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81.
Eriko Kamiya Shinji Izumiyama Masahiko Nishimura James G. Mitchell Kazuhiro Kogure 《Journal of Oceanography》2007,63(1):101-112
Flow cytometry (FCM) is now becoming a routine tool for the enumeration and optical characterization of bacteria in marine
environments. We investigated the effects of sample fixation and storage upon flow cytometric determination of marine bacteria.
Fixed and unfixed seawater samples were analyzed by FCM immediately aboard ship and/or later in the laboratory, and the appearances
of the fluorescence signals and bacterial counts of these samples were compared. Fixation and storage led to the formation
of multiple peaks in fluorescence histograms; this was also seen in 22 out of 36 samples frozen in liquid nitrogen. Fixation
did not, but storage did induce a decrease of bacterial counts: a rapid decrease during the first 3 days followed by a slower
decline. The decline of cell numbers in stored samples was expressed by a regression model. Our studies indicate that precaution
is necessary when interpreting the data from fixed and/or stored marine bacterial samples analyzed by FCM. The possibility
that the procedure of fixation and storage leads to the appearance of high DNA and low DNA bacterial groups should be considered. 相似文献
82.
Paleomagnetism of the middle Cretaceous Iritono granite in the Abukuma region, northeast Japan 总被引:1,自引:0,他引:1
Ken-ichi Wakabayashi Hideo Tsunakawa Nobutatsu Mochizuki Yuhji Yamamoto Yutaka Takigami 《Tectonophysics》2006,421(1-2):161-171
We have studied the paleomagnetism of the middle Cretaceous Iritono granite of the Abukuma massif in northeast Japan together with 40Ar–39Ar dating. Paleomagnetic samples were collected from ten sites of the Iritono granite (102 Ma 40Ar–39Ar age) and two sites of its associated gabbroic dikes. The samples were carefully subjected to alternating field and thermal demagnetizations and to rock magnetic analyses. Most of natural remanent magnetizations show mixtures of two components: (1) H component, high coercivity (Bc > 50–90 mT) or high blocking temperature (Tb > 350–560 °C) component and (2) L component, relatively low Bc or low Tb component. H component was obtained from all the 12 sites to give a mean direction of shallow inclination and northwesterly declination (I = 29.9°, D = 311.0°, α95 = 2.7°, N = 12). This direction is different from the geocentric axial dipole field at the present latitude (I = 56.5°) and the typical direction of the Cenozoic remagnetization in northeast Japan. Since rock magnetic properties indicate that the H component of the Iritono granite is carried mainly by magnetite inclusions in plagioclase, this component probably retains a primary one. Thus the shallow inclination indicates that the Abukuma massif was located at a low latitude (16.1 ± 1.6°N) about 100 Ma and then drifted northward by about 20° in latitude. The northwesterly deflection is attributed mostly to the counterclockwise rotation of northeast Japan due to Miocene opening of the Japan Sea. According to this model, the low-pressure and high-temperature (low-P/high-T) metamorphism of the Abukuma massif, which has been well known as a typical location, would have not occurred in the present location. On the other hand, the L component is carried mainly by pyrrhotite and its mean direction shows a moderate inclination and a northwesterly declination (I = 42.8°, D = 311.5°, α95 = 3.3°, N = 9). Since this direction is intermediate between the H component and early Cenozoic remagnetization in northeast Japan, some thermal event would have occurred at lower temperature than pyrrhotite Curie point ( 320 °C) during the middle Cretaceous to early Cenozoic time to have resulted in partial remagnetization. 相似文献
83.
84.
85.
峨眉山地区大气漂尘化学组成研究 总被引:2,自引:0,他引:2
为了揭示峨眉山大气漂尘的化学特征,研究小组分别在1998,1999,2000年使用小型大气采样器进行采样,并测得样品中含有水溶性化学成分(Na^ ,K^ ,Mg^2 ,Ca^2 ,SO4^2-,NO3^-,NH4^ 和Cl^-)和酸溶性化学成分(Pb和Zn)。这一地区三年的大气成分与1990年的相似,而且峨眉山的Na^ ,Cl^-,SO4^2-,NO3^-,Ca^2 ,NH4^ ,Pb和Zn浓度分别比日本山形县鹤岗的要高出4-15,3-19,3-5,3-6,13-23,4-7,11-28和10-23倍之多。 相似文献
86.
Helium and carbon isotopes in fluorites: implications for mantle carbon contribution in an ancient subduction zone 总被引:1,自引:0,他引:1
Junji Yamamoto Makoto Watanabe Yoshiyuki Nozaki Yuji Sano 《Journal of Volcanology and Geothermal Research》2001,107(1-3)
The concentrations of helium and carbon in fluorite associated with Cretaceous to Neogene (90–13 Ma) granitic magmatism in the Japanese arc have been measured. Concentrations of Li, U, Th and Gd were measured to correct for secondary generated 3He. The CO2/3He of fluorites are almost uniform (1.5×1010–4×1010) and in fair agreement with the range of present island arc volcanic gases. The calculated mantle C contribution in the Mesozoic subduction zone appear to have been identical to the present one (7–19%) indicating that the C flux from the mantle in supra-subduction zone environments has remained fairly constant during the past 70 million years. 相似文献
87.
