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31.
Dimer formation was observed during ultraviolet (UV) photolysis of the anti-inflammatory drug diclofenac, and confirmed with mass spectrometry, NMR and fluorescence analysis. The dimers were combinations of the two parent molecules or of the parent and the product of photolysis, and had visible color. Radical formation during UV exposure and dissolved oxygen photosensitized reactions played a role in dimer formation. Singlet oxygen formed via photosensitization by photolysis products of diclofenac. It reacted with diclofenac to form an epoxide which is an intermediate in some dimer formation pathways. Quantum yield of photolysis for diclofenac was 0.21 ± 0.02 and 0.19 ± 0.02 for UV irradiation from medium pressure and low pressure mercury vapor lamps, respectively. Band pass filter experiments revealed that the quantum yield is constant at wavelengths >200 nm. The same dimers formed in laboratory grade water when either of the two UV sources was used. Dimers did not form in wastewater effluent matrix, and diclofenac epoxide molecules may have formed bonds with organic matter rather than each other Implications for the importance of dimer formation in NOM are discussed. 相似文献
32.
Lígia M. Salvo Maria Ivette C. Malucelli José Roberto M. C. da Silva Geraldo C. Alberton Helena C. Silva De Assis 《Journal of environmental science and health. Part. B》2013,48(7):449-455
In this study, we used primary cultures of fish hepatic cells as a tool for evaluating the effects of environmental contamination. Primary hepatic cell cultures derived from the subtropical fish Metynnis roosevelti were exposed to different concentrations (0.275, 2.75 and 27.5 μg L?1) of the herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA). Cellular respiratory activity was evaluated by polarography using three substrates: 0.5 M glucose, 0.5 M succinate and 0.5 M α-ketoglutarate. Significant changes were observed in cellular oxygen consumption with 0.5 M α-ketoglutarate. Even at low concentrations, 2,4-D and MCPA were potent uncouplers of oxidative phosphorylation. Primary cultures of M. roosevelti liver cells may provide a useful tool for the evaluation of environmental contaminant effects. A review of regulations regarding permitted concentrations of these herbicides is needed. 相似文献
33.
Luis Cardona Mónica Revelles Mari Luz Parga Jesús Tomás Alex Aguilar Ferran Alegre Antonio Raga Xavier Ferrer 《Marine Biology》2009,156(12):2621-2630
Previous studies of loggerhead sea turtles have concluded that drifting longlines were the main threat for immature specimens
in the western Mediterranean, because immature loggerhead sea turtles mainly inhabit oceanic waters. However, recent aerial
surveys have revealed large numbers of immature loggerhead sea turtles over the continental shelf of eastern mainland Spain,
where turtles are exposed to neritic fishing gears but not to drifting longlines. We satellite-tracked seven loggerhead sea
turtles (minimum straight carapace length (SCLmin) range: 36.5–55.0 cm) to assess whether the turtles in this region are vagrants
from the adjoining oceanic regions or whether these loggerheads mostly inhabit the continental shelf. Satellite-tracking revealed
that six of the tagged turtles avoided the oceanic realm and made extended use of the continental shelf, whereas only one
individual could be considered a true vagrant as it avoided the continental shelf and primarily used the oceanic habitat.
These results are in sharp contrast with those previously reported for immature loggerhead sea turtles of similar size from
the south-western Mediterranean and fit well a relaxed ontogenic model that was recently proposed for loggerhead sea turtles
in the central Mediterranean. Furthermore, these results demonstrate the vulnerability of loggerhead sea turtles of eastern
mainland Spain to neritic fishing gears, as three of the seven turtles died and one was bycaught incidentally while being
tracked over the continental shelf. 相似文献
34.
This paper presents a sonographic diagnosis of exencephaly made during the last trimester of gestation. The sonogram showed the absence of bones in the cranial vault together with the presence of a disorganized cerebral mass, with loss of its normal anatomy. Post-partum examination of the newborn confirmed the findings of the sonogram. We briefly review the characteristics of exencephaly, its aetiology, and its relationship to anencephaly. 相似文献
35.
Bustamante Mercedes M. C. Silva José Salomão Scariot Aldicir Sampaio Alexandre Bonesso Vieira Daniel Luis Mascia Garcia Edenise Sano Edson Fernandes Geraldo Wilson Durigan Giselda Roitman Iris Figueiredo Isabel Rodrigues Ricardo Ribeiro Pillar Valério D. de Oliveira Alba Orli Malhado Ana Claudia Alencar Ane Vendramini Annelise Padovezi Aurélio Carrascosa Helena Freitas Joberto Siqueira José Alves Shimbo Julia Generoso Leonel Graça Tabarelli Marcelo Biderman Rachel de Paiva Salomão Rafael Valle Raul Junior Brienza Nobre Carlos 《Mitigation and Adaptation Strategies for Global Change》2020,25(4):735-736
Mitigation and Adaptation Strategies for Global Change - The original version of the article unfortunately contained an error. 相似文献
36.
