Intercomparison of Boron Isotope and Concentration Measurements. Part II: Evaluation of Results   总被引：3，自引：1，他引：3  

Roberto Gonfiantini  Sonia Tonarini  Manfred Grning  Alessandra Adorni‐Braccesi  Assad S. Al‐Ammar  Marcus Astner  Sebastien Bchler  Ramon M. Barnes  Randy L. Bassett  Alain Cocherie  Annette Deyhle  Andrea Dini  Giorgio Ferrara  Jrme Gaillardet  Judith Grimm  Catherine Guerrot  Urs Krhenbühl  Graham Layne  Damien Lemarchand  Anette Meixner  D. Jack Northington  Maddalena Pennisi  Eva Reitznerov  Ilia Rodushkin  Naoji Sugiura  Regina Surberg  Sabine Tonn  Michael Wiedenbeck  Samuel Wunderli  Yingkai Xiao  Thomas Zack 《Geostandards and Geoanalytical Research》2003,27(1):41-57

The Istituto di Geoscienze e Georisorse (IGG), on behalf and with the support of the International Atomic Energy Agency (IAEA), prepared eight geological materials (three natural waters and five rocks and minerals), intended for a blind interlaboratory comparison of measurements of boron isotopic composition and concentration. The materials were distributed to twenty seven laboratories - virtually all those performing geochemical boron isotope analyses in the world -which agreed to participate in the intercomparison exercise. Only fifteen laboratories, however, ultimately submitted the isotopic and/or concentration results they obtained on the intercomparison materials. The results demonstrate that interlaboratory reproducibility is not well reflected by the precision values reported by the individual laboratories and this observation holds true for both boron concentration and isotopic composition. The reasons for the discrepancies include fractionations due to the chemical matrix of materials, relative shift of the zero position on the δ¹¹B scale and a lack of well characterized materials for calibrating absolute boron content measurements. The intercomparison materials are now available at the IAEA (solid materials) and IGG (waters) for future distribution.  相似文献   

Orientation of planetary nebulae within the Galaxy     

Romano L. M. Corradi  Regina Aznar  & Antonio Mampaso 《Monthly notices of the Royal Astronomical Society》1998,297(2):617-623

Narrow-band CCD images of 209 axially symmetrical planetary nebulae (PNe) have been examined in order to determine the orientation of their axes within the disc of the Galaxy. The nebulae have been divided into the bipolar (B) and elliptical (E) PNe morphological types, according to the scheme of Corradi &38; Schwarz. In both classes, contrary to the results of Melnick &38; Harwit and Phillips we do not find any strong evidence for non-random orientations of the nebulae in the Galaxy. Compared with previous work in this field, the present study takes advantage of the use of larger and morphologically more homogeneous samples and offers a more rigorous statistical analysis.  相似文献   

Women, Disempowerment and Resistance: An Analysis of Logging and Mining Activities in the Pacific   总被引：1，自引：0，他引：1  

Regina Scheyvens  & Leonard Lagisa 《Singapore journal of tropical geography》1998,19(1):51-70

There are many arguments supporting the need for a reduction of large scale logging and mining activities in Pacific Island countries. In addition to ecological and economic concerns, logging and mining have had significant social impacts, including gendered impacts. Women tend to be excluded from decision-making processes, and they have limited access to royalty payments and business and employment opportunities which emerge. Women also bear a disproportionate share of the responsibility for dealing with the social and environmental mess which accumulates. However, women are not simply passive victims of logging and mining activities, as this discussion of the Solomon Islands and Papua New Guinea will argue. They are often the first to feel dissatisfaction with logging and mining and it is such dissatisfaction which has fuelled civil unrest, from family break-ups to sabotage of machinery to civil war, in some communities. It may thus be useful for companies to more carefully monitor the effects of their activities on women and involve women more actively in decision-making bodies if they wish to avoid such unrest in the future.  相似文献   

Assessing streams in Germany with benthic invertebrates: selection of candidate metrics   总被引：3，自引：0，他引：3  

Daniel Hering  Carolin Meier  Claudia Rawer-Jost  Christian K. Feld  Regina Biss  Armin Zenker  Andrea Sundermann  Susanne Lohse  Jürgen Bhmer 《Limnologica》2004,34(4):398-415

