1,721,066 research outputs found
SOLUBLE/INSOLUBLE SPECIATION OF LIGHT ELEMENTS IN POLAR ICE AS MEASURED BY PIXE AND SEM-EDAX
No full textTHE SPECIATION OF LIGHT ELEMENTS IN SOLUBLE/INSOLUBLE SAMPLES FROM POLAR ICE IS DETERMINED BY PIXE AND SEM-EDAX MEASUREMENT
PALEOCLIMATIC STUDY OF ATMOSPHERIC AEROSOLS IN ICE CORE
No full textATMOSPHERIC AEROSOL COMPOSITION IS DETERMINED FROM PIXE ANALYSIS OF ICE CORE SAMPLES TO SUPPORT PALEOCLIMATIC STUD
Coupling PIXE and SEM/EDAX for characterizing atmospheric aerosols in ice-cores
No full textThe atmospheric aerosol plays a key role in controlling the Earth's climatic system. This climatic forcing is related to its dimension and chemical composition and therefore, understanding temporal and spatial fluctuations related to changing environmental conditions is a key step in assessing future climatic change. The atmosphere's chemical constituents are deposited onto polar ice sheets, and conserved by accumulation of snow layers. Drillings in Greenland and Antarctica have provided long-term records of atmospheric constituents spanning the last 150 000 years. Within the framework of the Greenland Ice Core Project (GRIP), we have developed a methodology coupling PIXE to SEM-EDAX analysis for the characterization of the aerosols deposited in polar precipitation. In this paper, we present initial results on soluble/insoluble speciation for both Antarctic and Greenland samples. This study provides new information in the interpretation of ice core paleo-environmental records
Elemental and mineral characterisation of coastal antarctic aerosols in snow using PIXE and SEM-EDAX
No full textThe chemical constituents of snow from a 3 m pit sampled at a coastal Antarctic site were characterised by means of PIXE and SEM-EDAX. Oxygen isotope dating revealed that the pit spanned an 8-year period. from 1986 to 1994. Concentrations measured by PIXE ranged from less than 1 ng g(-1) of H2O for Cu, and Zn to several tens of ng g(-1) for Si, S and Cl. The major elements found were Si, S, Al, and Na, which contributed more than 75% of the element loading. Snow layers with elevated Cl concentration were regularly found along the pit. The mineralogy of the insoluble particles determined by SEM-EDAX analyses showed that quartz, plagioclase and clays were the prevalent minerals. The proportion of each element in the insoluble phase was comparable with that previously found in similar studies. (C) 1999 Elsevier Science B.V. All rights reserved
TRACE ELEMENTS IN POLAR ICE. INVESTIGATION OF THEIR PAST VARIATION IN THE ATMOSPHERE
No full textThe past variation of trace element concentration in atmosphere is studied by PIXE analysis of polar ice samples
DEVELOPMENTS IN ENVIRONMENTAL RESEARCH OF FISAMB MO PIXE GROUP
No full textTHE DEVELOPMENTS IN ENVIRONMENTAL RESEARCH ACTIVITY AT LNL OF FISAMB MO PIXE GROUP ARE PRESENTE
Procedures of target preparation to improve PIXE efficiency in environmental research
No full textThe capability of the PIXE technique to investigate trace elements in the environment (non-living phases) can be improved by suitable target preparation procedures. This work describes the methodologies performed to apply PIXE in the study of a coastal lagoon ecosystem, with fresh and sea water, surface bottom sediment and pore water analysis, and to approach glaciochemical research, with analysis of atmospheric aerosols deposited in firn and ice
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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