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Resultados 1031-1040 de 4,291
A facile and cost-effective method for removal of indoor airborne psychrotrophic bacterial and fungal flora based on silver and zinc oxide nanoparticles decorated on fibrous air filter
2017
Pokhum, Chonlada | Intasanta, Varol | Yaipimai, Wittaya | Subjalearndee, Nakarin | Srisitthiratkul, Chutima | Pongsorrarith, Voraluck | Phanomkate, Nipon | Chawengkijwanich, Chamorn
In tropical countries, food and agricultural crops need to be kept cool to reduce spoilage and quality losses. Airborne psychrotrophic bacteria and fungi can cause adverse effects on food quality and consumers' health safety. The present study aimed to present a facile and cost-effective approach to remove airborne microbes from indoor air by employing silver (Ag) and zinc oxide (ZnO) to decorate fibrous air filters. A water-based anti-germ solution containing Ag/ZnO nanoparticles was first prepared using high-speed homogenization. Second, a commercially available washable non-woven air filter (thickness 50 mm) was coated by aerosol generated from the mixture using spray coating process. This facile method successfully led to homogeneous coating of active nanomaterials on the filter's surface as unveiled by scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX). On laboratory scale, the Ag/ZnO air filter was shown to exhibit antibacterial effectiveness against Staphylococcus aureus and Escherichia coli under contact mode following an antibacterial standard method (AATCC 147-2011). Finally, the Ag/ZnO filter was assembled into a commercial air filtration system (670 × 820 × 1420 mm) containing two UVA light lamps (365 nm). The Ag/ZnO air-filtration unit was placed in a 45-m3 cold storage room (4–5 °C) for evaluation of airborne psychrotrophic microbial reduction efficiency. The developed Ag/ZnO air filter reduced the airborne psychrotrophic germs concentrations by ∼50% and its efficiency increased to ∼70% when combined with UVA illumination. Based on these results, a simple and low-cost ZnO/Ag air filter was successfully introduced as an effective strategy for removal of psychrotrophic microbes from indoor air.
Mostrar más [+] Menos [-]Spatial distribution of heavy hydrocarbons, PAHs and metals in polluted areas. The case of “Galicia”, Spain
2017
Monaco, D. | Chianese, E. | Riccio, A. | Delgado-Sanchez, A. | Lacorte, S.
The aim of this work is to verify the impact of anthropogenic activities and the effects of accidental events, e.g. oil spills, on the marine environment. For this reason, marine sediments and soil samples were collected in the inner part of Vigo and Pontevedra bays, in the Galicia region, northwest Spain, an area interested by many events of oil spills and also characterized by coastal areas with intense anthropic activities; also Cíes Islands, a natural protected area facing the Vigo bay, was investigated, as background site. PAHs, heavy hydrocarbons and metals were analyzed according to standard methods, in order to satisfy quality assurance and quality check constraints. Total PAHs concentration (Σ₁₆ compounds) were in the range of 25–4000ng/g, and 30–800ng/g for marine sediments and soil samples, respectively. Even some samples from the Cíes Islands, show a contamination with values achieving >200ng/g of PAHs. Although contamination levels have been shown to be strong at several locations in the study area, their ranges are those typical of other estuarine sites, with PAHs and hydrocarbons primarily of pyrolytic origin. This observation was further confirmed by enrichment factors of some metals (Cd, Cu, Pb and Zn) that match to those of harbor and shipyard zones of the main industrial and commercial maritime areas.
Mostrar más [+] Menos [-]Presence of arsenic, mercury and vanadium in aquatic organisms of Laizhou Bay and their potential health risk
2017
Liu, Yuan | Liu, Guijian | Yuan, Zijiao | Liu, Houqi | Lam, Paul K.S.
This study aims at describing and interpreting concentrations of arsenic (As), mercury (Hg) and vanadium (V) in seven species of fish, three species of shellfish, one species of crab and two species of shrimp from the typical estuary-bay ecosystem. Arsenic, Hg and V differed among species, and the highest As, Hg and V were observed in shellfish. The stable nitrogen (δ15N) and carbon (δ13C) isotopes were determined to investigate the trophic interactions between fluctuating environment and aquatic species. Arsenic concentrations in samples were found negatively correlated with δ15N, implying biodilution effect of As through the food web, while Hg concentrations in samples were positively correlated with δ15N, indicating their biomagnification effect. The estimated daily intake values of Hg and V in this study were all below the oral reference dose. However, elevated As intakes of some aquatic organisms suggested a potential risk for frequent consumers.
