Using Optical Properties to Quantify Fringe Mangrove Inputs to the Dissolved Organic Matter (DOM) Pool in a Subtropical Estuary     

Kaelin M. Cawley  Youhei Yamashita  Nagamitsu Maie  Rudolf Jaffé 《Estuaries and Coasts》2014,37(2):399-410

Dissolved organic carbon (DOC) concentration and dissolved organic matter (DOM) optical properties were analyzed along two estuarine river transects during the wet and dry seasons to better understand DOM dynamics and quantify mangrove inputs. A tidal study was performed to assess the impacts of tidal pumping on DOM transport. DOM in the estuaries showed non-conservative mixing indicative of mangrove-derived inputs. Similarly, fluorescence data suggest that some terrestrial humic-like components showed non-conservative behavior. An Everglades freshwater-derived fluorescent component, which is associated with soil inputs from the Northern Everglades, behaved conservatively. During the dry season, a protein-like component behaved conservatively until the mid-salinity range when non-conservative behavior due to degradation and/or loss was observed. The tidal study data suggests mangrove porewater inputs to the rivers following low tide. The differences in quantity of DOM exported by the Shark and Harney Rivers imply that geomorphology and tidal hydrology may be a dominant factor controlling the amount of DOM exported from the mangrove ecotone, where up to 21 % of the DOC is mangrove-derived. Additionally, nutrient concentrations and other temporal factors may control DOM export from the mangroves, particularly for the microbially derived fluorescent components, contributing to the seasonal differences. The wet and dry season fluxes of mangrove DOM from the Shark River is estimated as 0.27?×?10⁹ mg C d^?1 and 0.075?×?10⁹ mg C d^?1, respectively, and the Harney River is estimated as 1.9?×?10⁹ mg C d^?1 and 0.20?×?10⁹ mg C d^?1.  相似文献   

Erratum to: Characterization of submarine canyon bathymetries in northern Ionian Sea,Italy, using sediment geochemical variation induced by transportation distance and basin depth     

Francesco Perri  Tohru Ohta  Salvatore Critelli 《International Journal of Earth Sciences》2015,104(7):1907-1907

  相似文献   

InFOCμS Hard X-ray Imaging Telescope     

J. Tueller  H. A. Krimm  T. Okajima  S. D. Barthelmy  S. M. Owens  P. J. Serlemitsos  Y. Soong  K.-W. Chan  Y. Ogasaka  R. Shibata  K. Tamura  A. Furuzawa  Y. Tawara  H. Kunieda  K. Yamashita 《Experimental Astronomy》2005,20(1-3):121-129

InFOCμS is a new generation balloon-borne hard X-ray telescope with focusing optics and spectroscopy. We had a successful 22.5-hour flight from Fort Sumner, NM on September 16,17, 2004. In this paper, we present the performance of the hard X-ray telescope, which consists of a depth-graded platinum/carbon multilayer mirror and a CdZnTe detector. The telescope has an effective area of 49 cm² at 30 keV, an angular resolution of 2.4 arcmin (HPD), and a field of view of 11 arcmin (FWHM) depending on energies. The CdZnTe detector is configured with a 12 × 12 segmented array of detector pixels. The pixels are 2 mm square, and are placed on 2.1 mm centers. An averaged energy resolution is 4.4 keV at 60 keV and its standard deviation is 0.36 keV over 128 pixels. The detector is surrounded by a 3-cm thick CsI anti coincidence shield to reduce background from particles and photons not incident along the mirror focal direction. The inflight background is 2.9 × 10⁻⁴ cts cm⁻² sec⁻¹ keV⁻¹ in the 20–50 keV band.  相似文献   

Observation of cosmic soft X-rays     

S. Hayakawa  T. Kato  T. Kohno  K. Nishimura  Y. Tanaka  K. Yamashita 《Astrophysics and Space Science》1972,17(1):30-38

Cosmic X-rays in the energy range between 0.210 keV were observed with polypropylene window proportional counters on board a sounding rocket. The field of view crossed the galactic plane in the Sgr region and reached galactic latitudes of 50° and –90°. A new soft X-ray source was found in the Aries-Taurus region. The soft X-ray flux from the direction of NGC 1275 was conspicuous, whereas that of Sgr region source were very weak. The distribution of the intensity of diffuse soft X-rays over the scanned region indicates the galactic emission of soft X-rays.  相似文献   

