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النتائج 711 - 720 من 1,546
Pearl Oysters Pinctada margaritifera grazing on natural plankton in Ahe atoll lagoon (Tuamotu archipelago, French Polynesia) النص الكامل
2012
Fournier, Jonathan | Dupuy, Celie | Bouvy, Marc | Couraudon-reale, Marine | Charpy, Loic | Pouvreau, Stephane | Le Moullac, Gilles | Le Pennec, Marie-annick | Cochard, Jean-claude
In atoll lagoons of French Polynesia, growth and reproduction of pearl oysters are mainly driven by plankton concentration. However, the actual diet of black-lip pearl oysters P. margaritifera in these lagoons is poorly known. To fill this gap, we used the flow through chamber method to measure clearance rates of P. margaritifera in Ahe atoll lagoon (Tuamotu Archipelago, French Polynesia). We found : (i) that pearl oysters cleared plankton at a rate that was positively related to plankton biovolume, (ii) that nanoflagellates were the main source of carbon for the pearl oysters, (iii) that the quantity and origin of carbon filtrated by pearl oysters was highly dependent on the concentration and composition of plankton. These results provide essential elements for the comprehension of growth and reproduction variability of pearl oysters in atoll lagoons of French Polynesia.
اظهر المزيد [+] اقل [-]Metazooplankton communities in the Ahe atoll lagoon (Tuamotu Archipelago, French Polynesia): Spatiotemporal variations and trophic relationships النص الكامل
2012
Pagano, Marc | Sagarra, Pascual-boi | Champalbert, Gisele | Bouvy, Marc | Dupuy, Christine | Thomas, Yoann | Charpy, Loic
Metazooplankton abundance, biomass (<80 mu m, 200-500 mu m and >500 mu m) and community structure in the Ahe atoll were studied together with their relationships with environmental factors (temperature, salinity, wind) and trophic factors (phytoplankton, bacteria, heterotrophic nanoflagellates (HNF) and ciliates) during three periods in 2008-2009. Meroplankton, mainly bivalve and gastropod larvae, was dominant. Holoplankton was dominated by copepods, the main species being Oithona spp., Paracalanus parvus, Clausocalanus spp., Corycaeus spp., Acartia fossae and Undinula vulgaris. The results suggest a clear wind influence on the structure and horizontal distribution of the zooplankton communities. The metazooplankton appeared to be controlled mainly by food resources, suggesting a bottom-up control. The low nanophytoplankton biomass in contrast to the high abundance of picophytoplankton, HNF and nano-particle grazers (mainly Oithona spp., Paracalanus and bivalve larvae) highlighted the importance of the microbial loop in the food web. (C) 2012 Elsevier Ltd. All rights reserved.
اظهر المزيد [+] اقل [-]Differential biomagnification of PCB, PBDE, Hg and Radiocesium in the food web of the European hake from the NW Mediterranean النص الكامل
2012
Harmelin-vivien, Mireille | Bodiguel, Xavier | Charmasson, Sabine | Loizeau, Veronique | Mellon, Capucine | Tronczynski, Jacek | Cossa, Daniel
Consumption of marine organisms represents one of the main exposure sources of contaminants for human populations. To obtain a global view of the contamination in commercial fish in the NW Mediterranean Sea, we analysed four types of priority contaminants (PCBs, PBDEs, Hg and Cs-137) in the European hake, Merluccius merluccius, from the Gulf of Lions in relation with organism's trophic level (delta N-15). All contaminants presented a significant increase in concentration in hake muscle with trophic level. However, obvious differences between contaminants were evidenced. Biomagnification factors (BMF and FWMF) along the hake food web were higher for Hg and CB-153 than for BDE-47 and Cs-137, and increase in contaminant concentration with trophic level occurred at different rates depending on contaminants. Such differences of biomagnification patterns can be related to physico-chemical properties of the different contaminants. (C) 2012 Elsevier Ltd. All rights reserved.
