Numerical study of coastal sandbar migration, by hydro-morphodynamical coupling

We present a numerical model based on the hydro-morphodynamical coupling to study coastal sandbar migration. In order to improve both nonlinear and dispersive wave processes in relatively shallow water, we developed a finite element model based on the Legendre polynomials and on the Extended Boussinesq model. This model reproduces the propagation of wave trains with a high degree of accuracy on a greater range of depths than the standard Boussinesq models. We also implemented the Total Variation Diminishing schemes to improve the quality of the computed hydrodynamic fields, especially in areas where sharp flow gradients occurred. The coupled morpho-hydrodynamical model is then used to simulate the migration of real sandbars observed at Rousty beach (Mediterranean French coast). For verification the model results are compared with field measurements obtained from a small-scale field campaign carried out over two years at Rousty beach, and the results of this comparison are thoroughly discussed and analyzed.     

Effects of nanoparticles on Daphnia magna population dynamics

Spherical TiO₂ nanoparticles (npTiO₂) were prepared by controlled hydrolysis of tetraethoxy orthotitanate under a nitrogen atmosphere. ZnO nanoparticles (npZnO) were prepared using hydrothermal methods. The crystal structure, chemical, thermal and morphological properties of npZnO and npTiO₂ were characterised using Fourier Transform Infrared Spectrometer, enery-dispersive X-ray spectroscopy, X-ray diffraction, and scanning electron microscope techniques. The short- and long-term experiments were started with neonates taken from the same culture and laboratory condition. In the acute experiments, npTiO₂, npZnO, and cocktail concentrations were applied. 96h-LC₅₀ values were 1.8, 0.7, and 0.1?mg?L^?1, respectively (p?<?.05). For the chronic experiments, different npTiO₂ concentrations were performed. 21d-LC₅₀ value was 1.0?mgL^?1 (p?<?.05). Morphometry became progressively worse in concentrations of more than 1?mgL^?1 npTiO₂. Neonate and young individuals were more sensitive to death because of their low tolerance. This result was affected by population progeny and growth rates (p?<?.05). While control and 0.5?mgL^?1 npTiO₂ groups were determined as growing population, 1.5 and 2?mgL^?1 npTiO₂ groups had decreased population size as R₀ values. Consequently, the relationships between nanoparticle accumulation within Daphnia magna and its population structure and body morphometry for each concentration were important indicators. Its tolerance level to nanoparticles under laboratory conditions reflected its replacement and behaviour in the ecosystem.     

Molecular insight into the population structure of common and spotted dolphins inhabiting the pelagic waters of the Northeast Atlantic

Several cetacean species exhibit fine-scale population structure despite their high dispersal capacities and the apparent continuity of the marine environment. In dolphins, most studies have focused on coastal areas and continental margins, and they revealed differentiated populations within relatively small geographic areas, sometimes in conjunction with a specialisation for different habitats (ecotypes). We analysed the population genetic structure of short-beaked common dolphins (Delphinus delphis) and Atlantic spotted dolphins (Stenella frontalis) in the Azores and Madeira, the two most isolated archipelagos of the North Atlantic. The archipelago of the Azores is divided into three groups of islands and stands 900 km away from Madeira. It is not known whether individuals migrate between groups of islands and archipelagos, nor whether distinct ecotypes are present. These questions were investigated by genetic analyses of 343 biopsy samples collected on free-ranging dolphins. The analyses consisted in sequencing part of the mitochondrial hyper-variable region, screening up to 14 microsatellite loci, and molecular sexing. Results did not unravel any population structure at the scale of the study area. Lack of differentiation matches expectations for spotted dolphins, which are transient in both archipelagos, but not for common dolphins, which are present year-round in the Azores and potentially resident. Absence of genetic structure over hundreds and even thousands of kilometres implies the existence of gene flow over much larger distances than usually documented in small delphinids, which could be achieved through individual movements. This finding indicates that population structure in oceanic habitat differs from that observed in coastal habitat.     

