1,721,104 research outputs found
Historical accumulation of mercury from mining and industrial activities in the Marano & Grado Lagoon (northern Adriatic sea)
No full text7th International SedNet Conference on 6-9 April 2011, Venice, Italy, Book of Abstrac
Historical flux of mercury associated with mining and industrial sources in the Marano and Grado Lagoon (northern Adriatic Sea)
No full textThe “MIRACLE” Project was established in order to assess the feasibility of clam farming and high levels of sediment mercury (Hg) contamination coexisting in the Marano and Grado Lagoon, Italy. This lagoon has been subjected to Hg input from both industrial waste (chlor-alkali plant) and long-term mining activity (Idrija mine, NW Slovenia). One of the subtasks of the “MIRACLE” Project was to determine the historical evolution of Hg accumulation in the lagoon’s bottom sediments. Thirteen 1-m deep sediment cores were collected from the subtidal and intertidal zones, plus one in a saltmarsh, all of which were then analyzed for total Hg content and several physicochemical parameters. Sedimentation rate assessments were performed by measuring short-lived radionuclides (excess 210Pb and 137Cs). For most of the analyzed cores, natural background levels of Hg were observed at depths of 50 e 100 cm. In the eastern area, Hg contamination was found to be at its maximum level at the core top (up to 12 mg g-1) as a consequence of the long-term mining activity. The vertical distribution of Hg was related to the influence of the single-point contamination sources, whereas the grain-size variability or organic matter content seemed not to affect it. In the western area, Hg content at the surface was found not to
exceed 7 mg g1 and contamination was recorded only in the first 20e30 cm. Geochronological measurements showed that the depositional flux of Hg was influenced by anthropogenic inputs after 1800, when mining activity was more intense. After 1950, Hg in the surface sediment, most remarkable in the central-western sector, seemed to also be affected by the discharge of the Aussa River, which delivers Hg from the chlor-alkali plant. In 1996, Hg mining at Idrija ceased, however the core profiles did
not show any subsequent decreasing trend in terms of Hg flux, which implies the system retaining some “memory” of contamination. Thus, in the short term, a decrease in Hg inputs into the nearby Gulf of Trieste and the lagoon seems unlikely. A preliminary rounded-down gross estimate of total Hg “trapped”
in the lagoon’s sediments amounted to 251 t. Such a quantity, along with the complexity of the lagoon ecosystem, suggests that an in toto reclamation of the sediments at the lagoon scale is unfeasible, both economically and environmentally
Living and dead benthic foraminiferal distribution in two areas of the Ross Sea (Antarctica)
No full textWe investigated the living (stained) and dead benthic foraminiferal assemblages collected in surface sediment samples (0–1 cm) from two different areas (JOIDES Basin and Mawson Bank) of the Ross Sea (Antarctica). Samples were collected during the BEDROSE oceanographic cruise from January to February 2017. Four living and dead benthic foraminiferal fauna assemblages have been distinguished based on cluster analysis. The differences observed in the living and dead foraminiferal content from the two investigated areas are the result of taphonomic processes induced by the different oceanographic settings and environmental conditions. In the JOIDES Basin, agglutinated taxa Rhabdamminella cylindrica, Lagenammina difflugiformis, Adercotryma glomeratum, Recurvoides contortus, Reophax subfusiformis with high percentages of Trochammina group and Reophax spiculifer associated with the calcareous species Nonionella bradii and Astrononion echolsi characterize the living assemblages. The comparison between living and dead benthic foraminifera reveals considerable similarities in terms of the presence/absence of agglutinated species and differences in relative abundance of calcareous taxa. However, the major influencing factor in foraminiferal preservation appears to be the carbonate dissolution. Results from Mawson Bank show an almost exclusive presence of calcareous taxa with high percentages of Globocassidulina group in both living and dead assemblages. The dead fauna assemblage differs from the corresponding living assemblage by being more diverse documenting high-energy current influence on marine sedimentation. Graphic abstract[Figure not available: see fulltext.]
Mesoscale variability of the carbonate system in the Ross Sea (Antarctica) during the 2014 summer season
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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
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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