1,721,005 research outputs found
Comparison of microplastic type, size, and composition in atmospheric and foliage samples in an urban scenario
Get PDFThe rising trend of plastic production in last years and the inadequate disposal of related waste has raised concerns regarding microplastic-related environmental issues. Microplastic particles disperse by means of transport and deposition processes to different ecosystems and enter food chains. In this paper, atmospheric deposition and foliage samples of two species (i.e., Hedera helix and Photinia glabra) were collected and analysed for the quantity and identity of microplastics (MPs). A preliminary methodology to treat foliage samples and subsequently identify MPs using a quantum cascade laser IR spectrophotometer is presented. The treatment of airborne samples involved filtration, mild digestion, concentration, and transfer onto reflective slides whereas that for foliage involved washing, concentration, and transference of putative MPs onto reflective slides. Fibers and fragments were differentiated according to their physical features (size, width, height, etc.) and calculating derived characteristics (namely, circularity and solidity). The preliminary results obtained suggest a good agreement between atmospheric-deposited and foliage-retained MPs, showing the capability of leaves to act as passive samplers for environmental monitoring
Qualidade do ar ambiente em áreas classificadas de Portugal Continental
Get PDFDissertação de Mestrado em Engenharia do AmbienteA qualidade do ar ambiente em áreas classificadas é um tema para o qual não existe muita informação. O presente trabalho pretende contribuir para o aumento do conhecimento sobre a qualidade do ar em áreas protegidas de Portugal Continental. Para atingir este objetivo, identificaram-se e caracterizaram-se as estações rurais de fundo pertencentes à rede nacional de monitorização da qualidade do ar de Portugal Continental, bem como as áreas classificadas localizadas na sua área de representatividade (de 1000 km2 a 10 000 km2). Compilaram-se os valores das concentrações de ozono troposférico (O3) e partículas em suspensão (PM10) medidos nas treze estações de monitorização selecionadas e disponibilizados pela Agência Portuguesa do Ambiente, I.P., para o período de 2005 até 2019 (período anterior à crise pandémica COVID-19). Recorreu-se à utilização do programa R Studio, do pacote “openair”, para o tratamento dos dados. Verificou-se a taxa de recolha dos dados, bem como o cumprimento da conformidade para os poluentes em estudo, de acordo com a legislação em vigor. No que diz respeito ao O3, durante um decénio (2005-2015), os critérios de validação para a agregação de dados e para o cálculo dos parâmetros estatísticos, de maneira geral, foram cumpridos em todas as estações em análise, permitindo assim inferir sobre a qualidade do ar ambiente nas áreas classificadas influenciadas pelas concentrações medidas nestas estações. Constatou-se que no Parque Natural do Alvão, na estação Douro Norte, ocorreram um total de 743 excedências ao limiar de informação para o O3 (180 μg/m3 em uma hora), no período em estudo, 400 das quais foram registadas em 2005. Foi também nesta estação que se verificou, no dia 4 de agosto de 2018, às 15 horas, o valor horário máximo medido: 410 μg/m3. Importa salientar que ocorreram eventos de três horas consecutivas de excedência ao limiar de alerta para o O3 (240 μg/m3 em uma hora), tanto na estação de monitorização Douro Norte (em 2005 e 2010) como na de Monte-Velho (em agosto de 2018) implicando, não só a divulgação ao público, como também o estabelecer planos de ação de curto prazo (aplicação do artigo 29.º, Decreto-Lei nº 102/2010 de 23 de setembro, na sua atual redação). A estação de Ervedeira apresentou o maior número de excedências ao valor limite diário de PM10 (50 μg/m3), tendo também registado o valor máximo diário médio mais elevado deste poluente, no período em análise: 500,33 μg/m3 (em 2017). Concluiu-se ainda que a maioria das concentrações elevadas de PM10 no ar ambiente é detetada em anos em que ocorreram grandes e numerosos incêndios florestais (2005 e 2017). As áreas classificadas sob a influências das concentrações medidas nas estações rurais de fundo da zona interior sul do país (Terena e Cerro) são as que apresentam melhor qualidade do ar, nos 15 anos em análise. Uma maior cobertura espacial da rede de monitorização e/ou a execução de campanhas de medição periódicas, abrangendo as áreas classificadas de Portugal Continental, permitiria uma caracterização mais completa e representativa da qualidade do ar ambiente nestas áreas.Ambient air quality in classified areas is an understudied topic. The present work aims to contribute to the increase of knowledge about air quality in protected areas of mainland Portugal. To achieve this goal, the rural background stations and respective classified areas located in their representative area (from 