1,720,960 research outputs found
Geochemical characterization and rare earth elements anomalies in surface- and groundwaters of the Romagna area (Italy)
No full textHighly industrialized and urbanized areas can be affected by microcontamination due to the inefficiency of wastewater treatment plants to remove micropollutants from effluents, with the consequence of reversing them totally or only partially undegraded in the environment. Gd, one of the rare earth elements (REE) group, can be considered as a tracer of wastewaster effluents contamination. It is commonly used as contrast agent in magnetic resonance imaging and it can be detected in hospital and wastewater discharges. In this study, surface- and groundwater quality of the Romagna area was assessed, with a particular focus on REE content in water. The efficiency of two drinking water treatment plants in removing microcontamination was also evaluated comparing REE concentrations at the entrance and exit of the plants. Chemical analyses on a large set of trace elements, as well as major ion content, were performed to geochemically characterize surface- and groundwaters and to investigate possible relations with REEs. The study revealed water chemistry of both surface- and groundwaters mainly controlled by carbonates and clay minerals contribution. As regards REEs, Gd contamination was detected only in surface waters in the northern part of the study area; in the Lamone river, this contamination was accompanied by the detection of La anomalies, reflecting a contaminated environment. The two drinking water treatment plants showed that common water treatment techniques are often inefficient to remove microcontamination
Distribution and partition of endocrine disrupting compounds in water and sediment: Case study of the Romagna area (North Italy)
No full textThe study aimed to assess the occurrence and partitioning of estrogens (ß-estradiol, E2; estrone, E1; 17α-ethinylestradiol, EE2), phenolic compounds (nonylphenol, NP; octylphenol, OP; bisphenol A, BPA) and perfluorinated compounds (perfluorooctanoic acid, PFOA; perfluorooctane sulfonate, PFOS) in waters and sediments of the main rivers and the coastal lagoon of Pialassa Baiona, in the north-eastern part of Italy. Overall, water samples showed a wide distribution of the three classes of compounds in the study area, with the exception of estrogens which recorded only some local detections, at concentrations <10 ng/L. Sediments were found to be affected only by contamination of phenolic chemicals, namely BPA and NP, whereas perfluorinated compounds were almost undetected (<LOQ) in all sampling stations. Estrogens displayed only some local measurements in sediments, in accordance with water results. BPA and NP in sediments were highly correlated with organic carbon content and were dependent on the grain size of sediments. The greatest partition coefficients were registered in the coastal lagoon, proving that salinity enhances phenolic adsorption onto sediments. Globally, based on estrogenicity data taken from literature, the current environmental concentrations of the different chemicals in the study area are not likely to cause adverse estrogenic effects on the aquatic biota
Occurrence and distribution of six selected endocrine disrupting compounds in surface- and groundwaters of the Romagna area (North Italy)
No full textEndocrine disrupting compounds (EDCs) are a wide group of contaminants of emerging concern known to be harmful for organisms. The aim of the study was to assess the occurrence and distribution of six EDCs (estroneâE1, Ã-estradiolâE2, 17α-ethinylestradiolâEE2, bisphenol AâBPA, perfluooctanoic acidâPFOA, perfluorooctane sulfonateâPFOS) in the Apenninic rivers and groundwaters of the Romagna area (North of Italy). Groundwaters were unaffected by EDC contamination, while all classes of compounds were detected at concentrations above the method quantification limit (MQL) in the majority of the river bodies. In detail, PFOA and PFOS concentrations varied between <MQL and 17.7 ng/l (PFOA) and between <MQL and 5.5 ng/l (PFOS), and their occurrence in the aquatic compartment was related to the discharge of wastewater treatment plant effluents. Concerning estrogens, EE2 was below the MQL in all samples, whereas E1 and E2 reached concentrations up to 39.7 ng/l (E2) and 28 ng/l (E1) in surface waters. The highest estrogen values were registered in those areas where livestock and farming are the main activities, indicating a close relation between these activities and estrogen release into the aquatic compartment. BPA (<MQLâ171.3 ng/l) distribution in river waters did not show any correlation with a specific anthropic activity; a mixture of sources of contamination (e.g., industries of food packaging and plastic production) is rather responsible for its detection in river bodies. Overall, the northern part of the Romagna area showed a higher contamination by EDCs, in contrast with the southern part, which was almost unaffected by this kind of microcontamination
Sediment quality assessment in a coastal lagoon (Ravenna, NE Italy) based on SEM-AVS and sequential extraction procedure
Full text linkSediments fromthe Pialassa Piomboni coastal lagoon (NE Italy) were studied to assess the degree of contamination and ecological risk related to trace metals by combining a geochemical characterization of bulk sediments with the assessment of the bioavailable forms of trace metals. With this purpose, sediment contamination (Cd, Cu, Hg, Ni, Pb, and Zn) was assessed by Enrichment Factors (EFs), and potential bioavailability by the Simultaneously Extracted Metals and Acid Volatile Sulfides (SEM-AVS) approach (Cd, Cu, Ni, Pb, and Zn), and by Sequential Extraction Procedure (Co, Cr, Cu, Ni, Pb, and Zn). On average, Cr and Ni exhibited no contamination (EF ≤1.5), and a predominance in the residual fraction of the sediment, indicating natural origin for these metals. Cu, Pb and Zn displayed a local contamination, which resulted in a higher proportion of Cu bound to the reducible and oxidizable fractions (~30% and ~40% as median, respectively), and Pb mostly associated with the reducible phase (~60% asmedian). Hence, Cu and Pb could bemobilized when environmental conditions become reducing or oxidizing. Zn resulted mainly partitioned into the reducible and residual fractions (~50% as median, in both fractions). The Risk Assessment Code (RAC) indicated that approximately 30% of samples had N10% of total Zn weakly bound to the sediment, suggesting a medium risk of exposure for aquatic organisms. RAC results were consistent with theΣSEM-AVS findings, pointing to possible adverse effects for aquatic biota in ~30% of samples, with Zn mostly accounting for the totalmetal bioavailability. Hg showed a moderate to very severe enrichment, indicating that a substantial amount of this metal derives from anthropogenic sources and may pose adverse effects on the aquatic biota of the Pialassa Piomboni lagoon
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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