A sudden strong coastal current called a “kyucho” occurred in August 2013 in the eastern coastal waters of Wakasa Bay, Japan. This study examined its characteristics based on both observational data collected by intensive field investigations and the simulation results of a numerical model. The field investigations comprised moored buoy observations near the coast and voyages by a research vessels and fishing boats. The mooring observations indicated that a current speed exceeding 50 cm s?1 occurred abruptly near the eastern coast of the bay, in association with a synchronous change in the current direction. Data collected by acoustic Doppler current profilers (ACDPs) mounted on the vessels showed that a clockwise eddy existed in the bay and that the current on the east side of the eddy generated the kyucho near the coast. Based on the results of the numerical model and the analysis of the ADCP data, it was considered that the clockwise eddy was generated by a strong current at the tip of the Tango Peninsula, in the western part of the bay. As the eddy propagated from west to east across the bay, it induced the kyucho in the coastal waters in the east of the bay. 相似文献
The aim of this study was to investigate whether coral photosynthetic efficiencies and recovery processes are affected by CO2‐driven ocean acidification in symbiont photosynthesis and coral calcification. We investigated the effects of five CO2 partial pressure (pCO2) levels in adjusted seawater ranging from 300 μatm (pre‐industrial) to 800 μatm (near‐future) and strong and weak light intensity on maximum photosynthetic efficiency and calcification of a branching coral, Stylophora pistillata, as this species has often been used in rearing experiments to investigate the effects of acidified seawater on calcification and photosynthetic algae of corals. We found that, the photosynthetic efficiencies and recovery patterns under different light conditions did not differ among pCO2 treatments. Furthermore, calcification of S. pistillata was not affected by acidified seawater under weak or strong light conditions. Our results indicate that the photosynthetic efficiency and calcification of S. pistillata are insensitive to changes in ocean acidity. 相似文献
The horizontal distribution of the epipelagic zooplankton communities in the western Arctic Ocean was studied during August–October 2008. Zooplankton abundance and biomass were higher in the Chukchi Sea, and ranged from 3,000 to 274,000 ind. m?2 and 5–678 g WM m?2, respectively. Copepods were the most dominant taxa and comprised 37?94% of zooplankton abundance. For calanoid copepods, 30 species belonging to 20 genera were identified. Based on the copepod abundance, their communities were classified into three groups using a cluster analysis. The horizontal distribution of each group was well synchronized with depth zones, defined here as Shelf, Slope and Basin. Neritic Pacific copepods were the dominant species in the Shelf zone. Arctic copepods were substantially greater in the Slope zone than the other regions. Mesopelagic copepods were greater in the Basin zone than the other regions. Stage compositions of large-sized Arctic copepods (Calanus glacialis and Metridia longa) were characterized by the dominance of late copepodid stages in the Basin. Both the abundance and stage compositions of large copepods corresponded well with Chl. a concentrations in each region, with high Chl. a in the Shelf and Slope supporting reproduction of copepods resulting in high abundance dominated by early copepodid stages. 相似文献
A database on thirty-one Geological Survey of Japan (GSJ) geochemical reference samples has been set up on Internet which allows the retrieval of recommended or preferable values, compiled data, location, sample preparation and other relevant information. The URL location on WWW server is: http://www.aist.go.jp./RIODB/geostand/welcome.html 相似文献
Gold has been determined in 26 geochemical reference samples with graphite furnace AAS after digesting the samples with aqua regia and hydrofluoric acid and extracting gold by methyl isobutyl ketone (MIBK). This method yields clearly higher values than those by the partial attack using aqua regia digestion. 相似文献
Summary The paper gives a survey of the blue-green algae found in Japan and used as food, medicine and nitrogenous fertilizer.
Since time immemorial four kinds (Aphanothece sacrum, Nostoc verrucosum, Nostoc commune, Blachytrichia quoyi) have been used for cooking purposes; yet it is only now that man is trying to cultivate a species, theAphanothece sacrum. Recently a bluegreen alga (Spirulina maxima), which is particularly rich in protein and vitamins and has always been eaten by the natives, became known in Africa.
The medicinal effects of linolenic acid was examined connection with the circulation of fatty acid. Only two of the species
analysed (Spirulina platensis, Arthrospira sp.) produce relatively large quantities of γ-linolenic acid.
The effects of the nitrogen-producing blue-green algaTolypothrix tenuis were observed in over 40 rice fields in various regions in Japan. In some places a considerable increase in the yield was
noticed, but this was never as high as in India. Presumably the difference can be traced back to 3 main factors: air temperature,
alkalinity of the water and the amount of nitrogen fertilizer.
