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Resultados 1851-1860 de 4,367
Lost in the North: The first record of Diretmichthys parini (Post and Quéro, 1981) in the northern North Sea Texto completo
2017
Cresson, Pierre | Rouquette, Manuel | Marco-miralles, Francoise | Dufour, Jean-louis | Causse, Romain | Bouchoucha, Marc | Mahe, Kelig
In June 2015, an individual of Diretmichthys parini (Post and Quero, 1981) was trawled at 530 m depth, in the North Sea off Norway and donated to research. This capture, the first for this species in the North Sea was the northernmost recorded so far, and provided an opportunity to document some aspects of the biology and ecology of this data-poor species. This individual was a female, 331 mm total length of 33 years old, with low mercury content in muscle and liver (~ 0.2 μg g− 1 wet mass). Stable isotope ratios (C and N) in muscle and liver were consistent with the planktonic diet expected for this species. The capture of this fish at the northern latitude known so far would be consistent with the extension of the home range and the latitudinal shift hypothesized for this species in the 1990′s.
Mostrar más [+] Menos [-]Underestimation of chemical contamination in marine fish muscle tissue can be reduced by considering variable wet:dry weight ratios Texto completo
2017
Cresson, Pierre | Travers-trolet, Morgane | Rouquette, Manuel | Timmerman, Charles-andre | Giraldo, Carolina | Lefebvre, Sebastien | Ernande, Bruno
Underestimation of chemical contamination in marine fish muscle tissue can be reduced by considering variable wet:dry weight ratios Texto completo
2017
Cresson, Pierre | Travers-trolet, Morgane | Rouquette, Manuel | Timmerman, Charles-andre | Giraldo, Carolina | Lefebvre, Sebastien | Ernande, Bruno
Whether considered as a risk for human health or as ecological tracers, contaminants' concentrations measured in fish muscles are commonly expressed relative to wet or dry mass. Comparison of results required conversion factors (CF) but accurate values are scarce and case-specific. The present paper is aimed at investigating errors linked with the use of the theoretical value. Muscles dry and wet masses were measured in 15 fish species to determine the actual CF. Most CF were lower than the theoretical wet:dry ratio of 5 classically used, with variations at individual and species level. Muscle lipid content (inferred by C/N ratios) was a crucial factor explaining discrepancies, claiming for caution when working with lipid-rich species. The observed variability demonstrated that using the theoretical CF may be inaccurate, when actual CF largely differs from the theoretical value. Dedicated measurement is the better approach when accuracy is required.
Mostrar más [+] Menos [-]Underestimation of chemical contamination in marine fish muscle tissue can be reduced by considering variable wet:dry weight ratios Texto completo
2017
Cresson, Pierre | Travers-Trolet, Morgane | Rouquette, Manuel | Timmerman, Charles-André | Giraldo, Carolina | Lefebvre, Sébastien | Ernande, Bruno
Whether considered as a risk for human health or as ecological tracers, contaminants' concentrations measured in fish muscles are commonly expressed relative to wet or dry mass. Comparison of results required conversion factors (CF) but accurate values are scarce and case-specific. The present paper is aimed at investigating errors linked with the use of the theoretical value. Muscles dry and wet masses were measured in 15 fish species to determine the actual CF. Most CF were lower than the theoretical wet:dry ratio of 5 classically used, with variations at individual and species level. Muscle lipid content (inferred by C/N ratios) was a crucial factor explaining discrepancies, claiming for caution when working with lipid-rich species. The observed variability demonstrated that using the theoretical CF may be inaccurate, when actual CF largely differs from the theoretical value. Dedicated measurement is the better approach when accuracy is required.
Mostrar más [+] Menos [-]Concentrations of mercury and other trace elements in two offshore skates: sandy ray Leucoraja circularis and shagreen ray L. fullonica Texto completo
2017
Nicolaus, E. E. Manuel | Barry, Jon | Bolam, Thi P. C. | Lorance, Pascal | Marandel, Florianne | Phillips, Sophy R. Mccully | Neville, Suzanna | Ellis, Jim R.