Melt inclusion analysis of the Unzen 1991–1995 dacite: implications for crystallization processes of dacite magma     

Koshi Nishimura  Tatsuhiko Kawamoto  Tetsuo Kobayashi  Takeshi Sugimoto  Shigeru Yamashita 《Bulletin of Volcanology》2005,67(7):648-662

Dacitic magma, a mixture of high-temperature (T) aphyric magma and low-T crystal-rich magma, was erupted during the 1991–1995 Mount Unzen eruptive cycle. Here, the crystallization processes of the low-T magma were examined on the basis of melt inclusion analysis and phase relationships. Variation in water content of the melt inclusions (5.1–7.2 wt% H₂O) reflected the degassing history of the low-T magma ascending from deeper levels (250 MPa) to a shallow magma chamber (140 MPa). The ascent rate of the low-T magma decreased markedly towards the emplacement level as crystal content increased. Cooling of magma as well as degassing-induced undercooling drove crystallization. With the decreasing ascent rate, degassing-induced undercooling decreased in importance, and cooling became more instrumental in crystallization, causing local and rapid crystallization along the margin of the magma body. Some crystals contain scores of melt inclusions, whereas there are some crystals without any inclusions. This heterogeneous distribution suggests the variation in the crystallization rate within the magma body; it also suggests that cooling was dominant cause for melt entrapment. Numerical calculations of the cooling magma body suggest that cooling caused rapid crystal growth and enhanced melt entrapment once the magma became a crystal-rich mush with evolved interstitial melt. The rhyolitic composition of melt inclusions is consistent with this model.Editorial responsibility: H Shinohara  相似文献   

Nouvelles données sur le téphra de Sarliève et le téphra CF7, marqueurs chrono-stratigraphiques de Grande Limagne (Massif central,France)     

Didier Miallier  Serge Sanzelle  Thierry Pilleyre  Gérard Vernet  Sarah Brugière  Tohru Danhara 《Comptes Rendus Geoscience》2004,336(1):1-8

A trachytic tephra, discovered in the ancient lake of Sarliève, ‘Grande Limagne’, has been dated using the thermoluminescence technique. The obtained age, 16±4 ka ($\text{2}\text{σ}$), is older than that of the trachytic volcanoes of the Cha??ne des Puys, the ashes of which have already been locally recognised in the region. Its analysis confirms its originality. In the course of the comparisons made to search for its spring, it appears that the wide-dispersion tephra CF7, beforehand correlated by hypothesis to the Puy de Clierzou, probably originates from the Kilian crater or the Puy de Vasset. To cite this article: D. Miallier et al., C. R. Geoscience 336 (2004).  相似文献   

The δ13C–δ18O variations in marble in the Hida Belt,Japan     

Hironobu Harada  Tatsuki Tsujimori  Keitaro Kunugiza  Katsuyuki Yamashita  Shogo Aoki  Kazumasa Aoki  Hideko Takayanagi  Yasufumi Iryu 《Island Arc》2021,30(1):e12389

Marble has a great potential to understand a history of various geological events occurring during tectonic processes. In order to decode metamorphic–metasomatic records on C–O isotope compositions of marble at mid-crustal conditions, we conducted a C–O–Sr isotope study on upper amphibolite-facies marbles and a carbonate–silicate rock from the Hida Belt, which was once a part of the crustal basement of the East Asian continental margin. Carbon and oxygen isotope analyses of calcite from marbles (Kamioka area) and a carbonate–silicate rock (Wadagawa area) show a large variation of δ¹³C [VPDB] and δ¹⁸O [VSMOW] values (from −4.4 to +4.2 ‰ and +1.6 to +20.8 ‰, respectively). The low δ¹³C values of calcites from the carbonate–silicate rock (from −4.4 to −2.9 ‰) can be explained by decarbonation (CO₂ releasing) reactions; carbon–oxygen isotope modeling suggests that a decrease of δ¹³C strongly depends on the amount of silicate reacting with carbonates. The occurrence of metamorphic clinopyroxene in marbles indicates that all samples have been affected by decarbonation reactions. All δ¹⁸O values of calcites are remarkably lower than the marine-carbonate values. The large δ¹⁸O variation can be explained by the isotope exchange via interactions between marble, external fluids, and/or silicates. Remarkably low δ¹⁸O values of marbles that are lower than mantle value (~+5 ‰) suggest the interaction with meteoric water at a later stage. Sr isotope ratios (⁸⁷Sr/⁸⁶Sr = 0.707255–0.708220) might be close to their protolith values. One zircon associated with wollastonite in a marble thin-section yields a U–Pb age of 222 ± 3 Ma, which represents the timing of the recrystallization of marble, triggered by H₂O-rich fluid infiltration at a relatively high-temperature condition. Our isotope study implies that the upper amphibolite-facies condition, like the Hida Belt, might be appropriate to cause decarbonation reactions which can modify original isotope compositions of marble if carbonates react with silicates.  相似文献   

