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.     

Variability of Kuroshio velocity assessed from the sea-level difference between Naze and Nishinoomote

Variations of current velocity of the Kuroshio are examined using the 1965–1983 sea-level difference between Naze and Nishinoomote, located on the offshore and onshore sides of the Kuroshio in the Tokara Strait south of Kyûshû.Interannual variations of Kuroshio velocity are large, especially at periods longer than five years and around 2.1 years. They are almost determined by those of sea level on the offshore side of the Kuroshio. They are highly coherent with the offshore sea level at periods longer than 1.7 years, and incoherent with the onshore sea level at periods longer than 2.8 years.The mean seasonal variation averaged for 19 years is at its maximum in July and at its minimum in the second half of October, with a sharp decrease in August and September. However, such a variation does not repeat every year. Amplitude, dominant period and phase are greatly different by year, and they can be roughly divided into four groups: small-amplitude group, semiannual-period group, and two annual-period groups with different phases. The only feature found in almost all years is a weak velocity from September to December.The amplitude of seasonal variation tends to be large in the formation years of the large meander (LM) of the Kuroshio and small during the LM period. It is also large in the years preceding El Niño, and diminishes remarkably in El Niño years.Kuroshio velocity in the Tokara Strait is incoherent with position of the Kuroshio axis over the Izu Ridge, but highly coherent with 70-day variations of coastal sea levels which are dominant during the LM period.     

Characterization of water quality variation in the Mekong River at Vientiane by frequent observations

To better understand the variation of water quality in the Mekong River, sampling and measurement were scheduled twice a week for about 3 years at Vientiane, followed by basic statistical analysis of the observed data. The frequent measurement revealed detailed characteristics of the water quality variation, which had not been detected by monthly observation in the previous studies. The variation in total ionic content was considered to be governed by dilution of the amount of water. Increases in turbidity could be attributed to physical effects including surface soil erosion and bed material resuspension at the time of discharge increase. Nitrogen concentrations were stably low during the low flow period and abruptly increased in May. After the annual maximum in late May, the nitrate concentration steadily decreased regardless of the remarkable rise in the discharge from mid‐July, whereas the ammonium concentration remained at a similar level until October. It was considered that the first small discernable runoff after the long dry season flushed the accumulated nitrogen in the surface soil and mobilized the nitrogen in the riverbed. The variation in phosphorus concentrations was different from that in nitrogen concentrations. During the high flow period, continual dilutions at discharge peaks and occasional large additions of phosphorus by surface runoff were suggested. Copyright © 2011 John Wiley & Sons, Ltd.     

Tree-ring based hydroclimate reconstruction over northern Vietnam from Fokienia hodginsii: eighteenth century mega-drought and tropical Pacific influence

We present here the first statistically calibrated and verified tree-ring reconstruction of climate from continental Southeast Asia. The reconstructed variable is March–May (MAM) Palmer Drought Severity Index (PDSI) based on ring widths from 22 trees (42 radial cores) of rare and long-lived conifer, Fokienia hodginsii (Po Mu as locally called) from northern Vietnam. This is the first published tree ring chronology from Vietnam as well as the first for this species. Spanning 535 years, this is the longest cross-dated tree-ring series yet produced from continental Southeast Asia. Response analysis revealed that the annual growth of Fokienia at this site was mostly governed by soil moisture in the pre-monsoon season. The reconstruction passed the calibration-verification tests commonly used in dendroclimatology, and revealed two prominent periods of drought in the mid-eighteenth and late-nineteenth centuries. The former lasted nearly 30 years and was concurrent with a similar drought over northwestern Thailand inferred from teak rings, suggesting a “mega-drought” extending across Indochina in the eighteenth century. Both of our reconstructed droughts are consistent with the periods of warm sea surface temperature (SST) anomalies in the tropical Pacific. Spatial correlation analyses with global SST indicated that ENSO-like anomalies might play a role in modulating droughts over the region, with El Niño (warm) phases resulting in reduced rainfall. However, significant correlation was also seen with SST over the Indian Ocean and the north Pacific, suggesting that ENSO is not the only factor affecting the climate of the area. Spectral analyses revealed significant peaks in the range of 53.9–78.8 years as well as in the ENSO-variability range of 2.0 to 3.2 years.     

