Is there any seasonal variation in marine nematodes within the sediments of the intertidal zone?

The sediment parameters and nematode assemblages in the intertidal zone of the Hichirippu shallow lagoon, Hokkaido, Japan, were investigated. The objectives of this study were to observe the seasonal variation in the nematodes in the sediment, and to investigate the relationships between the nematodes and environmental factors. Samples were collected bi-monthly from five stations on the tidal flat from April 2003 to February 2004. It was found that the sediment parameters (Chl a concentration, AVS, TOC and TN contents) varied throughout the 10-month study. Fifty-four species of nematodes were found in the study area. The density and biomass of the nematodes varied in accordance with the sediment temperature during the sampling period. In this study, there was a seasonal variation in the nematode assemblage found in the intertidal zone of this shallow lagoon. The important factors affecting this variation were sediment temperature, and food competition among the nematodes themselves. The seasonal variation of the nematode also showed a relationship with the Chl a concentration in the sediment during the sampling period.     

利用地幔内反射波探测日本列岛下660 km不连续面的深度变化（英文）

通过分析发生在日本周边深源地震的宽频带波形资料,估计了日本列岛下的660km不连续面(d660)的深度变化。许多宽频带波形记录到了在d660顶部发生反射的sScS的后续波。sScS后续波与sScS间的到时差包含了震中与台站下方的d660深度变化的信息。我们成功地检测到这两种震相并将其分离,到目前为止还没有这方面研究的报道。我们由sScS与其后续波的到时差来求每个震中与记录台站下的d660的深度变化。研究结果显示,西部日本下的d660较深(大于660km),这可能是滞留在地幔转换带中的冷的太平洋板块造成的。在日本中部,d660变深,显然这不是太平洋板块本身造成的,因为日本中部已经位于该滞留板片的东部。日本东北部下的d660变得较浅,这可能是太平洋板片形状变化或下地幔热物质上涌形成局部热异常造成的。     

Chemical and Isotopic Characteristics of the Kuroko‐Forming Volcanism

The Miocene northeast Honshu magmatic arc, Japan, formed at a terrestrial continental margin via a stage of spreading in a back‐arc basin (23–17 Ma) followed by multiple stages of submarine rifting (19–13 Ma). The Kuroko deposits formed during this period, with most forming during the youngest rifting stage. The mode of magma eruption changed from submarine basalt lava flows during back‐arc basin spreading to submarine bimodal basalt lava flows and abundant rhyolitic effusive rocks during the rifting stage. The basalts produced during the stage of back‐arc basin spreading are geochemically similar to mid‐ocean ridge basalt, with a depleted Sr–Nd mantle source, whereas those produced during the rifting stage possess arc signatures with an enriched mantle source. The Nb/Zr ratios of the volcanic rocks show an increase over time, indicating a temporal increase in the fertility of the source. The Nb/Zr ratios are similar in basalts and rhyolites from a given rift zone, whereas the Nd isotopic compositions of the rhyolites are less radiogenic than those of the basalts. These data suggest that the rhyolites were derived from a basaltic magma via crystal fractionation and crustal assimilation. The rhyolites associated with the Kuroko deposits are aphyric and have higher concentrations of incompatible elements than do post‐Kuroko quartz‐phyric rhyolites. These observations suggest that the aphyric rhyolite magma was derived from a relatively deep magma chamber with strong fractional crystallization. Almost all of the Kuroko deposits formed in close temporal relation to the aphyric rhyolite indicating a genetic link between the Kuroko deposits and highly differentiated rhyolitic magma.     

Impacts of absorbing aerosols on South Asian rainfall

Anthropogenic aerosols in the lower troposphere increase the absorption and scattering of solar radiation by air and clouds, causing a warmer atmosphere and a cooler surface. It is suspected that these effects contribute to slow down the hydrological cycle. We conducted a series of numerical experiments using a limited area atmospheric model to understand the impacts of aerosol radiative forcing on the rainfall process. Experiments with different radiative conditions under an idealized setting revealed that increasing atmospheric forcing and decreasing surface forcing of radiation causes reductions in rainfall. There was no relationship of top of the atmosphere forcing to the rainfall yield. The model was then used to simulate a domain covering southern part of Sri Lanka, over for the period from November 2002 to July 2003. For a given radiative forcing, instances with lower rainfall yields showed larger fractional reductions in rainfall. The trends in seasonal rainfall observed over the site in past 30 years in a different study confirms this finding. We conclude that the negative impact of increase of anthropogenic aerosols on rainfall would be more severe on regions and seasons with lower rainfall yields. The consequences of this problem on the industries that critically depend on well-distributed rainfall like non-irrigated agriculture and on the general livelihood of societies in low-rain areas can be serious.     

