1,720,986 research outputs found
Combined preparative and analytical use of normal-phase and reversed- phase high-performance liquid chromatography for the determination of aliphatic and polycyclic aromatic hydrocarbons in sediments of the Adriatic sea
No full textHigh-performance liquid chromatography (HPLC) has been used for the preparative separation of environmentally relevant aliphatic and polycyclic aromatic hydrocarbons (PAHs), and for quantifying PAHs. Normal-phase HPLC was employed as a fractionation step, whereas the quantitative determination of the PAHs was accomplished by using reversed-phase HPLC. In both cases, GC and GC/MS were used as confirmatory techniques. The concentrations of twelve unsubstituted PAHs in sixteen surface and deeper sediments, taken from the northern and central Adriatic Sea, are reported, together with an evaluation of their dependence upon the percentages of fine material and total organic carbon. © 1986
Radiometric dating and pollutant profiles in a sediment core from the lagoon of Venice
No full textThe super(210)Pb radioactive dating technique on two cores from the northern part of the Lagoon of Venice gives an average sedimentation rate of 0.7 cm/year. This is used to date the vertical profiles of member of DDT, Hg, Cd, Pb, Cr, Cu, Ni, Co, Zn and Fe concentrations. A maximum member of DDT concentration is found at a depth of 10 cm, corresponding to about 1955, in accordance with the time of the largest use of this pesticide in the area drained by the Dese river. Due to antropogenic origin the concentrations of heavy metals in the upper sediment layers are 1.3-12.7 times higher than those in the lower ones. The average concenttrations of these elements in the layers below 80 cm are tentatively proposed as natural background concentrations for the Lagoon of Venice
Polychlorinated biphenyl pollution caused by resuspension of surface sediments in the lagoon of Venice
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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
DDT and PCBs in sediments of the Venice gulf
No full textThe concentrations of DDT and PCBs in surface sediments collected in the Gulf of Venice are reported. The contribution of the lagoon and of the rivers to sea sediment contamination is discussed. Fresh waters reaching the sea through the lagoon or directly from rivers are responsible for relatively high ?DDT concentrations. The Porto Marghera industrial zone located in the inner border of the lagoon is probably the main PCB source. Two transport mechanisms have been identified: mobilization of suspended solids by tidal movements and direct dumping of industrial tailing and/or dredged materials from the lagoon canals. © 1983 Taylor & Francis Group, LLC
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The role of alkaline phosphatase in the sediments of the Venice lagoon on nutrient regeneration
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