Long-term temperature monitoring in a borehole drilled into the Nojima Fault, southwest Japan   总被引：2，自引：0，他引：2  

Makoto Yamano  Shusaku Goto 《Island Arc》2001,10(3-4):326-335

Abstract Long-term monitoring of temperature distribution in an active fault zone was carried out using the optical fiber temperature-sensing technique. An optical fiber cable was installed in a borehole drilled into the Nojima Fault in Awaji Island, south-west Japan, and the temperature profile to a depth of 1460 m had been measured for 2.5 years (July 1997–January 2000). Although the obtained temperature records showed small temporal variations due to drifts of the measurement system all along the cable, local temperature anomalies were detected at two depths. One at around 80 m seems to correspond to a fracture zone and may be attributed to groundwater flow in the fracture zone. This anomaly had been stable throughout the monitoring period, whereas the other anomaly at around 500 m was a transient one. The water level in the borehole could be estimated from the diurnal temperature variations in the uppermost part of the borehole and may provide information on the hydrological characteristics of the fault zone, which is connected to the borehole through perforations on the casing pipe. Except for these minor variations, the temperature profile had been very stable for 2.5 years. The conductive heat flow calculated from this profile and the thermal conductivity measured on core samples increases with depth, probably resulting from errors in thermal conductivity due to sampling problems and/or from advective heat transfer by regional groundwater flow. Assuming that the middle part of the borehole (less fractured granite layer) is least affected by these factors, heat flow at this site is estimated to be approximately 70 mW/m².  相似文献   

Zooplankton investigations in Yatsushiro-kai,western Kyushu,I     

Reiichiro Hirota  Makoto Hara 《Journal of Oceanography》1975,31(3):115-123

The occurrence of the zooplankton at 21 stations in Yatsushiro-kai, western Kyushu, was investigated in June, September and November of 1968, and March of 1969. Copepods formed the most predominant constituent among the collected Zooplankton. AlthoughParacalanus parvus was abundant in most of the surveyed region, other copepods occurred dominantly in the following order when going from the northeastern area toward the southwest: Oithona nana→Acartia clausi→Microsetella norvegica→Oithona similis→Corycaeus spp. Yatsushiro-kai can be characterized biologically by dividing it into two main regions. The northern half is more embaymental and the southern half is more oceanic, bordered by an area whereMicrosetella norvegica occurred as the dominant. The area whereAcartia clausi occurred dominantly is the most embaymental in the northern half, and the area whereCorycaeus spp. occurred dominantly is the most oceanic in the southern half.  相似文献   

Growth characteristics ofChattonella antiqua     

Yasuo Nakamura  Makoto M. Watanabe 《Journal of Oceanography》1983,39(4):151-155

Nutrient requirements of a red tide flagellate,Chattonella antiqua, were investigated in a laboratory culture experiment. Growth ofC. antiqua was supported by nitrate and ammonium, and by urea to a limited extent, but not by glycine, alanine and glutamate. Orthophosphate served as a good phosphorus source but glycerophosphate did not. Fe³⁺ (1µM) fully promoted the flagellate's growth in the presence of 80µM of EDTA. The addition of Mn²⁺ (0–20µM), Zn²⁺ (0–10µM) and Co²⁺ (0–0.4µM) did not show any effect. Among three vitamins tested, only B₁₂ (6 ng 1^?1) served as a growth factor. Glucose, acetate and glycolate did not improve growth in the light nor did they support growth in darkness. The minimum cell quotas for nitrogen, phosphorus, iron and B₁₂ were estimated to be 11 pmoles ce^?1, 1.0, ～0.09 and 1.1 fg cell^?1, respectively.  相似文献   

Two records of patchy occurrences of the oceanic shrimpSergestes similis Hansen off the east coast of Honshu,Japan     