Ikeda M Maezawa H Ito T Saito G Sekimoto Y Yamamoto S Tatematsu K Arikawa Y Aso Y Noguchi T Shi SC Miyazawa K Saito S Ozeki H Fujiwara H Ohishi M Inatani J 《The Astrophysical journal》1999,527(1):L59-L62
Large-scale mapping observations of the 3P1-3P0 fine-structure transition of atomic carbon (C i, 492 GHz) and the J=3-2 transition of CO (346 GHz) toward the Orion A molecular cloud have been carried out with the Mount Fuji submillimeter-wave telescope. The observations cover 9 deg2 and include the Orion Nebula M42 and the L1641 dark cloud complex. The C i emission extends over almost the entire region of the Orion A cloud and is surprisingly similar to that of 13CO (J=1-0). The CO (J=3-2) emission shows a more featureless and extended distribution than C i. The C i/CO (J=3-2) integrated intensity ratio shows a spatial gradient running from the north (0.10) to the south (1.2) of the Orion A cloud, which we interpret as a consequence of the temperature gradient. On the other hand, the C i/13CO (J=1-0) intensity ratio shows no systematic gradient. We have found a good correlation between the C i and 13CO (J=1-0) intensities over the Orion A cloud. This result is discussed on the basis of photodissociation region models. 相似文献
88.
Gold decoration and platinum-carbon-shadowing techniques of electron microscopy have been applied to study the surface microtopographs of noncleavage (001) faces of porphyroblastic white micas and sericite crystals collected from the chlorite, biotite, and garnet zones in the Shiragayama area in the Sanbagawa metamorphic terrain, Shikoku, Japan. Two different types of surface microtopograph have been observed; parallel step system and saw-tooth step system. The former is interpreted as representing the surface microtopographs formed either by growth or under near equilibrium conditions, the latter either by dissolution or under rigorous kinetic conditions. The former has been observed on porphyroblastic white micas occurring in the middle portion of each metamorphic zone and on all sericite crystals, the latter on most sericites and on porphyroblastic white micas occurring along the boundaries of the neighboring metamorphic zones. It is suggested that the observed variations in the surface microtopographic characteristics are due to Ostwald ripening during a kind of sintering process in which interstitial water plays an essential role, and that the drastic changes along the metamorphic zone boundaries are due to dehydration reactions. Retrogressive metamorphism is considered to have an almost negligible effect, if any, upon the surface microtopographs. 相似文献
89.
Young,olivine xenocryst-bearing alkali-basalt from the oceanward slope of the Japan Trench 总被引:3,自引:0,他引:3
Naoto?HiranoEmail author Junji?Yamamoto Hiroyuki?Kagi Teruaki?Ishii 《Contributions to Mineralogy and Petrology》2004,148(1):47-54
Young (6 Ma) alkali-basalts were collected from the toe of the oceanward slope of the northern Japan Trench. Two types of olivine are present in these lavas, xenocrysts with reaction rims and magmatic. The forsterite (Fo) (no. 91–92) values and NiO contents (0.3–0.5 wt%) of the xenocrysts are similar in composition to those of the depleted mantle peridotite. The groundmass olivines have relatively lower Fo values (no. 81–88) and NiO contents (0.1–0.5 wt%). Reaction rims and the vicinity of the silicate inclusion in xenocrysts show the intermediate compositions between the xenocryst and magmatic olivines. Chromian spinel inclusions in the xenocrysts also show the depleted composition in the range of abyssal peridotite. CO2 fluid inclusions in the xenocryst records pressures before entrainment into the host magma up to 0.4 GPa, which corresponds to a depth of up to 14 km of lithospheric mantle. These data indicate that the xenocrysts originate from MORB-depleted mantle. 相似文献
90.
Water and sediment quality, partial mass budget and effluent N loading in coastal brackishwater shrimp farms in Bangladesh 总被引:2,自引:0,他引:2
Shahidul Islam M Jahangir Sarker M Yamamoto T Abdul Wahab M Tanaka M 《Marine pollution bulletin》2004,48(5-6):471-485
The present study aimed to quantify the water and sediment quality and growth and production parameters and to establish nutrient budgets for an average of five selected semi-intensive shrimp ponds in Bangladesh over a growing cycle. Physico-chemical parameters of water and sediments were measured and analyzed by standard methods. Gross yield (kg ha-1) of shrimp was calculated from the stocking and harvesting data. Finally, a partial nutrient mass budget for N and P was calculated. Most of the parameters of water and sediments correlated significantly with each other suggesting a high degree of interactions between different parameters in the system. Significantly higher concentrations of all species of nitrogenous nutrients were recorded in the effluent waters than that entering into the ponds. Therefore, a high loading and net output of nitrogenous nutrients in effluent waters was documented. The study also indicated a net discharge of solids and minerals through effluent loading. However, significantly lower concentrations of phosphorus in the effluent water indicated a net retention and trapping of phosphatic nutrients in the environment. Total production ranged between 532.0 and 697.0 kg ha-1 cycle-1 and P. monodon production between 484.0 and 562.0 kg ha-1 cycle-1. Ponds gained nitrogen primarily from intake water (55%) and fertilizers (29%), and nitrogen was lost primarily from water exchange (78%) and harvested shrimp (12%). Phosphorus gain occurred mostly from intake water (52%) and fertilizers (25%), and phosphorus was lost primarily from water exchange (52%) and harvested shrimp (3.3%). About 10% of input nitrogen and 44% of phosphorus were not accounted for in measured losses, and presumably were fixed or metabolized in the system. On average, 78 g N was discharged to and 25 g P was removed from the surrounding water by the system for each kilogram of shrimp produced. Mean conversion of feed nitrogen and phosphorus to shrimp flesh averaged 74% and 40%, respectively. It was concluded that semi-intensive systems serve as net supplier of N to and net remover of P from the surrounding water. 相似文献