Concentrations of mercury and other trace elements in two offshore skates: sandy ray Leucoraja circularis and shagreen ray L. fullonica Texto completo
2017
Nicolaus, E. E. Manuel | Barry, Jon | Bolam, Thi P. C. | Lorance, Pascal | Marandel, Florianne | Phillips, Sophy R. Mccully | Neville, Suzanna | Ellis, Jim R.
Trace metal concentrations in muscle and liver tissues from two offshore species of skate were examined. Concentrations of mercury in muscle of Leucoraja circularis (n = 20; 23–110.5 cm total length, 157–490 m water depth) and L. fullonica (n = 24; 28.5–100 cm total length, 130–426 m water depth) were 0.02–1.8 and 0.04–0.61 mg kg− 1, respectively. Concentrations of both As and Hg increased with total length. Only the largest specimen had a concentration of Hg in muscle > 1.0 mg kg− 1. Data were limited for specimens > 90 cm long, and further studies on contaminants in larger-bodied skates could usefully be undertaken.
Mostrar más [+] Menos [-]Concentrations of mercury and other trace elements in two offshore skates: sandy ray Leucoraja circularis and shagreen ray L. fullonica Texto completo
2017
Nicolaus, E.E Manuel | Barry, Jon | Bolam, Thi P.C. | Lorance, Pascal | Marandel, Florianne | McCully Phillips, Sophy R. | Neville, Suzanna | Ellis, Jim
Trace metal concentrations in muscle and liver tissues from two offshore species of skate were examined. Concentrations of mercury in muscle of Leucoraja circularis (n=20; 23–110.5cm total length, 157–490m water depth) and L. fullonica (n=24; 28.5–100cm total length, 130–426m water depth) were 0.02–1.8 and 0.04–0.61mgkg−1, respectively. Concentrations of both As and Hg increased with total length. Only the largest specimen had a concentration of Hg in muscle >1.0mgkg−1. Data were limited for specimens>90cm long, and further studies on contaminants in larger-bodied skates could usefully be undertaken.
Mostrar más [+] Menos [-]Modeling of real time exhaust emissions of passenger cars under heterogeneous traffic conditions Texto completo
2017
Jaikumar, Rohit | Shiva Nagendra, S.M. | Sivanandan, R.
This paper presents the characterization and modeling of exhaust emissions released from the passenger cars on urban roads under heterogeneous traffic conditions. Onboard exhaust emissions measurement were made at selected corridors in a populous urban area of India. Exhaust emissions were characterized for different driving modes classified according to vehicle specific power (VSP). Results indicated that emissions at VSP modes under cruising speeds were 10–12 times less than idling (which is the mode used for emission standard certification), braking and accelerating conditions. Also it has been found that more than 20% of time vehicles were in idling conditions at most of the roads.Real-time exhaust emission prediction models for heterogeneous traffic conditions were developed using artificial neural network (ANN) technique. The vehicle characteristics such as revolutions per minute (RPM), speed, acceleration and VSP were used as input to the model. The onboard measurements of CO, HC and NOx concentrations were used to train the ANN based exhaust emission prediction models. Result showed good agreement with onboard measured emissions data (index of agreement = 0.9) of all driving modes. Further, ANN model's emissions were compared with emissions estimated from the COPERT model and emission factors recommended by the Automotive Research Association of India (ARAI). It was found that the ANN model emissions were edge over the ARAI and COPERT model emissions and useful for urban air quality management and traffic planning.
