Altitude variation of ultraviolet oxygen night airglow

Night airglow of oxygen 130.4 and 135.6 nm emissions was measured by a spectrophotometer aborad an S520 sounding rocket, launched at 19:50 JST (10:50 UT) on 14 February, 1982 from Kagoshima, Japan. The altitude variation of the emissions was obtained from 110 to 266 km at zenith angles of 35.5°±4°. The emission intensity around 260 km was about 160R and is roughly compatible with model calculations taking account of O⁺+e ^– radiative recombination as well as O⁺–O^– mutual neutralization. Some excess of about 50R, compared to the model calculation, was observed around 200 km. Possible explanations of the excess are: (i) remnant oxygen ions during the transition period from day to night and (ii) diffuse radiation from the background sky. Model calculations taking account of remnant oxygen ions were also performed by adding an excess electron density to the original density profile. However, it was found that an unreasonably large electron density is required around 200 km (5×10⁵ cm^–3) to produce the observed intensity. It is also probable that some contribution from the background sky is present in the observed intensity.     

Deformation processes in the shallow levels of an accretionary prism: The Mesozoic Torlesse Terrane, South Island, New Zealand

Abstract The deformation style of the Torlesse Terrane along the southern Kaikoura coast, South Island, New Zealand, records shallow level deformation processes within an accretionary prism during the Early Cretaceous. The beds exhibit complicated structural features resulting from multistage deformations in a lithological unit, that were intimately related with the dewatering and lithification of terrigenous sediments. The earliest phase of deformation throughout the transect studied was the development of pinch-and-swell structures and boudinage fabrics due to layer-parallel extension while the beds were poorly consolidated. This was followed locally by mesoscopic tight to close recumbent folding. The beds are cut locally by two phases of mudstone intrusions. The earlier phase was initiated by 'in situ' fluidization of mudstone layers, whereas the later phase represented intrusion of siliceous claystone probably derived from an overpressured decollement. Minor faults at high-angles to bedding by layer-normal shortening then disrupted the beds throughout the transect. The deformation was followed by formation of meso- and macroscopic scale open to gentle folds by layer-parallel shortening. Kilometer-scale differential stratal rotations were produced during the final main tectonic phase that occurred in association with post-accretion Neogene regional disturbance.     

Influence of submarine fumaroles on the distribution of mercury in the sediment of Kagoshima Bay,Japan

To estimate the influence of mercury emitted from submarine fumaroles, the horizontal and vertical distribution of mercury in sediment of Kagoshima Bay was studied. The fumaroles are located in the northern bay head area, and the sediment samples had been taken from 52 points throughout the bay with a gravity core sampler. The core samples obtained were cut at a thickness of 1–2 cm and used for measurements. The total concentration of mercury in surface sediment in the northern and central areas of the bay was 51–679 μg kg^− 1 (average 199 μg kg^− 1, n = 22) and 23–100 μg kg^− 1 (average 55 μg kg^− 1, n = 30), respectively. The highest value was obtained in the vicinity of the fumaroles. The mercury concentration in sediment near the fumaroles varied with depth, which may reflect the variation in fumarolic activity. A successive extraction method was applied to the speciation of mercury in the sediment. The results showed that sediment taken in the vicinity of submarine fumaroles contained a higher percentage of mercury bound with organic matter.     

Effects of CO<Subscript>2</Subscript> on Marine Fish: Larvae and Adults

CO₂-enriched seawater was far more toxic to eggs and larvae of a marine fish, silver seabream, Pagrus major, than HCl-acidified seawater when tested at the same seawater pH. Data on the effects of acidified seawater can therefore not be used to estimate the toxicity of CO₂, as has been done in earlier studies. Ontogenetic changes in CO₂ tolerance of two marine bony fishes (Pag. major and Japanese sillago, Sillago japonica) showed a similar, characteristic pattern: the cleavage and juvenile stages were most susceptible, whereas the preflexion and flexion stages were much more tolerant to CO₂. Adult Japanese amberjack, Seriola quinqueradiata, and bastard halibut, Paralichthys olivaceus, died within 8 and 48 h, respectively, during exposure to seawater equilibrated with 5% CO₂. Only 20% of a cartilaginous fish, starspotted smooth-hound, Mustelus manazo, died at 7% CO₂ within 72 h. Arterial pH initially decreased but completely recovered within 1-24 h for Ser. quinqueradiata and Par. olivaceus at 1 and 3% CO₂, but the recovery was slower and complete only at 1% for M. manazo. During exposure to 5% CO₂, Par. olivaceus died after arterial pH had been completely restored. Exposure to 5% CO₂ rapidly depressed the cardiac output of Ser. quinqueradiata, while 1% CO₂ had no effect. Both levels of ambient CO₂ had no effect on blood O₂ levels. We tentatively conclude that cardiac failure is important in the mechanisms by which CO₂ kills fish. High CO₂ levels near injection points during CO₂ ocean sequestration are likely to have acute deleterious effects on both larvae and adults of marine fishes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Coastal polynyas off East Queen Maud Land observed from NOAA AVHRR data

