Utility of Nd isotope ratio as a tracer of marine animals : regional variation in coastal seas and causal factors

Isotopic compositions of animal tissue are an intrinsic marker commonly used to trace animal origins and migrations; however, few isotopes are effective for this purpose in marine environments, especially on a local scale. The isotope ratio of the lanthanoid element neodymium (Nd) is a promising tracer for coastal animal migrations. Neodymium derives from the same geologic materials as strontium, well known as an isotopic tracer (87Sr/86Sr) for terrestrial and anadromous animals. The advantage of the Nd isotope ratio (143Nd/144Nd, expressed as εNd) is that it varies greatly in the ocean according to the geology of the neighboring continents, whereas oceanic 87Sr/86Sr is highly uniform. This study explored the utility of the Nd isotope ratio as a marine tracer by investigating the variation of εNd preserved in tissues of coastal species, and the causes of that variation, in a region of northeastern Japan where the bedrock geology is highly variable. We measured εNd and 87Sr/86Sr in seawater, river water, and soft tissues of sedentary suspension feeders: the mussels Mytilus galloprovincialis and Mytilus coruscus and the oyster Crassostrea gigas. We also measured concentrations of three lanthanoids (La, Ce, and Pr) in shellfish bodies to determine whether the Nd in shellfish tissue was derived from solution in seawater or from suspended particulates. The εNd values in shellfish tissue varied regionally (−6 to +1), matching the ambient seawater, whereas all 87Sr/86Sr values were homogeneous and typical of seawater (0.7091–0.7092). The seawater εNd values were in turn correlated with those in the adjacent rivers, linking shellfish εNd to the geology of river catchments. The depletion of Ce compared to La and Pr (negative Ce anomaly) suggested that the Nd in shellfish was derived from the dissolved phase in seawater. Our results indicate that the distinct Nd isotope ratio derived from local geology is imprinted, through seawater, on the soft tissues of shellfish. This result underscores the potential of εNd as a tracer of coastal marine animals

Seismic exploration at Fuji volcano with active sources : The outline of the experiment and the arrival time data

Fuji volcano (altitude 3,776m) is the largest basaltic stratovolcano in Japan. In late August and early September 2003, seismic exploration was conducted around Fuji volcano by the detonation of 500 kg charges of dynamite to investigate the seismic structure of that area. Seismographs with an eigenfrequency of 2 Hz were used for observation, positioned along a WSW-ENE line passing through the summit of the mountain. A total of 469 seismic stations were installed at intervals of 250-500 m. The data were stored in memory on-site using data loggers. The sampling interval was 4 ms. Charges were detonated at 5 points, one at each end of the observation line and 3 along its length. The first arrival times and the later-phase arrival times at each station for each detonation were recorded as data. P-wave velocities in the surface layer were estimated from the travel time curves near the explosion points, with results of 2.5 km/s obtained for the vicinity of Fuji volcano and 4.0 km5/s elsewhere

Seismological observations on Mount Erebus, Ross Island, Antarctica, 1980-1981

Mount Erebus (3794m) on Ross Island is one of active volcanoes in Antarctica. Two high sensitive seismic networks were installed during the 1980-1981 austral summer field season for studying seismicity in Ross Island. The one was a three-station radio telemetry network, and the other was a six-station network with long-life portable data recorders. The latter was installed temporarily around the main crater near the summit from December 20,1980 to January 6,1981. In spite of wild and harsh environment for the seismic observations, many volcanic earthquakes were recorded by the seismic networks. The number of 111 shallow events were located using the data of the above two networks. The hypocenters clustered beneath the summit in a range from near the surface to 6km. Many events accompanied the explosive eruptions were recorded at summit stations around the main crater

Activities of Japanese party in the McMurdo Sound area during the 1980-1981 field season

Under the coordination and supervision of the National Institute of Polar Research, a 3-man Japanese party installed on Mt. Erebus three permanent seismological networks with radio telemetry links to Scott Base in cooperation with the U. S. and New Zealand parties during the 1980-81 field season. The Japanese party also installed a temporary seismological network of six seismometers around the main crater. The summit station also telemeters data from two acoustic channels which were used to monitor explosions in the crater and to monitor the flux of electrically charged gases with an experimental induction loop. A preliminary study showed that the seismic activity of Mt. Erebus was exceedingly high, namely, many micro-or ultramicro-shocks have occurred and their time sequence was swarms

Electrical properties of GaAs metal–oxide–semiconductor structure comprising Al2O3 gate oxide and AlN passivation layer fabricated in situ using a metal–organic vapor deposition/atomic layer deposition hybrid system

This paper presents a compressive study on the fabrication and optimization of GaAs metal–oxide–semiconductor (MOS) structures comprising a Al2O3 gate oxide, deposited via atomic layer deposition (ALD), with an AlN interfacial passivation layer prepared in situ via metal–organic chemical vapor deposition (MOCVD). The established protocol afforded self-limiting growth of Al2O3 in the atmospheric MOCVD reactor. Consequently, this enabled successive growth of MOCVD-formed AlN and ALD-formed Al2O3 layers on the GaAs substrate. The effects of AlN thickness, post-deposition anneal (PDA) conditions, and crystal orientation of the GaAs substrate on the electrical properties of the resulting MOS capacitors were investigated. Thin AlN passivation layers afforded incorporation of optimum amounts of nitrogen, leading to good capacitance–voltage (C–V) characteristics with reduced frequency dispersion. In contrast, excessively thick AlN passivation layers degraded the interface, thereby increasing the interfacial density of states (Dit) near the midgap and reducing the conduction band offset. To further improve the interface with the thin AlN passivation layers, the PDA conditions were optimized. Using wet nitrogen at 600 °C was effective to reduce Dit to below 2 × 1012 cm−2 eV−1. Using a (111)A substrate was also effective in reducing the frequency dispersion of accumulation capacitance, thus suggesting the suppression of traps in GaAs located near the dielectric/GaAs interface. The current findings suggest that using an atmosphere ALD process with in situ AlN passivation using the current MOCVD system could be an efficient solution to improving GaAs MOS interfaces

On the Establishment of GPS Observation Station around Mt. Fuji

＜短報

1980-1981 ネン マクマード チイキ コクサイ キョウドウ カンソク ホウコク

本報告は1980-1981年の野外調査期間中, 南極マクマードサウンド地域における日本・米国・ニュージーランド3国の国際共同観測計画「エレバス火山の地球物理学的研究」に基づいて実施した調査活動の概要報告である。調査期間中, スコット基地(77.85°S, 166.75°E)を受信点とするエレバス山(77.58°S, 167.17°E, 3796m)の3点テレメトリー地震観測, 山頂火口付近での6点臨時地震観測およびドライバレー地域における微小地震観測を実施した。エレバス山では, 微小または極微小地震が絶えず観測され, 地震学的にみて, 同山が世界有数の活火山であろうことが推察された。Under the coordination and supervision of the National Institute of Polar Research, a 3-man Japanese party installed on Mt. Erebus three permanent seismological networks with radio telemetry links to Scott Base in cooperation with the U. S. and New Zealand parties during the 1980-81 field season. The Japanese party also installed a temporary seismological network of six seismometers around the main crater. The summit station also telemeters data from two acoustic channels which were used to monitor explosions in the crater and to monitor the flux of electrically charged gases with an experimental induction loop. A preliminary study showed that the seismic activity of Mt. Erebus was exceedingly high, namely, many micro-or ultramicro-shocks have occurred and their time sequence was swarms