A method for assessing generalized data accuracy with linear object resolution verification

The article is composed of two sections. In the first section, the authors describe the application of minimum line dimensions which are dependent on line shape, width and the operational scale of the map. The proposed solutions are based on the Euclidean metric space, for which the minimum dimensions of Saliszczew’s elementary triangle (Elementary triangle – is the term pertaining to model, standard triangle of least dimensions securing recognizability of a line. Its dimensions depend on scale of the map and width of the line representing it. The use of a triangle in the simplification process is as follows: triangles with sides (sections) on an arbitrary line and bases (completing the sides) are compared with lengths of the shorter side and the base of the elementary triangle.) were adapted. The second part of the article describes an application of minimum line dimensions for verifying and assessing generalized data. The authors also propose a method for determining drawing line resolution to evaluate the accuracy of algorithm simplification. Taking advantage of the proposed method, well-known simplification algorithms were compared on the basis of qualitative and quantitative evaluation. Moreover, corresponding with the methods of simplified data accuracy assessment the authors have extended these solutions with the rejected data. This procedure has allowed the identification of map areas where graphic conflicts occurred.     

Abundance and biomass of scyphomedusae, Aurelia aurita and Chrysaora melanaster, and Ctenophora, Bolinopsis mikado, with estimates of their feeding impact on zooplankton in Tokyo Bay, Japan

The abundance of a scyphomedusae, Aurelia aurita and Chrysaora melanaster, and a ctenophore, Bolinopsis mikado, in Tokyo Bay was investigated from 1995 to 1997. Aurelia aurita appeared throughout the year with a peak in abundance occurring from spring to summer. The average abundance and biomass during this period for the three successive years was 4.8, 43.8 and 3.2 ind. m⁻², and 1.02, 10.0 and 0.42 gC m⁻², respectively. The values in 1995 and 1997 were comparable with those previously reported for A. aurita abundance from 1990 to 1992. Values were very high in 1996, but the size composition of the bell diameter did not differ from other years, which suggested the absence of food limitation for A. aurita in 1996. C. melanaster was scarce over the survey period (<1.0 ind. m⁻²) while Bolinopsis mikado was more abundant during September to December, with maximum values of 172 ind. m⁻² and 0.33 gC m⁻² observed in December 1997. The weight-specific clearance rate for A. aurita on zooplankton (mainly copepods and their nauplii) was 0.16 ± 0.05 lgWW⁻¹ h⁻¹ (n = 13). Population clearance rate peaked from spring to summer, with average levels of 14.2%, 162% and 5.0% day⁻¹ obtained from spring to summer for respective years. Population clearance rates for B. mikado, calculated based on minimum carbon requirements, was 7.1% day⁻¹ in December 1997. Consequently, the trophic role of gelatinous zooplankton as predators in Tokyo Bay is important all the year round, considering the high impact of A. aurita from spring to summer and B. mikado from autumn to winter.     

Internal characteristics and numerical analysis of plunging breaker on a slope

Many investigations about the direct measurements of velocities to clarify the internal mechanism of the breaker have been carried out as a result of recent progress in the measuring techniques.This research attempts to clarify the breaking wave transformation system on a slope by an experiment and numerical analysis. In an experiment, the velocities in the surf zone were measured directly using an electromagnetic current meter, and the space distribution characteristic of the vorticity ω = (∂u/∂y − ∂u/∂x) and the skewness γ = (∂u/∂y + ∂u/∂x) were examined. Also, occurrence situations of the vortices at the time of water mass inrush were measured by video tape recorder (VTR) image processing. However, because the breaker is a violent phenomenon that is entrained with plentiful bubbles, the extent to which we can clarify breaker transformation in experiments is limited. Numerical simulations are substituted for experiments as a method to clarify breaker transformation.In numerical analysis, finite amplitude wave analysis based on the potential theory (non-viscous fluid) is possible before wave breaking; however, the analysis must take into account the viscous fluid after breaking. So, we use the Reynolds equations to develop a numerical simulation system of the breaker transformation on a sloping bottom. The numerical energy dissipation model of the breaker was compared to the experimental results, and a modified Simplified Marker and Cell (SMAC) method is presented. The internal characteristics of the breaker transformation are described using application examples.     

