Notes　on　Extended-Range　Atmospheric　Prediction　in　the　Northern　Hemisphere　Winter     

Shingo Yamada Forecast Division  Japan Meteorological Agency  Tokyo    Japan Shuhei Maeda Administration Division  Climate  Marine Department  Japan Meteorological Agency  Tokyo    Japan K. Gambo c/o Department of Earth  Planetary Physi 《大气科学进展》1997,(1)

ＮｏｔｅｓｏｎＥｘｔｅｎｄｅｄ－ＲａｎｇｅＡｔｍｏｓｐｈｅｒｉｃＰｒｅｄｉｃｔｉｏｎｉｎｔｈｅＮｏｒｔｈｅｒｎＨｅｍｉｓｐｈｅｒｅＷｉｎｔｅｒＳｈｉｎｇｏＹａｍａｄａＦｏｒｅｃａｓｔＤｉｖｉｓｉｏｎ，ＪａｐａｎＭｅｔｅｏｒｏｌｏｇｉｃａｌＡｇｅｎｃｙ...  相似文献   

Isolation and characterization of some polycyclic aromatic hydrocarbon degrading bacteria from Nsukka soils in Nigeria     

C. I. Nnamchi M.Sc.  J. A. N. Obeta MS.c.  Ph.D.  L. I. Ezeogu Ph.D. 《International Journal of Environmental Science and Technology》2006,3(2):181-190

Twenty-four bacteria capable of utilizing naphthalene, as their sole source of carbon and energy for growth were isolated from three different sites in Nsukka, Nigeria. By standard bacteriological methods, these bacteria were characterized taxonomically as belonging to the genus Pseudomonas, Burkholderia or Actinomycetes. Two of the isolates, which showed the highest growth during screening as demonstrated by an increase in their optical densities (OD₆₀₀) and identified as Pseudomonas aeruginosa and Burkholderia cepacia respectively, were also able to grow in anthracene and carbazole, but not very much so in 2,4-dichlorophenol and D-camphor. The isolates showed a concentration-dependent growth in all the compounds they grew in. There were visible changes in the colour of the growth medium of the isolates during their incubation, suggesting the production of different metabolites. There were also changes in their medium pH during growth. These studies demonstrate the possession by the bacterial species of novel degradative systems.  相似文献   

Interaction of tectonics, eustasy, climate and carbonate production on the sedimentary evolution of an early/middle Jurassic extensional basin (Southern Provence Sub-basin, SE France)     

Philippe Léonide  Marc Floquet  Loïc Villier 《Basin Research》2007,19(1):125-152

This paper describes the evolution of an extensional basin in regard to the nature and sequence stratigraphic arrangement of its carbonate deposits. The purpose of this study is to evaluate the respective effects of tectonism, eustasy, climate and oceanography on a carbonate sedimentary record. The case study is the early to mid‐Jurassic age carbonate succession of the Southern Provence Sub‐basin (SE France), located within the southern part of the extensional Western European Tethyan Margin. This work is based on sedimentologic, biostratigraphic (using ammonites and brachiopods) and sequence stratigraphic analysis of the carbonate facies of the Cherty Reddish Limestone Formation (late Sinemurian to earliest Bajocian). These strata were deposited in shoreface to lower offshore depositional environments. The succession of the various environments together with the recognition of key stratigraphic surfaces allow us to define four second‐order depositional sequences; of late Sinemurian to earliest Pliensbachian, early Pliensbachian to late Pliensbachian, earliest Toarcian to middle Aalenian and late Aalenian to early Bathonian ages. The architecture of the depositional sequences (thickness and facies variations within the systems tracts, wedge‐shaped geometries) reflects a strong tectonic control. The sub‐basin was structured by extensional faults (oriented approximately 070–090/250–270). Sea‐level variations, fluctuations in carbonate production and preservation, and environmental changes were also significant controlling factors of the carbonate deposition. The interplay of the tectonic control with the other factors resulted in five main phases in the sedimentary evolution of the sub‐basin: (1) dominant tectonic control during the initial rifting stage (late Sinemurian to early Pliensbachian); (2) increasing extensional tectonics (mid‐Pliensbachian); (3) global climato‐eustatic sea‐level fall (latest Pliensbachian) and global climato‐eustatic sea‐level rise plus hypoxia/anoxia (early Toarcian); (4) relative sea‐level fall linked to tectonic uplift related to the ‘Mid‐Cimmerian phase’ (mid‐Aalenian) and (5) oceanographic events (upwelling) and reduction in carbonate production (hypoxia/anoxia) plus tectonic downwarping (late Aalenian/earliest Bajocian).  相似文献   