Coastal polynyas off East Queen Maud Land in Antarctica are examined using NOAA AVHRR infrared data. From image analyses, two locations of coastal polynyas in this region are identified; one in Breid Bay and the other along the shelf break. The areal coverage of the Breid Bay polynya is significantly related to the strength of katabatic winds, which maintain their strength over the coastal sea due to land topography favoring for their confluence, thereby being capable of removing newly formed ice. Land fast ice in the eastern part of the bay also plays an additional role in the formation mechanism. It is also found that the areal coverage of coastal polynyas in this region fluctuate coherently. Moreover, these fluctuations correspond to the synoptic index, which measures the strength of the offshore wind, with their peaks closely associated with the areal peaks. These facts strongly suggest the influence of synoptic scale weather on the formation and maintenance of polynyas in this region.     

Change in the microzooplankton community during decay of aHeterosigma akashiwo bloom

The temporal change in the microzooplankton community during the decay of a bloom ofHeterosigma akashiwo was investigated over a 10-day period in June–July 1991 at a site in western Hiroshima Bay, the Seto Inland Sea, Japan. The density ofH. akashiwo was at the order of 10⁴ cells·ml^–1 during the first 5 days, and decreased drastically when vertical mixing occurred.Heterosigma akashiwo cells disappeared after the eighth day. When the density ofH. akashiwo decreased suddenly, the density of microzooplankton increased rapidly. The increase in microzooplankton density was due to non-tintinnid ciliates. The species diversity of tintinnids was significantly higher in 1 and 2-m layers during the post-bloom period than during the bloom period. One species of tintinnid,Codonellopsis nipponica, was the most abundant in the bottom layer during the bloom period but decreased in abundance during the decay of the bloom. Populations of two species of hyaline tintinnids,Eutintinnus tubulosus andHelicostomella longa, were at low levels during the bloom period, and then developed suddenly after the bloom disappeared. It was demonstrated that the abundance and species composition of the ciliate community change dramatically during the decay of theHeterosigma bloom.     

Influence ofNoctiluca's predation on theAcartia population in Ise Bay,central Japan

The influence ofNoctiluca's predation on theAcartia population in Ise Bay was examined by taking samples at 27 stations once a month from May to December, 1974.The copepod eggs were found inNoctiluca mainly in May and June. Considering from various spawning types of copepods, the eggs were presumed to beAcartia, the most numerous species of all copepods in the bay.Noctiluca was dominant plankton in May and June whenAcartia was abundantly distributed.Acartia eggs were found in 33.2–39.3% of individuals ofNoctiluca in May and June.Noctiluca was more frequently observed to contain one egg ofAcartia per individual. It was suggested that 55.0 eggs perAcartia female per day were eaten by theNoctiluca population in May wherease 3.5 eggs in June. It was deduced that 74% of the eggs produced byAcartia was preyed on byNoctiluca (about 5% in June). The predation byNoctiluca as well as that by the sand-eel must influence greatly to the production ofAcartia in the bay.     

Possible source of the antarctic bottom water in the Prydz Bay Region

It has been inferred that the Prydz Bay region is one of the source regions of Antarctic Bottom Water (AABW) based on rather indirect evidence. In order to examine this inference, we investigate the hydrographic condition of the bay based mainly on XCTD data obtained during the Japanese Whale Research Program in the Antarctic (JARPA). The JARPA hydrographic data reveal Circumpolar Deep Water (CDW), which is a salty, warm water mass approaching the shelf break, and capture Modified CDW (MCDW) intruding into the shelf water. AABW production requires mixing of CDW and cold shelf water saltier than 34.6 psu, which is a saltier type of Low Salinity Shelf Water (LSSW). Saltier LSSW is observed near the bottom over the shelf, being mixed with MCDW. We further identify saltier LSSW near the shelf break. This saltier LSSW appears close enough to unmodified CDW to be mixed with it over the continental slope, indicating a possible source of AABW in Prydz Bay.