Temporal variation of Be concentrations in atmosphere for 8 y from 2000 at Yamagata,Japan: solar influence on the Be time series

We have been continuously observing the daily ⁷Be concentrations in surface air at Yamagata, Japan (38.25° N, 140.35° E) since 2000. The yearly profile of the ⁷Be concentration indicates the variation in galactic cosmic rays owing to solar modulation. Over 8 y, the ⁷Be concentration, cosmic neutrons, and number of sunspots varied by 37.4%, 12.2%, and 92.8%, respectively. The influence of precipitation on the ⁷Be variability was approximately 5%. Hence, the yearly ⁷Be concentration was mainly varied by the solar modulation of the ⁷Be production rates. Based on the production rates found in an EXPACS simulation, the observed variability indicates ⁷Be transport from high latitudes. The daily ⁷Be concentrations have two significant periodic components of 19 d and 36 d. The 36-d component implies a relationship between the sun's rotation and the vertical transport of air masses under quiet solar activity.     

Analysis of availability and accessibility of hydrogen production: An approach to a sustainable energy system using methane hydrate resources

It is considered that use of hydrogen as an energy source may contribute to environmental improvement and provide an alternative energy system. Moreover, it is anticipated that hydrogen will be in great demand in the near future for use in such vehicles as fuel cell-based cars. Research and development of a number of advanced methods of hydrogen production (OTEC, water photolysis using a semiconductor, a municipal waste gasification—smelting system, etc.) is currently under way.A comparison of different hydrogen-rich fuels in this paper shows that methane is advantageous for hydrogen production from the viewpoint of energy efficiency as measured by thermodynamic analysis. This paper therefore proposes combining existing technology for hydrogen production with an unconventional methane source in order to facilitate the realization of a hydrogen energy system: i.e., this paper proposes combining the process of steam reforming, which is commercialized worldwide, with use of untouched natural gas hydrate (NGH) resources. Gas hydrate deposits, which are distributed worldwide, hold great amounts of methane gas and have hardly been touched. This paper presents the economic parameters of NGH development and discusses the concept of devising useful applications of NGHs, with consideration given to (1) independence from current fossil fuels; (2) energy transport using the hydrate system; (3) CO₂ sequestration — replacement of methane hydrate with CO₂ hydrate in the submarine layer and (4) improvement of current steam reforming of methane by CO₂ reuse and zeolite application. This paper thus proposes a new solution that will make a key contribution to the systematic development of a new sustainable energy structure.Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Method for evaluation of immunotoxicity of dioxin compounds using human T-lymphoblastic cell line, L-MAT

Caspase-3 was activated in apoptotic L-MAT cells by treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Treatment with tributyltin, which has been reported to induce apoptosis in rat thymocytes, also activated caspase-3 and led to cell death in L-MAT cells. Blocking caspase-3 activity with the peptide inhibitor, DEVE-CHO, prevented TCDD from inducing subsequent apoptotic changes. The potent Ah receptor ligand, 2,3,7,8-tetrachlorodibenzofuran (TCDF), the low acute toxicity compound, 1,2,3,4,6,7,9-heptachlorodibenzo-p-dioxin (HCDD), and one of the major contaminants in human milk, 3,3',4,4',5-pentachlorobiphenyl (PCBP), increased the activation level of caspase-3, each in a dose-dependent manner. Thus, we propose that measuring caspase-3 activation in the human T-lymphoblastic cell line, L-MAT, is a useful evaluation method for the immunotoxicity of dioxin compounds.     

Adsorption of Cu and Mn on covalently cross-linked alginate gel beads

The covalently cross-linked alginate gel beads were prepared by the reactions of Ca(2+)-doped alginate gel beads, which were formed by spraying a viscous alginate solution into a calcium chloride solution, with cyanogen bromide and following 1,6-diaminohexane. The cross-linking of alginate matrix decreased the mean bead diameter by about 30% and made the beads durable in some extent under alkaline conditions. The adsorption of metal ions on the covalently cross-linked alginate gel beads was rapid and reached at equilibrium within 30 min at 25 degrees C. Adsorption isotherms of Cu(II), Mn(II), and Ca2+ on the beads possessed a stepwise shape, which was firstly determined by Rorrer et al. [Ind. Eng. Chem. Res. 32 (1993) 2170] for cross-linked chitosan gel beads and explained by a pore-blockage mechanism. Higher selectivity was determined against Cu(II) over Mn(II) and Ca2+, especially at a low concentration region. These metal adsorption profiles for the covalently cross-linked alginate gel beads was almost the same as those for the un-cross-linked beads, indicating that the cross-linking reactions were performed without interfering the adsorption characteristics of alginate gel beads.     

