Diel tuning of photosynthetic systems in ice algae at Saroma-ko Lagoon, Hokkaido, Japan   总被引：1，自引：0，他引：1  

Shimpei Aikawa  Hiroshi Hattori  Yasushi Gomi  Kentaro Watanabe  Sakae Kudoh  Yasuhiro Kashino  Kazuhiko Satoh 《Polar Science》2009,3(1):57-72

Ice algae are the major primary producers in seasonally ice-covered oceans during the cold season. Diurnal change in solar radiation is inevitable for ice algae, even beneath seasonal sea ice in lower-latitude regions. In this work, we focused on the photosynthetic response of ice algae under diurnally changing irradiance in Saroma-ko Lagoon, Japan. Photosynthetic properties were assessed by pulse-amplitude modulation (PAM) fluorometry. The species composition remained almost the same throughout the investigation. The maximum electron transport rate (rETR_max), which indicates the capacity of photosynthetic electron transport, increased from sunrise until around noon and decreased toward sunset, with no sign of the afternoon depression commonly observed in other photosynthetic organisms. The level of non-photochemical quenching, which indicates photoprotection activity by dissipating excess light energy via thermal processes, changed with diurnal variations in irradiance. The pigment composition appeared constant, except for xanthophyll cycle pigments, which changed irrespective of irradiance. These results indicate that ice algae tune their photosynthetic system harmonically to achieve efficient photosynthesis under diurnally changing irradiance, while avoiding damage to photosystems. This regulation system may be essential for productive photosynthesis in ice algae.  相似文献   

Geometry of the Nojima Fault at Nojima-Hirabayashi, Japan – I. A Simple Damage Structure Inferred from Borehole Core Permeability     

David A. Lockner  Hidemi Tanaka  Hisao Ito  Ryuji Ikeda  Kentaro Omura  Hisanobu Naka 《Pure and Applied Geophysics》2009,166(10-11):1649-1667

The 1995 Kobe (Hyogo-ken Nanbu) earthquake, M = 7.2, ruptured the Nojima fault in southwest Japan. We have studied core samples taken from two scientific drillholes that crossed the fault zone SW of the epicentral region on Awaji Island. The shallower hole, drilled by the Geological Survey of Japan (GSJ), was started 75 m to the SE of the surface trace of the Nojima fault and crossed the fault at a depth of 624 m. A deeper hole, drilled by the National Research Institute for Earth Science and Disaster Prevention (NIED) was started 302 m to the SE of the fault and crossed fault strands below a depth of 1140 m. We have measured strength and matrix permeability of core samples taken from these two drillholes. We find a strong correlation between permeability and proximity to the fault zone shear axes. The half-width of the high permeability zone (approximately 15 to 25 m) is in good agreement with the fault zone width inferred from trapped seismic wave analysis and other evidence. The fault zone core or shear axis contains clays with permeabilities of approximately 0.1 to 1 microdarcy at 50 MPa effective confining pressure (10 to 30 microdarcy at in situ pressures). Within a few meters of the fault zone core, the rock is highly fractured but has sustained little net shear. Matrix permeability of this zone is approximately 30 to 60 microdarcy at 50 MPa effective confining pressure (300 to 1000 microdarcy at in situ pressures). Outside this damage zone, matrix permeability drops below 0.01 microdarcy. The clay-rich core material has the lowest strength with a coefficient of friction of approximately 0.55. Shear strength increases with distance from the shear axis. These permeability and strength observations reveal a simple fault zone structure with a relatively weak fine-grained core surrounded by a damage zone of fractured rock. In this case, the damage zone will act as a high-permeability conduit for vertical and horizontal flow in the plane of the fault. The fine-grained core region, however, will impede fluid flow across the fault.  相似文献   

Origin of felsic volcanism in the Izu arc intra-arc rift     

Satoru?HaraguchiEmail author  Jun-Ichi?Kimura  Ryoko?Senda  Koichiro?Fujinaga  Kentaro?Nakamura  Yutaro?Takaya  Teruaki?Ishii 《Contributions to Mineralogy and Petrology》2017,172(5):25