Recycling glass-polishing sludge and aluminum anodising sludge in polyurethane and cement composites: fire performance and mechanical properties

Journal of Material Cycles and Waste Management - This article aims to study the mechanical strength and fire resistance of polyurethane/cement (PuCem) composites containing glass sludge and sludge...     

Body burden of contaminants and biological effects in mussels: an integrated approach

An investigation of contaminants and biological effects in mussels from Halifax Harbour, Nova Scotia, Canada, focused on a 6 km section in the central most industrialized core of the harbour, where a site was previously identified as highly contaminated. The aim of the study was to compare the body burden of mussels in terms of polycyclic aromatic hydrocarbons (PAH), dichlorophenyltrichloroethane (DDT family), coprostanol and elements, relative to biological parameters such as condition indices, sex ratio, survival time in air, and to biochemical indicators of mussels' health analysed in gills, digestive gland and gonad tissues. These markers are total sugar and lipid content of gonads, mitochondrial electron transport activity in digestive gland and gonad tissues, lipid peroxidation in gill, digestive gland and gonad tissues, and heme oxidase activity in the digestive gland. At the north western end of the area, near a major sewage effluent, shorter survival time, higher oxidative stress and metabolism, gonad electron transport activity, levels of coporostanol, PAH, p,p'-dichlorophenyldichlo-roethylene (p,p'-DDE), Ag, Cu, Fe and P were observed. At the opposite south eastern end, longer survival time, higher lipid content, lowest condition indices and concentrations of coprostanol, PAH and p,p'-DDE, but higher concentrations of Sn and Cd, were detected. On-going improvements to sewage treatment in Halifax Harbour, including construction of sewage treatment plants that will discharge into deeper parts of the central harbour, should improve inter-tidal mussels' health in our study area.     

Cobalt and secondary poisoning in the terrestrial food chain: data review and research gaps to support risk assessment

Cobalt is a naturally occurring element found in rocks, soil, water, plants, and animals and has diverse industrial importance. It is cycled in surface environments through many natural processes (e.g. volcanic eruptions, weathering) and can be introduced through numerous anthropogenic activities (e.g. burning of coal or oil, or the production of cobalt alloys). The environmental behaviour of cobalt in terrestrial environment is relatively poorly studied and in particular where Co is used in industrial processes, the baseline information to support wider and long-term environmental impacts is widely dispersed. To support the adoption of new EU regulations on the risk assessment of chemicals, we review here the various aspects of the environmental chemistry, fate and transport of Co across environmental interfaces and discuss the toxicology and potential for bio magnification and food chain accumulation. The soil-to-plant transfer of Co appears to be viable route to expose lower trophic levels to biologically significant concentrations and Co is potentially accumulated in biomass and top soil. Evidence for further accumulation through soil-invertebrate transfer and to higher trophic levels is suggested by some studies but this is obscured by the relatively high variability of published transfer data. This variation is not due to one particular aspect of the transfer of Co in terrestrial environments. Influences are from the variability of geological sources within soil systems; the sensitivity of Co mobility to environmental factors (e.g. pH) and the variety of life strategies for metal elimination/use within biological species. Toxic effects of Co have been suggested for some soil-plant animal studies however, uncertainty in the extrapolation from laboratory to field is a major limitation.     

Measuring the Social Recreation Per-Day Net Benefit of the Wildlife Amenities of a National Park: A Count-Data Travel-Cost Approach

In this article, we apply count-data travel-cost methods to a truncated sample of visitors to estimate the Peneda-Gerês National Park (PGNP) average consumer surplus (CS) for each day of visit. The measurement of recreation demand is highly specific because it is calculated by number of days of stay per visit. We therefore propose the application of altered truncated count-data models or truncated count-data models on grouped data to estimate a single, on-site individual recreation demand function, with the price (cost) of each recreation day per trip equal to out-of-pocket and time travel plus out-of-pocket and on-site time costs. We further check the sensitivity of coefficient estimations to alternative models and analyse the welfare measure precision by using the delta and simulation methods by Creel and Loomis. With simulated limits, CS is estimated to be €194 (range €116 to €448). This information is of use in the quest to improve government policy and PNPG management and conservation as well as promote nature-based tourism. To our knowledge, this is the first attempt to measure the average recreation net benefits of each day of stay generated by a national park by using truncated altered and truncated grouped count-data travel-cost models based on observing the individual number of days of stay.     

