Measurements of Rare Earth Element and Other Element Mass Fractions in Environmental Reference Materials (NIST SRM 1646a,NIST SRM 1400, IAEA‐395 and IAEA‐450) by INAA,ICP‐AES and ICP‐MS          下载免费PDF全文

Vu Dong Cao  Raymond Sucgang  Thien Quang Tran  Doanh Van Ho  Naoki Shirai  Mitsuru Ebihara 《Geostandards and Geoanalytical Research》2017,41(2):303-315

INAA, ICP‐AES and ICP‐MS were used to elementally characterise four environmental reference materials – NIST SRM 1646a (Estuarine Sediment), NIST SRM 1400 (Bone Ash), IAEA‐395 (Urban Dust) and IAEA‐450 (Algae). An analytical scheme consisting of the three methods was first applied to NIST SRM 1646a to validate the methodology because it has been extensively analysed and has certified values for many elements. With repeated analyses of NIST SRM 1646a, the accuracy and measurement repeatability of the data obtained were evaluated based on two statistical calculations (zeta‐score and Horwitz ratio) and were observed to be good enough for the analytical scheme to be applied to similar sorts of environmental/geochemical samples. Applying the same approach to NIST SRM 1400, IAEA‐395 and IAEA‐450, enabled mass fractions of 29, 38 and 28 elements to be determined, respectively. Among these results, the data for rare earth elements are of particular interest, not only for IAEA‐450 but also for the other three reference samples. The data for Pr, Gd, Dy, Ho, Er and Tm in NIST SRM 1646a are newly reported in this study. By using small test portions (< 100 mg) for NIST SRM 1646a and IAEA‐395, and recommended minimum amounts for NIST SRM 1400 and IAEA‐450, sample homogeneity was evaluated.  相似文献   

High-resolution terrestrial carbon isotope and planktic foraminiferal records of the Upper Cenomanian to the Lower Campanian in the Northwest Pacific     

Reishi Takashima  Hiroshi Nishi  Toshiro Yamanaka  Keiichi Hayashi  Amane Waseda  Akiko Obuse  Takashige Tomosugi  Naoki Deguchi  Sunao Mochizuki 《Earth and Planetary Science Letters》2010,289(3-4):570-582

Making Upper Cretaceous biostratigraphic correlations between the Northwest Pacific and Tethyan–Atlantic sections have been difficult because of rare frequencies of age-diagnostic macro- and microfossils in the sequences in the Northwest Pacific region. In order to correlate these sections precisely, an integrated planktic foraminiferal and bulk wood carbon-isotope stratigraphy from the upper Cenomanian to the lower Campanian succession (the middle–upper part of the Yezo Group) of Hokkaido, northern Japan is established with an average resolution of 50 k.y. The δ¹³C curves from bulk wood of the Yezo Group and from bulk carbonate of English Chalk show remarkably similar patterns of isotopic fluctuation, allowing the correlation of 22 carbon isotopic events between these sections. This high-resolution correlation greatly improves the previous micro- and macrofossil biostratigraphic schemes in the Northwest Pacific region, and reveals that global events, such as the oxygen depletion at the OAE 2 horizon, the constant decrease in pCO₂ during the Late Cretaceous, and the eustatic sea-level falls in the late middle Turonian, Santonian/Campanian Boundary and early Campanian, are recorded in the Upper Cretaceous sequence of the Northwest Pacific.  相似文献   

How do hydrologic modeling decisions affect the portrayal of climate change impacts?          下载免费PDF全文

Pablo A. Mendoza  Martyn P. Clark  Naoki Mizukami  Ethan D. Gutmann  Jeffrey R. Arnold  Levi D. Brekke  Balaji Rajagopalan 《水文研究》2016,30(7):1071-1095

End users face a range of subjective decisions when evaluating climate change impacts on hydrology, but the importance of these decisions is rarely assessed. In this paper, we evaluate the implications of hydrologic modelling choices on projected changes in the annual water balance, monthly simulated processes, and signature measures (i.e. metrics that quantify characteristics of the hydrologic catchment response) under a future climate scenario. To this end, we compare hydrologic changes computed with four different model structures – whose parameters have been obtained using a common calibration strategy – with hydrologic changes computed with a single model structure and parameter sets from multiple options for different calibration decisions (objective function, local optima, and calibration forcing dataset). Results show that both model structure selection and the parameter estimation strategy affect the direction and magnitude of projected changes in the annual water balance, and that the relative effects of these decisions are basin dependent. The analysis of monthly changes illustrates that parameter estimation strategies can provide similar or larger uncertainties in simulations of some hydrologic processes when compared with uncertainties coming from model choice. We found that the relative effects of modelling decisions on projected changes in catchment behaviour depend on the signature measure analysed. Furthermore, parameter sets with similar performance, but located in different regions of the parameter space, provide very different projections for future catchment behaviour. More generally, the results obtained in this study prompt the need to incorporate parametric uncertainty in multi‐model frameworks to avoid an over‐confident portrayal of climate change impacts. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Structure of the inner core inferred from observations of seismic core modes     