Mostrar más [+] Menos [-]Light absorption characteristics of brown carbon during foggy and non-foggy episodes over the Indo-Gangetic Plain Texto completo
2017
Atmospheric PM1 (particulate matter with aerodynamic diameter ≤ 1 μm) samples have been collected during foggy (n = 17) and non-foggy nights (n = 19) in wintertime at Kanpur in central Indo-Gangetic Plain (IGP) to assess light absorption characteristics and direct radiative forcing of water-extractable brown carbon (BrC). We have observed a significant enhancement (two-tailed t-test: t = 2.2; at significance level: p < 0.05) in the absorption coefficient of water-extractable BrC at 365 nm (babs-BrC-365) from non-foggy (Avg.: 53.5 Mm⁻¹) to foggy episodes (69.3 Mm⁻¹). Enhancement in mass absorption efficiency (MAE) of BrC (1.8 m²/g C) during foggy episodes is consistent with that of babs-BrC-365. Absorption Ångström exponent (AAE) remained similar (2.8) during foggy and non-foggy episodes. Significantly lower value of AAE (2.8) at Kanpur compared to other places in IGP (∼5) highlights more light absorbing potential of atmospheric BrC over central IGP. Furthermore, MAE of EC at 660 nm during foggy period (8.5 m²/g) is relatively high as compared to that during the non-foggy episode (7.0 m²/g). The MAE of BrC and EC exhibited enhancement by ∼15% and 20%, respectively during foggy events. These observations are also reflected by an increase (t = 11.1; p < 0.05) in direct radiative forcing of water-extractable BrC (relative to EC) in the atmosphere: from 23.7 ± 10.8% during non-foggy to 54.3 ± 16.5% during foggy episodes. Differences in chemical composition, loading, absorption properties and direct radiative forcing (DRF) of carbonaceous aerosols during non-foggy and foggy episodes indicate predominant influence of fog-processing.
Mostrar más [+] Menos [-]Changes in the diurnal variations of clouds and precipitation induced by anthropogenic aerosols over East China in August 2008 Texto completo
2017
We investigated the impacts of all anthropogenic aerosols and black carbon (BC) on the diurnal variations of cloud and precipitation over East China during August 2008 using a coupled meteorology and chemistry model (WRF-Chem). Comparison of the model results with observations showed that the model reproduced reasonably well the distribution patterns of the aerosol optical depth (AOD), the horizontal wind, precipitation, and the liquid water path (LWP). The results from ensemble numerical experiments showed the aerosol-induced cloud droplet number concentration (CDNC) increased by 20–160 cm⁻³ over East China. The aerosol-induced cloud fraction (CF) increased by 0.03–0.08 below 850 hPa and at around 750 hPa over East China; it decreased by up to 0.06 between 750 and 850 hPa at around 25°N and over Central China. These increases were larger at early morning and nighttime, whereas the decreases were larger in the afternoon and evening. Other scattering aerosols were the main contributor to the increase of CDNC and offset the decrease induced by BC. The decrease of CF over Central China was mainly caused by BC. The precipitation induced by aerosols decreased by 20–200 mm over South and North China with the largest decrease over the North China Plain and southwest China. There was an increase of 20–100 mm over Central China. The decrease in precipitation over South and North China mainly occurred during the day, whereas the increase in precipitation over Central China mainly occurred at night which was caused by BC.
Mostrar más [+] Menos [-]Preparation of Activated Carbon from Sugarcane Bagasse Soot and Methylene Blue Adsorption Texto completo
2017
Giusto, Luana A. R. | Pissetti, Fábio L. | Castro, Talita S. | Magalhães, Fabiano
Sugarcane bagasse soot is an agro-industrial residue rich in carbon that can be transformed into value-added materials, such as activated carbons. Therefore, this work aimed at producing activated carbon from sugarcane bagasse soot, using CO₂ at 800, 850, and 900 °C, and investigating its efficiency to adsorb methylene blue as model contaminant. The results showed that the surface area and pore volume increased in the obtained carbons, with high specific areas (up to 829 m²/g), and the isotherms of the N₂ adsorption describe mesoporous materials. The morphology of the prepared activated carbons showed that sugarcane bagasse soot and the activated carbons kept the fibrous structure of sugarcane bagasse, but after activation, they have cavities that resemble a honeycomb. Adsorption studies with methylene blue dye showed that the activation process resulted in adsorption capacities up to 11 times higher than sugarcane bagasse soot, which is comparable with commercial activated carbon. Dye adsorption kinetics could be described by a pseudo-second-order dependency in the studied materials, and the adsorption isotherms were better fitted by the Langmuir model. It is emphasized that cost-effective materials that are similar to commercial activated carbon were obtained.