Mitsumori Mutoh  Makoto Omori 《Journal of Oceanography》1978,34(1):36-38

Two recent records of the occurrences of the pelagic shrimp,Sergestes similis Hansen, are reported. They provide evidence of dense swarms ofS. similis in midwater off the east coast of Honshu, Japan, in spring. On one occasion,S. similis was found in a stomach of the basking shark,Cetorhinus maximus (Gunnerus). The shark, 8.11 m in total length, was accidentally trapped in a set net off Izu-oshima Island on April 18, 1974, and its foregut was filled only withS. similis. Feeding and swimming behavior of the basking shark, condition of the gut contents, and temperature profiles of the sea revealed thatS. similis was preyed upon by the shark near the island when the shrimp swarmed below 100 m depth at night. On another occasion,S. similis was fished by a commercial ground trawler 31 miles off Cape Shioyazaki on April 4 and 5 and off Hitachi on April 11, 1976. The trawlings were made around 500 m depth at daytime, and a total of 3.8 tons ofS. similis was caught and marketed. The size-frequency distribution and sex ratio ofS. similis in both occurrences from off Izu-oshima Island and off Cape Shioyazaki coincided very well. The samples consisted of identical population of probably 2nd year class having a body length mode between 46.0 and 50.0 mm. The sex ratio was skewed greatly toward females in both samples, that is 38∶2 and 100∶3 respectively. These two phenomena are discussed in relation to the life history ofS. similis.  相似文献   

A pump-sampler as a method of collecting plankton and its preliminary operation     

Akihiko Kuwahara  Tsuneyuki Abe  Masayuki Shimono  Makoto Kashiwai  Masatosi Sinoda 《Journal of Oceanography》1973,29(3):106-112

A pump-sampler was designed to study the distribution of marine plankton and its possible relationship with the temperature and salinity of the water. Sea water was pumped up through a 2 inch diameter hose and plankton contained in it was collected on a filter cup (2 inches in diameter, 139 meshes/inch) without being damaged. The filter cup, when clogged by plankton organisms, was washed by spraying with about 100 cu. cm of water. The differences between two continuous with an interval of more than 3–4 seconds could be detected.A preliminary operation along a 2.82 km course in Maizuru Bay was carried out simultaneously with temperature-salinity measurements at sampling intervals of 30 m. Temperature was measured by a thermistor resistance thermometer, and salinity was measured by a salinometer with a subsample of water which was collected from an additional opening of the pump-sampler. The temperature-salinity record showed that four zones of water were characterized.It was found that wide variation of plankton counts indicated dense concentrations of particular species or group of species, and on the mesoscale it was possible to examine the size of the aggregation.  相似文献   

An Ecological-Physical Coupled Model with Ontogenetic Vertical Migration of Zooplankton in the Northwestern Pacific     

Michio J. Kishi  Hitoshi Motono  Makoto Kashiwai  Atsushi Tsuda 《Journal of Oceanography》2001,57(5):499-507

A vertical one-dimensional ecosystem model with vertical migration of zooplankton was constructed and applied to Station A-7 off Sanriku district of Japan in the northwest Pacific Ocean. The model consists of an eight-compartment ecosystem model coupled with a physical model of the oceanic mixed layer. The transition of phytoplankton species responsible for the spring bloom is well reproduced by this model with vertical migration of zooplankton but is not simulated by the model without vertical migration. This new model also simulates an observed inter-annual variability of the spring bloom, with the timing and intensity of the simulated bloom in a given year depending upon the strength of mixing during the preceding winter. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Study of metal contents of elasmobranch fishes: part 1—metal concentration in the muscle tissues of a dogfish, squalus mitsukurii     

Masashi Taguchi  Kenji Yasuda  Shozo Toda  Makoto Shimizu 《Marine environmental research》1979,2(3):239-249