Naoki Suda  Yoshio Fukao 《Geophysical Journal International》1990,103(2):403-413

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Simulated biogeochemical responses to iron enrichments in three high nutrient, low chlorophyll (HNLC) regions   总被引：1，自引：0，他引：1  

Masahiko Fujii  Naoki Yoshie  Yasuhiro Yamanaka  Fei Chai 《Progress in Oceanography》2005,64(2-4):307

To fill temporal gaps in iron-enrichment experimental data and gain further understanding of marine ecosystem responses to iron enrichments, we apply a fifteen-compartment ecosystem model to three iron-enrichment sites, namely SEEDS (the Subarctic Pacific Iron Experiment for Ecosystem Dynamics Study; 48.5°N, 165°E) in the western North Pacific, SOIREE (the Southern Ocean Iron RElease Experiment; 61°S, 140°E) in the Southern Ocean, and IronExII (the second mesoscale iron enrichment experiment; 3.5°S, 104°W) in the Equatorial Pacific. The ecological effects of iron in the model are represented by changing two photosynthetic parameters during the iron-enrichment period. The model results successfully reproduce the observed biogeochemical responses inside and outside the iron patch at each site, such as rapid increases in plankton biomass and biological productivity, and decreases in surface nutrients and pCO₂, inside the patch. However, the modeled timing and magnitude of changes differ among the sites because of differences in both physical environments and plankton species. After the iron enrichment, the diatom productivity is strongly controlled by light at SOIREE and by silicate at IronExII and SEEDS. Light limitation due to self-shading by the phytoplankton is significant during the bloom at all sites. Sensitivity analysis of the model results to duration of the iron enrichment reveals that long-term multiple infusions over more than a week would not be effective at SEEDS because of strong silicate limitation on diatom growth. Sensitivity of the model to water temperature shows that export production is higher at lower temperatures, because of slower recycling of particulate organic carbon. Therefore, the e-ratio (the ratio of export production to primary production) is inversely correlated with temperature, and the relationship can be described with a linear function. Through this study, we conclude that ecosystem modeling is a powerful tool to help design future iron-enrichment experiments and observational plans.  相似文献   

Spatial/temporal variations in zooplankton biomass and ecological characteristics of major species in the southern part of the Japan Sea: a review     

Naoki Iguchi   《Progress in Oceanography》2004,61(2-4):213

During the 1990s many studies on zooplankton in the Japan Sea have been carried out. In this review, I have synthesized the study of horizontal distribution, seasonal and annual variations of zooplankton biomass, and ecological characteristics of major component species in the southern Japan Sea, which area is influenced by the warm Tsushima Current. The zooplankton biomass (annual mean) in the southern Japan Sea was lower than in the subarctic Pacific, including the northern Japan Sea, and similar to biomass levels in Kuroshio waters. Temporal variations in zooplankton biomass showed both seasonal and year-to-year components. Seasonal biomass increases to a maximum in spring with a weak secondary peak in autumn. As for long-term changes, 3–6 year cycles were identified, with the dynamics of the surface warm Tsushima Current and the subsurface cold water playing important roles in determining the yearly zooplankton community structure and biomass. Cold water species in the southern Japan Sea had extensive diel vertical migrations whose range is restricted in summer by the development of a thermocline. Among these species, the herbivores Euphausia pacifica and Metridia pacifica encounter a lower food supply, resulting in lower growth rates. The vertical dispersal of epipelagic carnivorous zooplankton such as Sagitta elegans and Themisto japonica to the deep-sea is probably facilitated by reduced interspecific competition. Their interaction with Japan Sea Proper Water, characterized by near-zero temperatures in the meso- and bathypelagic zones suppresses growth rates of the mesopelagic zooplankton. The lack of micronektonic predators in the mesopelagic zone may allow the persistence of slow growing populations.  相似文献