An intra-arc rift (IAR) is developed behind the volcanic front in the Izu arc, Japan. Bimodal volcanism, represented by basalt and rhyolite lavas and hydrothermal activity, is active in the IAR. The constituent minerals in the rhyolite lavas are mainly plagioclase and quartz, whereas mafic minerals are rare and are mainly orthopyroxene without any hydrous minerals such as amphibole and biotite. Both the phenocryst and groundmass minerals have felsic affinities with a narrow compositional range. The petrological and bulk chemical characteristics are similar to those of melts from some partial melting experiments that also yield dry rhyolite melts. The hydrous mineral-free narrow mineral compositions and low-Al₂O₃ affinities of the IAR rhyolites are produced from basaltic middle crust under anhydrous low-temperature melting conditions. The IAR basalt lavas display prominent across-arc variation, with depleted elemental compositions in the volcanic front side and enriched compositions in the rear-arc side. The across-arc variation reflects gradual change in the slab-derived components, as demonstrated by decreasing Ba/Zr and Th/Zr values to the rear-arc side. Rhyolite lavas exhibit different across-arc variations in either the fluid-mobile elements or the immobile elements, such as Nb/Zr, La/Yb, and chondrite-normalized rare earth element patterns, reflecting that the felsic magmas had different source. The preexisting arc crust formed during an earlier stage of arc evolution, most probably during the Oligocene prior to spreading of the Shikoku back-arc basin. The lack of systematic across-arc variation in the IAR rhyolites and their dry/shallow crustal melting origin combines to suggest re-melting of preexisting Oligocene middle crust by heat from the young basaltic magmatism.  相似文献   

Molecular orbital study on the onset of the pressure-induced transformations of the metastably compressed germanates     

T. Hattori  J. Mimaki  T. Yamanaka 《Physics and Chemistry of Minerals》2002,29(4):261-266

In order to elucidate the onset of the pressure-induced transformations of germanates consisting of GeO₄ tetrahedra at room temperature, we have investigated the stability of the crystal structures near the transition pressure in terms of the stability of the linkage of the tetrahedra. The stability of the linkage near the transition pressure is estimated from the results of the molecular orbital calculations for the model cluster H₆Ge₂O₇, which mimics the linkage of tetrahedra, as functions of the bond length d(Ge–O_br) with bridging oxygen and bond angles Ge–O_br–Ge. The calculation shows that the total energy of the linkage becomes minimum at d(Ge–O_br)=1.758 Å and br–Ge=130.4°, and that it increases with the deviation from the energy minimum geometry. From the compression behavior of framework and chain germanates, we find that the linkage of the tetrahedra becomes unstable with increasing pressure, and that these germanates commonly transform into their high-pressure phases when the linkage of the tetrahedra largely departs from the energy minimum geometry. This suggests that the high-pressure transformations of the metastably compressed germanates are induced by the instability of the linkage of tetrahedra.  相似文献   

Magmatic mineralization and hydrothermal enrichment of the High Grade Zone at the Lac des Iles palladium mine, northern Ontario, Canada   总被引：2，自引：0，他引：2  

