Standing stocks and production rates of phytoplankton and planktonic copepods in the Inland Sea of Japan

Standing stocks and production rates of phytoplankton and planktonic copepods were investigated at 15 stations in the Inland Sea of Japan during four cruises in October–November 1979, January, April and June 1980. The overall mean of phytoplankton biomass was relatively constant during the study period, ranging from 2.3 mg chl.a m^–3 in April to 3.6 mg chl.a m^–3 in October–November. Primary production was low in January (mean: 90 mg C m^–2 d^–1), but higher than 375 mg C m^–2 d^–1 on the other occasions. Integrated annual primary production was 122 g C m^–2 yr^–1. In terms of carbon weight,Paracalanus parvus was the most important copepod species. The variation of the mean copepod biomass (range: 7.6 mg C m^–3 in April to 20.2 mg C m^–3 in June) was smaller than that of copepod production, which was estimated by the Ikeda-Motoda's physiological method. Copepod producion was low in cold seasons (0.6 and 0.9 mg C m^–3 d^–1 in January and April, respectively), and increased, following the elevation of primary production, to 4.9 mg C m^–3 d^–1 in June. Annual copepod production was 33.7 g C m^–2 yr^–1, of which herbivore (secondary) production was 26.4 g C m^–2 yr^–1 (21.7% of primary production). The ratios of pelagic planktivorous fish catch and total fish catch to the primary production were 0.82 and 1.8%, respectively, indicating very high efficiency in exploiting fishery resources in the Inland Sea of Japan.     

Anelastic structure of the upper mantle beneath the northern Philippine Sea

We investigated the upper mantle anelastic structure beneath the northern Philippine Sea region, including the Izu-Bonin subduction zone and the Shikoku Basin. We used regional waveform data from 69 events in the Pacific and the Philippine Sea slabs, recorded on F-net and J-array network broadband stations in western Japan. Using the S–P phase pair method, we obtained differential attenuation factors, δt^*, which represent the relative whole path Q. We conducted a tomographic inversion using 978 δt^* values to invert for a fine-scale (50–100 km) three-dimensional anelastic structure.

The results shows two high-Q regions (Q_P>1000) which are consistent with the locations of the Pacific and the Philippine Sea slabs. Also there is a low-Q (Q_P110) area extending to the deeper parts (350–400 km) of the model just beneath the old spreading center and the Kinan Seamount Chain in the Shikoku Basin. A small depth dependence of the laterally averaged Q_P was found, with values of 266 (0–250 km), 301 (250–400 km), and 413 (400–500 km).     

Hydrogen sites in the dense hydrous magnesian silicate phase E: a pulsed neutron powder diffraction study

Hydrogen site positions and occupancy in the crystal structure of dense hydrous magnesium silicate (DHMS) phase E were determined for the first time by pulsed neutron powder diffraction. A fully deuterated pure phase E powder sample, which had space group \(R\overline{3} m\) and lattice parameters of a = 2.97065(8) Å and c = 13.9033(4) Å, was synthesized at 15 GPa and 1100 °C. Through quantitative evaluation of refined structure parameters obtained with sufficient spatial resolution and very high signal-to-background ratio, we conclude that the O–D dipoles in the refined phase E structure are tilted by 24° from the direction normal to the layers of edge-shared MgO₆ octahedra (octahedral layers). The tilted dipole structure of phase E is in remarkable contrast to that of brucite, Mg(OH)₂, which has dipoles exactly normal to the octahedral layer. This contrast exists because the O–Si–O bonding unique in the phase E structure connects two adjacent octahedral layers and thereby reduces the interlayer O···O distance. This shrinkage of the interlayer distance induces the tilting of the O–D dipole and also generates unique O–D···O hydrogen bonding connecting all the layers in the phase E structure.     

Detecting red tides in the eastern Seto inland sea with satellite ocean color imagery

A multi-spectral classification scheme is proposed to identify water with red tide(s) using satellite ocean color imagery obtained by the Sea-viewing Wide Field-of-view Sensor (SeaWiFS). The study area was the eastern Seto Inland Sea in Japan, where serious red tides frequently occur. “Background Ocean Colors” (BOCs hereafter), or colors of water around a red tide or those of the water before/after a red tide, are calculated as the monthly climatological average of normalized water-leaving radiances (nLw) with 0.01 degree spatial resolution with SeaWiFS imagery. Criteria for detecting red-tide pixels are established from analyses of characteristics of the nLws (in the 443, 490, 510, and 555 nm bands) anomalies from BOCs and the nLw spectra together with the red-tide records in Osaka Bay. The proposed scheme can efficiently indicate the presence or absence of red tides for independent match-ups with 83% accuracy. Additional validations of specific events indicate that the algorithm performed well in the study area. These results suggest that the scheme is appropriate to detect red tides in the optically complex coastal water of the eastern Seto Inland Sea.     