The development of Fe-nodules surrounding biological material mediated by microorganisms

Takashikozo is a phenomenon of Quaternary sediments in Japan. They are cylindrical Fe-oxyhydroxide nodules that form as plaques round plant roots, where Fe is preferentially concentrated to develop a solid wall. Structural features suggest that after the roots have decayed, the central space where the roots were situated acts as a flow path for oxidized water. Analysis of microbial 16S rDNA extracted from the nodules identified iron-oxidizing bacteria encrusted round the roots where they are the likely initiators of nodule formation. Direct microscopic observation revealed an accumulation of Fe-oxyhydroxides that fill the pore spaces and is also likely to be linked with the encrusting microbial colonies. Geological history and nanofossil evidence suggest that these Fe-nodules may have been buried at a depth of up to several tens of meters for at least 10⁵ years in reducing Quaternary sediments. Thus Fe-oxyhydroxide nodules that have formed in a geological environment at the interfaces between water and rock by microbial mediation can persist under reducing conditions. If this is the case, the phenomenon is significant as an analogue of post-closure conditions in radioactive waste repositories, since it could influence nuclide migration.     

Non-Gaussian cosmic microwave background temperature fluctuations from peculiar velocities of clusters

We use numerical simulations of a (480 Mpc  h ⁻¹)³ volume to show that the distribution of peak heights in maps of the temperature fluctuations from the kinematic and thermal Sunyaev–Zeldovich (SZ) effects will be highly non-Gaussian, and very different from the peak-height distribution of a Gaussian random field. We then show that it is a good approximation to assume that each peak in either SZ effect is associated with one and only one dark matter halo. This allows us to use our knowledge of the properties of haloes to estimate the peak-height distributions. At fixed optical depth, the distribution of peak heights resulting from the kinematic effect is Gaussian, with a width that is approximately proportional to the optical depth; the non-Gaussianity comes from summing over a range of optical depths. The optical depth is an increasing function of halo mass and the distribution of halo speeds is Gaussian, with a dispersion that is approximately independent of halo mass. This means that observations of the kinematic effect can be used to put constraints on how the abundance of massive clusters evolves, and on the evolution of cluster velocities. The non-Gaussianity of the thermal effect, on the other hand, comes primarily from the fact that, on average, the effect is larger in more massive haloes, and the distribution of halo masses is highly non-Gaussian. We also show that because haloes of the same mass may have a range of density and velocity dispersion profiles, the relation between halo mass and the amplitude of the thermal effect is not deterministic, but has some scatter.     

Separation of Heavy Lanthanoids by Flash Column Chromatography for Precise Determination of Er and Yb Isotope Compositions in Rock Samples

We present a new column chemistry technique for the quantitative separation of heavy lanthanoids by an ultra‐fine‐grained LN resin (20–50 µm) with a specific emphasis on the purification of Er and Yb for their isotopic analysis. To achieve the quantitative separation of Er and Yb within a reasonable timescale, flash column chromatography was applied, where the column was attached to a newly designed vacuum box system, thus accelerating the elution speed by ten times compared with that of the normal column procedure operated by gravity flow. The recovery yields of Er and Yb were confirmed to be approximately 100%, which is important to suppress the effect of the mass‐independent fractionation of the Er and Yb isotopes during chromatography. Additionally, we have developed precise Er and Yb isotope measurements by thermal ionisation mass spectrometry (TIMS) using multistatic and/or dynamic methods. Moreover, in most cases, the Er and Yb isotope compositions of the measured four terrestrial rock samples were indistinguishable from those of the commercially available Er and Yb Alfa Aesar solutions. The new method presented in this work will be useful for future studies on heavy lanthanoids in various geological materials.     

Ti-rich hydroandradites from the Sanbagawa metamorphic rocks of the Shibukawa area,central Japan

Ti-rich hydroandradite often occurs, though usually as a minor constituent, in serpentinized ultramafic rocks and associated gabbroic rocks of the Sanbagawa metamorphic belt. The chemistry of the host rocks is commonly characterized by undersaturation with SiO₂. Two Ti-rich hydroandradites from metasomatized gabbroic rocks of the Shibukawa area have been chemically analysed by the wet method. Mössbauer experiments indicate the presence of Fe³⁺ and Fe²⁺ in the octahedral sites of these Ti-rich hydroandradites. Wet chemical analyses for total reducing capacity of the present garnets by two different methods together with Mössbauer data imply the presence of octahedral Ti³⁺ in their structure. Ti-rich hydroandratites, apart from their hydrous property, have a similar crystal chemistry to natural Ti-rich andradites. Ti-rich hydroandradites were probably formed in rocks with unusual chemical compositions within a P-T region of 300–400° C and 4–7 kb under limited conditions of relatively low oxygen fugacity and low μCO₂.