1,721,011 research outputs found
Mercury contamination in Marano Lagoon (Northern Adriatic sea, Italy): source identification by analyses of Hg phases
No full textTotal Hg concentrations and Hg speciation were determined in bottom sediments of Marano lagoon to investigate the consequences of Hg phases on Wsh farms and shellWsh cultivation areas. Mercury phases were separated into cinnabar
(HgS) and non-cinnabar compounds, via a thermo-desorption technique, in surface and core sediments; both of which had been contaminated by industrial wastes and mining activity residues. The former are due to an industrial complex, which has been producing cellulose, chlor-alkali and textile artiWcial Wbres since 1940. Processing and seepage wastewaters, which were historically discharged into the Aussa-Corno river system and therefore into the lagoon, have been signiWcantly reduced since 1984 due to the construction of wastewater treatment facilities. The second source is the Isonzo River, which has been the largest contributor of Hg into the northern Adriatic Sea since the 16th century due to Hg mining at the Idrija mine (western Slovenia). Red cinnabar (HgS) derived from the mining area is mostly stable and insoluble under current environmental conditions. In contrast, organically bound Hg, such as Hg bound to humic acids,
has the potential to be transformed into bioavailable Hg compounds (for example, methylmercury). The presence of the
two Hg forms permitted each Hg source to be quantiWed. It also allowed the areas with the highest risk of Hg contamination from Hg-rich sediment to be identiWed; thus potentially avoiding the transfer of Hg from the sediment into the water column and eventually into living biota. The results show that Hg Enrichment Factors in bottom sediments exceed values of 10 and cinnabar dominates the central sector near the main tidal channel where tidal Xux is more eVective. Non-cinnabar compounds were found to be enriched in Wne grained material and organic matter. In fact, up to 98% of total Hg at the Aussa-Corno river mouth and in the inner margin of the basin occurred in an organic form. This evidence, combined with the high contents of total Hg (4.1–6.6 g g¡1 and EF >10) measured in surface sediments, suggest that Hg in Marano lagoon is involved in biogeochemical transformations (e.g., methylation)
Mercury speciation in sediments affected by dumped mining residues in the drainage area of the Idrija mercury mine
No full textMercury (Hg) concentrations and Hg phases were investigated in contaminated sediments and flooded soils in the drainage area of the Idrija Hg mine, Slovenia. The main aim of this study was the analytical separation and quantification of cinnabar (HgS) and noncinnabar Hg compounds in sediments contaminated by mining residues. Separation of Hg phases was performed by means of a solidphase-Hg-thermo-desorption technique complemented by
selective extraction of organically bound Hg. Speciation measurements indicate the occurrence of two major Hg
forms: cinnabar the primary ore and an unspecified group
of matrix-bound, noncinnabar Hg compounds. The results show that Hg concentrations and dispersion of the two Hg phases within the river system depend on the distribution of different sediment grain size fractions. Accumulation of cinnabar predominately occurs in coarse grained river sediments, where it constitutes on average more than 80% of total Hg (up to 1000 mg/kg) in present- and past day sediments. In contrast noncinnabar Hg was
found to be enriched in areas where fine grained material was deposited reaching up to 40% of Hgtot (1-60 mg/kg) in flooded soils and up to 55% (<1-18 mg/kg) in sediments of the Gulf of Trieste
MERCURY PHASES IN MARANO LAGOON (NORTHERN ADRIATIC SEA, ITALY): A TOOL TO IDENTIFY DIFFERENT SOURCES OF HG POLLUTION.
No full textDISTRIBUTION, PARTITIONING AND GEOCHRONOLOGY OF HG IN COASTAL SEDIMENTS OF THE GULF OF TRIESTE.
No full text
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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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