خيارات البحث
النتائج 2161 - 2170 من 62,084
The zebrafish embryotoxicity test (ZET) for nanotoxicity assessment: from morphological to molecular approach
2019
Pereira, Aryelle Canedo | Gomes, Tânia | Ferreira Machado, Mônica Rodrigues | Rocha, Thiago Lopes
Embargo until 28 June 2021 | Nanotechnology and use of nanomaterials (NMs) improve life quality, economic growth and environmental health. However, the increasing production and use of NMs in commercial products has led to concerns about their potential toxicity on human and environment health, as well as its toxicological classification and regulation. In this context, there is an urgent need to standardize and validate procedures for nanotoxicity testing. Since the zebrafish embryotoxicity test (ZET) has been indicated as a suitable approach for the toxicity assessment of traditional and emergent pollutants, the aim of this review is to summarize the existing literature on embryotoxic and teratogenic effects of NMs on zebrafish. In addition, morphological changes in zebrafish embryos induced by NMs were classified in four reaction models, allowing classification of the mode of action and toxicity of different types of NM. Revised data showed that the interaction and bioaccumulation of NMs on zebrafish embryos were associated to several toxic effects, while the detoxification process was limited. In general, NMs induced delayed hatching, circulatory changes, pigmentation and tegumentary alterations, musculoskeletal disorders and yolk sac alterations on zebrafish embryos. Recommendations for nanotoxicological tests are given, including guidance for future research. This review reinforces the use of the ZET as a suitable approach to assess the health risks of NM exposure. | publishedVersion
اظهر المزيد [+] اقل [-]Study on how oil type and weathering of crude oils affect interaction with sea ice and polyethylene skimmer material
2019
Øksenvåg, Jane Helén Carlsen | Fossen, Martin | Farooq, Umer
Understanding the fate of spilled oil in cold environments is essential for oil spill response in Arctic areas. The potential for oils to adhere to sea ice and mechanical skimmers can significantly impact the success of oil spill response and influence the fate of oil in the marine environment. Therefore, the affinity of oil to sea ice and skimmer material was quantified experimentally for three different types of oils at various degrees of weathering. Contact angle measurements of crude oil droplets were performed on the top of and under sea ice and polyethylene-based skimmer material, being submerged in seawater (−2 °C). In addition, “dip- and refloat” tests were performed to quantify the adhesion and study the re-floating process of oil from sea ice at −2 °C (moist ice) and −20 °C (cold dry ice), and from a skimmer material prior to and subsequently to its submersion in seawater (−2 °C). The results indicated limited interaction of oils with sea ice submerged in seawater, but a strong affinity of oils towards polyethylene-based skimmer material. | Study on how oil type and weathering of crude oils affect interaction with sea ice and polyethylene skimmer material | publishedVersion
اظهر المزيد [+] اقل [-]On the use of random walk schemes in oil spill modelling
2019
Nordam, Tor | Nepstad, Raymond | Litzler, Emma | Röhrs, Johannes
In oil spill models, vertical mixing due to turbulence is commonly modelled by random walk. If the eddy diffusivity varies with depth, failing to take the derivative of the diffusivity into account in the random walk scheme will lead to incorrect results. Depending on the diffusivity profile, the result may be either over- or underprediction of the amount of surfaced oil. The importance of using consistent random walk schemes has been known for decades in, e.g., the plankton modelling community. However, it appears not to be common knowledge in the oil spill community, with inconsistent random walk schemes appearing even in recent publications. We demonstrate and quantify the error due to inconsistent random walk, using a simplified oil spill model, and two different diffusivity profiles. In the two cases considered, a commonly used inconsistent scheme predicts respectively 54% and 202% the amount of surface oil, compared to a consistent scheme. | publishedVersion
اظهر المزيد [+] اقل [-]Benthic community status and mobilization of Ni, Cu and Co at abandoned sea deposits for mine tailings in SW Norway
2019
Schaanning, Morten Thorne | Trannum, Hilde Cecilie | Øxnevad, Sigurd | Ndungu, Kuria
