1,721,096 research outputs found
Environmental exposure assessment
No full textEnvironmental exposure is usually assessed by evaluating the concentration of a specific chemical in the main environmental media (air, soil, water, sediment) and in biota as food source for other organisms (predators) by secondary poisoning. The study of exposure is complicated by the complexity of the many ecosystems to protect and the high number of chemicals that can be found in the environment. Exposure in the environment can be evaluated using monitoring data or predictive approaches, such as environmental fate models. When more details on organism uptake and levels are needed, specific bioaccumulation models can be used
Prediction of surface water input of chloridazon and chlorpyrifos from an agricultural watershed in Chile
No full textTwo compartmental fugacity-based models (Agrifug and SoilFug) for the prediction of pesticide runoff from agricultural fields were applied and experimentally validated in a river watershed, of about 106 km(2), in central Chile. Chloridazon and chlorpyrifos, two of the most widely used pesticides in the study area, were selected for their different physico-chemical properties, in order to test a range of environmental fate patterns by means of these models. Theoretical values were compared with analytical determinations in river water and soil and a goad predictive capability was found for both models, at least at the order of magnitude level. Value and limitations of the application of this approach at the basin scale and its usefulness for the management of pesticides are discussed
Predicting the contribution of a local emission source in mid-range transport of DDT and its deposition in terrestrial and aquatic ecosystems in Northern Italy
No full textA recently developed dynamic multiple box multimedia fate model (Gridded-SoilPlusVeg, or GSPV) was developed and implemented to account for the environmental variation and the effect of directional advective transport of chemicals towards different compartments and geographical locations. A chemical plant located in Pieve Vergonte in Ossola Valley produced and emitted DDTs for around 50 years. In the previous study the fate and transport of p,p’-DDT emitted from the chemical plant were evaluated in nearby areas (up to 12 km). In this paper, the GSPV model was run for p,p’-DDT from its production period and decades after the production stop in 1996 (a total of 100 years) for a much larger study area (40,000 km2) in order to evaluate the contribution of a local source on a larger scale. Additionally, the deposition fluxes into the lakes were calculated and were used as input into a dynamic fugacity-based aquatic model to calculate DDT concentration in water and sediments of three Prealpine lakes: Lake Maggiore, Lake Como and Lake Lugano. The results of the simulations were compared with the monitoring and literature data. The results obtained from GSPV allowed to estimate the atmospheric deposition fluxes and identify the role of this source for the regional scale contamination in terrestrial and aquatic ecosystems
Spatially resolved environmental fate models: A review
No full textSpatially resolved environmental models are important tools to introduce and highlight the spatial variability of the real world into modeling. Although various spatial models have been developed so far, yet the development and evaluation of these models remain a challenging task due to several difficulties related to model setup, computational cost, and obtaining high-resolution input data (e.g., monitoring and emission data). For example, atmospheric transport models can be used when high resolution predicted concentrations in atmospheric compartments are required, while spatial multimedia fate models may be preferred for regulatory risk assessment, life cycle impact assessment of chemicals, or when the partitioning of chemical substances in a multimedia environment is considered. The goal of this paper is to review and compare different spatially resolved environmental models, according to their spatial, temporal and chemical domains, with a closer insight into spatial multimedia fate models, to achieve a better understanding of their strengths and limitations. This review also points out several requirements for further improvement of existing models as well as for their integration
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
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