1,721,015 research outputs found
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
Evasion of Gaseous Elemental Mercury from Forest and Urban Soils Contaminated by Historical and Modern Ore Roasting Processes (Idrija, Slovenia)
Full text linkConsiderable amounts of gaseous elemental mercury (Hg-0) can be released into the atmosphere from Hg-enriched substrates, such as those from former mining areas, posing a potential environmental threat. In this work, Hg-0 fluxes at the soil-air interface under natural vegetation covers were measured in various locations within the Idrija Hg mining area (Slovenia) and its surroundings. Sites were selected in order to compare Hg-0 fluxes from both forest soils heavily impacted by historical ore roasting and urban soils characterised by a different degree of Hg enrichment due to the natural occurrence of Hg in rocks or recent mining and roasting processes. Replicate measurements at each site were conducted using a non-steady state flux chamber coupled with a real-time Hg-0 analyser (Lumex RA-915M). Moreover, topsoil samples (0-2 cm) were analysed for Hg total concentration and speciation. Cinnabar was the predominant Hg form in almost all the sites. Despite Hg-0 being undetectable in soils using thermo-desorption, substantial emissions were observed (70.7-701.8 ng m(-2) h(-1)). Urban soils in a naturally enriched area showed on average the highest Hg-0 fluxes, whereas relatively low emissions were found at the historical roasting site, which is currently forested, despite the significantly high total Hg content in soils (up to 219.0 and 10,400 mg kg(-1), respectively). Overall, our findings confirm that shading by trees or litter may effectively limit the amount of Hg-0 released into the atmosphere even from extremely enriched soils, thus acting as a natural mitigation
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
Gaseous mercury emissions from forest and urban soils heavily impacted by past mining in the Idrija mining district (Slovenia)
No full textThe historical mining and ore roasting activities lasted for about 500 years at Idrija (Slovenia), the second largest mercury (Hg) mine worldwide, have caused a widespread contamination of the surrounding environments through direct losses and discharges of residues and atmospheric depositions (Gosar & Teršič, 2012). Substrate enriched in Hg can release notable amounts of gaseous elemental mercury (GEM) into the atmosphere (Agnan et al., 2016), potentially contributing to widen the spatial distribution of this metal and to
increase the exposure to Hg of inhabitants through inhalation.
This study is focused on the evaluation of GEM fluxes at the soil-air interface within both the urban area of Idrija and its surroundings. Site selection was aimed at comparing emissions from substrates subject to different Hg supplies. The selected urban soils were characterised by different degree of Hg enrichment due to its natural occurrence in underlying bedrock or variable atmospheric depositions related to ore roasting in modern furnaces. In addition, GEM fluxes were measured at an ancient roasting site in the forests surrounding Idrija subject to considerable Hg supplies during ore processing in XVI-XVII centuries. Measurements were performed during the summer season, the most favourable for GEM evasion (Floreani et al., 2023).
A non-steady state flux chamber coupled with a real-time GEM analyser was used to evaluate fluxes from soils with the natural vegetation cover performing replicate measurements at each site. Topsoil Hg content and speciation were also assessed through thermo-desorption technique.
Overall, GEM fluxes observed from undisturbed soils ranged between 70.7 and 702 ng m-2 h-1 with the highest average value obtained for the natural enriched site at Idrija. The spatial variability of fluxes was mainly related to total Hg content in soils. However, a more developed herbaceous vegetation may limit GEM releases at the atmospherically influenced site near the most recent furnace despite the greater availability of Hg bound to organic matter, which is potentially more available for reduction to GEM and evasion. This is especially evident considering the low fluxes observed at the forested ancient roasting site despite the extremely high Hg concentrations in soils (up to 10,400 mg kg-1).
Results from this study highlight that shading by vegetation can significantly limit GEM re-emission to the atmosphere even in extremely contaminated areas. However, a significantly high flux (2466 ng m-2 h-1) was recorded at the ancient roasting site on a bare soil surface under an uprooted tree, suggesting that care should be taken in forest management practices to avoid potential strong re-emission of GEM related to direct exposure of these heavily contaminated soils to solar radiation
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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