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Treatment of contaminated marine sediments by sonolysis
No full textThe sediments of the port areas are often affected by the presence of several contaminants, which are generated from anthropic activities. These compounds can be toxic for the human health, thus, also to ensure a correct management and avoid the disposal in landfills, the sediments need to be treated. A novel approach proposal by international literature for sediments remediation is the use of advanced oxidation processes, which include ultrasonic technologies. Ultrasounds could be applied mainly to mineralize organic compounds and to desorb inorganic compounds through chemical and mechanical effects, respectively. The present paper is focused on the effectiveness of sonication to abate organic contaminants. The tests were carried out by ultrasound bath at different times of the treatment and sonication frequencies. The treatment efficiency was evaluated in terms of removal percentage. High percentages of degradation were achieved during the treatments in all the tests. The results demonstrated that ultrasound technology is a possible alternative technology for the treatment of contaminated sediment
SITI CONTAMINATI ESPERIENZE NEGLI INTERVENTI DI RISANAMENTO
No full textI sedimenti delle aree portuali sono spesso interessati dalla presenza di contaminanti di natura organica ed inorganica, originati da fonti antropiche. Per un’adeguata gestione dei sedimenti contaminati indirizzata a promuoverne il riutilizzo, possono essere impiegate diverse tecnologie di trattamento. Scopo del presente lavoro è la verifica dell’applicabilità dei processi ad ultrasuoni per la decontaminazione di sedimenti marini contaminati da idrocarburi policiclici aromatici e metalli pesanti. Campioni rappresentativi di sedimenti sono stati contaminati artificialmente con benzo()antracene, benzo()pirene, piombo, zinco e cadmio e sono stati trattati mediante un bagno ad ultrasuoni. L’efficienza di trattamento, indagata al variare di tempo e frequenza di sonicazione, è stata valutata in termini di degradazione dei composti organici e desorbimento dei composti inorganici. I risultati hanno mostrato una buona efficienza di degradazione dei contaminanti organici, con percentuali superiori al 90%. Per i metalli pesanti, i risultati ottenuti relativi alla determinazione delle percentuali di desorbimento, hanno mostrato significativa variabilità. I primi test eseguiti hanno, dunque, evidenziato che gli ultrasuoni sono potenzialmente efficaci per il trattamento di sedimenti marini caratterizzati da contaminazioni complesse
Interventricular conduction disorders after orthotopic heart transplantation: risk factors and clinical relevance
No full textCauses and significance of interventricular conduction disorders (IVCDs) after orthotopic heart transplantation (OHT) are still unknown
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
Advanced processes for remediation of contaminated sediments
Full text link2016 - 2017Sediments play a fundamental role in the aquatic environment, especially for their interaction with the aquatic life. However, in the last decades, due to the increasing anthropic activities, a large amount of contaminants were released into the environment, as well as in the water bodies. The sediments, due to their characteristics, tend to adsorb the polluting compounds becoming a potential sink of contaminants.
Among the several hazardous compounds, polycyclic aromatic hydrocarbon (PAHs) and heavy metals represent the contaminants most frequently detected onto sediments. These compounds are classified as “known” or “probable” human carcinogen by U.S. Environmental Protection Agency (US EPA) and the International Agency for Research on Cancer (IARC).
The presence of hazardous compounds in the sediments constitutes a concern, not only for the possible negative effects on the environment and human health, but also for the technical-economical aspects related to their management. Indeed, contaminated sediments need a proper management and their free disposal in the aquatic system is not allowed. It was estimated that in Europe about 200 million cubic meters of sediments are dredged every year. These dredging activities are necessary not only for remediation purposes, but also to maintain adequate depth of navigation in the water bodies. Once removed, the traditional management options for the sediments include landfill and confined aquatic disposal, which are among the most used solutions. Nevertheless, these options are not sustainable under both an economic and an environmental point of view. The sediment reuse could be an effective alternative, but their adequate treatment is fundamental in order to avoid the possible release of hazardous compounds into the environment and the resulting adverse effects.