Solid waste management in European countries: a review of systems analysis techniques

In the past few decades, solid waste management systems in Europe have involved complex and multi-faceted trade-offs among a plethora of technological alternatives, economic instruments, and regulatory frameworks. These changes resulted in various environmental, economic, social, and regulatory impacts in waste management practices which not only complicate regional policy analysis, but also reshape the paradigm of global sustainable development. Systems analysis, a discipline that harmonizes these integrated solid waste management strategies, has been uniquely providing interdisciplinary support for decision making in this area. Systems engineering models and system assessment tools, both of which enrich the analytical framework of waste management, were designed specifically to handle particular types of problems. Though how to smooth out the barriers toward achieving appropriate systems synthesis and integration of these models and tools to aid in the solid waste management schemes prevalent in European countries still remains somewhat uncertain. This paper conducts a thorough literature review of models and tools illuminating possible overlapped boundaries in waste management practices in European countries and encompassing the pros and cons of waste management practices in each member state of the European Union. Whereas the Southern European Union (EU) countries need to develop further measures to implement more integrated solid waste management and reach EU directives, the Central EU countries need models and tools with which to rationalize their technological choices and management strategies. Nevertheless, considering systems analysis models and tools in a synergistic way would certainly provide opportunities to develop better solid waste management strategies leading to conformity with current standards and foster future perspectives for both the waste management industry and government agencies in European Union.     

Impact of excess and harmful radiation on energy budgets in scleractinian corals

Using dynamic energy budget (DEB) theory, this paper explores the potential of excess and harmful radiation, notably UV, to cause changes in performance and, ultimately, bleaching in scleractinian corals for a range of ambient nitrogen and (beneficial) photosynthetically active radiation levels. Two negative impacts of radiation are considered: a reduction in the capacity of the symbiont to generate energy through photosynthesis (defined in this paper as photoinhibition); an increase in the costs for the symbiont to remain viable due to repair of damage (defined in this paper as photodamage). Model predictions indicate that although both types of impact reduce the growth potential of host and symbiont, photoinhibition predominantly affects host features, except at very low ambient nitrogen levels, under which conditions the severity of nitrogen limitation is so strong that a reduction in photosynthetic rates due to photoinhibition has minimal impact. In steady state, photoinhibition leads to a reduction in host biomass, and an increase in symbiont density, implying that photoinhibition (as defined in this paper) is unlikely to cause bleaching. In contrast, the impact of photodamage is mostly affecting symbiont features, including a decline in symbiont density. Thus, photodamage may contribute to coral bleaching. Furthermore, the model predicts that, with both photoinhibition and photodamage, an increasing ratio of harmful to beneficial radiation accelerates the suppression of growth rates of symbiont and host, implying that coral health deteriorates progressively faster with increasing harmful radiation, such as UVb.     

Variations of periphytic diatom sensitivity to the herbicide diuron and relation to species distribution in a contamination gradient: implications for biomonitoring

Diatoms are commonly used as bioindicators of trophic and saprobic pollution in rivers. However, more knowledge is needed concerning their sensitivity to toxicants such as agricultural herbicides. In this study, seven species of periphytic diatoms were isolated from the Morcille River (Beaujolais area, France) which presents a streamward contamination gradient by pesticides and particularly diuron. The sensitivity of these species to diuron was assessed through ecotoxicological tests based on short-term growth inhibition of monospecific cultures. After application of an appropriate toxicological model, EC50 were determined and the species were ranked according to their tolerance. EC50 values ranged from 4.5 to 19 μg L(-1). Finally, the results were related to field periphyton samples from an upstream and a downstream site in order to check if variations in specific relative abundance between sites are consistent with differences in tolerance to diuron. Species distribution between sites was only partially in accordance with toxicological results suggesting that other factors (toxic or trophic) have an important influence on diatom communities in the river. Nevertheless, diatoms showed their potential to indicate water contamination by pesticides and toxic indices could be developed in complement to existing trophic indices.