1,720,972 research outputs found
Contaminants orgànics persistents i pseudopersistents en medi marí : estudi en biota i en consum humà
Get PDFDuring the last couple of decades the demand for good quality water in sufficient quantity has increased. The administration is now aware that water is not a commercial product; that hydrological management needs to be implemented to promote respect for the environment and a sustainable use of this natural resource. Consequently, directives have been developed to ensure the good status of water regarding quality and quantity. The Water Framework Directive (Directive 2000/60/CE) and the Marine Strategy Framework Directive (Directive 2008/56/CE) set frameworks to protect water and the environments connected to it. They establish requirements for avoiding new emissions of pollutants, reducing the current pollution.
Organic contaminants include a wide range of families. Some are grouped under the name persistent organic pollutants (POPs). Stockholm Convention describes POPs as persistent in the environment, bioaccummulable, with potential for long-range transport and with adverse effects on human health and the environment. By mid 2017, the Stockholm Convention included polybrominated diphenyl ethers (PBDEs) and hexabromocylcododecane (HBCD). There are still emerging organic compounds. Even though they are not persistent, some are considered pseudo-persistent contaminants as they are used in big quantities and they have a biological effect. That makes them always present in the environment and a possible threat. Pyrethroids are an example.
Contaminants reach the sea in wastewater, spills or runoff water, transported in rivers or through atmospheric deposition. Other products can be applied directly on one's body or are deliberatedly introduced in the environment, like pesticides. There is still another way of transport for POPs, which can be transported long distances in the air to colder areas or areas with cold periods, like the Arctic.
The present thesis will focus on the descriptors of the Marine Strategy Framework Directive saying that concentrations of contaminants should be low enough not to produce pollution effects and contaminants in seafood cannot exceed the regulated limits.
The occurrence and behavious of the following compounds is analysed: well known and studied POPs, legacy flame retardants (FRs) (PBDEs and HBCD), along with emerging contaminants, new FRs (dechloranes and three brominated FRs and pseudo-persistent pyrethroid insecticides. FRs are applied to materials to increase their fire resistance. The classic ones are persistent, they are easily released to the environment and can be found in all kind of environmental matrices. Pyrethroids seem ideal because, at first, they were believed not to bioaccumulate. However, they have toxic effects and are used in big quantities.
In this thesis the behaviour in the marine environment of classic flame retardants is compared to emerging flame retardants and pyrethroids. The matrices used in the analyses are marine mammals from the Mediterranean Sea, the Indian Ocean and the Antarctica on one side and seafood on the other. With these impact on both biota and humans will be assessed.
Dechloranes outstood with occurrences similar to PBDEs' and HBCD's, with potential for long-range transport and increasing levels through time. They could be a candidate to be listed in the Stockholm Convention. Brominated emerging flame retardants in general were not detected or non-quantifiable. They must be monitored to see if they remain like this. Finally, the occurrence of pyrethroids, pseudo-persistent contaminants, seemed to be linked to their use. An excessive use might make them as dangerous as POPs. Regarding seafood safety, a PBDE congener might pose a threat, but new factors such as the effects of cooking and the bioaccessibility of ingested contaminants need to be studied to make better risk assessments.Durant l'últim parell de dècades, ha incrementat la demanda d'aigua de bona qualitat en quantitats suficients. Ha crescut la consciència que l'aigua no és un producte comercial, que cal implementar una gestió hidrològica que respecti el medi ambient i que promogui un ús sostenible d'aquest recurs natural. Conseqüentment s'han desenvolupat directives per assegurar el bon estat de l'aigua pel que fa a qualitat i quantitat. La Directiva marc de l'aigua (Directiva 2000/60/CE) i la Directiva marc sobre l'estratègia marina (Directiva 2008/56/CE) estableixen marcs per protegir l'aigua i els ecosistemes que hi estan connectats. Aquestes posen requisits per evitar noves emissions de contaminants i reduir la contaminació actual. Els contaminants orgànics inclouen una àmplia gamma de famílies. Alguns d'ells estan agrupats sota el nom de contaminants orgànics persistents (COP). El Conveni d'Estocolm estableix que els COP persisteixen en el medi, es bioacumulen, es transporten a llargues distàncies i tenen efectes adversos en la salut humana o en el medi ambient. A mitjan 2017, el Conveni d'Estocolm va afegir a la llista els èters difenílics polibromats (PBDE) i l'hexabromociclododecà (HBCD). Dins dels compostos orgànics, encara hi ha compostos emergents. Tot i que no són persistents, alguns es consideren contaminants pseudopersistents perquè s'utilitzen en grans quantitats i