Duluth Complex apatites: Age reference material for LA–ICP–MS‐based fission‐track dating     

Hideki Iwano  Tohru Danhara  Takashi Yuguchi  Takafumi Hirata  Masatsugu Ogasawara 《地学学报》2019,31(3):247-256

Anorthositic series apatites of the Duluth Complex, Minnesota, USA, have high spontaneous fission‐track densities of up to ~10⁷ cm^–2 and a homogeneous age of ~900 Ma, allowing high‐precision fission‐track dating based on LA–ICP–MS U analysis. Absolute fission‐track dating, track‐length measurement and chemical composition analysis were performed to evaluate a cooling history, which is essential for age reference materials. Preliminary inverse modelling for a sample with a shortened track‐length distribution yielded a monotonic cooling history from ~100°C at 925 Ma. The apatites incur an over‐etching problem when employing the commonly used etching protocol involving 5.5 M HNO₃.  相似文献   

Simulation of the spontaneous growth of a dynamic crack without constraints on the crack tip path   总被引：2，自引：0，他引：2  

Nobuki Kame  & Teruo Yamashita 《Geophysical Journal International》1999,139(2):345-358

The spontaneous growth of a dynamic in-plane shear crack is simulated using a newly developed method of analysis in which no a priori constraint is required for the crack tip path, unlike in other classical studies. We formulate the problem in terms of boundary integral equations; the hypersingularities of the integration kernels are removed by taking the finite parts. Our analysis shows that dynamic crack growth is spontaneously arrested soon after the bending of the crack tips, even in a uniformly stressed medium with homogeneously distributed fracture strengths. This shows that the dynamics of crack growth has a significant effect on forming the non-planar crack shape, and consequently plays an essential role in the arrest of earthquake rupturing.  相似文献   

Progressive changes in lithological association of the Sanbagawa metamorphic complex,Southwest Japan: Relict clinopyroxene and detrital zircon perspectives          下载免费PDF全文

Shunsuke Endo  Kazuhiro Miyazaki  Tohru Danhara  Hideki Iwano  Takafumi Hirata 《Island Arc》2018,27(5)

The main tectono‐stratigraphic unit (Shirataki unit) of the Sanbagawa metamorphic complex in central Shikoku is characterized by abundant mafic schist layers that show the mid‐ocean ridge basalt (MORB) affinity. These MORB‐derived schist layers are absent in a southern (structurally lower) domain within the unit. Instead, sporadic occurrences of small metabasite lenses that contain relict igneous minerals (Ti‐rich augite and kaersutite) indicative of alkali basalt magmatism are newly recognized in the southern domain. Compositions of relict clinopyroxene in metabasalt are useful to identify the tectonic setting and origin of the protolith basalt, and those in each unit of the Sanbagawa metamorphic complex are presented. The metamorphic grade of the Shirataki unit generally increases structurally upwards in the southern side of the highest‐grade zone, and metamorphic zonation is subparallel to lithostratigraphic succession. The protolith assemblage of the Shirataki unit shows a distinct change from the southern low‐grade domain (lower Shirataki subunit) composed of terrigenous sedimentary rocks (mudstone and sandstone) with minor alkali basalt to the northern higher‐grade domain (upper Shirataki subunit) consisting of terrigenous and pelagic sedimentary rocks with abundant MORB. The youngest detrital zircon U–Pb ages (ca 95–90 Ma) suggest that both domains have Late Cretaceous depositional ages at the trench. Progressive peeling of oceanic plate stratigraphy during subduction can account for the observed change of lithological association in the Shirataki unit.  相似文献