Mostrar más [+] Menos [-]Factors Affecting the Growth of Microalgae on Blackwater from Biosolid Dewatering Texto completo
2017
Marazzi, Francesca | Ficara, Elena | Fornaroli, Riccardo | Mezzanotte, Valeria
This paper discusses the possibility of including the culturing of microalgae within a conventional wastewater treatment sequence by growing them on the blackwater (BW) from biosolid dewatering to produce biomass to feed the anaerobic digester. Two photobioreactors were used: a 12 L plexiglas column for indoor, lab-scale tests and a 85 L plexiglas column for outdoor culturing. Microalgae (Chlorella sp. and Scenedesmus sp.) could easily grow on the tested blackwater. The average specific growth rate in indoor and outdoor batch tests was satisfactory, ranging between 0.14 and 0.16 day⁻¹. During a continuous test performed under outdoor conditions from May to November, in which the off-gas from the combined heat and power unit was used as the CO₂ source, an average biomass production of 50 mgTSS L⁻¹ day⁻¹ was obtained. However, statistical analyses confirmed that microalgal growth was affected by environmental conditions (temperature and season) and that it was negatively correlated with the occurrence of nitrification. Finally, the biochemical methane potential of the algal biomass was slightly higher than that from waste sludge (208 mLCH₄ gVS⁻¹ vs. 190 mLCH₄ gVS⁻¹).
Mostrar más [+] Menos [-]Bacterial Degraders of Coexisting Dichloromethane, Benzene, and Toluene, Identified by Stable-Isotope Probing Texto completo
2017
Yoshikawa, Miho | Zhang, Ming | Kurisu, Futoshi | Toyota, Koki
Most bioremediation studies on volatile organic compounds (VOCs) have focused on a single contaminant or its derived compounds and degraders have been identified under single contaminant conditions. Bioremediation of multiple contaminants remains a challenging issue. To identify a bacterial consortium that degrades multiple VOCs (dichloromethane (DCM), benzene, and toluene), we applied DNA-stable isotope probing. For individual tests, we combined a ¹³C-labeled VOC with other two unlabeled VOCs, and prepared three unlabeled VOCs as a reference. Over 11 days, DNA was periodically extracted from the consortia, and the bacterial community was evaluated by next-generation sequencing of bacterial 16S rRNA gene amplicons. Density gradient fractions of the DNA extracts were amplified by universal bacterial primers for the 16S rRNA gene sequences, and the amplicons were analyzed by terminal restriction fragment length polymorphism (T-RFLP) using restriction enzymes: HhaI and MspI. The T-RFLP fragments were identified by 16S rRNA gene cloning and sequencing. Under all test conditions, the consortia were dominated by Rhodanobacter, Bradyrhizobium/Afipia, Rhizobium, and Hyphomicrobium. DNA derived from Hyphomicrobium and Propioniferax shifted toward heavier fractions under the condition added with ¹³C-DCM and ¹³C-benzene, respectively, compared with the reference, but no shifts were induced by ¹³C-toluene addition. This implies that Hyphomicrobium and Propioniferax were the main DCM and benzene degraders, respectively, under the coexisting condition. The known benzene degrader Pseudomonas sp. was present but not actively involved in the degradation.
Mostrar más [+] Menos [-]Phytoremediation of Jordanian Uranium-Rich Soil Using Sunflower Texto completo
2017
Alsabbagh, Ahmad H. | Abuqudaira, Thabit M.
Uranium-contaminated environments pose a risk to human health by means of its transfer to the food chain. Overcoming this issue requires using effective methods to minimize the availability of uranium and other metals in soils. Jordan has a promising project for electricity generation from nuclear power. To move forward with this nuclear project, the Jordan Central Area has been mined for uranium. The expansion of the mining activities in this area led to elevated contents of heavy metal in the surface soil. Phytoremediation efficiency in reducing uranium content from uranium-rich carbonate soil was tested using sunflower plants. Forty-eight sunflower plants were planted in three soil samples containing three different uranium concentrations. The plants were harvested after different planting periods in order to investigate the phytoremediation efficiency over time. The ability of sunflowers to translocate uranium was investigated and the results showed that the translocated amount of uranium to plant increased as the initial concentration of uranium in the soil increased. However, most of the uranium taken up by the sunflower was accumulated in the roots, and only 3% of the uranium concentration in the roots passed to the harvestable shoots. Moreover, the biomass of the plants was not affected by increasing uranium concentration in the plants indicating that sunflower is resistant to radiation and toxicity of uranium at these levels found in the soil.
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