1,720,959 research outputs found
Methodological approach to assessment of groundwater contamination risk in an agricultural area
No full textWater contamination by nitrates of agricultural origin is a major problem in Sardinia (Italy) where Nitrate Vulnerable Zones (NVZs) has been identified in the Arborea reclamation area (W. Sardinia), where intensive agriculture and farming are the mainstays of the local economy. Agricultural practices have seen an increase in the use of animal and chemical fertilizers for enhancing soil productivity. This, accompanied by the intensive use of groundwater resources for irrigation has led to the deterioration of groundwater quality, in areas particularly vulnerable to nitrate contamination. In the test area, the intrinsic nitrate contamination risk from agricultural sources has been evaluated through the combined application of the parametric methods, SINTACS, SI and IPNOA. Risk assessment, using vulnerability and hazard mapping, is considered a fundamental aspect of sustainable groundwater management. All parameters used in this risk assessment were prepared, classified, weighted and integrated in a GIS environment. Results show that nitrate concentrations are located in those areas where agricultural and livestock farming are concentrated. These results could, consequently, be interesting for future development and long term planning of groundwater protection management. The risk methods adopted, verified by comparing the distribution of nitrates in the groundwater with the different vulnerability classes, proved to be a valid tool. In fact the areas with nitrate concentration of more than 100 mg/l coincide well with those at high risk identified by the model and the areas with nitrate concentration of less than 25 mg/l closely match those areas with low and moderate risk
Implementazione in ambiente GIS di modelli parametrici per la valutazione della vulnerabilità del territorio di Arborea (Sardegna, Italia) all’inquinamento da nitrati di origine agricola
No full textPrediction of nitrate concentration in groundwater using an Artificial Neural Network (ANN) approach
No full textThis paper evaluates the effectiveness of Artificial Neural Networks (ANNs) for the estimation of the nitrate concentration in a study area located in the Nitrate Vulnerable Zone (NVZ) of the Arborea plain (Sardinia - Italy). Agricultural derived nitrate contamination of groundwater has been estimated by using easily and economical quantifiable parameters such as pH, electrical conductivity, temperature, groundwater level. Data used for training and validating the ANNs derive from a set of 225 measurements coming from 12 piezometers distributed in the study area. In order to define the best topology of the ANN and the best dimension of respectively the training and the validation sets a growing procedure has been applied
Numerical flow and transport models for simulating current and predicted nitrate contamination in groundwater in the Bonifica di Arborea area (W. Sardinia, Italy)
No full textIn Italy the protection of groundwater against the deterioration of both quality and quantity is
one of the top priorities of water policy and this is reflected in the substantial regulatory
developments. The assessment of groundwater vulnerability to contamination is required to be
conducted in accordance with environmental regulations, the most significant at the national
level being Legislative Decrees 152/2006 and 30/2009, which concern a variety of
environmental issues. One common form of pollution of both surface and groundwater that
has been afflicting industrialised countries for decades, is nitrate contamination. This is also a
major issue in Sardinia where, by means of the Water Protection Plan (PTA) it has been
possible to delineate potential Nitrate Vulnerable Zones (ZVN) at the regional scale. Pursuant
to the Regional Government resolution No. 1/12 of 18/01/2005, the Bonifica di Arborea,
where intensive agriculture and dairy farming form the mainstays of the local economy, has
been designated as a ZVN. Numerical flow and transport models have been employed to
simulate groundwater conditions for assessing current nitrate contamination of the shallow
aquifer. Using the calibrated and validated numerical model, it was also possible to simulate
future scenarios, essential for drawing up plans for effective interventions
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
- …