Zusammenfassung Das Referat gibt eine übersicht über essbare, medizinisch wirksame und stickstoffdüngende Blaualgen speziell aus Japan.
Vier Arten (Aphanothece sacrum, Nostoc verrucosum, Nostoc commune, Blachytrichia quoyi) werden seit alter Zeit als Zugabe zu den Mahlzeiten gebraucht, wobei man erst heute eine Art (Aphanothece sacrum) zu kultivieren versucht. Kürzlich wurde in Afrika eine Blaualge (Spirulina maxima), bekannt, die einen besonders hohen Gehalt an Eiweiss und Vitaminen aufweist und seit jeher von den Eingeborenen gegessen
wird.
Im Zusammenhang mit dem Kreislauf der Fetts?uren wurde die medizinische Wirkung der Linols?ure geprüft. Nur zwei der analysierten
Arten (Spirulina platensis, Arthrospira sp.) bilden relativ grosse Mengen Linols?ure.
In gut 40 Reisfeldern verschiedener Regionen in Japan wurde die Wirkung der stickstoff-bindenden BlaualgeTolypothrix tenuis beobachtet. Es konnten zum Teil betr?chtliche Steigerungen erzielt werden, doch nie so hohe wie in Indien. Vermutlich sind
die Unterschiede haupts?chlich auf drei Faktoren: Lufttemperatur, Alkalinit?t des Wassers und Menge an Stickstoffdünger zurückzuführen.
The northern Ryukyu Arc has active backarc rift, neutral-stress forearc, and active accretionary prism. The Okinawa Trough has been shaped by the episodic rifting in the backarc. Paleostresses were inferred in this study from mesoscale faults in Neogene forearc sediments called the Miyazaki Group, southeast Kyushu in the northern Ryukyu Arc. The forearc stress changed from compressional to extensional from the latest Miocene through Early Pliocene time. The stress history is concordant with the transition in tectonic regime from folding to rifting in the backarc. The transition in the stress state occurred simultaneously also with trenchward movement of the volcanic front. These phenomena suggest that the subducting slab under southern Kyushu became steeper in the Early Pliocene. Extensional tectonics ceased sometime in the late Pliocene or early to mid-Pleistocene, concordant with the counterclockwise change of subducting direction of the Philippine Sea Plate. 相似文献
Cretaceous granitic rocks are widely distributed in the northern to central parts of Kyushu Island, southwest Japan arc, and are divided into two types, granite and tonalite-granodiorite. These rocks are clearly defined by their mineral assemblage, that is, the granite contains mostly muscovite and/or garnet and does not have hornblende, whereas the tonalite-granodiorite is always observed with hornblende. Many workers suggest that most of the granite has low initial Sr isotopic ratios (SrI90 Ma: 0.7052-0.7059) whose values are similar to those of tonalite-granodiorite (SrI90 Ma: 0.7050-0.7056).
The SiO2 contents of the granite (67.9 to 78.0 wt.%) are higher than that of tonalite-granodiorite (54.2 to 68.2 wt.%). The granite is characterized by peraluminous compositions, while the tonalite-granodiorite shows metaluminous to peraluminous compositions. The petrogenetic relation between granite and tonalite-granodiorite is examined by a modal batch melting model, which referred to results of already published experiments. The result of the model suggests that the petrogenesis of the peraluminous granitic magma can be explained by an anatexis of metaluminous tonalite in the tonalite-granodiorite under lower to middle crustal conditions and variable fH2O.
Rocks of tonalite to granodiorite in a subduction system generally have low initial Sr isotopic ratios (<0.705), which imply that the magma derived from a highly metaluminous origin such as mafic magma, mafic lower crust and/or subducting slab. In this study, it is regarded that the peraluminous granitic magma can be directly produced by an anatexis of metaluminous tonalite. Therefore, peraluminous granite with low initial Sr isotopic ratios may imply to a first step of recycling of the granitic layer in an active plate margin. 相似文献
Volcanic breccia is a representative heterogeneous rock. As a preliminary study for determining its mechanical properties in laboratory and field experiments, its material properties and structural features were described. Three-dimensional clast-size distribution was also estimated for the study site using the theory of stereology. With this distribution determined, a numerical simulation was performed to investigate the relationship between the volumetric proportion of clasts in a sample and the areal proportion and maximum length of clasts on a lateral surface of the sample. The following observations were made: (1) coefficients of variation for volumetric proportion are dependent on the size of the sample, and became large when the size of the sample is small; (2) samples with a small coefficient of variation can be selected at any size if a restriction is placed on the ratio, Dmax/D0, of the maximum length of clasts to the size of the sample; and (3) the volumetric proportion of clasts in each sample can be estimated from the observed areal proportions within an error range that depends on the whole volumetric proportion. 相似文献