Trends and factors governing polycyclic aromatic hydrocarbon levels in Tokyo Bay sediments     

Keiichi Ohta  Nobuhiko Handa  Eiji Matsumoto 《Geochimica et cosmochimica acta》1983,47(9):1651-1654

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Biological organic carbon export estimated from the annual carbon budget observed in the surface waters of the western subarctic and subtropical North Pacific Ocean from 2004 to 2013     

Masahide Wakita  Makio C. Honda  Kazuhiko Matsumoto  Tetsuichi Fujiki  Hajime Kawakami  Sayaka Yasunaka  Yoshikazu Sasai  Chiho Sukigara  Mario Uchimiya  Minoru Kitamura  Toru Kobari  Yoshihisa Mino  Akira Nagano  Shuichi Watanabe  Toshiro Saino 《Journal of Oceanography》2016,72(5):665-685

The annual flux of biologically produced organic carbon from surface waters is equivalent to annual net community production (NCP) at a steady state and equals the export of particulate and dissolved organic carbon (POC and DOC, respectively) to the ocean interior. NCP was estimated from carbon budgets of salinity-normalized dissolved inorganic carbon (nDIC) inventories at two time-series stations in the western subarctic (K2) and subtropical (S1) North Pacific Ocean. By using quasi-monthly biogeochemical observations from 2004 to 2013, monthly mean nDIC inventories were integrated from the surface to the annual maximum mixed layer depth and corrected for changes due to net air–sea CO₂ exchange, net CaCO₃ production, vertical diffusion from the upper thermocline, and horizontal advection. The annual organic carbon flux at K2 (1.49 ± 0.42 mol m^?2 year^?1) was lower than S1 (2.81 ± 0.53 mol m^?2 year^?1) (p < 0.001 based on t test). These fluxes consist of three components: vertically exported POC fluxes (K2: 1.43 mol m^?2 year^?1; S1: 2.49 mol m^?2 year^?1), vertical diffusive DOC fluxes (K2: 0.03 mol m^?2 year^?1; S1: 0.25 mol m^?2 year^?1), and suspended POC fluxes (K2: 0.03 mol m^?2 year^?1; S1: 0.07 mol m^?2 year^?1). The estimated POC export flux at K2 was comparable to the sum of the POC flux observed with drifting sediment traps and active carbon flux exported by migrating zooplankton. The export fluxes at both stations were higher than those reported at other time-series sites (ALOHA, the Bermuda Atlantic Time-series Study, and Ocean Station Papa).  相似文献   

Comparison of sinking particles in the upper 200 m between subarctic station K2 and subtropical station S1 based on drifting sediment trap experiments     

Makio C. Honda  Hajime Kawakami  Kazuhiko Matsumoto  Masahide Wakita  Tetsuichi Fujiki  Yoshihisa Mino  Chiho Sukigara  Toru Kobari  Mario Uchimiya  Ryo Kaneko  Toshiro Saino 《Journal of Oceanography》2016,72(3):373-386

Drifting sediment trap experiments were conducted during various seasons to elucidate the characteristics of particles sinking through the upper 200 m of the water column in the western Pacific at subarctic station K2 and subtropical station S1. The sinking particle flux increased when primary productivity was high at each station, during June–July at K2 and during February at S1. Biogenic opal (Opal) and CaCO₃ were the major components of the fluxes at K2 and S1, respectively. Contrary to the expectation of a high flux at the eutrophic station K2 and low flux at the oligotrophic station S1, the annual average organic carbon fluxes at 100 m were comparable at both stations: 62.7 mg C m^?2 day^?1 at K2 and 56.1 mg C m^?2 day^?1 at S1. The similarity of the fluxes was perhaps a reflection of the unexpectedly high primary production at S1. At K2, the organic carbon export ratio (organic carbon flux/primary productivity) was significantly and negatively correlated with primary production and tended to decrease with depth. The magnitude of the rate of attenuation of the organic carbon flux with depth was larger at S1 than at K2. This rate of attenuation tended to decrease and increase with primary production at K2 and S1, respectively. The explanation for these patterns may be that the flux of labile organic carbon at relatively shallow depths decreased with increasing primary production at K2, and zooplankton grazing pressure increased with increasing primary productivity at S1.  相似文献   

Seasonal variability of phytoplankton community structure in the subtropical western North Pacific     

Tetsuichi Fujiki  Kosei Sasaoka  Kazuhiko Matsumoto  Masahide Wakita  Yoshihisa Mino 《Journal of Oceanography》2016,72(3):343-358

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Three-dimensional P-wave velocity structure in the upper crust beneath Kuju Volcano, central Kyushu, Japan     

Yasuaki Sudo  Yoshihiro Matsumoto 《Bulletin of Volcanology》1998,60(3):147-159

 Kuju Volcano lies near Aso Caldera at the center of Kyushu Island, western Japan. After a few hundred years of dormancy, a phreatic explosion accompanied by a small ash eruption occurred on 11 October 1995. This study was undertaken to determine the subsurface seismic velocity structure associated with the active magmatic regime in the Kuju volcanic region. The three-dimensional, upper crustal, P-wave velocity structure beneath Kuju Volcano was determined using methods for the simultaneous inversion of P-wave arrival times from local earthquakes in and around the Kuju volcanic region for velocities and hypocentral parameters. Results reveal two shallower low-velocity anomalies located in the northern and southern parts of Kuju Volcano, consistent with the presence of significant negative Bouguer gravity anomalies. In addition, a high-velocity anomaly is located approximately 5 km northwest of Mt. Kuju, one of the domes in Kuju Volcano. Beneath this high-velocity anomaly, a low-velocity anomaly is present. This velocity structure suggests a magmatic regime that has a lid consisting of cooled solid material overlying a chamber of partially molten material. Received: 23 September 1997 / Accepted: 20 June 1998  相似文献   