Fe(II)-Na(I)-Ca(II) Cation Exchange on Montmorillonite in Chloride Medium: Evidence for Preferential Clay Adsorption of Chloride – Metal Ion Pairs in Seawater     

Laurent?Charlet  Christophe?TournassatEmail author 《Aquatic Geochemistry》2005,11(2):115-137

Fe(II)–Ca(II), Fe(II)–Na(I), and Fe(II)–Ca(II)–Na(I) exchange experiments on montmorillonite were performed in chloride background. These experiments show the possible sorption of Fe²⁺ and FeCl⁺ ion pairs in exchange site positions, a result confirmed with 77 K ⁵⁷Fe Mössbauer experiments. The sorption data were modeled and the cation exchange selectivity for Fe(II) were found to be nearly equal to that of Ca(II). Vanselow selectivity coefficients, for Na–Fe²⁺ and Na–FeCl⁺ reactions, were found to be equal to 0.4 (0.5 for Ca²⁺) and 2.3 (2.5 for CaCl⁺) respectively. High affinity of montmorillonite for chloride ion pairs seems to be a common mechanism as first stated by Sposito et al., (Soil Sci. Soc. Am. J. 47, 51–56, 1983a), and should have implications e.g., on the chemistry of suspended particles in seawater. Exchange selectivity coefficients derived from this study and others were used to model experimental data on river water and seawater equilibrated particles. The agreement between simulations and experimental data is very good. The simulation shows the predominance of monovalent ion (Na⁺ and chloride ion pairs) sorption on clay particles in seawater. This sorption of monovalent ions leads to the dispersion of particles in seawater and to the extension of a c="/content/g1522q46g2712106/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">plumec="/content/g1522q46g2712106/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0"> of particles spreading away from river deltas, such as that of the River Amazon.  相似文献   

A Holocene Record of Human Induced and Natural Environmental Change from Lake Forsyth (Te Wairewa), New Zealand     

C.A.?WoodwardEmail author  J.?Shulmeister 《Journal of Paleolimnology》2005,34(4):481-501

A 1.2 m sediment core from Lake Forsyth, Canterbury, New Zealand, records the development of the catchment/lake system over the last 7000 years, and its response to anthropogenic disturbance following European settlement c. 1840 AD. Pollen was used to reconstruct catchment vegetation history, while foraminifera, chironomids, Trichoptera, and the abundance of Pediastrum simplex colonies were used to infer past environmental conditions within the lake. The basal 30 cm of core records the transition of the Lake Forsyth Basin from a tidal embayment to a brackish coastal lake. Timing of closure of the lake mouth could not be accurately determined, but it appears that Lake Forsyth had stabilised as a slightly brackish, oligo-mesotrophic shallow lake by about 500 years BP. Major deforestation occurred on Banks Peninsula between 1860 AD and 1890 AD. This deforestation is marked by the rapid decline in the main canopy trees (Prumnopitys taxifolia (matai) and Podocarpus totara/hallii (totara/mountain totara), an increase in charcoal, and the appearance of grasses. At around 1895 AD, pine appears in the record while a willow (Salix spp.) appears somewhat later. Redundancy analysis (RDA) of the pollen and aquatic species data revealed a significant relationship between regional vegetation and the abundance of aquatic taxa, with the percentage if disturbance pollen explaining most (14.8%) of the constrained variation in the aquatic species data. Principle components analysis (PCA) of aquatic species data revealed that the most significant period of rapid biological change in the lakes history corresponded to the main period of human disturbance in the catchment. Deforestation led to increased sediment and nutrient input into the lake which was accompanied by a major reduction in salinity. These changes are inferred from the appearance and proliferation of freshwater algae (Pediastrum simplex), an increase in abundance and diversity of chironomids, and the abundance of cases and remains from the larvae of the caddisfly, Oecetis unicolor. Eutrophication accompanied by increasing salinity of the lake is inferred from a significant peak and then decline of P. simplex, and a reduction in the abundance and diversity of aquatic invertebrates. The artificial opening of the lake to the Pacific Ocean, which began in the late 1800s, is the likely cause of the recent increase in salinity. An increase in salinity may have also encouraged blooms of the halotolerant and hepatotoxic cyanobacteria Nodularia spumigena.  相似文献   

The P-wave upper mantle structure beneath an active spreading centre: the Gulf of California   总被引：1，自引：0，他引：1  