Hydrological setting of infertile species-rich wetland--a case study in the warm temperate Japan

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｐｅａｔｌｅｓｓｍｉｒｅ(Ｗｏｌｅｊｋｏ ,1986;Ｆｉｇ .1ａ)ｉｓｄｅｃｒｅａｓｉｎｇｅｘｔｅｎｓｉｖｅｌｙｄｕｅｔｏｔｈｅａｂａｎｄｏｎｍｅｎｔｏｆｔｒａｄｉｔｉｏｎａｌｍａｎａｇｅｍｅｎｔ,ｉｎｆｌｏｗｏｆｔｈｅｗａｓｔｅｄｗａｔｅｒ,ｆｉｒｅ,ｍｏｗｉｎｇ ,ｒｅｃｌａｉｍｉｎｇａｎｄｏｔｈｅｒａｒｔｉｆｉｃｉａｌｉｍｐａｃｔｓｉｎｔｈｅｍｏｄｅｒｎｌａｎｄｓｃａｐｅｏｆｓｏｕｔｈｗｅｓｔｅｒｎＪａｐａｎ(Ｆｕｊｉｗａｒａ ,1979) .Ｍｉｒｅｏｆｔｈｉｓｔｙｐｅｉｓｎｏｗ…     

Effects of ethynylestradiol and bisphenol A on the development of sea urchin embryos and juveniles

The effects of various concentrations of a synthetic estrogen, ethynylestradiol (EER), and an estrogenic compound, bisphenol A (BPA), on the development of two sea urchin species, Hemicentrotus pulcherrimus and Strongylocentrotus nudus, were examined. At concentrations of 2.5 μM or higher of EER the zygotes did not hatch; at 0.98–1.25 μM they developed but had abnormal morphology; and at concentrations lower than 1 μM there was no effect on embryogenesis. The dose dependency was the same for both species, but more embryos of S. nudus showed exogastrulation at 3–10 μM EER. The effect of BPA on early development was less remarkable than that of EER; most embryos developed normally even in the presence of 2.5 μM BPA. The feeding larvae progressed and finally metamorphosed into juveniles even at 0.1–3 μM EER. The chemicals had opposing effects on the growth of the juveniles. A low dose of EER (0.1–1 μM) promoted growth and the average diameter of the test was bigger than that of the control group; the same dose of BPA suppressed growth and the test was smaller than that of the control group. These results show that the sensitivity and response to endocrine disrupter chemicals changes markedly during the ontogeny of sea urchins. Physical and Chemical Impacts on Marine Organisms, a Bilateral Seminar Italy-Japan held in November 2004     

Spatio-temporal changes in diversity and community structure of planktonic copepods in Sagami Bay, Japan

Seasonal changes in diversity and community structure of planktonic copepods at a shelf site in Sagami Bay, Japan was studied in relation to cross-shelf interaction of species components. Seasonal mesozooplankton samples were collected from the shelf station (St. M) of the north-west part of Sagami Bay from 1995 to 1997. Vertical multi-layered samples were collected near the center of Sagami Bay (St. P) in June 1996. A total 185 copepod species were identified from the two stations. We observed a clear seasonal succession in calanoid diversity and community structure at St. M from a simple shelf water community (>11 species) during spring blooming periods to highly diverse and mixed communities (ca 20–30 species) of shelf water species coupled with various Kuroshio Current species during late summer to autumn. Cluster and non-metric multidimensional scaling ordination analyses showed two distinct calanoid community groups. One group, which included samples of St. M and the surface layer of St. P, consisted of shelf water species, such as Calanus sinicus, Ctenocalanus vanus, Paracalanus spp., and Kuroshio species, such as, Canthocalanus pauper, Scolecithrix danae, etc. The other cluster was restricted to the samples collected from mid and deep layers at St. P, which consisted of meso- and bathypelagic species and Oyashio species (cold-current species, such as Neocalanus cristatus, Pseudocalanus spp., Eucalanus bungii and Metridia pacifica). In the mid and deep layers at St. P, the population of dormant copepodid stage V (CV) of Eucalanus californicus and C. sinicus were dominant. The deep CV population of C. sinicus might be ecologically discriminated from the surface and shelf water population due to their larger body length and dormant life cycle. E. californicus was also collected at the shelf site during each spring bloom period, whereas the population might descend into the mid- and deep-layers of the central bay before summer. Our results suggest that the seasonal fluctuation of community structure in the shelf water was controlled by both physical (Kuroshio Current) and biological factors, i.e., spring bloom and ontogenetic vertical migration of E. californicus. In particular, transport and diffusion processes of Kuroshio Current in Sagami Bay played a key role in controlling the shelf water calanoid community.