Adsorption of tributyltin by tributyltin resistant marine Pseudoalteromonas sp. cells

The isolate, Pesudoalteromonas sp. TBT1, could grow to overcome the toxicity of tributyltin chloride (TBTCl) up to 30 μM in the absence of Cl⁻ in the medium until the cells reached an exponential phase of growth. The viability, however, was reduced after the cells reached a stationary phase. The degradation products, such as dibutyltin (DBT) and monobutyltin (MBT), were not detected in the growth medium, indicating that the isolate has no ability to degrade TBT into less toxic DBT and MBT. Up to about 10^7.5 TBT molecules were adsorbed by a single cell. The observation of morphological changes with an electron microscope showed that the cell surface became wrinkled after exposure to the lethal concentration of 10 mM TBTCl. These results indicate that the resistance of the isolate toward the toxicity of TBTCl is not related to the unique cell surface, which seems to play an important role in preventing the diffusion of TBTCl into the cytoplasm.     

Effects of heavy oil in the developing spotted halibut, Verasper variegatus

It is well known that heavy oil (HO) on the sea surface causes serious problems in the aquatic environment. In particular, some species of teleosts which develop on the sea surface are thought to be affected by the HO which flows out from tankers or coastal industry. However, the toxicological effects of HO are not fully understood. We performed exposure experiments using the Pleuronectiformean fish, spotted halibut (Verasper variegatus), which is an important fishery resource in Japan. In course of the development, HO-exposed embryos showed remarkable delay in developmental processes including somite formation. We further observed abnormal development of the head morphology. Notably, treated embryos had relatively small eyes and craniofacial structures. These findings strongly suggest that HO seriously affects the cell proliferation and differentiation of the embryo. In addition, HO-exposed embryos showed abnormal neuronal development. We also performed the exposure in the larval stage. Treatment of post-hatching larvae with HO resulted in significantly greater mortality compared with controls. Through these observations, we finally conclude that HO is strongly toxic to halibut in their early life stages.     

Unusual behavior of the Kuroshio Current System from winter 1996 to summer 1997 revealed by ADEOS-OCTS and other data— Suggestion of topographically forced alternating-jet instability

While the Advanced Earth Observing Satellite (ADEOS) was operating, the Kuroshio and the Kuroshio Extension, or the Kuroshio Current System, exhibited unusual behavior from the winter of 1996 to the summer of 1997. This behavior of the Kuroshio Current System has been closely studied using a time series of satellite observation images of SST and ocean color obtained by ADEOS-OCTS, reinforced by SST images obtained by NOAA-AVHRR. Our findings include (i) a long lasting, very southerly path of the Kuroshio Extension; (ii) a Kuroshio path very distant from Japan with the following alternating-jet-like north-south flow pattern of the Kuroshio Extension, which occurred twice, once in February and once in April 1997, as independent events and which was observed to be affected by the bottom topography of the Izu-Ogasawara Ridge and Trench, and of the Japan Trench; (iii) cutting off of a cold water mass after the February event; and (iv) the formation of a vortex pair after the April event. A new mechanism is suggested for the formation of the alternating-jet flow pattern: a topographically forced alternating-jet instability (AJI). An SST-Chlorophyll Diagram (T-Chl Diagram) generated using simultaneous data from a single satellite is useful for analyzing the water mass structure of this region, including biological processes.     

Future Projections of Precipitation Characteristics in East Asia Simulated by the MRI CGCM2

Projected changes in precipitation characteristics around the mid-21st century and end-of-the-century are analyzed using the daily precipitation output of the 3-member ensemble Meteorological Research Institute global ocean-atmosphere coupled general circulation model (MRI-CGCM2) simulations under the Special Report on Emissions Scenarios (SRES) A2 and B2 scenarios. It is found that both the frequency and intensity increase in about 40% of the globe, while both the frequency and intensity decrease in about 20% of the globe. These numbers differ only a few percent from decade to decade of the 21st century and between the A2 and B2 scenarios. Over the rest of the globe (about one third), the precipitation frequency decreases but its intensity increases, suggesting a shift of precipitation distribution toward more intense events by global warming. South China is such a region where the summertime wet-day frequency decreases but the precipitation intensity increases. This is related to increased atmospheric moisture content due to global warming and an intensified and more westwardly extended North Pacific subtropical anticyclone, which may be related with an E1 Nin^-o-like mean sea surface temperature change. On the other hand, a decrease in summer precipitation is noted in North China, thus augmenting a south-to-north precipitation contrast more in the future.     

