1,721,026 research outputs found
Effecy of parathion-methyl on Amazonian fish and freshwater invertebrates: A comparison of sensivity with temperate data
No full textParathion-methyl is an organophosphorous insecticide that is widely used in agricultural production sites in the Amazon. The use of this pesticide might pose a potential risk for the biodiversity and abundance of fish and invertebrate species inhabiting aquatic ecosystems adjacent to the agricultural fields. Due to a lack of toxicity data for Amazonian species, safe environmental concentrations used to predict the ecological risks of parathion-methyl in the Amazon are based on tests performed with temperate species, although it is unknown whether the sensitivity of temperate species is representative for those of Amazonian endemic species. To address this issue, the acute toxic effect (LC50–96 h) of parathion-methyl was assessed on seven fish and five freshwater invertebrate species endemic to the Amazon. These data were used to compare their pesticide sensitivity with toxicity data for temperate species collected from the literature. The interspecies sensitivity was compared using the Species Sensitivity Distribution (SSD) concept. The results of this study suggest that Amazonian species are no more, or less, sensitive to parathion-methyl than their temperate counterparts, with LC50 values ranging from 2900 to 7270 µg/L for fish and from 0.3 to 319 µg/L for freshwater arthropods. Consequently, this evaluation supports the initial use of toxicity data of temperate fish and freshwater invertebrate species for assessing the effects of parathion-methyl on Amazonian freshwater ecosystems
Contrasting sensitivities to toxicants of the freshwater amphipods Gammarus pulex and G. fossarum
No full textAmphipods are an important component of freshwater ecosystems. They are very often used in ecotoxicology, particularly the freshwater amphipod Gammarus pulex. However, there is scarce information on the sensitivity to toxicants of other species within the genus Gammarus. The present study aims to: (1) to compare sensitivities to ivermectin and cadmium between two species of freshwater amphipods (G. pulex and G. fossarum); (2) to compare sensitivities to these toxicants between juveniles and adults within each species; and (3) to assess whether the sensitivity to toxicants of these co-generic species is related with the wideness of their natural distribution area. Eight independent short-term bioassays (96 h) were conducted to assess sensitivity for ivermectin and cadmium for juvenile and adult life stages for each species. The LC50 (mortality) and EC50 (mortality plus immobility) were calculated to 48 and 96 h of continuous exposure. Our results showed that G. pulex was less tolerant to ivermectin than G. fossarum, the reverse being true for cadmium. In general, juveniles of both species were less tolerant to cadmium than adults. In the case of ivermectin, only for G. fossarum EC50 values were different between life stages. These results suggest that the risk assessment of toxicants to freshwater amphipods should include bioassays with the most sensitive species and life stag
Leidraad voor het afleiden van milieurisicogrenzen
No full textReplaces RIVM reports 719102018, 950011003 and
601506001Het rapport is een update van voorgaande gidsdocumenten voor het afleiden van milieurisicogrenzen in Nederland. De herziene methode voor het afleiden van deze grenzen voor water, grondwater, bodem, sediment en lucht en hun onderlinge harmonisatie wordt gepresenteerd. Het betreft de milieurisicogrenzen 'Serious Risk Concentration' voor het ecosysteem (SRC-ECO), het Maximum Toelaatbaar Risico (MTR) en het Verwaarloosbaar Risico (VR).This report is an update of previous guidance documents for deriving environmental risk limits in the Netherlands. The updated methodology to derive risk limits for water, groundwater, soil, sediment and air and their harmonisation is presented. The document covers the derivation of the Serious Risk Concentration (SRC), the Maximum Permissible Concentration (MPC) and the Negligible Concentration (NC).DGM-SA
Evaluation of mixture toxicity in deriving environmental risk limits
No full textIn de normstelling wordt voor bepaalde groepen verbindingen rekening gehouden met de totale toxiciteit van een mengsel van stoffen in het milieu. De huidige concepten om hier normen voor af te leiden zijn geevalueerd en getoetst aan de huidige praktijk. Het rapport bevat aanbevelingen om op een consistente manier om te gaan met mengseltoxiciteit in de normstelling.Toxicity of mixtures can be taken into account when deriving environmental risk limits. Current concepts for deriving risk limits for mixtures of toxic substances are evaluated. Recommendations are given for a consistent use of mixture toxicity theory in deriving risk limits.VROM-DG
Evaluation of mixture toxicity in deriving environmental risk limits
No full textToxicity of mixtures can be taken into account when deriving environmental risk limits. Current concepts for deriving risk limits for mixtures of toxic substances are evaluated. Recommendations are given for a consistent use of mixture toxicity theory in deriving risk limits.In de normstelling wordt voor bepaalde groepen verbindingen rekening gehouden met de totale toxiciteit van een mengsel van stoffen in het milieu. De huidige concepten om hier normen voor af te leiden zijn geevalueerd en getoetst aan de huidige praktijk. Het rapport bevat aanbevelingen om op een consistente manier om te gaan met mengseltoxiciteit in de normstelling
Leidraad voor het afleiden van milieurisicogrenzen
No full textThis report is an update of previous guidance documents for deriving environmental risk limits in the Netherlands. The updated methodology to derive risk limits for water, groundwater, soil, sediment and air and their harmonisation is presented. The document covers the derivation of the Serious Risk Concentration (SRC), the Maximum Permissible Concentration (MPC) and the Negligible Concentration (NC).Het rapport is een update van voorgaande gidsdocumenten voor het afleiden van milieurisicogrenzen in Nederland. De herziene methode voor het afleiden van deze grenzen voor water, grondwater, bodem, sediment en lucht en hun onderlinge harmonisatie wordt gepresenteerd. Het betreft de milieurisicogrenzen 'Serious Risk Concentration' voor het ecosysteem (SRC-ECO), het Maximum Toelaatbaar Risico (MTR) en het Verwaarloosbaar Risico (VR)
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
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