Concentrations of Hg, Zn, Fe, Cd and Cu in the muscle tissues of a dogfish, Squalus mitsukurii, were determined by atomic absorption spectrometry and found to be in the ranges of f0·019–2·13, 1·8–3·6, 1·5–5·7, 0·001–0·018 and 0·12–0·70 μg/g wet weight, respectively. The frequency distributions of concentrations, with the exception of mercury, were found to be log-normal. The correlation coefficient between mercury content and total length was positive and large and statistically highly significant. For other metals negative correlations were observed. Mercury concentration in the muscle was found to increase in proportion to the total length cubed. Regression of mercury concentration on age of sharks was shown to be linear. Analysis of covariance showed that the difference between sexes was not statistically significant, either in slope or in height. The concentration of mercury in the muscle tissues of embryos was considerably lower, Cd roughly the same and Zn and Fe higher than those of mothers. The concentrations of Zn, Fe and Cu are higher in the embryonic stage and immediately after birth than in later stages of growth.  相似文献   

Effect of dietary docosahexaenoic acid on lipogenesis and lipolysis in black sea bream, Acanthopagrus schlegeli   总被引：2，自引：0，他引：2  

JI Hong  OM Ahamd Dau  YOSHIMATSU Takao  UMINO Testuy  NAKAGAWA Heisuke  FURUHASHI Makoto  SAKAMOTO Shuichi 《海洋学报(英文版)》2007,26(1):112-121

1 IntroductionIt is well known that varying dietary fatty acidprofile affects the tissue fatty acid composition and e-ven the growth performance in fish ( Bell et al.,2002; Figueiredo -Silva et al., 2005; Harel andPlace, 2003; Schulz et al., 2005; Tocher et al.,2003). Docosahexaenoic acid (DHA), an importantessential fatty acid for marine species, has the effectnot only on the fatty acid profile of fish body tissue,but also on biological and physiological conditions(Ishizaki et al., 2000; …  相似文献   

Community structures of coral reefs around Peninsular Malaysia     

Tatsuki Toda  Tomoko Okashita  Takeshi Maekawa  Bin Abdul Adzis Kee Alfian  Mohd Kushairi Mohd Rajuddin  Ryota Nakajima  Wenxi Chen  Kunio T. Takahashi  Bin Haji Ross Othman  Makoto Terazaki 《Journal of Oceanography》2007,63(1):113-123

Coral community structures at eleven fringing reef sites were investigated along the coast of Peninsular Malaysia. Estimated coverage of coral communities is examined by applying quantitative digital image analysis to the line transect method. Four coral community types were characterized by dominant genera and lifeforms: Acropora branching community, Montipora-Acropora community, Porites massive community, and Heliopora community. Live coral coverage in all study sites ranged from 17.9% to 68.6%. Most reefs were in “fair” condition while some reefs were shown to be in “poor” condition. Coral community structures among the study sites were divided into the west coast of Peninsular Malaysia with a dominant Porites massive lifeform, and the east coast with a variety of lifeform categories of Montipora and Acropora. Physical effects such as the monsoon wind regime and sedimentation are likely to influence the formation of dominant coral communities around Peninsular Malaysia.  相似文献   

Invisible comets on evolutionary track of short-period comets     

Tsuko Nakamura  Makoto Yoshikawa 《Celestial Mechanics and Dynamical Astronomy》1992,54(1-3):261-266

We systematically surveyed the orbits of short-period (SP) comets that show a large change of perihelion distance (q) between 1–2 AU (visible comets) and 4–5 AU (invisible comets) during 4400 years. The data are taken from Cosmo-DICE (Nakamura and Yoshikawa 1991a), which is a long-term orbital evolution project for SP comets. Recognizing that q is the most critical element for observability of comets, an invisibility factor (f), defined as the ratio of unobservable time span to observable span during 4400 years, is calculated for each of the large-q-change comets. A detection limit for each comet is obtained from the heliocentric distance at discovery and/or the absolute magnitude at recent apparitions. A mean f value for 35 SP comets with 2.9 J (J is the Tisserand's invariant) is found to be 19.8. This implies that for each visible SP comet of this J-range, at every epoch of time, there exist about 20 invisible comets near the capture orbits by Jupiter, under the assumptions of steady-state flux and ergodicity for the SP-comet population.  相似文献