The process of selecting invertebrate-based candidate metrics for the German stream assessment system is described. The aim was to identify metrics indicating degradation types other than organic pollution and acidification (“general degradation”). For 18 out of 24 German stream types a data base of roughly 2,000 benthic invertebrate samples was generated; for each sample 79 metrics were calculated. Data on land use in the catchment were compiled for all sampling sites, together with data on hydromorphology for many sampling sites. Hydromorphological and land use parameters, which describe a clear gradient in the data sets were identified by Non-metric Multidimensional Scaling (NMS). Correlation analyses between land use/hydromorphological parameters and metric results were calculated separately for the individual stream types. Among those metrics best indicating catchment- and hydromorphological degradation in the majority of stream types are: proportion of Ephemeroptera, Plecoptera and Trichoptera; proportion of Plecoptera (mainly suited for mountain streams); number of Plecoptera taxa; proportion of xenosaprobic taxa; proportion of epirhithral preferring taxa. Differences of metric correlations between stream types and between degradation types are discussed, leading to a list of candidate metrics for assessing German streams.  相似文献   

激光剥蚀-等离子体质谱技术及其在地球化学宇宙化学和环境研究中的应用   总被引：1，自引：0，他引：1  

JOCHUM Klaus Peter  STOLL Brigitte  FRIEDRICH Jon M  AMINI Marghaleray  BECKER Stefan  DüCKING Marc  EBEL Denton S  ENZWEILER Jacinta  胡明月  KUZMIN Dmitry  MERTZ KRAUS Regina  MüLLER Werner E G  REGNERY Julia  SOBOLEV Alexander  王晓红  詹秀春 《岩矿测试》2009,28(1):53-68

激光剥蚀-等离子体质谱(LA-ICPMS)已成为地球化学、宇宙化学和环境研究领域元素和同位素原位分析最重要的技术之一。文章介绍了多种类型的质谱仪及其使用的激光器。用途最广的LA-ICPMS仪器之一是单接收器扇形磁场质谱仪,配有Nd:YAG激光剥蚀系统(激光波长分为193 nm和213 nm两种),MPI Mainz实验室使用的就是这套系统,文章对此作一详细介绍。文中阐述了数据优化技术及其多种校正过程;介绍LA-ICPMS在痕量元素和同位素分析领域的一些应用,包括参考物质的研制,Hawaiian玄武岩、Martian陨石、生物骨针和珊瑚虫中痕量元素分析及熔融包裹体和富钙-铝碳质球粒陨石中的铅和锶同位素测量。  相似文献   

Net Ecosystem Metabolism and Nonconservative Fluxes of Organic Matter in a Tropical Mangrove Estuary, Piauí River (NE of Brazil)     

Marcelo F. L. Souza  Viviane R. Gomes  Simone S. Freitas  Regina C. B. Andrade  Bastiaan Knoppers 《Estuaries and Coasts》2009,32(1):111-122

Net ecosystem metabolism (NEM) was measured in the Piauí River estuary, NE Brazil. A mass balance of C, N, and P was used to infer its sources and sinks. Dissolved inorganic carbon (DIC) concentrations and fluxes were measured over a year along this mangrove dominated estuary. DIC concentrations were high in all estuarine sections, particularly at the fluvial end member at the beginning of the rainy season. Carbon dioxide concentrations in the entire estuary were supersaturated throughout the year and highest in the upper estuarine compartment and freshwater, particularly at the rainy season, due to washout effects of carbonaceous soils and different organic anthropogenic effluents. The estuary served as a source of DIC to the atmosphere with an estimated flux of 13 mol CO₂ m^?2 year^?1. Input from the river was 46 mol CO₂ m^?2 year^?1. The metabolism of the system was heterotrophic, but short periods of autotrophy occurred in the lower more marine portions of the estuary. The pelagic system was more or less balanced between auto- and heterotrophy, whereas the benthic and intertidal mangrove region was heterotrophic. Estimated annual NEM yielded a total DIC production in the order of 18 mol CO₂ m^?2 year^?1. The anthropogenic inputs of particulate C, N, and P, dissolved inorganic P (DIP), and DIC were significant. The fluvial loading of particulate organic carbon and dissolved inorganic nitrogen (DIN) was largely retained in two flow regulation and hydroelectric reservoirs, promoting a reduction of C:N and C:P particulate ratios in the estuary. The net nonconservative fluxes obtained by a mass balance approach revealed that the estuary acts as a source of DIP, DIN, and DIC, the latter one being almost equivalent to the losses to the atmosphere. Mangrove forests and tidal mudflats were responsible for most of NEM rates and are the main sites of organic decomposition to sustain net heterotrophy. The main sources for this organic matter are the fluvial and anthropogenic inputs. The mangrove areas are the highest estuarine sources of DIP, DIC, and DIN.  相似文献   

Culture and Development in a Globalizing World: Geographies, Actors, and Paradigms – Edited by Sarah A. Radcliffe     

Regina Scheyvens 《Singapore journal of tropical geography》2008,29(1):101-104

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Study on the Historical Distribution of Metals in Aquatic Sediments     