John G. Hinchey  Kéiko H. Hattori 《Mineralium Deposita》2005,40(1):13-23

The economic mineralization of Pd at the Lac des Iles mine occurs in the gabbroic rocks of the Mine Block Intrusion in the 2.69 Ga Lac des Iles Intrusive Complex. The complex intruded the tonalitic rocks of the Lac des Iles greenstone belt in the Wabigoon Subprovince of the Superior Province of Canada. We conducted a detailed study on the Pd mineralization in the southern Roby Zone and the Twilight Zone. Sulphide minerals commonly display exsolution textures where pentlandite and chalcopyrite are exsolved from pyrrhotite. Sulphur contents from these zones display positive correlations with the contents of platinum group elements (PGE), Se, and Te, suggesting a magmatic origin of the mineralization where PGE were concentrated in immiscible sulphide melt in the parental magmas. The average ratios of Se/S (703±192×10^–6) and Te/S (192±104×10^–6) in the two zones are higher than the primitive mantle values of ~300×10^–6 and ~48×10^–6, respectively. The high ratios are consistent with the derivation of their parental magmas from a depleted mantle source. The High Grade Zone forms a narrow northwest-trending zone in the margin of the Roby Zone, and is hosted by an intensely altered clinopyroxenite/melanogabbroic unit. It contains two mineral assemblages; millerite + siegenite ± chalcopyrite ± pyrite co-existing with hornblende + plagioclase ± quartz ± carbonate, and pyrite ± chalcopyrite with chlorite + actinolite ± albite ± quartz ± carbonate. The ore is high in Pd (mean Pd/Pt ratio of 16.5; up to 25) compared to the southern Roby Zone and Twilight Zone where the Pd/Pt ratios are ~8. It shows positive correlations between Se and Te and between Se and immobile metals, such as Ni and Co. The data suggest a primary magmatic origin of mineralization of the High Grade Zone, but there is substantial scatter on diagrams involving S, such as the plot between S and Se. The evidence suggests that the primary magmatic mineralization was followed by hydrothermal transport of mobile elements. Using the relationships between Se and metals, the ore most likely had 0.8–2 ppm Pt and 8–21 ppm Pd during the primary mineralization. The subsequent hydrothermal activity resulted in the enrichment of Pd by up to 40 ppm. The lack of fluid pathways in the High Grade Zone and the distribution of the zone are consistent with magmatic-hydrothermal activity by aqueous fluids exsolved from the parental magmas of the Roby Zone and High Grade Zone. Sulphide minerals from the southern Roby Zone, Twilight Zone, and High Grade Zone have similar ³⁴S values, ranging from 0.0 to +1.5. The data are consistent with the derivation of S from the mantle. In individual samples from the southern Roby Zone and High Grade Zone, pyrite shows lower ³⁴S than chalcopyrite, suggesting isotopic disequilibrium of S. This likely reflects the crystallization and re-crystallization of sulphide minerals over a wide range of temperatures.Editorial handling: B. Lehmann  相似文献   

Light utilization efficiency of phytoplankton in the Western Subarctic Gyre of the North Pacific during summer     

Yuichi Nosaka  Tomonori Isada  Isao Kudo  Hiroaki Saito  Hiroshi Hattori  Atsushi Tsuda  Koji Suzuki 《Journal of Oceanography》2014,70(1):91-103

We investigated the water-column light utilization efficiency (Ψ) of phytoplankton photosynthesis in the Western Subarctic Gyre (WSG) of the North Pacific during summer 2008. The Ψ values (0.64–1.86 g C [g Chl a]^?1 [mol photon]^?1 m²) obtained were observed to increase significantly with decreasing daily photosynthetic available radiation (PAR) and were generally higher than those of previous studies, not only from the subarctic Pacific but also from the world’s oceans. To examine the effect of iron availability on Ψ in the WSG, Ψ values were estimated from the data of two in situ iron fertilization experiments: the Subarctic Pacific Iron Experiment for Ecosystem Dynamics Study I (SEEDS-I) and II (SEEDS-II). We found that iron availability did not affect Ψ values. Overall, this study revealed that Ψ values changed remarkably in the WSG during the summer, and that higher values were found at the stations where moderate PAR levels (ca. 10–30 mol photons m^?2 day^?1) were observed and where autotrophic flagellates predominated in the phytoplankton assemblages.  相似文献   

Experimental constraints on permeable gas transport in crystalline silicic magmas     

Satoshi Okumura  Michihiko Nakamura  Tsukasa Nakano  Kentaro Uesugi  Akira Tsuchiyama 《Contributions to Mineralogy and Petrology》2012,164(3):493-504