During 1960–94 tailings from an ilmenite mine in southwest Norway were placed in sea deposits in a sheltered fjord and a more exposed coastal basin. In 2015 both deposit sites were sampled to assess the state of metal contamination and macrobenthic communities 20–30 years after deposition was ended. The results showed that nickel and copper still exceeded environmental quality standards in sediment and pore water from the 0–1 cm layer, and fluxes of nickel, copper and cobalt to the overlying water was high compared to adjacent reference stations. Fauna communities were classified as good, but moderate disturbance was recorded along an environmental gradient defined by depth and tailings-induced parameters such as particle size and copper. The results were interpreted in terms of current discharges, biological sediment reworking and near-surface leaching of metal sulphides. No evidence was found for recycling of metals from tailings buried below the bioturbated surface layer. | publishedVersion
اظهر المزيد [+] اقل [-]The effect of long-range transport, trophic position and diet specialization on legacy contaminant occurrence in great skuas, Stercorarius skua, breeding across the Northeast Atlantic
2019
Leat, Eliza Helen Kelsey | Bourgeon, Sophie | Hanssen, Sveinn Are | Petersen, Ævar | Strøm, Hallvard | Bjørn, Tor Harry | Gabrielsen, Geir W. | Bustnes, Jan Ove | Furness, Robert W. | Haarr, Ane | Borgå, Katrine
Embargo until 08 October 2020 | High levels of halogenated organic contaminants (HOCs) have been found in the marine predatory seabird great skua (Stercorarius skua) from breeding colonies in the Northeastern Atlantic, with large unexplained inter-colony variation. The present study aimed at analyzing if the HOCs occurrence in breeding great skuas in remote colonies was explained by local baseline food web exposure determined by long-range transport, or by ecological factors such as diet specialization and relative trophic position in the breeding area. The occurrence of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) was analyzed in plasma of 204 adult great skuas collected over two years (2008 and 2009) and 5 colonies across the North-Atlantic from Shetland to Svalbard. The ΣHOCs levels in plasma ranged across two orders of magnitude, from 40 to 7600 ng/g (wet weight) and differed significantly across the great skua colonies. The variation in contaminant occurrence among colonies did not reflect long-range transport through a latitudinal or remoteness gradient, as the second northernmost colony (Bjørnøya), had the highest contaminant concentrations. No latitudinal or remoteness gradient was evident in the contaminant pattern among the colonies. The contaminant levels increased significantly with increasing δ15N values, and regurgitated pellets of undigested prey suggested that great skuas with higher δ15N values had a higher proportion of bird prey in their diet, mostly seabirds. In contrast, great skuas from colonies with lower δ15N and lower contaminant level fed mostly on fish. The enrichment of δ13C increased with decreasing δ15N and lower contaminant levels. Therefore, individual behavior of great skuas, such as migration strategies and diet specialization, rather than long-range transport and thus baseline food web exposure, explain among and within colony variance in contaminant occurrence. | acceptedVersion
اظهر المزيد [+] اقل [-]An interlaboratory comparison exercise for the determination of microplastics in standard sample bottles
2019
Isobe, Atsuhiko | Buenaventura, Nina T | Chastain, Stephen | Chavanich, Suchana | Cózar, Andrés | DeLorenzo, Marie | Hagmann, Pascal | Hinata, Hirofumi | Kozlovskii, Nikolai | Lusher, Amy L | Martí, Elisa | Michida, Yutaka | Mu, Jingli | Ohno, Motomichi | Potter, Gael | Ross, Peter S | Sagawa, Nao | Shim, Won Joon | Song, Young Kyoung | Takada, Hideshige | Tokai, Tadashi | Torii, Takaaki | Uchida, Keiichi | Vassillenko, Katerina | Viyakarn, Voranop | Zhang, Weiwei
An interlaboratory comparison exercise was conducted to assess the consistency of microplastic quantification across several laboratories. The test samples were prepared by mixing one liter seawater free of plastics, microplastics made from polypropylene, high- and low-density polyethylene, and artificial particles in two plastic bottles, and analyzed concurrently in 12 experienced laboratories around the world. The minimum requirements to quantify microplastics were examined by comparing actual numbers of microplastics in these sample bottles with numbers measured in each laboratory. The uncertainty was due to pervasive errors derived from inaccuracies in measuring sizes and/or misidentification of microplastics, including both false recognition and overlooking. The size distribution of microplastics should be smoothed using a running mean with a length of >0.5 mm to reduce uncertainty to less than ±20%. The number of microplastics <1 mm was underestimated by 20% even when using the best practice for measuring microplastics in laboratories. | publishedVersion
اظهر المزيد [+] اقل [-]Plasma concentrations of organohalogenated contaminants in white-tailed eagle nestlings – The role of age and diet
2019
Løseth, M. E. | Briels, N. | Eulaers, I. | Nygård, T. | Malarvannan, G. | Poma, G. | Covaci, A. | Herzke, D. | Bustnes, J. O. | Lepoint, Gilles | Jenssen, B. M. | Jaspers, V. L. B.
