Sunlight and tidal interaction as a mechanism of carbon transport in an ice-covered region: Results of a coupled ice–ocean ecosystem model     

Yoshiki Nishi  Shigeru Tabeta 《Continental Shelf Research》2007

In order to clarify the mechanism of carbon transport in an ice-covered ecosystem in Lake Saroma (44^°N${44}^{°}\mathrm{N}$, 143^°E${143}^{°}\mathrm{E}$, Hokkaido, Japan), a three-dimensional numerical calculation using a coupled ice–ocean ecosystem model was conducted. This model comprises an ocean ecosystem model, an ice ecosystem model, and equations for the coupling between ice and ocean. Comparisons of calculated results with observational data confirm that the calculation well reproduced the in situ phenomena with respect to tides, tidal currents, concentrations of POC and chlorophyll a in ice and in water, and sinking fluxes beneath the ice. The analysis of the organic carbon budget based on the calculation reveals that tide-induced transport, the enhancement of biological production in a pelagic system, and the physical release of organic matter from ice associated with ice-melting are important factors affecting the carbon transport during the ice-melting season. The carbon transport has a one-day time cycle. This is because principal driving forces are sunlight, and diurnal tides. The described mechanism of “sunlight and tidal pumping” is one of the most important features of carbon transport in a coupled ice–water ecosystem.  相似文献   

The Southern Annular Mode and opposite-phased Basin Mode of the Southern Ocean circulation     

Yuji Iijima  Shigeru Aoki  Kunio Kutsuwada 《Journal of Oceanography》2009,65(1):53-60

Over the Southern Ocean the dominant modes of the atmospheric field are known as the Southern Annular Mode (SAM) or Antarctic Oscillation, and the Pacific South American (PSA) pattern. Statistical analysis of sea surface wind (SSW) from satellite observation revealed two leading modes of SAM-like and PSA patterns. In the high latitudes, the SAM-like pattern of the SSW had a large amplitude over the Bellingshausen Basin and Australian-Antarctic Basin, with opposite phase between the two basins. On the intraseasonal time scale, large-scale sea surface height (SSH) also had notable variability, showing a basin-scale anti-phase mode over the two basins. To explain the response of oceanic variations to these atmospheric modes, we analyzed the relationship between the dominant modes of wind stress and large-scale SSH on the intraseasonal time scale. The SAM-like pattern of wind stress was correlated with the SSH variation over the two basins. The SSH basin mode was most simply explained by a simple barotropic response to the SAM-like mode of wind stress, with the curl of opposite phase between the two basins. We conclude that the zonal asymmetry of the wind field of the SAM plays an important role in driving the antiphase SSH basin modes.  相似文献   

Determination of Total Sulfur in Thirty One Geochemical Reference Materials Using an Inductively Coupled Plasma-Atomic Emission Spectrometer Fitted with a Semiconductor Photodiode Detector   总被引：2，自引：0，他引：2  

Takashi Okai  Shigeru Terashima  Noboru Imai 《Geostandards and Geoanalytical Research》2001,25(1):133-136

The total sulfur contents of thirty one geochemical reference materials were determined using an inductively coupled plasma-atomic emission spectrometer fitted with a semiconductor photodiode detector. Most samples were decomposed using an HF-aqua regia digestion. However, a few were incompletely decomposed by simple acid digestion, and these were decomposed by a fusion method. The agreement between the analytical results from this work and published data is generally good.  相似文献   

Geology and geochemistry of lavas at Nekoma volcano: Implications for origin of Quaternary low-K andesite in the north-eastern Honshu arc, Japan   总被引：4，自引：0，他引：4  

Jun-Ichi Kimura  Tomoyuki Tanji  Takeyoshi Yoshida  Shigeru Iizumi 《Island Arc》2001,10(2):116-134

Abstract Nekoma volcano forms part of the arc axis volcanic array of the North-eastern Honshu arc, Japan, which is commonly characterized by medium-K lava suites. However, Nekoma is exceptional because many of its lavas are low-K. This anomaly has been a matter of debate. Nekoma was active from 1.1 to 0.35 Ma. The volcano consists of thick andesite flows and domes associated with block and ash flow deposits produced during lava dome formation. A horseshoe-shaped collapse caldera was formed at the summit and small lava domes extruded into the caldera. Stratigraphy, published K–Ar ages, and tephrochronology define three stages of volcanic activity, about 1.1 Ma (Stage 1), 0.8–0.6 Ma (Stage 2) and 0.45–0.35 Ma (Stage 3; post caldera stage). Low-K andesites occur in all stages. Extremely low-K andesite was also associated in Stage 2 and medium-K andesite was dominant in Stage 3. In general, lavas changed from low-K to medium-K after caldera formation. Geochemical study of the Nekoma lavas shows that both low-K and medium-K lavas are isotopically similar and were derived from a common source. Adatara and Azuma volcanoes, which lie close to Nekoma, also have both low-K and medium-K andesites. However, Sr isotope ratios or temporal-spatial variations in K-level lava classification vary between the three centers. Comparisons of K suites and Sr isotope ratios with frontal arc volcanoes in North-east–Honshu suggest source heterogeneity existed in both medium- and low-K suites. The K contents of lavas and their Sr isotopes are not simply related. This requires re-examination of models for chemical variation of andesites in arcs.  相似文献   