Marianne c. Walck 《Geophysical Journal International》1984,76(3):697-723

  相似文献   

Spatial differences in macroinvertebrate communities in intertidal seagrass habitats and unvegetated sediment in three New Zealand estuaries   总被引：1，自引：0，他引：1  

K.?S.?S.?van?Houte-Howes  S.?J.?Turner  C.?A.?PilditchEmail author 《Estuaries and Coasts》2004,27(6):945-957

This study investigated macroinvertebrate community composition in seagrass beds at a range of spatial scales, with an emphasis on the transition between vegetated and unvegetated sediment. At four intertidal sites in three New Zealand estuaries (Whangamata, Wharekawa, and Whangapoua Harbours), a large continuous bed of seagrass (Zostera capricorni) was selected with adjacent unvegetated sediment. Macroinvertebrate community composition and biomass, as well as sediment characteristics, were determined at sampling locations 1 and 50 m inside seagrass beds, and 1, 10, and 50 m outside seagrass beds. Analysis of univariate measures of community composition (total abundance, number of species, and diversity) and total biomass indicated significant differences among sites and sampling locations, but contrary to many previous studies these measures were not higher inside than outside the seagrass beds. Multivariate analysis indicated that sites with high seagrass biomass supported a similar community composition. The remaining sampling locations were clustered by site, but there were also significant differences in community composition among sampling locations within a site. There were distinctive communities at the edge of seagrass beds at sites with high seagrass biomass, and evidence that the effects of seagrass beds may extend into the unvegetated sediment. At the low seagrass biomass site there was no evidence of any edge effects, although community composition differed inside and outside the bed. Differences in community composition were driven primarily by small changes in the relative abundance of the dominant taxa. At high seagrass biomass sites the absence of deep-burrowing polychaetes and low numbers of bivalves suggests that one possible mechanism underlying the observed variation in community composition was inhibition by the dense root-rhizome mat. The results of this study emphasize the need to consider the linkages between habitats in heterogeneous estuarine landscapes and how those linkages vary among sites, if the structure and functioning of macroinvertebrate communities in seagrass habitats are to be understood.  相似文献   

An Intelligent Method for Structural Reliability Analysis Based on Response Surface   总被引：1，自引：0，他引：1  

桂劲松刘红  康海贵 《中国海洋工程》2004,18(4):653-661

As water depth increases, the structural safety and reliability of a system become more and more important and challenging. Therefore, the structural reliability method must be applied in ocean engineering design such as offshore platform design. If the performance function is known in structural reliability analysis, the first-order second-moment method is often used. If the performance function could not be definitely expressed, the response surface method is always used because it has a very clear train of thought and simple progranuning. However, the traditional response surface method fits the response surface of quadratic polynomials where the problem of accuracy could not be solved, because the true limit state surface can be fitted well only in the area near the checking point. In this paper, an intelligent computing method based on the whole response surface is proposed, which can be used for the situation where the performance function could not be definitely expressed in structural reliability analysis. In this method, a response surface of the fuzzy noural network for the whole area should be constructed first, and then the structural reliability can be calculated by the genetic algorithm. In the proposed method, all the sample points for the training network come from the whole area, so the true limit state surface in the whole area can be fitted. Through calculational examples and comparative analysis, it can be known that the proposed method is much better than the traditional response surface method of quadratic polynomials, because, the amount of calculation of finite element analysis is largely reduced, the accuracy of calculation is improved, and the true limit state surface can be fitted very well in the whole area. So, the method proposed in this paper is suitable for engineering application.  相似文献   

A Finite Element Method for Cracked Components of Structures     

刘立名  段梦兰  秦太验  刘玉标  柳春图  余建星 《中国海洋工程》2003,17(2)

1 .IntroductionOffshoreplatformsarelargescalesteelorconcretestructures.Theyexperiencevariouskindsofdamagessuchasdents ,corrosionpits ,cracks ,deformation ,etc .,afteryearsofenvironmentalimpactofwinds ,waves ,currents ,soilreactions ,earthquakesandice (DuanandLiu ,1 995) .Thesafetyofthestructureshasalwaysbeenthemostimportantissueconcerned ,anditdependsontheassessmentoftheintegrityofthestructures,orspecificallyontheassessmentofthedamagesinthestructures .Riclesetal.( 1 994)experimentallyinvestig…  相似文献   

    

Lo?c Cahierre 《Journal of Geodesy》1948,22(3):251-263

  相似文献