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21.
The feeding ofSagitta nagae, the most predominant chaetognath species in Suruga Bay, was studied. Specimens were collected with ORI-100 net (1.0 mm in mesh aperture) and MTD net (0.35 mm in mesh aperture) and were fixed with neutralized formalin. The main food organisms ofSagitta nagae were the copepods,Candacia bipinnata, Calanus pacificus andPareuchaeta russelli. The food-containing ratio (P/T, %) was higher at night and lower in the daytime. Here, P is the number ofSagitta containing food organisms in the gut and T is the total number ofSagitta examined. P/T was almost constant vertically in the upper 100 m layer. P/T was generally influenced neither by food density nor by the copepod numbers perSagitta in this study.Sagitta nagae took food throughout life. Food ingested bySagitta per day was calculated as 37.6% ofSagitta in dry weight. 相似文献
22.
At each localized sphere for dynamics of organic matter in the sea, the total amount of nutrient substances is constant, and
the total and inorganic substances must keep a steady state within a certain time.
Based on the simplified assumptions, the mechanism of this steady state in the sea was analyzed using the data of primary
productivity, especialy nutrient absorption of diatom. When a certain amount of phosphate was supplied to different volume
of a basic medium, the absorded-phosphate per pigment unit (chlorophyll-a μg per liter) of diatom was constant. The absorbed-phosphate per pigment unit and initial concentration of phosphate in the
medium had linear relationship within about 200 μg phosphate per liter of the medium. The curves of experimental phosphate
absorption and growth of diatom were found to be consistent with the theoretical one. 相似文献
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24.
The locations of a specific geological boundary and aquifer were predicted, prior to reaching them, by a reflection method and the measurement of geothermic temperature. The determination was performed during tunnelling work which passed through the Median Tectonic Line in central Japan. The reflection method procedure was as follows. A P-wave was produced on the tunnel face by a small blasting. The location of the velocity layer boundary was predicted by the travel time of the direct wave and the reflected wave. The geothermic temperature was measured by a thermocouple which was set in the borehole at the face. The location of the aquifer was predicted by the thermal deviation between the measured value and the theoretical value that was determined from a mean geothermal gradient. Also, a water quality survey is performed, discussing the quality of the fissure water. In addition, we were able to confirm, using the Seismic Tomography method, that the sheared zone found, was the layer including lens-shaped low-velocity zone. The methods considered proved to be simple and effective for geological prognosis from within the tunnel. 相似文献
25.
Hiroshi Nagasawa 《Contributions to Mineralogy and Petrology》1973,39(4):301-308
Rare-earth, Sr and Ba abundances were determined for three basalts, one mugearite, one trachyandesite and five trachytes from Dogo, Oki Islands, Japan and Ca-rich clinopyroxene and feldspar phenocryst samples separated from them. It is concluded that rareearth, Sr and Ba abundance patters for basalts and three trachytes could be explained by crystallization differentiation of olivine basalt magma, while those for other samples suggest more complicated process of magma production. Calculated Eu2+ to total Eu ratios in the magmas showed a increasing trend with differentiation. It is found that Yb and Lu partition coefficients were larger than those of lighter rare earths for clinopyroxenes in trachytes suggesting preferential substitution of the heavy rare-earth ions for Mg-site in the clinopyroxenes. 相似文献
26.
Hiroshi Nagasawa Douglas P. Blanchard Hiroshi Shimizu Akimasa Masuda 《Geochimica et cosmochimica acta》1982,46(9):1669-1673
Concentrations of rare-earth elements (REE), Sc, Fe, Co, Cr, Na and Ir in the bulk sample and mineral separates of the isotopically unique Allende inclusion, EK 1-4-1, were determined by instrumental neutron activation analysis. REE concentrations were also determined by mass-spectrometric isotope dilution for two density separates.The inclusion showed enrichment of light REE over heavy REE with a positive Yb anomaly, thus showing a tendency to resemble group II fine-grained inclusions in REE abundances, although EK 1-4-1 is a coarse-grained inclusion. High Cr concentrations also indicate group II affinity. However, high Ir (6 ppm) and Sc (105 ppm), and low FeO (1.80%), and Co (13.8 ppm) concentrations in the bulk sample and low Na concentrations in mineral separates show group I affinity.Between melilite and pyroxene fractions, the same samples in which mass-fractionated O isotope ratios were observed (Clayton and Mayeda, 1977), REE, Sc, Co and Fe showed distributions which are substantially different from those observed for “ordinary” Allende type B inclusions. These two minerals do not appear to be in equilibrium with respect to trace element distributions.The results indicate that the isotopically unique EK 1-4-1 is also unusual in its elemental abundances and distributions. 相似文献
27.
Akihiko Murakami Tokio Matsuda Nobuhiro Watanabe Shinichi Nagasawa 《Journal of Oceanography》1976,32(5):242-248
The ability to degraden-paraffin mixture of two bacterial strains,Caulobacter sp. andFlavobacterium sp., isolated from sea water of Tokyo Bay was studied experimentally in the enriched seawater (ESW) medium. These bacteria degraded actively the mixture ofn-tridecane,n-tetradecane,n-pentadecane andn-hexadecane. The maximum rate of degradation was observed after a lag period of 2 to 8 day and these bacteria were found to degrade then-paraffin mixture at rates calculated to be in a range from 3.3×10?12 to 3.4×10?11 mg-oil cell?1 h?1 at 20°C. The maximum degradation rate,r m mg-oil l?1 h?1, was correlated with the amount of the initial totaln-paraffin,S mg-oil l?1, as expressed by the following equation: $$rm = (rm)\max \left( {\frac{S}{{S + Km}}} \right)$$ where (r m )max denotes the largest value ofr m whenn-paraffin exists in large excess andK m is a constant and represents the amount ofn-paraffin at which the degradation rate,r m , reaches 1/2 of its largest value, (r m )max. The values of (r m )max andK m were calculated to be as follows: In the case ofCaulobacter sp. (strain KM-1), (r m )max=6.0 mg-oil l?1 h?1 andK m =191 mg-oillesw ?1; in the case ofFlavobacterium sp., (r m )max=5.47 mg-oil l?1 h?1 andK m =152 mg-oillesw ?1. 相似文献
28.
Katsumi Marumo Keinosuke Nagasawa Yoshimasu Kuroda 《Earth and Planetary Science Letters》1980,47(2):255-262
Mineralogical and hydrogen isotopic studies have been made on clay minerals occurring in the Ohnuma geothermal area, northeastern Japan. Here, clay minerals such as smectite, kaolinite, dickite, sericite, and chlorite were formed by hydrothermal alteration of Miocene rocks. A chemical equilibrium can be assumed to be attained from the fact that the amount of expandable layer in the interstratified chlorite/smectite decreases and the polytype of sericite changes from 1M to 2M1 with increasing depth and temperature. The hydrogen isotopic composition (D/H) of the clay minerals is lighter than that of the geothermal and local meteoric waters by about 20–40‰. The hydrogen isotopic fractionation factors αmineral-water are as follows: 0.972–0.985 for kaolinite and dickite, 0.973–0.977 for sericite, and 0.954–0.987 for chlorite. In the temperature range from 100 to 250°C, the hydrogen isotopic fractionation factors between these minerals and water are not sensitive to the temperature. αchlorite-water depends on the kind of octahedrally coordinated cations which lie close to the hydroxyl groups; it becomes large with an increase of Mg content of chlorite. 相似文献
29.