1000 km2 to 10000 km2), belonging to the national air quality monitoring network of Mainland Portugal, were identified and characterized. The concentration values of tropospheric ozone (O3) and particulate matter (PM10), measured by the 13 monitoring stations and then selected and made available by the Portuguese Environment Agency, I.P., were compiled for the period between 2005 and 2019 (before the covid-19 pandemic crisis). The openair R package was used to process the data. The rate of data collection as well as compliance with the pollutants under study were verified in accordance with the legislation in force. Regarding O3, during a 10-year period (2005-2015), the validation criteria for data aggregation and calculation of statistical parameters were generally met in all stations under analysis, thus allowing to infer about the quality of ambient air in the classified areas. It was found that in the Alvão Natural Park, in the Douro Norte station, there was a total of 743 exceptions to the information threshold for O3 (180 μg/m3 in one hour), out of which 400 were recorded in 2005. It was also in this station that, on August 4th, 2018, at 3 pm, the highest concentration value was registered: 410 μg/m3. It should be noted that there were events of 3 consecutive hours in which the alert threshold for O3 (240 μg/m3 in one hour) was exceeded. These events happened in Douro Norte (in 2005 and 2010) and in Monte-Velho (in August 2018) and implied not only public disclosure, but also established short-term action plans (application of Article 29, Decree-Law No. 102/2010 of September 23, in its current wording). The Ervedeira station registered the highest number of exceeds to the daily limit value of PM10 (50 μg/m3), having also recorded the highest average daily maximum value of this pollutant: 500.33 μg/m3 (in 2017). It was also concluded that most high concentrations of PM10 in ambient air are found in years in which large and numerous forest fires occurred (2005 and 2017). The protected areas measured by the rural stations of the southern interior of the country (Terena and Cerro) were the ones with the best air quality during the 15 years under analysis. Greater spatial coverage of the monitoring network and/or the execution of periodic measurement campaigns, covering the classified areas of mainland Portugal, would allow for a more complete and representative characterization of ambient air quality in these areas
Matrix solid phase dispersion method for determination of polycyclic aromatic hydrocarbons in moss
No full textIn this work a matrix solid-phase dispersion extraction method, followed by programmed temperature vaporization-gas chromatography-tandem mass spectrometry determination is proposed for the analysis of polycyclic aromatic hydrocarbons (PAHs) in moss samples. A devitalized, cultivated Sphagnum palustre L. moss clone obtained from the "Mossclone" EU-FP7 Project was used for the optimization and validation of the proposed method. Good trueness (84-116%), precision (intermediate precision lower than 11%) and sensitivity (quantitation limits lower than 1.7ngg(-1)) were obtained. The proposed method was compared with other procedures applied for this complex matrix, achieving a considerable reduction of sample amount, solvent volume and time consumption. The procedure was successfully tested for the analysis of PAHs in exposed moss clone samples for the monitoring of air pollution. Finally, the method was also tested for its suitability in the analysis of PAHs in other moss species as well as a lichen species
Color, origen botánico y composición del polen apícola
Get PDFEl polen es conocido por el hombre desde la antigüedad como alimento potencial (SAENZ, 1978). Por su contenido en proteínas, hidratos de carbono, lípidos, minerales y vitaminas, representa la fuente insustituible de la alimentación de las larvas y abejas jóvenes, siendo indispensable para su crecimiento. Esta interesante composición permite. asegurar su uso en la alimentación humana ya que además de lo mencionado anteriormente posee 20 de los 22 aminoácidos de nuestras proteínas (PERIS, 1984). En la actualidad existe una tendencia generalizada hacia el uso de productos naturales, por lo que el polen es cada vez más apreciado con objeto de paliar las carencias de nuestra alimentación actual. Este producto no se menciona en el Código Alimentario Español (1967) citándose desde 1976 dentro de la Reglamentación Técnico Sanitaria sobre preparados alimenticios para regímenes dietéticos y jo especiales (BOE, 1976). Figura registrado, por una parte como polen de flores en productos de parafarmacia en el apartado de regímenes tradicionales y por otra, como especialidad farmacéutica (desde 1987) dentro de los urológicos en forma de comprimidos, conteniendo las fracciones oleosoluble e hidrosoluble del polen
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
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