peer reviewed | Concentrations of organohalogenated contaminants (OHCs) can show significant temporal and spatial variation in the environment and wildlife. Most of the variation is due to changes in use and production, but environmental and biological factors may also contribute to the variation. Nestlings of top predators are exposed to maternally transferred OHCs in the egg and through their dietary intake after hatching. The present study investigated spatial and temporal variation of OHCs and the role of age and diet on these variations in plasma of Norwegian white-tailed eagle (Haliaeetus albicilla) nestlings. The nestlings were sampled at two locations, Smøla and Steigen, in 2015 and 2016. The age of the nestlings was recorded (range: 44 – 87 days old) and stable carbon and nitrogen isotopes (δ13C and δ15N) were applied as dietary proxies for carbon source and trophic position, respectively. In total, 14 polychlorinated biphenyls (PCBs, range: 0.82 – 59.05 ng/mL), 7 organochlorinated pesticides (OCPs, range: 0.89 – 52.19 ng/mL), 5 polybrominated diphenyl ethers (PBDEs, range: 0.03 – 2.64 ng/mL) and 8 perfluoroalkyl substances (PFASs, range: 4.58 – 52.94 ng/mL) were quantified in plasma samples from each location and year. The OHC concentrations, age and dietary proxies displayed temporal and spatial variations. The age of the nestlings was indicated as the most important predictor for OHC variation as the models displayed significantly decreasing plasma concentrations of PCBs, OCPs, and PBDEs with increasing age, while concentrations of PFASs were significantly increasing with age. Together with age, the variations in PCB, OCP and PBDE concentrations were also explained by δ13C and indicated decreasing concentrations with a more marine diet. Our findings emphasise age and diet as important factors to consider when investigating variations in plasma OHC concentrations in nestlings. © 2018 Elsevier Ltd | 230465
اظهر المزيد [+] اقل [-]Microbial communities in seawater from an Arctic and a temperate Norwegian fjord and their potentials for biodegradation of chemically dispersed oil at low seawater temperatures | Microbial communities in seawater from an Arctic and a temperate Norwegian fjord and their potentials for biodegradation of chemically dispersed oil at low seawater temperatures
2018
Ribicic, Deni | Netzer, Roman | Winkler, Anika | Brakstad, Odd Gunnar
Biodegradation of chemically dispersed oil at low temperature (0–2 °C) was compared in natural seawater from Arctic (Svalbard) and a temperate (Norway) fjords. The oil was premixed with a dispersant (Corexit 9500) and small-droplet oil dispersions prepared. Faster biotransformation of n-alkanes in the Arctic than in the temperate seawater were associated with the initially higher abundance of the alkane-degrading genus Oleispira in the Arctic than the temperate seawater. Comparable transformation of aromatic hydrocarbons was further associated with the late emergences Cycloclasticus in both seawater sources. The results showed that chemically dispersed oil may be rapidly biodegraded by microbial communities in Arctic seawater. Compared to oil biodegradation studies at higher seawater temperatures, longer lag-periods were experienced here, and may be attributed to both microbial and oil properties at these low seawater temperatures. | acceptedVersion
اظهر المزيد [+] اقل [-]Marine microplastic debris: An emerging issue for food security, food safety and human health
2018
Barboza, Luís G.A. | Dick Vethaak, A | Lavorante, Beatriz RBO | Lundebye, Anne-Katrine | Guilhermino, Lucia
Recent studies have demonstrated the negative impacts of microplastics on wildlife. Therefore, the presence of microplastics in marine species for human consumption and the high intake of seafood (fish and shellfish) in some countries cause concern about the potential effects of microplastics on human health. In this brief review, the evidence of seafood contamination by microplastics is reviewed, and the potential consequences of the presence of microplastics in the marine environment for human food security, food safety and health are discussed. Furthermore, challenges and gaps in knowledge are identified. The knowledge on the adverse effects on human health due to the consumption of marine organisms containing microplastics is very limited, difficult to assess and still controversial. Thus, assessment of the risk posed to humans is challenging. Research is urgently needed, especially regarding the potential exposure and associated health risk to micro- and nano-sized plastics. | publishedVersion
اظهر المزيد [+] اقل [-]Les espaces périurbains : entre pollution des villes et pollution des champs aux échelles régionale et locale
2016
Stella, Patrick | Bedos, Carole | Génermont, Sophie, | Loubet, Benjamin | Personne, Erwan | Petit, Caroline, | Saint-Jean, Sébastien
Les territoires périurbains, zones de transition entre les zones urbaines et rurales, sont soumis à de nombreuses pollutions à la fois gazeuses et particulaires. Ces pollutions proviennent de sources locales comme les activités résidentielles, le trafic routier et les activités agricoles, mais également de sources régionales issues des activités urbaines et des émissions des zones (pseudo-)naturelles adjacentes. Cet article présente une synthèse des différentes sources de pollution affectant la qualité de l’air en milieu périurbain. Il est évident que les pollutions purement anthropiques ne peuvent être dissociées de celles issues du fonctionnement des écosystèmes (pseudo-)naturels dans ces espaces. Enfin, les enjeux vis-à-vis de l’agriculture périurbaine, fortement présente et en développement du fait d’une volonté de consommer des productions locales, sont discutés. | Periurban areas, zone of transition between urban and rural areas, are submitted to several sources of pollution, both gaseous and particulate. These pollutions originate from local sources such as residential sector, traffic road and agricultural activities, but also from regional ones from adjacent urban and (pseudo-)natural areas. This paper presents a synthesis of the different sources affecting air quality in periurban areas. It is clear that pollutions from anthropogenic activities cannot be fully dissociated to those from (pseudo-)natural ecosystem functioning in these areas. Finally, the atmospheric pollution issues are discussed in emphasis with periurban agriculture, already present and under development in these areas due to the development of short food supply chains and local food consumptions.
اظهر المزيد [+] اقل [-]