CO<Subscript>2</Subscript> Flux Measurements over the Sea Surface by Eddy Correlation and Aerodynamic Techniques     

Toru?Iwata  Keiko?Yoshikawa  Katsutoshi?Nishimura  Yoshihisa?Higuchi  Takao?Yamashita  Shigeru?Kato  Eiji?OhtakiEmail author 《Journal of Oceanography》2004,60(6):995-1000

The measurements of the vertical transport of CO₂ were carried out over the Sea of Japan using the specially designed pier of Kyoto University on September 20 to 22, 2000. CO₂ fluxes were measured by the eddy correlation and aerodynamic techniques. Both techniques showed comparable CO₂ fluxes during sea breeze conditions: −0.001 to −0.08 mg m⁻²s⁻¹ with the mean of −0.05 mg m⁻²s⁻¹. This means that the measuring site satisfies the fetch requirement for meteorological observations under sea breeze conditions. Moreover, the eddy diffusivity coefficient used in the aerodynamic technique is found to be consistent with the coefficient used in the eddy correlation technique. The present result leads us to conclude that the aerodynamic technique may be applicable to underway CO₂ flux measurements over the ocean and may be used in place of the bulk technique. The important point is the need to maintain a measuring accuracy of CO₂ concentration difference of the order of 0.1 ppmv on the research vessels or the buoys.  相似文献   

Mercury distribution in seawater in Minamata Bay and the origin of particulate mercury     

Mikio Kumagai  Hajime Nishimura 《Journal of Oceanography》1978,34(2):50-56

Horizontal and vertical distributions of mercury were determined in seawater in Minamata Bay and Yatsushiro Sea. The concentrations of total and particulate mercury respectively ranged from 56–285 ng l^–1 and 2.1–506 ng l^–1. They were both highest in the inner most part of Minamata Bay where the sediment was most heavily polluted, and decreased with increasing distance from there. Vertically, an evident increase in concentration was observed near the bottom. A good agreement was found between the mercury content in suspended matter and that in fine sediment particles.These facts show that the particulate mercury is supplied mostly from the bottom sediment, and that it is spreading offshore with dispersing in seawater. This process would eventually result in the pollution of sediment in Yatsushiro Sea.  相似文献   

Degradation of lubricating oils by marine bacteria observed by quantitative mass spectrometry     

Yasushi Kawakami  Hajime Nishimura 《Journal of Oceanography》1981,37(1):1-7

Bacterial degradation of the hydrocarbons of lubricating oils was investigated by mass spectrometric analysis which gives both total amount and the composition of hydrocarbon types of residual oil. An unused lubricating oil, which mainly consisted of hydrocarbon types with only a small percentage ofn-alkanes, was degraded by marineBacillus sp. andPseudomonas sp. with 55 % and 25 % decreases in 10 days, respectively. Susceptibility of respective hydrocarbon types to biodegradation was in the following order: alkanes > non-condensed cycloalkanes, mono-aromatics > condensed cycloalkanes. A used lubricating oil of different brand showed a larger decrease than the unused oil. Both species of bacteria degraded large portions of alkane fraction of Arabian light crude oil.  相似文献   

An energy conversion method in the ocean using the density difference of water     

Hitoshi Mochizuki  Wataru Mitsuhashi 《Ocean Engineering》1981,8(1):91-96

A new method which produces energy from the ocean by utilizing the density difference of water, by means of a “chimney effect”, is proposed. Density difference of water in the ocean occurs in two ways, namely differences of consistency and water temperature. For instance, fresh river and melting floes and icebergs are pointed out as some origins of the former, while thermal effects of volcanoes and hot springs may account for the latter. Furthermore, sunlight power transmitted into the sea through glass fibre power lines can be an artificial source in the latter case.This paper concentrates on regions near estuaries where low density river water can be piped into the high density ocean. An analysis estimates that the proposed method extracts energy of several thousands or more kW in the above case.  相似文献   

Bedrock structure in Adapazari, Turkey—a possible cause of severe damage by the 1999 Kociaeli earthquake     

Masao Komazawa  Hitoshi Morikawa  Kajuro Nakamura  Junpei Akamatsu  Keiichi Nishimura  Sumio Sawada  Ayfer Erken  Akin Onalp 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):829-836

The 1999 Kocaeli earthquake brought serious damage to downtown of Adapazari. To study why strong motions were generated at the town, a bedrock structure was investigated on the basis of Bouguer gravity anomaly, and SPAC and H/V analyses of microseisms. It was revealed that, the basin consists of three narrow depressions of bedrock with very steep edges, extending in E–W or NE–SW directions along the North Anatolia faults, and the depth to bedrock reaches 1000 m or more. Downtown of Adapazari is located 1–2 km apart from the basin-edge. It is considered that, the specific configuration of bedrock amplifies ground motions at the downtown area by focusing of seismic waves and/or interference between incident S-waves and surface-waves secondarily generated at the basin-edge. Studying 3D bedrock structure is an urgent issue for microzoning an urban area in a sedimentary basin.  相似文献   

Metamorphism and metamorphic K–Ar ages of the Mesozoic accretionary complex in Northland, New Zealand     

