Suchergebnisse

Riparian spiders are being used increasingly to track spatial patterns of contaminants in and fluxing from aquatic ecosystems. However, our understanding of the circumstances under which spiders are effective sentinels of aquatic pollution is limited. The present study tests the hypothesis that riparian spiders may be effectively used to track spatial patterns of sediment pollution by polychlorinated biphenyls (PCBs) in aquatic ecosystems with high habitat heterogeneity. The spatial pattern of ΣPCB concentrations in 2 common families of riparian spiders sampled in 2011 to 2013 generally tracked spatial variation in sediment ΣPCBs across all sites within the Manistique River Great Lakes Area of Concern (AOC), a rivermouth ecosystem located on the south shore of the Upper Peninsula, Manistique (MI, USA) that includes harbor, river, backwater, and lake habitats. Sediment ΣPCB concentrations normalized for total organic carbon explained 41% of the variation in lipid-normalized spider ΣPCB concentrations across 11 sites. Furthermore, 2 common riparian spider taxa (Araneidae and Tetragnathidae) were highly correlated (r(2) > 0.78) and had similar mean ΣPCB concentrations when averaged across all years. The results indicate that riparian spiders may be useful sentinels of relative PCB availability to aquatic and riparian food webs in heterogeneous aquatic ecosystems like rivermouths where habitat and contaminant variability may make the use of aquatic taxa less effective. Furthermore, the present approach appears robust to heterogeneity in shoreline development and riparian vegetation that support different families of large web-building spiders. Environ Toxicol Chem 2017;36:1278–1286. Published 2016 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Les données du Conseil scolaire du district de Toronto sont utilisées pour déterminer quelles sont les répercussions de vivre sous le seuil de faible revenu (SFR) sur le décrochage à l'école secondaire, en tenant compte du statut de la génération d'immigrants ainsi que d'une diversité de facteurs de risques (par exemple, le pays d'origine, l'âge à l'entrée de l'école secondaire, la réussite scolaire). Les résultats ont indiqué que la mesure SFR du voisinage constituait un prédicteur significatif du décrochage scolaire, indépendamment du statut d'immigrant. L'explication du taux de décrochage des immigrants à partir du facteur de la génération n'a obtenu que peu de soutien. La région d'origine s'est avérée un prédicteur marquant du décrochage où l'on constatait des différences entre les groupes d'immigrants et entre les étudiants immigrants et les étudiants originaires du pays.While education statistics confirm that there is little difference in the dropout rates of native‐born and immigrant youth, analyses of Toronto District School Board (TDSB) data have revealed significant variation in school persistence within immigrant groups. Among newcomer youth, the decision to leave school early has been reported to be strongly influenced by socioeconomic status as well as such factors as country of origin, age at arrival, generational status, family structure, and academic performance. While living in low‐income conditions is thought to place both foreign‐ and Canadian‐born youth at risk of poor school performance and early school withdrawal, their substantially higher incidence of poverty suggests that today's immigrant youth are likely to face greater obstacles to academic success that may in turn have detrimental, long‐term consequences. This paper uses TDSB data to investigate the extent to which living below the low‐income cutoff affects the likelihood of dropping out of secondary school, while taking into account generational status as well as a variety risk factors, noted above. Policy implications are discussed.

This article combines data from two separate studies of the shipping industry, one on enforcement of new regulations on the use of low-sulphur fuel and one on supply chain influences on ship operators' health and safety policies and practices. The shipping industry is a valuable natural laboratory for the study of patterns of compliance and governance in late modernity because it is characterised both by highly developed polycentric governance structures and by globalising economic processes including vertically disaggregated global value chains, outsourcing and offshoring. Segmented markets have permitted some 'blue riband' companies to operate a social license 'beyond compliance', and that such social licenses are more extensive in respect of environment policies than in health and safety policies that may be attributed to supply chain influences. Ship operators' compliance is seen as a combination of instrumental compliance, normative compliance, a taken for granted culture of compliance and corporate policies of labour-force governance. A taken for granted culture of compliance is identified as the main reason for compliance with the new low-sulphur regulations, which are currently (uncharacteristically) subject to only limited enforcement effort.