tenen un efecte biològic. Això fa que siguin sempre presents al medi i que suposin un risc. Un exemple són els pesticides piretroides. Els contaminants arriben al mar en aigües residuals, vessaments, aigües d'escorriments o transportats per rius o a través de la deposició atmosfèrica. Altres productes es poden aplicar sobre el cos o s'alliberen deliberadament al medi, com els pesticides. Hi ha un altre sistema de transport per als COP, que es poden transportar a llargues distàncies en l'aire cap a àrees fredes o amb períodes freds com ara l'Àrtic. Aquesta tesi se centra en els punts de la Directiva marc sobre l'estratègia marina segons els quals les concentracions de contaminants han de ser prou baixes per no causar efectes de contaminació i els contaminants presents en peix i marisc de consum humà no poden superar els límits regulats. S'analitzen la presència i el comportament de COP coneguts i caracteritzats, retardants de flama (FR) clàssics (PBDE i HBCD), junt amb contaminants emergents, FR nous (declorans i tres FR bromats) i insecticides piretroides pseudopersistents. Els FR s'afegeixen als materials per incrementar-ne la resistència al foc. Els més coneguts són persistents, s'alliberen al medi amb facilitat i es troben en tot tipus de matrius ambientals. Els piretroides semblen ideals perquè, a priori, es creia que no es bioacumulaven. Això no obstant, presenten efectes tòxics i se'n fa un ús abundant. En aquesta tesi es compara el comportament dels FR coneguts amb els emergents i amb els piretroides estudiant-los en el medi marí. Les matrius analitzades són d'una banda mamífers marins del mar Mediterrani, de l'oceà Índic i de l'Antàrtida i de l'altra peixos i marisc de consum humà. Així s'estudiarà l'impacte tant en biota com en humans. Els declorans han destacat amb presències similars als PBDE o a l'HBCD, amb potencial de transport a llarga distància i concentracions creixents amb el temps. Podrien ser un candidat a afegir al Conveni d'Estocolm. Els FR emergents bromats en general no s'han detectat o no s'han pogut quantificar. Caldrà seguir estudiant-los per veure si es mantenen així. Finalment, ha semblat que la presència de piretroides està relacionada amb l'ús que se'n fa, però un ús abundant els podria arribar a fer tan perillosos com els COP. Pel que fa al risc del consum de peix i marisc, un congènere dels PBDE podria suposar un risc, però s'han d'estudiar nous factors, com ara els efectes de cuinar el peix i la bioaccessibilitat dels contaminants ingerits, per millorar les avaluacions de riscs.DOCTORAT EN ENGINYERIA AMBIENTAL (Pla 2012
Catalan names of the new chemical elements
Get PDFEl mes de novembre de l’any passat, la IUPAC publicava els noms anglesos oficials dels darrers quatre elements incorporats a la taula periòdica: nihonium, moscovium, tennessine i oganesson. Gairebé simultàniament, el Consell Supervisor del TERMCAT va iniciar l’estudi d’aquests neologismes per establir-ne la denominació adequada en català. Aquest article presenta les denominacions normalitzades en català, amb els principals arguments terminològics en què es fonamenten: nihoni, moscovi, tennessi i oganessó. S’hi inclou una referència a les propostes denominatives en català que, un cop considerades, es van desestimar.Paraules clau: Consell Supervisor del TERMCAT, normalització terminològica, nous elements químics, química inorgànica, taula periòdica.Last November, the IUPAC published the official names of the four latest elements to be added to the periodic table: nihonium, moscovium, tennessine and oganesson. Almost at the same time, the TERMCAT Supervisory Council started the study of these neologisms to set their appropriate names in Catalan. This article introduces the standardized Catalan denominations with the main terminological arguments that support them: nihoni, moscovi, tennessi and oganessó. Alternative Catalan names that were rejected after consideration are also included.Keywords: TERMCAT Supervisory Council, terminological standardization, new chemical elements, inorganic chemistry, periodic table
Els noms en català dels nous elements químics
Get PDFEl mes de novembre de 2016, la IUPAC publicava els noms anglesos oficials dels darrers quatre elements incorporats a la taula periòdica: nihonium, moscovium, tennessine i oganesson. Gairebé simultàniament, el Consell Supervisor del TERMCAT va iniciar l'estudi d'aquests neologismes per a establir-ne la denominació adequada en català.
Aquest article presenta les denominacions normalitzades en català, amb els principals arguments terminològics en què es fonamenten: nihoni, moscovi, tennessi i oganessó. S'hi inclou una referència a les propostes denominatives en català que, un cop considerades, es van desestimar.Last November, the IUPAC published the official names of the four latest elements to be added to the periodic table: nihonium, moscovium, tennessine and oganesson. Almost at the same time, the TERMCAT Supervisory Council started the study of these neologisms to set their appropriate names in Catalan. This article introduces the standardized Catalan denominations with the main terminological arguments that support them: nihoni, moscovi, tennessi and oganessó. Alternative Catalan names that were rejected after consideration are also included
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