Hydrological response to earthquakes in the Haibara well, central Japan – II. Possible mechanism inferred from time-varying hydraulic properties     

N. Matsumoto  E. A. Roeloffs 《Geophysical Journal International》2003,155(3):899-913

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Parameters of the fluid core resonance inferred from superconducting gravimeter data     

Tadahiro Sato  Yoshiaki Tamura  Koji Matsumoto  Yuichi Imanishi  Herbert McQueen 《Journal of Geodynamics》2004,38(3-5):375

We have estimated the parameters of fluid core resonance (FCR) due to the nearly diurnal free wobble of the Earth's core based on the superconducting gravimeter (SG) data obtained at the following four observation sites; Esashi and Matsushiro in Japan, Canberra in Australia and Membach in Belgium. By fitting the tidal admittances normalized with the O1 wave at each site to a model of the damped harmonic oscillator, we obtained values of 429.66 ± 1.43 sidereal days, 9350–10,835, −4.828E−4 ± 3.4E−6, −3.0E−5 ± 4.5E−6 for the eigenperiod, the Q-value and the real and imaginary parts of the resonance strength, respectively. Our values obtained from only using the gravity data are very consistent with those inferred from the VLBI nutation data. Our study strongly indicates that the systematic difference between two estimations from the gravity and the nutation in particular for the Q-value, which has been shown in previous works, is mainly caused by the inaccurate correction for the ocean tide effects. The error in the ocean tide correction is discussed based on the comparison among four global ocean tide models; Schwiderski model (1980), NAO.99b (Matsumoto et al., 2000), CSR4.0 (Eanes and Bettadpur, 1994) and GOT99.2b (Ray, 1999).  相似文献   

Vertical Nutrient Distributions in the Western North Pacific Ocean: Simple Model for Estimating Nutrient Upwelling, Export Flux and Consumption Rates     

Katsumi Hirose  Hitomi Kamiya 《Journal of Oceanography》2003,59(2):149-161

A one-dimensional, steady-state model has been developed to understand the factors controlling vertical distributions of nutrients such as nitrate and phosphate in the western North Pacific water columns. The model includes simple physics and some biogeochemical processes. Nutrients are supplied by upwelling of nutrient-rich deep waters with a constant upwelling velocity and nutrient regeneration due to decomposition of sinking particulate matter; the latter is expressed by an exponential-type export flux. Nutrients are consumed in the water column due to uptake by marine organisms, represented by a first-order substrate kinetics. The consumption rate constant is given as an exponential function of depth. The model has been applied to a data set of WOCE (World Ocean Circulation Experiment) P9 one-time measurements observed in the western North Pacific. The calculated curves fit well to observed vertical nutrient profiles from 100 m depth to over 2,500 m depth at 35 stations from 19°N to 33°30′ N along 137°E with correlation factors of greater than 0.998. A modified model, including a correction term representing a depth-dependent upwelling velocity, can reproduce observed vertical nutrient profiles at 32 stations from 5°N to 18°30′ N along 137°E with correlation factors greater than 0.993. The results support the hypothesis that most of the vertical nutrient profiles in the western North Pacific are controlled by particle export flux, consumption rate, remineralization rate and upwelling velocity. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Partitioning of heavy metals into mineral and organic fractions in a sediment core sample from Osaka Bay     

Yasushi Kitano  Masahiro Sakata  Eiji Matsumoto 《Journal of Oceanography》1981,37(5):259-266

Partitioning of copper, zinc, iron and manganese into oxide, sulfide, organic and silicate fractions has been determined with a selective chemical leaching technique on sediment samples from a core collected in Osaka Bay. The samples have been dated by the²¹⁰Pb method. Most of the copper and zinc in the polluted surface sediment layer are contained in both oxide and sulfide fractions. This suggests that the transformation of oxides and hydroxides to sulfides under anoxic conditions within the sediment is significant for the fixation of copper and zinc discharged through human activities into the sediment. Manganese is apparently enriched in oxide and hydroxide fractions of the surface layer due to the post-depositional migration of manganese within the sediment. The copper, zinc and manganese contents of the 30 % H₂O₂ soluble fraction (mostly organic fraction) decrease with depth in the sediment core, and correlate significantly with the organic carbon content. The heavy metal (Cu, Zn, Fe and Mn) contents of the silicate fraction, without exchangeable sites, are almost constant with depth.  相似文献   

Experimental studies on the possible influences of composition changes of pore water on the stability conditions of methane hydrate in marine sediments   总被引：4，自引：1，他引：4  

Hailong Lu  Ryo Matsumoto 《Marine Chemistry》2005,93(2-4):149-157

Experiments with a set of electrolyte solutions have been carried out to investigate the effects of pore water composition changes on the stability conditions of methane hydrate in marine sediments. The results reveal that (1) SO₄²⁻ and Cl⁻ concentration changes can affect hydrate stability slightly, (2) the changes in both the type and the concentration of cations, which occur in normal diagenetic processes, do not exert a significant influence on the methane hydrate stability conditions, and (3) the shift of hydrate stability in pore water can be expressed as a function of the Cl⁻ concentration only. Based on the results above, an empirical equation ΔT (K)=0.00206 Cl⁻ (mmol/dm³) has been obtained for estimating the shift in the equilibrium temperature of methane hydrate in pore water at a given pressure.  相似文献