Long-term bottom water warming in the north Ross Sea

We measured potential temperature, salinity, and dissolved oxygen profiles from the surface to the bottom at two locations in the north Ross Sea (65.2°S, 174.2°E and 67.2°S, 172.7°W) in December 2004. Comparison of our data with previous results from the same region reveals an increase in potential temperature and decreases in salinity and dissolved oxygen concentration in the bottom layer (deeper than 3000 m) over the past four decades. The changes were significantly different from the analytical precisions. Detailed investigation of the temperature, salinity, dissolved oxygen and σ ₃ value distributions and the bottom water flow in the north Ross Sea suggests a long-term change in water mass mixing balance. That is to say, it is speculated that the influence of cool, saline, high-oxygen bottom water (high-salinity Ross Sea Bottom Water) formed in the southwestern Ross Sea has possibly been decreased, while the influences of relatively warmer and fresher bottom water (low-salinity Ross Sea Bottom Water) and the Adélie Land Bottom Water coming from the Australia-Antarctic Basin have increased. The possible impact of global warming on ocean circulation needs much more investigation.     

Oxidative–reductive photodecomposition of perfluorooctanoic acid in water

This article aims to elucidate on usefulness of vacuum ultraviolet (VUV) for photoreductive degradation of perfluorooctanoic acid (PFOA), a representative perfluorinated compound (PFC), in water for the first time. Bench-scale tests were conducted on oxidative and reductive (with aquated electron: e _aq ^? ) mineralization of PFOA using low-pressure UV (LPUV) lamps and potassium iodide. Unlike with 254 nm wavelength (UVC), the reductive mineralization with VUV was very inefficient compared to the corresponding oxidative mineralization. The inefficiency is attributed to low reactivity of e _aq ^? with PFOA and its fluorinated products than that of 185 nm photons. Direct VUV photolysis of PFOA and its products in reductive reaction conditions was not apparent due to a very big difference in reactivity of 185 and 254 nm photons with iodide. The results demonstrated that highly energetic VUV photons are not suitable for photoreductive degradations of PFCs involving e _aq ^? , but they can be best used for oxidative degradations. These findings should serve as an important reference on VUV usage to decompose refractory micropollutants.     

Out‐of‐plane stability of buckling‐restrained braces including moment transfer capacity

Buckling‐restrained braces (BRBs) are widely used as ductile seismic‐resistant and energy‐dissipating structural members in seismic regions. Although BRBs are expected to exhibit stable hysteresis under cyclic axial loading, one of the key limit states is global flexural buckling, which can produce an undesirable response. Many prior studies have indicated the possibility of global buckling of a BRB before its core yields owing to connection failure. In this paper, BRB stability concepts are presented, including their bending‐moment transfer capacity at restrainer ends for various connection stiffness values with initial out‐of‐plane drifts, and a unified simple equation set for ensuring BRB stability is proposed. Moreover, a series of cyclic loading tests with initial out‐of‐plane drifts are conducted, and the results are compared with those of the proposed equations. © 2013 The Authors. Earthquake Engineering & Structural Dynamics published by John Wiley & Sons Ltd.     

Temperature measurements of electrostatic shocks in?laser-produced counter-streaming plasmas

Collisionless shocks in counter-streaming plasmas, created by the high-power laser system Gekko XII HIPER, are investigated. The shock structure and density are measured by optical diagnostics such as shadowgraphy, interferometry, and streaked interferometry. The plasma density and temperature are estimated from self-emission measurements with visible light by streaked optical pyrometer and gated optical imager. Brightness temperatures are calculated considering the efficiency of the detectors, and electron temperatures are estimated.     

Influence of the ground profile on the reduction of earthquake motion at the filled man-made islands in the Kobe harbor during the 1995 Hyogoken Nambu earthquake

During the 1995 Hyogoken Nambu earthquake in Kobe, the ground motion at the filled man-made islands in the Kobe harbor was not as severe as that at the mainland. The building damage was also less compared to that on the mainland. It was found by comparative study of earthquake records that the magnitude of acceleration response on the ground surface decreases at the islands as opposed to the mainland. One dimensional effective stress analysis is adopted in this study. Input data has been generated from test results, e.g. the SPT N-value by standard penetration test and shear wave velocity V_s by PS logging. Results obtained by the analyses showed good agreement with the observed records, which is an indication of the suitability of the adopted analysis procedure. From this study, the followings are concluded. By the increase of SPT N-value of the filled layers, liquefaction near ground surface is restrained and damage modes such as ejection of water and soil can be prevented. Since the ground profile at the islands is that considerably soft filled layer and marine clay layers, etc. are present and the thickness of the surface layer is large, the initial natural period of the ground is above 1 s and the natural period is elongated further under the earthquake excitation, which is deemed to be the principal reason for the reduction of the earthquake motion at the ground surface.     

Radiative Shock Experiments At Luli

We present the set-up and the results of a supercritical radiative shock experiment performed with the LULI nanosecond laser facility. Using specific designed targets filled with xenon gaz at low pressure, the propagation of a strong shock with a radiative precursor is evidenced. The main measured quantities related to the shock (electronic density, propagation velocities, temperature, radial dimension) are presented and compared with various numerical simulations.