Rain‐induced deep‐seated catastrophic rockslides controlled by a thrust fault and river incision in an accretionary complex in the Shimanto Belt,Japan

To clarify the geological causes of rockslides induced by rainstorms in accretionary complexes, the geology and geomorphology of two large rockslides (volumes > 10⁶ m³) induced by the heavy rainfall of Typhoon Talas in the Shimanto Belt, Kii Mountains, Japan in 2011 are investigated. Our analysis reveals that thrusts with brittle crush zones controlled the occurrence of the rockslides. The properties and distribution of thrusts were poorly constrained before this study. Flooding during the rainstorm removed surface materials along rivers, allowing thorough geological mapping to be performed. Gravitationally deformed slopes were studied using GIS analysis of 1 m digital elevation models (DEMs) and fieldwork, and X‐ray diffraction (XRD) analysis, permeability, and direct shear tests were used to characterize the mineralogy and geotechnical properties of fault gouge. The Kawarabi thrust has a brittle crush zone up to 6 m thick and acts as the sliding surface for both landslides. The thrust dips 34° downslope and is cut by high‐angle faults and joints along one or both sides of each landslide body. Prior to failure, the upper part of the slope contained small scarps, suggesting that the slopes were already gravitationally deformed. The slope instability can be attributed to long‐term river erosion, which has undercut the slope and exposed the thrust at the base of the slope. The groundwater level, monitored in boreholes, suggests that the Kawarabi thrust is a barrier to groundwater flow. The weak and impermeable nature of the thrust played an essential role in the generation of gravitational slope deformation and catastrophic failure during periods of increased rainfall. Thrusts are a common feature of accretionary complexes, including in the Shimanto Belt, and the mechanism of slope failure stated above can be typical of rockslides in accretionary complexes and provide new insights into landslide disaster mitigation.     

Age of the Solomon Sea Basin from magnetic lineations

Magnetic anomalies measured in the central to western half of the Solomon Sea, when considered with other magnetic data, reveal the existence of linear patterns. Magnetic lineation anomaly models of the Cenozoic, 65 to 0 Ma, suggest that an age between 34 and 28 Ma and a half-rate spreading speed of 5.8 cm/yr for the northern flank of a former spreading center best fits our present magnetic data in the Solomon Sea Basin. Heat flow and bathymetry data support this preferred model.     

Dynamical evolution of two-component star clusters

The dynamical evolution of two-component star clusters, each of which is enclosed within a perfectly reflecting sphere, is investigated by numerically solving moment equations derived from the Boltzmann equation. One of the two adopted model clusters evolves, starting from a state of no mass segregation, toward an equilibrium state at a quite slow rate. The other one evolves away from an equilibrium state and its central density increases without limit. The different evolutionary behaviors of the two model clusters are explained by the fact that there exists no equilibrium state for such clusters if the total energy is less than a certain critical value. The critical value increases with increasing total mass fraction of the heavier stars. This is qualitatively the same as Spitzer's theorem (1969) expressed in another way.     

Vertical structure of hard X-ray flare

This paper presents studies of the vertical structure of hard X-ray flares for two contrasting examples. The 1981 May 13 flare contained a coronal hard X-ray source which was located above 50000 km above the photosphere. On the other hand, the 1981 July 20 flare had a chromospheric double source structure in the initial phase. Electrons in this case were able to stream freely from the corona to the chromosphere.