Sources and Sinks of Microplastics in Canadian Lake Ontario Nearshore, Tributary and Beach Sediments

Microplastics contamination of Lake Ontario sediments is investigated with the aim of identifying distribution patterns and hotspots in nearshore, tributary and beach depositional environments. Microplastics are concentrated in nearshore sediments in the vicinity of urban and industrial regions. InHumber Bay and Toronto Harbour microplastic concentrations were consistently greater than 500 particles per kg dry sediment. Maximum concentrations of ~28,000 particles per kg dry sediment were determined in Etobicoke Creek. The microplastic particles were primarily fibres and fragments less than 2 mm in size. Both low- and high-density plastics were identified using Raman spectroscopy. We provide a baseline for future monitoring and discuss potential sources of microplastics in terms of how and where to implement preventative measures to reduce the contaminant influx. Although the impacts of microplastics contamination on ecosystem health and functioning is uncertain, understanding, monitoring and preventing further microplastics contamination in Lake Ontario and the other Great Lakes is crucial

Grassroots Agency: Participation and Conflict in Buenos Aires Shantytowns seen through the Pilot Plan for Villa 7 (1971–1975)

open access articleIn 1971, after more than a decade of national and municipal policies aimed at the top-down removal of shantytowns, the Buenos Aires City Council approved the Plan Piloto para la Relocalización de Villa 7 (Pilot Plan for the Relocation of Shantytown 7; 1971–1975, referred to as the Pilot Plan hereinafter). This particular plan, which resulted in the construction of the housing complex, Barrio Justo Suárez, endures in the collective memory of Argentines as a landmark project regarding grassroots participation in state housing initiatives addressed at shantytowns. Emerging from a context of a housing shortage for the growing urban poor and intense popular mobilizations during the transition to democracy, the authors of the Pilot Plan sought to empower shantytown residents in novel ways by: 1) maintaining the shantytown’s location as opposed to eradication schemes that relocated the residents elsewhere, 2) formally employing some of the residents for the stage of construction, as opposed to “self-help” housing projects in which the residents contributed with unpaid labor, and 3) including them in the urban and architectural design of the of the new housing. This paper will examine the context in which the Pilot Plan was conceived of as a way of re-assessing the roles of the state, the user, and housing-related professionals, often seen as antagonistic. The paper argues that residents’ fair participation and state intervention in housing schemes are not necessarily incompatible, and can function in specific social and political contexts through multiactor proposals backed by a political will that prioritizes grassroots agency

Gated communities: Definitions, causes and consequences

Gated communities became an 'object of study' in the 1990s as social scientists observed their growth in several cities; they are now a feature of the urban landscape in most cities around the world. The expansion of gated communities has led to prolific research, examining different aspects of this type of residential development and providing evidence from case studies worldwide. This paper reviews how gated communities are conceptualised according to the literature and identifies the main factors influencing their development. It also considers spatial, economic, political and social consequences of the development of gated communities. These elements should be taken into account by planners and policymakers to minimise their negative impacts and maximise the positive consequences of a residential option that is likely to be part of the urban landscape for a long time

Latest Cretaceous climatic and environmental change in the South Atlantic region

Latest Maastrichtian climate change caused by Deccan volcanism has been invoked as a cause of mass extinction at the Cretaceous-Paleogene (K-Pg) boundary (~66.0 Ma). Yet late Maastrichtian climate and ecological changes are poorly documented, in particular on the Southern Hemisphere. Here we present upper Maastrichtian-lower Danian climate and biotic records from the Bajada del Jagüel (BJ) shelf site (Neuquén Basin, Argentina), employing the TEX86 paleothermometer, marine palynology (dinoflagellate cysts), and micropaleontology (foraminifera). These records are correlated to the astronomically tuned Ocean Drilling Program Site 1262 (Walvis Ridge). Collectively, we use these records to assess climatic and ecological effects of Deccan volcanism in the Southern Atlantic region. Both the TEX86-based sea surface temperature (SST) record at BJ and the bulk carbonate δ18O-based SST record of Site 1262 show a latest Maastrichtian warming of ~2.5-4°C, at 450 to 150 kyr before the K-Pg boundary, coinciding with the a large Deccan outpouring phase. Benthic foraminiferal and dinocyst assemblage changes indicate that this warming resulted in enhanced runoff and stratification of the water column, likely resulting from more humid climate conditions in the Neuquén Basin. These climate conditions could have been caused by an expanding and strengthening thermal low over the South American continent. Biotic changes in response to late Maastrichtian environmental changes are rather limited, when compared to the major turnovers observed at many K-Pg boundary sites worldwide. This suggests that environmental perturbations during the latest Maastrichtian warming event were less severe than those following the K-Pg boundary impact

Global Boundary Stratotype Section and Point (GSSP) for the Anthropocene Series: Where and how to look for potential candidates

International audienc

Les paturages de vallee dans les Pyrenees centrales - Caracteristiques et productivite des terroirs de Soulane