Organic geochemistry of the Japan Sea sediments-1: Bulk organic matter and hydrocarbon analyses of Core KH-79-3, C-3 from the Oki Ridge for paleoenvironment assessments

Organic geochemical study of bulk organic matter (OM), hopanoid hydrocarbon and normal hydrocarbon (C₂₃C₃₅) was conducted for a 936-cm-long sediment core sample from the Oki Ridge of the Japan Sea (Core KH-79-3, C-3; 37°03.5 N, 134°42.6E, water depth 935 m). Stable carbon isotopic ratios were also measured for both bulk OM and individual hydrocarbons. The following results were obtained: (1) The weight ratios of total organic carbon to total nitrogen range from 6.2 to 9.4 in the core. The ¹³C values of bulk OM range from –25.1–20.7%.. The ¹³C values of OM in the sections of 140190 cm are lower (–25–24) than those in the other sections (–23–21). This result indicates that OM in the core except for the 140190 cm sections is essentially of marine origin. (2) The ¹³C value of diploptene (a hopanoid hydrocarbon) in the last glacial maximum (LGM), is –66.3 (vs. PDB), which indicates it originating in methanotrophic bacteria. This result provides evidence to support for the previous ideas (Oba et al., 1980, 1984; Masuzawa and Kitano, 1984) that the bottom waters in the Japan Sea were anoxic in LGM. (3) Long chain (C₂₃C₃₅) n-alkanes of higher-plant wax origin were found throughout the core. Their concentration is high in 140190 cm in depth, suggesting that eolian dust load was high in LGM. (4) The n-alkane/TOC ratio increases with decreasing ¹³C values of bulk OM. This result indicates that the load of terrestrial (probably eolian dust-derived) OM to the Japan Sea became higher in colder climates. (5) The CPI values of long-chain n-alkanes are different in different ¹³O stages of paleoclimate, probably reflecting variations in species of terrestrial higher plants as a result of climatological adaptations.     

The inventory and chemical characterization of dissolved proteins in oceanic waters

One-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and high resolution two-dimensional electrophoresis (2-DE) were applied to separate protein molecules in dissolved organic matter (DOM) from oceanic waters. Results were: (1) The 2-DE distinguished a total of 412 protein spots in 10 samples from five water columns over the Pacific, although fewer than 30 proteins were resolved as bands from the identical samples by SDS-PAGE. (2) Major and ubiquitous protein bands (34 and 39 kDa proteins) on the SDS-PAGE gel were resolved into horizontally spread arrays (trains) of spots on the 2-DE gels, indicating that these bands were a mixture of protein species that have the same molecular weight (MW) but different isoelectric points (pIs). (3) Proteins that exhibited such electrophoretic patterns on the 2-DE gels were glycosylated with variable linkages between the sugar and polypeptide chains. (4) N-terminal amino-acid sequencing demonstrated that individual spots within each train of spots had identical N-terminal amino-acid sequences.The N-terminal amino-acid sequences of the 39 and 34 kDa glycoprotein spots in samples collected at different sites were also identical. Protein isoforms with the same amino-acid sequence but different glycosylation profiles, termed glycoforms, were often observed on the 2-DE gel. Thirty-one and 24 spots on the 2-DE gels were glycoforms of two glycoproteins with MWs of 39 and 34 kDa, respectively; they were one protein species. The glycoforms of the 39 kDa protein were identified as a low molecular weight alkaline phosphatase (L-AP) of Pseudomonas aeruginosa PAO1 by a homology search through five amino-acid sequence databases. The present and earlier work indicates that all identified source organisms of dissolved proteins belong to the Pseudomonas group. We propose the hypothesis that proteins associated with membrane vesicles liberated from a minor member of the bacterioplankton assemblage, the marine Pseudomonas group, are one of the important sources of dissolved proteins in oceanic waters. This hypothesis may apply to the source pathway and survival not only of proteins and also to the universally occurring bacterial peptidoglycan and lipopolysaccharide components in DOM.