1,720,971 research outputs found
Detection and quantitative analysis of organochlorine compounds (PCBs and DDTs) in deep sea fish liver from Mediterranean Sea
No full textBACKGROUND, AIM AND SCOPE: Polychlorinated biphenyls (PCB) and dichlorodiphenyltrichloroethane (DDT) concentrations were determined in the liver of two deep sea fish species, Mediterranean slimehead and blackfin sorcerer, from the Adriatic Sea (southeastern Mediterranean Sea).
RESULTS AND DISCUSSION: The examination of congener profiles showed that hexachlorinated molecules were dominant (hexa-CBs, 55.3-56.2%), followed by penta-CBs (21.5-21.8%) and hepta-PCB 180 (14.9-16.0%). PCB 138, 153 and 180 were the prominent congeners accounting for 69.3% of the total PCBs. Among the compounds of DDT, p,p'-DDE was the most dominant molecule (Mediterranean slimehead, 86.6%; blackfin sorcerer, 92.8%), demonstrating the old age of these compounds in the environment. In both species, PCB contents were higher than those of DDTs. Contaminant load was higher in Mediterranean slimehead (PCBs, 1,086 ng g(-1) lipid weight; DDTs, 799 ng g(-1) lipid weight) than in blackfin sorcerer (PCBs, 561 ng g(-1) lipid weight; DDTs, 224 ng g(-1) lipid weight).
CONCLUSION: The high ratios SPCBs/SDDTs indicated predominantly industrial versus agrarian activities in the area. Dioxins toxic equivalent (TEQ) concentrations (8.1-18.7 pg TEQ per gram wet weight) reached those encountered in marine organisms at higher levels in the trophic chain, revealing the onerous status of contamination by PCBs in Mediterranean deep sea biota
Risk characterization for polycyclic aromatic hydrocarbons and toxic metals associated with fish consumption.
No full textConcentrations of 11 polycyclic aromatic hydrocarbons (PAHs) and toxic metals (Hg, Cd and Pb) were measured in three fish species [(Raja miraletus (brown ray), Lepidorhombus whiffiagonis (megrim) and Lophius piscatorius (angler)] from Mediterranean Sea (Adriatic Sea). No significant difference in PAHs and metal concentrations was encountered among the fish species examined. Total PAH concentrations ranged from 209.9ngg-1 wet weight to 227.2ngg-1 wet weight. Low-molecular weight (two and three rings) PAHs were observed dominating over the high molecular weight (from four to six rings) PAHs. With regard to metals, Hg exhibited the highest concentrations (0.68-0.98μgg-1 weight wet), followed by Pb (0.08-0.12μgg-1 weight wet) and Cd (0.05-0.10μgg-1 weight wet). The health risks by consumption of these species were assessed and did not present threat to public health concerning PAH, Pb and Cd intakes. However, the estimated exposure from Hg illustrates the importance of limiting the dietary consumption of larger-sized fish
Organochlorine contamination (PCBs and DDTs) in deep-sea fish from the Mediterranean Sea
No full textOrganochlorine residues (PCBs and DDTs) in two Torpedinid species liver from the Southeastern Mediterranean Sea
No full textPCB and DDT concentrations were determined in the liver of two torpedinid species, electric ray and marbled electric ray from the Adriatic Sea (South-Eastern Mediterranean Sea). In both species PCB contents were higher than those of DDTs. Contaminant load was higher in electric ray (PCBs: 1040 ng g-1 lipid weight; DDTs: 234 ng g-1 lipid weight) than in marbled electric ray (PCBs: 434 ng g-1 lipid weight; DDTs: 78 ng g-1 lipid weight). The examination of congener profiles showed that hexachlorinated molecules were dominant (hexa-CBs: 63.7-64.5%), followed by hepta-PCB 180 (20.9-22.3%) and penta-CBs (13.1-15.4%). PCB 138, 153 and 180 were the prominent congeners constituting from 84.6 to 86.8% of the total PCBs. Among the compounds of DDT, p,p’-DDE was the most dominant molecule (electric ray: 92.9%; marbled electric ray: 85.4%), demonstrating the old age of these compounds in the environment. The high ratios PCBs/DDTs indicated predominantly industrial versus agrarian activities in the area. TEQs concentrations (marbled electric ray: 15.4 pg-TEQ g-1 lipid weight, electric ray: 28.5 pg-TEQ g-1 lipid weight) were comparable with those encountered in other elasmobranch and teleost fish. Further studies are needed to better evaluate the toxicological significance of the organochlorine levels measured in these organisms
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
Persistent organic Pollutants (PCBs and DDTs) in European Conger EEl, Conger conger L., from the Ionian Sea (Mediterranean Sea)
No full textThe present study provides novel data regarding levels of polychlorinated biphenyls (PCBs) and organochlorine pesticides (DDTs) in muscle tissue of European conger eel (Conger conger) from Ionian Sea (Mediterranean Sea). The mean concentration of PCBs (891 ng g(-1) lipid weight) was higher than those of DDTs (543 ng g(-1) lipid weight). PCB pattern was dominated by higher chlorinated congeners (hexa-CBs: 69.3 %, penta-CBs: 17.2 %, hepta-CBs: 13.3 %). Regarding DDT pattern, p,p'-DDE was prevalent in all samples (85.5 %), suggesting no recent DDT input. The total 2,3,7,8-TCDD toxic equivalent (TEQs) of coplanar PCBs, including mono-and non-ortho congeners was 0.41 pg g(-1) wet weight (29.92 pg g(-1) lipid weight). The PCB and DDT levels, as well as TEQ concentrations were lower than most of the corresponding published data for fish from Mediterranean and non-Mediterranean regions, probably reflecting a moderately contaminated area
Residui di metalli pesanti (Zn, Cu, Hg, Cd) nel tessuto muscolare di differenti specie di molluschi cefalopodi: valutazione del rischio tossicologico per il consumatore.
No full textMuscle tissue of bluefin tuna (Thunnus thynnus) was analysed for PCBs to ascertain whether the
concentrations exceeded the levels fixed by the European Commission and whether this fish was suitable for human
consumption. PCB concentrations were comprised between 96 and 6571 ng/g l. w. (mean: 764 ng/g l.w.). Isomer-specific
analysis revealed a profile dominated by hexa- (65.4%) and pentachlorobiphenyls (18.0%), followed by hepta- (15.4%)
and tetrachlorobiphenyls (1.2%). The dietary intake was below the limit of 14 pg TEQs/kg body weight/week set by
European Commission. The results obtained are not to underestimate, considering that the daily intake do not include
other food which might also pass these contaminants to man
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