Mostrar más [+] Menos [-]An estimation of the average residence times and onshore-offshore diffusivities of beached microplastics based on the population decay of tagged meso- and macrolitter
2017
Hinata, Hirofumi | Mori, Keita | Ohno, Kazuki | Miyao, Yasuyuki | Kataoka, Tomoya
Residence times of microplastics were estimated based on the dependence of meso- and macrolitter residence times on their upward terminal velocities (UTVs) in the ocean obtained by one- and two-year mark-recapture experiments conducted on Wadahama Beach, Nii-jima Island, Japan. A significant linear relationship between the residence time and UTV was found in the velocity range of about 0.3–0.9ms−1, while there was no significant difference between the residence times obtained in the velocity range of about 0.9–1.4ms−1. This dependence on the UTV would reflect the uprush-backwash response of the target items to swash waves on the beach. By extrapolating the linear relationship down to the velocity range of microplastics, the residence times of microplastics and the 1D onshore-offshore diffusion coefficients were inferred, and are one to two orders of magnitude greater than the coefficients of the macroplastics.
Mostrar más [+] Menos [-]Shallow rocky nursery habitat for fish: Spatial variability of juvenile fishes among this poorly protected essential habitat
2017
Chemineé, Adrien | Rider, Mary | Lenfant, Philippe | Zawadzki, Audrey | Mercière, Alexandre | Crec'hriou, Romain | Mercader, Manon | Saragoni, Gilles | Neveu, Reda | Ternon, Quentin | Pastor, Jérémy
Coastal nursery habitats are essential for the renewal of adult fish populations. We quantified the availability of a coastal nursery habitat (shallow heterogeneous rocky bottoms) and the spatial variability of its juvenile fish populations along 250km of the Catalan coastline (France and Spain). Nurseries were present in 27% of the coastline, but only 2% of them benefited from strict protection status. For nine taxa characteristic of this habitat, total juvenile densities varied significantly between nursery sites along the coastline, with the highest densities being found on the northern sites. Recruitment level (i.e. a proxy of nursery value) was not explained by protection level, but it was moderately and positively correlated with an anthropization index. Patterns of spatial variations were taxa-specific. Exceptional observations of four juveniles of the protected grouper Epinephelus marginatus were recorded. Our data on habitat availability and recruitment levels provides important informations which help to focus MPA management efforts.
Mostrar más [+] Menos [-]Acute toxicity of organic antifouling biocides to phytoplankton Nitzschia pungens and zooplankton Artemia larvae
2017
Jung, S.M. | Bae, J.S. | Kang, S.G. | Son, J.S. | Jeon, J.H. | Lee, H.J. | Jeon, J.Y. | Sidharthan, M. | Ryu, SH | Shin, H.W.
The toxicity of the antifouling biocides Irgarol 1051, Diuron, Chlorothalonil, Dichlofluanid, Sea-nine 211, Copper pyrithione, Zinc pyrithione, Ziram and Zineb were evaluated on Nitzschia pungens and Artemia larvae. Results showed that EC50 for Irgarol 1051 was 0.586μgl−1 was the strongest effect on N. pungens following by Copper pyrithione (4.908μgl−1), Ziram (5.421μgl−1), Zinc pyrithione (5.513μgl−1), Diuron (6.640μgl−1), Zineb (232.249μgl−1), Sea-nine 211(267.368μgl−1), Chlorothalonil (360.963μgl−1) and Dichlofluanid (377.010μgl−1) in 96h. In Artemia larvae, the biocides were evaluated the LC50 for larval survivals at 48h. Sea-nine 211 and Copper pyrithione were 0.318 and 0.319mgl−1. Chlorothalonil, Zinc pyrithione and Ziram were 2.683, 3.147 and 4.778mgl−1. Irgarol 1051, Diuron, Zineb and Dichlofluanid were 9.734, 30.573, 41.170 and 154.944mgl−1. These results provide baseline data concerning the toxicity of antifouling biocides against marine environment.