In scientific literature different remediation technologies were proposed for treatment of contaminated soil. Few attempts have been also provide to adapt some of these techniques to polluted sediments. However, due to the specific characteristics of the sediments, including the prevalent fine grain size fraction, the technologies used for soil remediation are not always suitable for sediment treatment.
Advanced Oxidation Processes (AOPs), which are widely used for the wastewater treatment, were also applied for the treatment of other environmental matrices thanks to their technology flexibility.
Among AOPs, ultrasound (US) has raised growing interest in the scientific community, as an environmental friendly technology holding several advantages over conventional treatment solutions.
In the field of wastewater treatment, US has been studied in order to promote either the partial degradation of organic compounds before biological process or the mineralization of the same kind of contaminants. Few research experiences also focused on US application to solid matrices, with the main aim of desorbing inorganic compounds.
In polluted sediments, both organic and inorganic contaminants are simultaneously present and this aspect represents a major challenge in the choice of a remediation technology that could be effective for each kind of polluting compound. In this regard, the application of US can promote both the contaminant desorption from the solid particles and the degradation of the dissolved organic compounds.
Therefore, aim of this work was in the study of the advanced technology effectiveness for the remediation of contaminated sediments. For this purpose, the experimental activity was divided in two main parts:
- the first one focused on the study of US treatment effectiveness in promoting the reduction of both organic and inorganic contamination in a single stage;
- the second part, performed on the basis of the results of the previous phase, was devoted to the assessment of the US effectiveness as treatment prior to another main remediation technique. In particular, US was implemented as pretreatment for electrokinetic (EK) processes.
The first step was conducted at the laboratory of the Sanitary Environmental Engineering Division (SEED) of Salerno University. During this step both sonication frequency and treatment time were varied to investigate their effect on the removal yields of organic (B[]A and B[]P) as well as inorganic (Cd, Pb and Zn) contaminants.
Experimental results demonstrated that the application of ultrasonic waves led to an overall reduction of the contaminant concentration. The best performances were achieved for the organic compounds, with high removal efficiencies reached after few minutes of treatment. Heavy metals showed removal yields almost constant in all experiments, despite the sonication frequency as well as the treatment time. The desorption of inorganic compounds was variable for each compound and the best results were obtained for Cd and Zn compared to Pb.
In order to improve the heavy metal desorption by US, two different processing solutions, namely citric acid and ethylenediaminetetraacetic acid (EDTA), were tested as sonication medium. Both solutions determined an improvement in the desorption yields. However, the best performances were achieved with the citric acid, at a sonication frequency of 130 kHz. As previously noted, the variation of the treatment time was observed to be not significant, thus a long US treatment is not justified. In this regard, the process optimisation was pursued by reducing the treatment time. To this end, further tests were performed using a citric acid solution at 130 kHz and 2,5 min of sonication.
An slight decrease in desorption percentage, was observed for each metal. Nevertheless, the desorption yields were satisfactory, with percentages always more than 75%.
The second part of the work was performed at the laboratory of the Bioengineering and Sustainable Processes (BIOSUV) group at the University of Vigo (Spain). In order to evaluate the effectiveness of US as pre-treatment, this technology was applied before the electrokinetic process (EK). To this end, the combined process (US+EK) was compared with the remediation performances provided by the EK alone. Referring to the Cd and Zn, the results demonstrated a comparable desorption efficiency, close to the complete removal, for both EK process alone and US+EK. For Pb, instead, the use of US pre-treatment was able to improve the its desorption promoted a synergetic effect.
The results obtained from the experimental activity proved that US technology could be a promising alternative for the reduction of both organic compounds and heavy metals from contaminated sediments.
The studied process was observed to be very versatile, providing interesting performances as either stand-alone treatment or in combination with other remediation technologies. [edited by Author]XXX cicl
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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