اظهر المزيد [+] اقل [-]Use of Physiologically Based Pharmacokinetic (PBPK) Models in Marine Mammal Toxicology النص الكامل
2012
Weijs, Liesbeth | Yang, Raymond S.H. | Das, Krishna | Blust, Ronny | Covaci, Adrian
peer reviewed | Physiologically based pharmacokinetic (PBPK) models are mathematical models that are largely based upon the physiological characteristics of the species and the biochemical properties of the chemical of interest. They quantitatively describe and predict the kinetics of pollutants inside the body and can be of major importance for risk assessment of chemicals in marine mammals. PBPK models which consist of five compartments (liver, blubber, kidney, brain, and the rest of the body) were made for selected polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in order to address the bioaccumulation of these compounds in tissues of harbour porpoises (Phocoena phocoena). Harbour porpoises have relatively long life spans, are common cetaceans in the North Sea, a heavily polluted area, and are known to be very sensitive to pollution. Models developed for all compounds (some PCBs and PBDEs) were evaluated using existing datasets from the literature and from analyses performed by GC-MS, the latter being obtained from stranded porpoises in the Black Sea and the North Sea over a period of 18 years (1990–2008) to assess spatial and temporal trends in bioaccumulation of the respective PCBs and PBDEs. We demonstrate that PBPK models are a feasible computational approach that can be used as a non-destructive tool for predicting the chemical pollution status of the marine mammals.
اظهر المزيد [+] اقل [-]The plant family Brassicaceae
2012
Anjum, Naser A.
X-ray difraction analysis of desulfurant sorbents prepared by mixing calcined sewage sludge and CaO in distilled or seawater النص الكامل
2012
Renedo Omaechevarría, Josefina | González Pellón, Lorenzo | Fernández Ferreras, Josefa | Universidad de Cantabria
Desulfurant sorbents prepared by hydration, in sea or distilled water, of calcined sewage sludge (ash) and CaO at CaO/ash weight ratios of 0.2 or 3 at room temperature or at 90 º C, were characterized by X-ray diffraction in order to relate the X-ray composition of the sorbents to the preparation process and to the specific surface area of the obtained sorbents. Results show that the main compounds detected in the sludge´s ash are the same than those found in bibliography for the calcined sludge. In all the sorbents, independently of the preparation conditions, Ca(OH)2 was found instead of CaO used as raw material. New and different crystalline products were found in the sorbents depending on the preparation conditions. All the sorbents prepared in seawater contain NaCl in their composition; the specific surface area of the sorbents increased with hydration time and temperature and was lower when seawater was used for hydration. | We are thankful to MICINN in Spain, National Plan for scientific Research, Development and innovation, for financial support under Project: MAT2010-18862.
اظهر المزيد [+] اقل [-]Best available techniques in municipal solid waste incineration: state of the art in Spain and Portugal النص الكامل
2012
Margallo Blanco, María | Aldaco García, Rubén | Bala Gala, Alba | Fullana i Palmer, Pere | Irabien Gulías, Ángel | Universidad de Cantabria
In the year 2010 more than 24 Mt and 5 Mt of Municipal Solid Waste (MSW) were generated in Spain and Portugal. Landfilling, incineration and recycling are the most common treatments. In 2010, in the Iberian Peninsula between 58-6 2 % of the MSW generated was sent to the landfill, 9-19 % was incinerated and the rest was recycled and composting (EUROSTAT, 2010). Despite landfilling is still the most common practice, waste treatment by means of an incineration process has increased. The main advantages of this type of waste treatment are the reduction of mass and volume of residues and the energy recovery. Nevertheless, incineration had gained a bad reputation owing to the environmental impact, in particular, due to the emissions of acid gases, dioxins and furans (PCDD/F) and greenhouse gases. To assess the environmental advantages and disadvantages as well as the potential environmental impacts of waste incineration a life cycle perspective is required. Within this framework is the development of FENIX-Giving Packaging a New Life, a 3-year European LIFE+ funded project. This work is just the first step within this project where a database and a model based on Life Cycle Assessment (LCA) to assess the environmental impacts of waste incineration in Spain and Portugal will be developed. Particularly, the aim of this paper is to review the different technologies applied to MSW solid waste incineration and to carry out both the diagnosis of the current situation at the incineration plants in Spain and Portugal and to collect data to develop the Life Cycle Inventory (LCI).
اظهر المزيد [+] اقل [-]Can pollution bias peatland palaeoclimate reconstruction? النص الكامل
2012
Payne, R.J. | Mitchell, E.A.D. | Hung Nguyen-Viet | Gilbert, D.