Mostrar más [+] Menos [-]Occurrence and assessment of perfluoroalkyl acids (PFAAs) in commonly consumed seafood from the coastal area of Bangladesh
2017
Habibullah-Al-Mamun, Md | Ahmed, Md Kawser | Raknuzzaman, Mohammad | Islam, Md Saiful | Ali, Mir Mohammad | Tokumura, Masahiro | Masunaga, Shigeki
This study reports the first evidence of the occurrence of PFAAs in commonly consumed seafood from the coastal area of Bangladesh. Fifteen target PFAAs in 48 seafood samples (5 finfish and 2 shellfish species) were measured by HPLC-MS/MS. The ΣPFAAs in finfish and shellfish were in the range of 0.32–14.58 and 1.31–8.34 (ng/g wet weight), respectively. Perfluorooctanesulfonate (PFOS) in finfish (0.1–3.86ng/g ww), whereas perfluorooctanoic acid (PFOA) in shellfish (0.07–2.39ng/g ww) were the most abundant PFAAs. The results were comparable with other studies worldwide, particularly from China, Spain, Sweden, and USA. The majority of monitored PFAAs did not show clear seasonal variation. However, seafood from the southeast area (Cox's Bazar and Chittagong) showed relatively higher levels of PFAAs. Moreover, the dietary exposure assessment revealed that the daily intakes of PFAAs via seafood consumption were far less than the health-based guidelines, indicating low health risk for the Bangladeshi coastal residents.
Mostrar más [+] Menos [-]Widespread microplastic ingestion by fish assemblages in tropical estuaries subjected to anthropogenic pressures
2017
Vendel, A.L. | Bessa, F. | Alves, V.E.N. | Amorim, A.L.A. | Patrício, J. | Palma, A.R.T.
Our aim was to quantify microplastic ingestion by fish assemblages in two tropical Brazilian estuaries and to evaluate whether biological and ecological factors influence the ingestion of microplastics by fish species. Of 2233 fish from both estuaries (from 69 species) examined in this study, 9% of the individuals (24 species) had microplastics in their gut contents. Microplastic ingestion occurred irrespective of fish size and functional group. The diet of fish species was analyzed based on prey items identified in the fish's full stomach contents and five feeding guilds were defined. Microplastics were common throughout all feeding guilds. Low (average ingestion values 1.06±0.30 items/total fish) but widespread occurrence among estuaries also indicates proliferation of microplastic pollution. Our findings highlight the need to focus on assemblage level studies to understand the real magnitude of the problem and emphasize the urgency of mitigation measures directed at microplastic pollution in estuarine ecosystems.
Mostrar más [+] Menos [-]Characterization of emissions and residues from simulations of the Deepwater Horizon surface oil burns
2017
Gullett, Brian K. | Aurell, Johanna | Holder, Amara | Mitchell, William | Greenwell, Dale | Hays, Michael | Conmy, Robyn | Tabor, Dennis | Preston, William | George, Ingrid | Abrahamson, Joseph P. | Vander Wal, Randy | Holder, Edith
The surface oil burns conducted by the U.S. Coast Guard from April to July 2010 during the Deepwater Horizon disaster in the Gulf of Mexico were simulated by small scale burns to characterize the pollutants, determine emission factors, and gather particulate matter for subsequent toxicity testing. A representative crude oil was burned in ocean-salinity seawater, and emissions were collected from the plume by means of a crane-suspended sampling platform. Emissions included particulate matter, aromatic hydrocarbons, polychlorinated dibenzodioxins/dibenzofurans, elements, and others, the sum of which accounted for over 92% by mass of the combustion products. The unburned oil mass was 29% of the original crude oil mass, significantly higher than typically reported. Analysis of alkanes, elements, and PAHs in the floating residual oil and water accounted for over 51% of the gathered mass. These emission factors, along with toxicity data, will be important toward examining impacts of future spill burning operations.
Mostrar más [+] Menos [-]Hepatic trace element concentrations of breeding female common eiders across a latitudinal gradient in the eastern Canadian Arctic
2017
Mallory, Conor D. | Gilchrist, H Grant | Robertson, Gregory J. | Provencher, Jennifer F. | Braune, Birgit M. | Forbes, Mark R. | Mallory, Mark L.
We examined hepatic concentrations of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), manganese (Mn), mercury (Hg), rubidium (Rb), selenium (Se) and zinc (Zn) in 10 breeding female common eiders (Somateria mollissima) from each of three colonies across 20° of latitude. Levels of many elements were elevated in eiders, although generally below levels of toxicological concern. We found significant differences in concentrations of As, Rb, Hg, Mn and Se among colonies, but not in a consistent pattern with latitude, and Hg:Se molar ratios did not vary among colonies. Furthermore, overlap in element concentrations from birds at different colonies meant that we could not reliably differentiate birds from different colonies based on a suite of their hepatic trace element concentrations. We encourage other researchers to assess baseline trace element levels on this important, harvested species, as a means of tracking contamination of nearshore benthic environments in the circumpolar Arctic.
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