75 research outputs found
DETERMINATION OF DECHLORANE PLUS AND RELATED COMPOUNDS IN THE ENVIRONMENT
No full textDechlorane Plus (DP) is a chlorinated flame retardant used in wire coatings, furniture and hard plastic connectors in computer monitors. It is manufactured in high volumes with production facilities located in the United States and China bringing into question whether the flame retardant existed in the environment. DP was detected in Lake Ontario sediments at concentrations 60-fold greater than in Lake Erie sediments; the maximum values were 586 ng g-1 and 8.6 ng g-1, respectively. These data suggest there is DP source into the Niagara River, which contributed to Lake Ontario’s DP burden. Analyses of Lake Ontario sediment core slices showed that recent concentrations were two orders of magnitude less than the core’s maximum concentration of 920 ng g-1 (1976-1980). New chemicals related to DP were also found in this core which DP’s profile, suggesting these compounds maybe impurities or side products in the manufacture of DP. The concentrations of one of the mono Diels-Alder adducts, 1,3-DPMA, was found in Lake Ontario lake trout to be two orders of magnitude greater than that of DP, suggesting the monoadduct is more bioaccumulative than DP. Analysis of a Lake Ontario food web illustrated that 1,3-DPMA was being diluted up the food chain, much like DP, while a second monoadduct, 1,5-DPMA was only detected in lower trophic species. In vitro lake trout liver microsomal exposures to the individual DPMA isomers showed that the depletion rate constant for 1,3- and 1,5-DPMA were 0.34 and 0.84 h-1, respectively, with corresponding t1/2’s of 2.02 ± 0.50 and 0.83 ± 0.18 h, respectively. The shorter 1,5-DPMA half-life was ascribed to the unsterically hindered double bond which allowed for greater enzyme attack. Dechlorination of DP was observed during the analysis of sediment extracts and was attributed as being an artefact of dirty injector liners; care needs to be taken to insure this dechlorination does not occur during analysis of environmental samples. This was important as dechlorinated DP products were observed in Lake Ontario sediment and core extracts. DP was shown to be a worldwide airborne contaminant from analysis of passive samplers over a period of one year. The maximum concentration was detected in Delhi, India (226 pg m-3). Middle Eastern and Indo-Asian regions exhibited the greatest concentrations in the world providing likely the result of other DP manufactures and/or that the practice of open pit burning of wires and cables was adding to the regions air burden.Doctor of Philosophy (PhD
Analytical methods for PCBs and organochlorine pesticides in environmental monitoring and surveillance: a critical appraisal
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Introduzione alla Psicologia dei Valori Lavorativi
No full textA valle dei lavori pionieristici sul tema dei valori (Allport e Vernon, 1931;
Allport, Vernon, e Lindzey, 1960; Rokeach, 1973; Super, 1969), nel corso
degli anni ’80 sono state effettuate diverse ricerche cross-cultural, secondo
prospettive psicologiche che hanno focalizzato rispettivamente il significato
del lavoro (MOW international resarch team, 1987), la sua importanza rispetto
agli altri ruoli della vita (Super e Sverko, 1995) ed altre dimensioni (Hofstede,
1990; Zanders, 1993) con esplicito riferimento al tema in oggetto. Ciò ha consentito,
da un lato di delineare alcune differenze, in termini di sistemi valoriali,
tra le aree geo-culturali esplorate e, dall’altro lato, di individuare una serie di
relazioni tra i valori che le persone esprimono e le scelte o i comportamenti che
adottano nella propria vita lavorativa
(Table 1) Air concentrations of PBDE congeners and temperatures between 2002-2004 at Point Petre
No full text(Table 1) Air concentrations of PBDE congeners and temperatures between 2002-2004 at Point Petr
Synthesis of deuterated 5(Z),11(Z)-eicosadienoic acid as a biomarker for trophic transfer
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Occurrence of triazine herbicides and metolachlor in the Niagara River and other major tributaries draining into Lake Ontario
No full textThe ABC of linear regression analysis: What every author and editor should know
No full textRegression analysis is a widely used statistical technique to build a model from a set of data on two or more variables. Linear regression is based on linear correlation, and assumes that change in one variable is accompanied by a proportional change in another variable. Simple linear regression, or bivariate regression, is used for predicting the value of one variable from another variable (predictor); however, multiple linear regression, which enables us to analyse more than one predictor or variable, is more commonly used. This paper explains both simple and multiple linear regressions illustrated with an example of analysis and also discusses some common errors in presenting the results of regression, including inappropriate titles, causal language, inappropriate conclusions, and misinterpretation
(Table 4) Annual mean atmospheric concentrations of selected organochlorine pesticides and PCBs at monitoring stations around the Arctic
No full text(Table 4) Annual mean atmospheric concentrations of selected organochlorine pesticides and PCBs at monitoring stations around the Arcti
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