National audienc

Modelled transport of benthic marine microplastic pollution in the Nazaré Canyon

With knowledge of typical hydrodynamic behavior of waste plastic material, models predicting the dispersal of benthic plastics from land sources within the ocean are possible. Here we investigated the hydrodynamic behavior (density, settling velocity and resuspension characteristics) of non-buoyant preproduction plastic pellets in the laboratory. From these results we used the MOHID modelling system to predict what would be the likely transport and deposition pathways of such material in the Nazaré Canyon (Portugal) during the spring/summer months of 2009 and the autumn/winter months of 2011. <br><br> Model outputs indicated that non-buoyant plastic pellets would likely be transported up and down canyon as a function of tidal forces, with only a minor net down canyon movement resulting from tidal action. The model indicated that transport down canyon was likely greater during the autumn/winter, primarily as a result of occasional mass transport events related to storm activity and internal wave action. Transport rates within the canyon were not predicted to be regular throughout the canyon system, with stretches of the upper canyon acting more as locations of pellet deposition than conduits of pellet transport. Topography and the depths of internal wave action are hypothesized to contribute to this lack of homogeneity in predicted transport

The pharmacokinetics of orally administered ivermectin in African elephants (loxodonta Africana): Implications for parasite elimination

Loxodonta africana are susceptible to a wide variety of parasites that are often treated with the broad spectrum antiparasitic ivermectin (IVM) based on empirical knowledge. The objectives of this study were to 1) measure plasma IVM levels following administration of 0.1 mg/kg IVM p.o., 2) compare plasma IVM levels following administration with regular versus restricted feed rations, 3) measure IVM excretion in feces, and 4) use these findings to generate dosing recommendations for this species. Using a crossover design, six African elephants were divided into two groups. Ivermectin was administered and typical grain rations were either provided or withheld for 2 hr. Blood and fecal samples were collected for 7 days following drug administration. After a 5-wk washout period, groups were switched and the procedure repeated. Plasma and fecal IVM were analyzed using high-performance liquid chromatography. There was no statistically significant difference detected in the pharmacokinetic data between the fed and fasted groups. Peak plasma concentration, area under the curve, and half-life for plasma ranged between 5.41-8.49 ng/ml, 17.1-20.3 ng × day/ml, and 3.12-4.47 day, respectively. High IVM concentrations were detected in feces. The peak concentration values in feces were between 264-311-fold higher than those obtained in plasma. The comparatively large area under the curve and short time to maximum concentration in feces indicate elimination prior to absorption of much of the drug. Plasma IVM concentrations were low when compared to other species. Based on these findings, administration of 0.2-0.4 mg/kg p.o. should be appropriate for eliminating many types of parasites in elephants, and could minimize development of parasite resistance.Fil: Gandolf, A. Rae. Pittsburgh Zoo; Estados Unidos. PPG Aquarium; Estados UnidosFil: Lifschitz, A.. Pittsburgh Zoo; Estados Unidos. PPG Aquarium; Estados UnidosFil: Stadler, C.. Pittsburgh Zoo; Estados Unidos. PPG Aquarium; Estados UnidosFil: Watson, B.. PPG Aquarium; Estados Unidos. Pittsburgh Zoo; Estados UnidosFil: Galvanek, L.. Pittsburgh Zoo; Estados Unidos. PPG Aquarium; Estados UnidosFil: Ballent, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; ArgentinaFil: Lanusse, Carlos Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; Argentin

Moxidectin and ivermectin metabolic stability in sheep ruminal and abomasal contents

The oral administration of macrocyclic lactones to sheep leads to poorer efficacy and shorter persistence of the antiparasitic activity compared to the subcutaneous treatment. Gastrointestinal biotransformation occurring after oral treatment to ruminant species has been considered as a possible cause of the differences observed between routes of administration. The current work was addressed to evaluate on a comparative basis the in vitro metabolism of moxidectin (MXD) and ivermectin (IVM) in sheep ruminal and abomasal contents. Both compounds were incubated under anaerobic conditions during 2, 6 and 24 h in ruminal and abomasal contents collected from untreated adult sheep. Drug concentrations were measured by high-performance liquid chromatography with fluorescence detection after sample clean up and solid phase extraction. Neither MXD nor IVM suffered metabolic conversion and/or chemical degradation after 24-h incubation in ruminal and abomasal contents collected from adult sheep. Unchanged MXD and IVM parent compounds represented between 95.5 and 100% of the total drug recovered in the ruminal and abomasal incubation mixtures compared with those measured in inactive control incubations. The partition of both molecules between the solid and fluid phases of both sheep digestive contents was assessed. MXD and IVM were extensively bound (>90%) to the solid material of both ruminal and abomasal contents collected from sheep fed on lucerne hay. The results reported here confirm the extensive degree of association to the solid digestive material and demonstrates a high chemical stability without evident metabolism and/or degradation for both MXD and IVM in ruminal and abomasal contents.Fil: Lifschitz, Adrian Luis. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Fisiopatología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Virkel, Guillermo Leon. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Fisiopatología; ArgentinaFil: Ballent, Mariana. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Fisiopatología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Sallovitz, Juan Manuel. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Fisiopatología; ArgentinaFil: Pis, A.. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Fisiopatología; ArgentinaFil: Lanusse, Carlos Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Fisiopatología; Argentin