Wagner José Barreto  Dílson Norio Ishikawa  Andressa Clara Nicolau  Evandro Domingues Magalhães  Fabiana Inoue  Paulo dos Santos Nora  Rodolfo Funfas  Sônia Regina Giancoli Barreto 《洁净——土壤、空气、水》2010,38(7):608-613

In this study, the historical distribution of metals, phosphorous, and sulfur at four different depths in the sediments of different lakes formed in the course of an urban river (in Londrina, Parana State, Brazil) were determined. The transport of metals along the course of the river was observed mainly for Mn, Cr, and Zn. High concentrations of Pb in the Capivara Bay and Cr in the river were attributed to contamination from a battery plant and a tannery, respectively. The concentrations of heavy metals in the deepest layers of the sediments remain high several years after deposition.  相似文献   

Synchronous Scan and Excitation-Emission Matrix Fluorescence Spectroscopy of Water-Soluble Organic Compounds in Atmospheric Aerosols     

Regina M.B.O. Duarte  Casimiro A. Pio  Armando C. Duarte 《Journal of Atmospheric Chemistry》2004,48(2):157-171

Three-dimensional excitation–emission matrix (EEM) fluorescence spectra of water-soluble organic compounds (WSOC) from aerosol samples were measured and compared with those reported in the literature for natural dissolved organic matter. The EEM profiles of the WSOC presented three characteristic excitation/emission (_Exc/_Em) peaks: 240/405 nm, 310/405 nm and 280/340 nm. The fluorescence intensities at _Exc/_Em240/405 nm and _Exc/_Em310/405 nm are located at wavelengths shorter than those reported for aquatic humic substances, indicating a smaller content of both aromatic structures and condensed unsaturated bond systems in the WSOC fraction. The EEM profiles of fractions obtained by the isolation procedure of the WSOC by the XAD resins showed that a fractionation has occurred and the XAD-8 eluate is highly representative of the total WSOC of collected aerosol. Synchronous scan spectra were more detailed than conventional fluorescence emission spectra, appearing more suitable for studying multicomponent samples such as the WSOC from atmospheric aerosols.  相似文献   

Hydrochemical and isotopic characteristics of groundwater in the Ndop plain,northwest Cameroon: resilience to seasonal climatic changes     

Mengnjo Jude Wirmvem  Takeshi Ohba  Justice Yuven Suila  Wilson Yetoh Fantong  Nchemty Oscar Bate  Seigo Ooki  Engome Regina Wotany  Asobo Nkengmatia Elvis Asaah  Samuel Ndonwi Ayonghe  Gregory Tanyileke  Joseph Victor Hell 《Environmental Earth Sciences》2014,72(9):3585-3598

Shallow groundwater (>30 mbgl) is an essential source of drinking water to rural communities in the Ndop plain, northwest Cameroon. As a contribution to water management, the effect of seasonal variation on the groundwater chemistry, hydrochemical controls, drinking quality and recharge were investigated during the peaks of the dry (January) and rainy (September) seasons. Field measurements of physical parameters were preceded by sampling 58 groundwater samples during both seasons for major ions and stable isotope analyses. The groundwater, which was barely acidic (mean pH of 6) and less mineralised (TDS < 272 mg/l), showed no significant seasonal variation in temperature, pH and TDS during the two seasons. The order of cation abundance (meq/l) was Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ and Na⁺ > Mg²⁺ > Ca²⁺ > K⁺ in the dry and rainy seasons, respectively, but that of anions ( \( {\text{HCO}}_{3}^{ - } \)  >  \( {\text{NO}}_{3}^{ - } \)  > Cl^? >  \( {\text{SO}}_{4}^{2 - } \)  > F^?) was similar in both seasons. This suggests a negligible effect of seasonal variations on groundwater chemistry. The groundwater, which was CaMgHCO₃ and NaHCO₃, is chemically evolved rainfall (CaMgSO₄Cl) in the area. Silicate mineral dissolution and cation-exchange were the main controls on groundwater chemistry while there was little anthropogenic influence. The major ions and TDS concentrations classified the water as suitable for human consumption as per WHO guidelines. The narrow cluster of δ¹⁸O and δD of same groundwater from both seasons between the δ¹⁸O and δD values of May–June precipitation along the Ndop Meteoric Water Line indicates meteoric origin, rapid recharge (after precipitation) and timing of recharge between May and June rainfall. Diffuse groundwater recharge mainly occurs at low altitudes (<1,400 m asl) within the plain. Besides major ions and TDS, the similar δ¹⁸O and δD of groundwater from both seasons indicate a consistent groundwater recharge and flow pattern throughout the year and resilience to present day short-term seasonal climatic variations. However, controlled groundwater abstraction is recommended given the increasing demand.  相似文献