Yujiro  Nishimura  Philippa M.  Black  Tetsumaru  Itaya 《Island Arc》2004,13(3):416-431

Abstract A southwest dipping Mesozoic accretionary complex, which consists of tectonically imbricated turbiditic mudstone and sandstone, hemipelagic siliceous mudstone, and bedded cherts and basaltic rocks of pelagic origin, is exposed in northern North Island, New Zealand. Interpillow limestone is sometimes contained in the basaltic rocks. The grade of subduction‐related metamorphism increases from northeast to southwest, indicating an inverted metamorphic gradient dip. Three metamorphic facies are recognized largely on the basis of mineral parageneses in sedimentary and basaltic rocks: zeolite, prehnite‐pumpellyite and pumpellyite‐actinolite. From the apparent interplanar spacing d₀₀₂ data for carbonaceous material, which range from 3.642 to 3.564 Å, the highest grade of metamorphism is considered to have attained only the lowermost grade of the pumpellyite‐actinolite facies for which the highest temperature may be approximately 300°C. Metamorphic white mica K–Ar ages are reported for magnetic separates and <2 µm hydraulic elutriation separates from 27 pelitic and semipelitic samples. The age data obtained from elutriation separates are approximately 8 m.y. younger, on average, than those from magnetic separates. The age difference is attributed to the possible admixture of nonequilibrated detrital white mica in the magnetic separates, and the age of the elutriation separates is considered to be the age of metamorphism. If the concept, based on fossil evidence, of the subdivision of the Northland accretionary complex into north and south units is accepted, then the peak age of metamorphism in the north unit is likely to be 180–130 Ma; that is, earliest Middle Jurassic to early Early Cretaceous, whereas that in the south unit is 150–130 Ma; that is, late Late Jurassic to early Early Cretaceous. The age cluster for the north unit correlates with that of the Chrystalls Beach–Taieri Mouth section (uncertain terrane), while the age cluster for the south unit is older than that of the Younger Torlesse Subterrane in the Wellington area, and may be comparable with that of the Nelson and Marlborough areas (Caples and Waipapa terranes).  相似文献   

A deep seismic transect from Hovgård Ridge to northwestern Svalbard across the continental-ocean transition: A sheared margin study     

O. Ritzmann  W. Jokat  W. Czuba  A. Guterch  R. Mjelde  Y. Nishimura 《Geophysical Journal International》2004,157(2):683-702

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Habitability analyses of aquatic bacteria     

Md. Nurul Haider  Masahiko Nishimura  Minoru Ijichi  Ching-chia Yang  Wataru Iwasaki  Kazuhiro Kogure 《Journal of Oceanography》2018,74(2):197-207

Habitability is defined as an ability of an organism to inhabit different environments. Habitability of organisms, however, cannot be inferred from analyses such as a whole genome or community structures. A recently developed database, the MetaMetaDB, gives us information from what kind of environments one particular 16S rRNA sequence data has ever been obtained, and thus enables us to infer the habitability of the bacterium in question. In order to check the applicability of this database to study the habitability of aquatic bacteria, samples collected at two Naka River stations, one estuarine station from Naka River Estuary, two coastal stations at Oarai in Ibaraki Prefecture, Japan and one station in the Kuroshio Current of the western North Pacific were examined. The phylotypes were tracked against the MetaMetaDB and it was reasonably found that the low-salinity stations were dominated by sequences with “freshwater and groundwater”, “human” and “wastewater” habitat identities, while the high-salinity stations were dominated by those with a “marine” identity. The phylotypes of low-salinity stations with a particular habitat identity were absent or rare in the high-salinity stations and vice versa. The MetaMetaDB also showed that sequences of Cyanobacteria or related phylogenetic groups may be present in the human gut, as well as the probable distribution of the relatives (ancestors/descendants/siblings) of some bacteria. These overall findings proved that the MetaMetaDB is useful as a new tool to infer microbial habitability and it gives us new information on the possible origin and ecology of microorganisms in the environments.  相似文献   

The influence of ENSO on the equatorial Atlantic precipitation through the Walker circulation in a CGCM     

Wataru Sasaki  Takeshi Doi  Kelvin J. Richards  Yukio Masumoto 《Climate Dynamics》2015,44(1-2):191-202

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Similarity of palaeocurrent: A tool for stratigraphic correlation     

Rabindra Nath Hota  Wataru Maejima 《Journal of the Geological Society of India》2016,87(4):397-400

Conventional stratigraphic correlations are based on similarity of lithology, order of superposition, marker bed, unconformity, grade of metamorphism, fossil content and geochronology of the rock units. The Gondwana strata have been correlated referring to the above mentioned criteria. In the present work, the Talchir and Karharbari formations of two adjacent Gondwana basins separated by over 200 Km were examined with respect to their palaeocurrent directions. The study suggests that the palaeocurrent populations of different formations in both the basins are statistically dissimilar, this is because, both are stratigraphically distinct in order of superposition and thus are not correlatable. On the other hand, the palaeocurrent populations of the same formation in both the basins are statistically similar and stratigraphically correlatable. It is suggested that the similarity of palaeocurrent can be regarded as a criterion for stratigraphic correlation at least in local and regional scale.  相似文献