Peatland testate amoebae are widely used to reconstruct paleohydrological/climatic changes, but many species are also known to respond to pollutants. Peatlands around the world have been exposed to anthropogenic and intermittent natural pollution through the late Holocene. This raises the question: can pollution lead to changes in the testate amoeba paleoecological record that could be erroneously interpreted as a climatic change? To address this issue we applied testate amoeba transfer functions to the results of experiments adding pollutants (N, P, S, Pb, O3) to peatlands and similar ecosystems. We found a significant effect in only one case, an experiment in which N and P were added, suggesting that pollution-induced biases are limited. However, we caution researchers to be aware of this possibility when interpreting paleoecological records. Studies characterising the paleoecological response to pollution allow pollution impacts to be tracked and distinguished from climate change.
اظهر المزيد [+] اقل [-]Study of the thermal behavior of sewage sludge from a WWTP in Cantabria (Spain) by TG-DSC-MS النص الكامل
2012
Fernández Ferreras, Josefa | González Martínez, Fernando | Pesquera González, Carmen | Blanco Delgado, Carmen | Renedo Omaechevarría, Josefina | Universidad de Cantabria
According to European Directive and national regulations in Spain, techniques based on thermal decomposition are proposed for the sewage sludge disposal. In this work, the sludge from the wastewater treatment plant (WWTP) of Casar de Periedo, in Cantabria (Spain) is studied by Thermogravimetry – Differential Scanning Calorimetry – Mass Spectrometry (TG –DSC – MS). A sample of this sludge was submitted, after drying, to different atmospheres: 100 % He, N2 /air or He/air 80/20 and 100 % air, from 20 to 900 ºC, to study primary decomposition reactions in pyrolysis, gasification and combustion respectively. The purpose was to determine the weight loss at different temperatures, the heat flow at each atmosphere and the presence of some gas products like H2, CO, CO2, CH4, or HCl, SO2, SO3, NO and NO2 released, these last five gases to know the contaminants emitted. Combustion conditions (air) rend the greatest mass loss and energy production. Reactions take place at lower temperatures, being mainly CO2 and H2O the products detected in MS, with little amounts of CH4, as it is expected for mainly total oxidation reactions. In gasification conditions, essayed with two atmospheres (N2-air and He-air), quantitative results found are similar, but the highest thermal conductivity of He produces exothermic reactions at lower temperatures, observed in the mass loss and heat flow profiles. From reactions of decomposition, partial oxidation and total oxidation, CO2, H2, H2O and CH4, were identified by MS. Pyrolysis conditions (He) produce the lowest mass loss and slightly endothermic reactions, mainly because of decomposition reactions. Higher H2 amounts were obtained at higher temperatures than in gasification conditions. No gas contaminant (HCl, SO2, SO3, NO and NO2) has been detected by MS, considering this sewage sludge as a “clean sludge”. Comparing the thermal behaviour of the sewage sludge of this plant to that obtained in the WWTP of Santander, the sludge from Casar de Periedo is more appropriated to thermal valorization. | We are thankful to MICINN in Spain, National Plan for scientific Research, Development and innovation, for financial support under Project: MAT2010-18862.
اظهر المزيد [+] اقل [-]Minimization of energy consumption for chemicals ultrapurification processes النص الكامل
2012
Abejón Elías, Ricardo | Garea Vázquez, Aurora | Irabien Gulías, Ángel | Universidad de Cantabria
Semiconductor industry requires ultrapure chemicals to manufacture microelectronic devices. Hydrogen peroxide is one of the most demanded chemical by the semiconductor industry and ultrapurification processes are needed to achieve the electronic grade requirements for this chemical. Among all the ultrapurification alternatives, reverse osmosis emerges as the most desirable option according to environmentally friendly criteria. Through modelling based on membrane transport equations and mass balances, different integrated reverse osmosis membrane cascades have been previously optimized. All the optimal solutions were characterized by the maximum allowed values for the applied pressures in the reverse osmosis stages, corresponding to the highest energy consumption and the lowest energy productivity (expressed as economic profit of the process for each unit of energy consumed). In this work, the energy productivity of the process was maximized and the optimal operation conditions were those with minimum applied pressures. However, under those conditions the membrane area required increased and the membrane productivity (expressed as economic profit of the process for each unit of membrane area employed) decreased. Therefore, multi-objective optimization was formulated to maximize simultaneously the productivities of both resources (energy and membranes).
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