⁵N content of soil organic matters in Andosol soils was higher than that of Alluvial soils. Long-term fertilization experimental rice fields were investigated to elucidate the general principles that govern the variation of ¹⁵N content of soil organic nitrogen. In paddies, δ¹⁵N value in rice plant was variable depending upon the kinds of applied fertilizers. Significant difference of δ¹⁵N was observed between rice plants and fertilizers, especially in a chemical fertilizer plot and in a green manure plot. Nitrification and denirification seemed to be responsible for the difference. However, these seem to have a small effect on the variation of soil δ¹⁵N, as rice plants completely assimilate available nitrogen and later are harvested from the paddy fields. The effects of nitrification-denitrification, and of ammonia volatilization were, thus, observed only in biological processes related to relatively short-term phaenomena such as the growth of rice plants and hydrophytes. A long-term addition of a fertilizer clearly increased the amount of soil organic nitrogen in the paddy fields enriched in organic matter. Based on isotope mass balance, nitrogen isotope fractionation factor of 0.9942 was estimated for the process of epidiagenesis, indicating that the heavier isotopic species are preferably decomposed. An addition of ammonium sulfate with a low δ¹⁵N decreased ¹⁵N content of soil nitrogen in a paddy field depleted in soil organic nitrogen. Org.C/Clay ratio was demonstrated to be an important factor that governs the δ¹⁵N value in paddy soils. The relation between δ¹⁵N value in soil organic nitrogen and Org.C/Clay ratio could be presented by a hyperbola for paddy soils so far examined. A simple model is presented to elucidate major factors that govern ¹⁵N content of soil organic materials. It is emphasized that δ¹⁵N of source and plant nitrogen and two isotopic fractionations associated with epidiagenesis of soil organic matters and with adsorption of ammonia by clay minerals, constitute three major factors that determine the δ¹⁵N of soil organic nitrogen.

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The behaviour of a model magma in the vicinity of a critical region is in agreement with results of studies of structures in the melt in basaltic rocks from Sicily. The behaviour of ionic-non ionic fluid mixtures simulating a magma has been analysed in the light of results obtained recently with simple statistical mechanical approximations. It is suggested that the Sicilian magma is to be considered as an extremely rare natural example of two immiscible liquids having almost consolute composition.

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Organic volatiles emitted by a grass Miscanthus sinensis were collected using a Tedlar film bag and Tenax GC adsorbent. Analyses were performed on a gas chromatograph and a GC/MS system. The result indicates that this plant emits cis-3-hexen-1-o1 (leaf alcohol) as a major volatile component. The emission rate of this alcohol determined in May and September showed a marked diurnal variation, increasing in the morning with a maximum at noontime followed by a rapid decrease. This alcohol was also emitted by certain herbaceous and woody plants.

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Relationship between strontium and magnesium contents of marine calcitic carbonates has been studied. The strontium content of marine skeletal calcites increases with increasing magnesium carbonate content (0 to 20mol%) of the calcites, whereas the strontium content of natural protodolomites decreases with increasing magnesium carbonate content (40 to 48mol%) of the protodolomites.

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Chemical compositions of magnetic, stony spherules from deep sea sediments were determined by instrumental neutron activation analysis. High Ir, Au, Ni and Co contents indicate their extraterrestrial origin. The obtained compositions are considerably different from those of chondrites. It can be qualitatively interpreted, however, that cosmic matters having the compositions of chondrites are changed into magnetic, stony spherules by thermal degenerations during their atmospheric entry.

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The Tokoro Belt, a tectonic unit of the central axial zone of Hokkaido, is characterized by preponderant occurrence of Jurassic pillow lavas. These pillow lavas occur separately in the Eastern and the Western masses of the northern Tokoro Belt. The pillow lavas from the Eastern mass are tholeiitic basalt which is considered to have been produced in an abyssal sea floor, while, those from the Western mass are alkali basalt probably related to the formation of seamounts in Jurassic time. REE abundances of above two types of pillow lavas were studied and the results revealed pronounced contrasts between the two masses.

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Noble gas isotopic anomalies in naturally occurring gases have been recently explained by isotopic fractionation (e.g., NAGAO et al., 1979; 1981). In this note, gaseous diffusion processes are examined in order to investigate their cause.

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Kerogen in sedimentary rocks metamorphosed by an igneous dyke intrusion was studied by ¹H-NMR and elemental analyses. The spin-lattice relaxation time (T₁) of kerogen in ¹H-NMR increases toward the contact of the dyke, and atomic ratios in H/C, N/C and O/C of kerogen decrease in the dyke proximity. ¹H-NMR T₁ of kerogen is a useful parameter for contact metamorphism.

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