Deuterium abundance of natural waters

The deuterium abundance of natural water of various sources has been determined by the use of a deuterium mass spectrometer. The absolute deuterium contents of the reference sample nos. 1 and 1a of the U.S. National Bureau of Standards were found to be 0·0149 and 0·0128 mole % D₂O, respectively, by the comparison of the samples with the standard samples of known deuterium content. Relative enrichment of no. la to no. 1 (R_1a−R₁)/R₁×100 was 14·13 ± 0·23, which agrees perfectly to the value reported by . The variation of deuterium contents of tap waters of Tokyo and Osaka during last 2 years were within ± 1 per cent and any seasonal regularities could not be detected. Marine waters of the West Pacific have almost the same deuterium content as those of the Pacific coast of the United States. Marine waters at various depths of the Antarctic showed relatively large variation of deuterium content (from +0·84 to −1·16 per cent on the SMOW-scale), whereas the samples of Black Current of the Pacific showed little variation. It was found that the deuterium content of spring water suggests the origin of springs in some cases.     

Multielemental accumulation and its intracellular distribution in tissues of some aquatic birds

This study was aimed at determining multielemental concentration and its intracellular distribution in selected tissues of cormorant and waterfowl species. Non-essential elements such as Hg, Tl, Cd, Pb and V in tissues were generally consistent with those in ingested items, indicating the significance of food sources of non-essential metal accumulation in great cormorants and mallards. Great cormorants and four waterfowl species examined reflected natural background levels of toxic metals such as Cd, Hg and Pb as well as some essential elements, indicating no specific metal exposure from local sources. Most of Cu, Zn, Se, Rb, Ag, Cd, Cs, and Hg contents were present in the hepatocytosolic fraction, whereas a large percentage of V and Mo were present in insoluble fraction in great cormorant, mallard, and spot-billed duck. The major role of these subcelluar fractions in elemental regulation accounts for the high percentage contribution of each cellular fraction to the total metal contents. Cadmium and Cu are chiefly sequestered through binding to metallothioneins (MTs) of hepatocytosolic fraction in these three avian species. Both MTs and high-molecular-weight substance (HMWS) for Zn and low-molecular-weight substance (LMWS) for Rb were also involved in their sequestration in cytosolic fractions. Relatively different species-specific cytosolic substances were responsible for varying degrees of Ag, Mn, and Co accumulation. It is worth noting that these intracellular metal levels in birds are closely regulated by metal-associated cellular constituents. Therefore, risk assessment studies of metal accumulation in such wild birds should take intracellular metal distribution and specific cellular constituents into account.     

Energy balance of the tidal current in the Obatake Seto Strait

Current measurements made with a Doppler Current Profiler were taken along cross sections in the Obatake Seto Strait, a small strait in the western part of the Seto Inland Sea.The energy loss between two cross sections of the strait was estimated using the control volume analysis of the stationary one-dimensional energy equation. The large energy loss observed in the strait cannot be explained in terms of general bottom friction in the coastal region. The loss is attributed to the form loss, which is accompanied by internal turbulence and vortices generated by the specific topography of the strait, in addition to the loss by friction. This is supported by the fact that the energy loss in the strait differs, depending upon the current direction.     

Abyssal circulation in the Japan Sea

Journal of Oceanography - The water below a depth of 1,000 m in the Japan Sea was found to consist of two water masses, the upper layer (the Deep Water) and the lower layer (the Bottom Water). The...     

Lethality of increasing CO2 levels on deep-sea copepods in the western North Pacific

The first CO₂ exposure experiments on several species of pelagic copepods inhabiting surface and deep layers in the western North Pacific were conducted. Living organisms were collected from two layers between the surface and 1,500 m between latitudes of 11 and 44°N, and they were exposed aboard ship to various pCO₂ up to about 98,000 μatm. Mortality of copepods from both shallow and deep layers in subarctic to subtropical regions increased with increasing pCO₂ and exposure time. Deep-living copepods showed higher tolerance to pCO₂ than shallow-living copepods. Furthermore, deep-living copepods from subarctic and transitional regions had higher tolerances than the subtropical copepods. The higher tolerances of the deep-living copepods from subarctic and transitional regions may be due to the adaptation to the natural pCO₂ conditions in the subarctic ocean.     

Recent Advances in Larval Recruitment Processes of Scyllarid and Palinurid Lobsters in Japanese Waters

Phyllosoma larvae collected to date in Japanese and Taiwanese waters have been classified into two genera (Linuparus, Panulirus) of the Palinuridae, four genera (Ibacus, Parribacus, Scyllarides, Scyllarus) of the Scyllaridae, and one genus (Palinurellus) of the Synaxidae. However, phyllosoma larvae of three Scyllarus species (S. bicuspidatus, S. cultrifer, S. kitanoviriosus) are absolutely dominant among the larvae collected in the waters. Scyllarus larvae are abundant in coastal waters while those of Panulirus are often collected in offshore/oceanic waters. Based on previous and ongoing studies dealing with spatial distributions of phyllosoma larvae in Japanese and Taiwanese waters, it appears that phyllosoma and nisto larvae of the Scyllarus are retained within coastal waters north of the Kuroshio Current. On the other hand, the life history of the Panulirus (particularly P. japonicus) may be completed within the Kuroshio Subgyre: their phyllosoma larvae may be flushed out from coastal waters into the Kuroshio, then transported through the Counter Current south of the Kuroshio into the water east of Ryukyu Archipelago and Taiwan where they attain the subfinal/final phyllosoma or puerulus stages, once again entering the Kuroshio and dispersing into coastal waters. This revised version was published online in July 2006 with corrections to the Cover Date. An erratum to this article is available at .     

Uptake of selenium and other oxyanionic elements in marine ferromanganese concretions of different origins

The concentration of selenium in marine ferromanganese concretions varies between 0.02 and 1.2 mg kg⁻¹, with an average of 0.6 mg kg⁻¹. This is about two orders of magnitude lower than previously reported. In contrast to minor cationic elements, the concentrations of selenium are relatively uniform between ferromanganese concretions of different origins, except for hydrothermal crusts. It shows the same trends of element enrichment as other oxyanionic elements. The incorporation of selenium into ferromanganese concretions is attributed to adsorption of selenate on iron and manganese oxides.