The gas and fluid transport in magmas via permeable flow through interconnected bubble networks controls the rate of outgassing from magmas ascending in volcanic conduits and the fluid transport in the mushy boundary layer of magma reservoirs. Hence, clarifying its mechanism and rate is crucial to understanding the explosivity of volcanic eruptions and the evolution and dynamics of a magma reservoir. Recent experimental studies have determined the gas permeabilities in crystal-free rhyolite and basalt. However, no experimental study has investigated the effect of the crystal contents on the permeable gas transport in magmas. In this study, we performed decompression experiments for hydrous rhyolitic melts having crystallinities of 30 and 50 vol% to examine the effect of crystals on the bubble microstructure and gas permeability during magma vesiculation. Size-controlled (100-meshed) corundum crystals were used as an analog of the phenocrysts in silicic magmas. Microstructural analyses using X-ray CT showed that bubbles coalesce and their connectivity increases with a decrease in the final pressure after the decompression, that is, an increase in the vesicularity. As long as the vesicularities of melt part in the crystal-free basis (melt vesicularity) were similar, no clear effect of the crystallinity on the degree of bubble coalescence and connectivity was observed at melt vesicularities <68 vol%. The corundum showed a large contact angle with aqueous fluid as well as plagioclase and alkaline feldspar; this failed to induce the efficient heterogeneous nucleation and coalescence of bubbles on its surface. The gas permeabilities of all the run products were lower than the detection limits of the present analysis (the order of 10⁻¹⁶ m²) at melt vesicularities <68 vol%. These results show that silicic magmas containing 30 and 50 vol% phenocrysts with a large contact angle have low gas permeabilities until the vesicularity becomes large (at least >68 vol%). This result indicates that the permeable fluid transport through a deep volcanic conduit, which has been proposed on the basis of the observations of volcanic gases and natural products, is so slow that other processes, like shear deformation or magma convection, may be needed to explain the observations.  相似文献   

Ceramic waste glass fiber-reinforced plastic-containing filtering materials for turbid water treatment     

Kentaro Yasui  Shogo Goto  Hiroyuki Kinoshita  Shuta Kamiunten  Toshifumi Yuji  Yoshimi Okamura  Narong Mungkung  Mitsuhiro Sezaki 《Environmental Earth Sciences》2016,75(15):1135

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Determination of U–Pb Ages for Young Zircons using Laser Ablation‐ICP‐Mass Spectrometry Coupled with an Ion Detection Attenuator Device     

Shuhei Sakata  Kentaro Hattori  Hideki Iwano  Takaomi D. Yokoyama  Tohru Danhara  Takafumi Hirata 《Geostandards and Geoanalytical Research》2014,38(4):409-420

We have developed new analytical procedures to measure precise and accurate ²³⁸U–²⁰⁶Pb and ²³⁵U–²⁰⁷Pb ages for young (~ 1 Ma) zircons using laser ablation‐ICP‐mass spectrometry. For young zircons, both careful correction for the background counts and analysis of very small Pb/U ratios (i.e., ²⁰⁶Pb/²³⁸U < 0.00016 and ²⁰⁷Pb/²³⁵U < 0.0001 for 1 Ma zircons) are highly desired. For the correction of the background, the contribution of the background signal intensities for the analytes, especially for the residual signal intensities for ²⁰⁶Pb and ²⁰⁷Pb, was defined through laser ablation of synthesised zircons (ablation blank) containing negligible Pb. The measured signal intensities for ²⁰²Hg, ²⁰⁶Pb and ²⁰⁷Pb signals obtained by the ablation blank were slightly higher than those obtained by data acquisition without laser ablation (gas blank). For the wider dynamic range measurements on Pb/U ratios, an attenuator device for the ion detection system was employed to extend the capability to monitor high‐intensity signals (i.e., > 3 Mcps). Through the attenuator device, the ion currents were reduced to 1/450 of the signal intensity without the attenuator. Because the switching time for the attenuator was shorter than 1 ms, signal intensities for only specific isotopes could be reduced. With attenuation of the ²³⁸U signal, counting statistics on ²⁰⁶Pb and ²⁰⁷Pb isotopes could be improved and counting loss on the ²³⁸U signal could be minimised. To demonstrate the reliability of this new analytical technique, ²³⁸U–²⁰⁶Pb and ²³⁵U–²⁰⁷Pb ages for three young zircon samples (collected from Osaka Group Pink Volcanic Ash, Kirigamine and Bishop Tuff) were measured. The data presented here demonstrate clearly that the present technique could become a major analytical tool for in situ U–Pb age determination of young zircons (~ 1 Ma).  相似文献