THREE NEW GSJ ROCK REFERENCE SAMPLES: RHYOLITE JR-3, GABBRO JGB-2 AND HORNBLENDITE JH-1     

Shigeru TERASHIMA  Shiro ITOH  Masumi UJIIE  Hikari KAMIOKA  Tsuyoshi TANAKA  Hitoshi HATTORI 《Geostandards and Geoanalytical Research》1993,17(1):1-4

Three new rock reference samples, Rhyolite JR-3, Gabbro JGb-2 and Hornblendite JH-1 have been prepared by the Geological Survey of Japan for collaborative studies on their chemical composition. Twenty-eight major, minor and trace elements were determined and presented. The results of homogeneity tests showed that all elements are considered to be distributed homogeneously in each reference sample. Geological and mineralogical characteristics are also described.  相似文献   

Temporal variation in primary magma compositions in the northeast Japan Arc     

Shigeru  Yamashita  Yoshiyljki  Tatsump Susumu  Nohda 《Island Arc》1996,5(3):276-288

Abstract A remarkable temporal variation in primary magma compositions has been found in the Northeast Japan arc. The trench-side magmas have become more enriched in FeO* and the backarc-side magmas have become more depleted in FeO* while retaining almost constant SiO, levels for the last ∼20 million years. In order to understand the origin of the temporal variation, FeO* and SiO, contents in partial melts are modeled for an adiabatically-rising mantle as a function of potential temperature and original composition of the mantle material. The result demonstrates that the primary magmas that are more depleted in FeO* were derived from the mantle materials either at lower potential temperatures or with compositions more depleted in basaltic components. A possible mechanism for the inferred primary magma variability is the change in depth intervals with time of magma production in a compositionally-layered mantle wedge; greater degrees of depletion at a greater depth is reconciled with a probable thermal regime in the mantle wedge.  相似文献   

Determination of Total Carbon and Sulfur in Fifty-two Geochemical Reference Samples by Combustion and Infrared Absorption Spectrometry     

Shigeru TERASHIMA 《Geostandards and Geoanalytical Research》1988,12(2):249-252

The contents of total carbon and sulfur in 52 international geochemical reference samples have been determined by a method of infrared absorption following combustion in a high-frequency induction furnace. A comparison with published data shows clearly the need for much more data on most samples before consensus values could be assigned.
Les teneurs en carbone et soufre totaux ont été déterminées dans 52 échantillons géochimiques de référence par combustion suivie de spectrométrie d'absorption infra-rouge. Une comparaison de ces résultats avec ceux de la littérature montre bien la nécessité de disposer davantage de données pour pouvoir fixer des valeurs de consensus.  相似文献   

Determination of Uranium in Thirty-six Geological Reference Samples by Fluorimetry and Extractive Spectrophotometry     

Yutaka KANAI  Noboru IMAI  Shigeru TERASHIMA 《Geostandards and Geoanalytical Research》1986,10(1):73-76

The uranium contents of 36 geological reference samples have been determined by fluorimetry after ion-exchange separation, and spectrophotometry using Arsenazo III after solvent extraction with tri-n-octylphosphine oxide. The agreement between present results and published data is generally good. The methods of fluorimetry and spectrophotometry proved very convenient in the determination of uranium in geological materials.  相似文献   

1986 Values for Fifteen GSJ Rock Reference Samples, "Igneous Rock Series"     

Atsushi ANDO  Naoki MITA  Shigeru TERASHIMA 《Geostandards and Geoanalytical Research》1987,11(2):159-166

During the five-year period (April 1981 - March 1986), a series of fifteen rock reference samples, "Igneous rock series", has been prepared by the Geological Survey of Japan (GSJ). Based on the data available (published and communicated), consensus values for major, minor and trace elements have been derived; these values are presented for this second series of samples as well as for the first series of two samples, Granodiorite JG-1 and Basalt JB-1.  相似文献   

Determination of Selenium in Twenty-Eight Geological Reference Materials by Atomic Absorption Spectrometry     

Noboru IMAI  Shigeru TERASHIMA  Atsushi ANDO 《Geostandards and Geoanalytical Research》1984,8(1):39-41

Twenty-eight geological reference samples have been analysed for selenium using atomic absorption spectrometry with hydride generation and quartz cell atomizer and/or with solvent extraction and carbon tube atomizer. Data are presented for 5 CCRMP, 6 USGS, 3 NBS, 6 NIM and 8 GSJ reference materials.  相似文献