The Allee effect (the positive relationship between population growth rate and population size) is a constraint of some animal populations at low numbers, which increases their likelihood of extinction because of a decrease in reproduction and/or survival. We were able to demonstrate that the Allee effect can be the result of a mortality increase affecting floaters (i.e. dispersing individuals able to enter as breeders in the reproductive population when a breeding territory or a potential mate – owner of a suitable breeding territory – becomes available). Previously, potential mechanisms underlying Allee effects were always related to the breeding portion of a population only. In contrast, our understanding of or solutions to population declines due to the Allee effects can reside elsewhere, away from breeding territories. 相似文献
37.
Pasquale Avino Geraldo Capannesi Alberto Rosada 《Environmental science and pollution research international》2014,21(6):4527-4538
Many studies have focused their attention on the determination of elements of toxicological and environmental interest in atmospheric particulate matter using analytical techniques requiring chemical treatments. The instrumental nuclear activation analysis technique allows achieving high sensitivity, good precision, and excellent limit of detection without pretreatment, also considering the problems related to the radioisotope characteristics (e.g., half-life time, interfering reactions, spectral interferences). In this paper, elements such as Al, As, Br, Cl, Cu, I, La, Mg, Mn, Na, Sb, Si, Ti, and V are studied in atmospheric PM10 sampled in downtown Rome: The relative radionuclides after activation of the sample are characterized by very short (ranging from 2.24 to 37.2 min) and short (ranging from 2.58 h to 2.70 days) half-lives. Furthermore, As, Br, La, Mn, and Sb were also determined for evaluating the aerosol characteristics. The results, elaborated considering the matrix effects and the interfering reaction contribution to the radioisotope formation (e.g., 28Al generated by both (n,γ) reaction from 27Al and (n,p) reaction from 28Si), show interesting values of As (0.3–6.1 ng m?3), Cu (22–313 ng m?3), Mn (17–125 ng m?3), V (7–63 ng m?3), higher than those determined in an area not influenced by autovehicular traffic, and significant levels of I (1–11 ng m?3) and Ti (25–659 ng m?3) in Rome PM10. The other elements show a pattern similar to the very few data present in the literature. It should be underlined the good correlation (r 2) of Al vs. Mg (0.915) and Al vs. La (0.726), indicating a same sources for these species as well as Br–Sb showing a little lower correlation (0.623). This last hypothesis is confirmed by the study of the enrichment factors: Sb and Br may be attributed to anthropogenic sources; Cu, Cl, and I show a mixed origin (natural and anthropogenic), whereas Al, Si, Ti, Mn, Na, Mg, and As are of crustal origin. For having more information, a statistical approach based on the principal component analysis and the canonical discriminant analysis has been performed: All the samples (except one) are grouped in a cluster, and elements such as As, Br, Cu, I, La, Mn, Sb, Ti, and V are highly correlated, whereas Na and Cl and Mg and Al assemble in two different clusters. Finally, a comparison with other similar studies is reported showing interesting values for Al, As, Mg, Mn, and Ti. 相似文献
38.
Lucas A. Salas Laia Font-Riber Mariona Bustamante Lauro Sumoy Joan O. Grimalt Sarah Bonnin Maria Aguilar Heidi Mattlin Manuela Hummel Anna Ferrer Manolis Kogevinas Cristina M. Villanueva 《环境科学学报(英文版)》2017,29(8):250-261
Exposure to disinfection by-products(DBP) such as trihalomethanes(THM) in swimming pools has been linked to adverse health effects in humans, but their biological mechanisms are unclear. We evaluated short-term changes in blood gene expression of adult recreational swimmers after swimming in a chlorinated pool. Volunteers swam 40 min in an indoor chlorinated pool. Blood samples were drawn and four THM(chloroform,bromodichloromethane, dibromochloromethane and bromoform) were measured in exhaled breath before and after swimming. Intensity of physical activity was measured as metabolic equivalents(METs). Gene expression in whole blood m RNA was evaluated using Illumina Human HT-12v3 Expression-Bead Chip. Linear mixed models were used to evaluate the relationship between gene expression changes and THM exposure. Thirty-seven before-after pairs were analyzed. The median increase from baseline to after swimming were: 0.7 to 2.3 for MET, and 1.4 to 7.1 μg/m~3 for exhaled total THM(sum of the four THM).Exhaled THM increased on average 0.94 μg/m~3 per 1 MET. While 1643 probes were differentially expressed post-exposure. Of them, 189 were also associated with exhaled levels of individual/total THM or MET after False Discovery Rate. The observed associations with the exhaled THM were low to moderate(Log-fold change range:-0.17 to 0.15). In conclusion, we identified short-term gene expression changes associated with swimming in a pool that were minor in magnitude and their biological meaning was unspecific. The high collinearity between exhaled THM levels and intensity of physical activity precluded mutually adjusted models with both covariates. These exploratory results should be validated in future studies. 相似文献
39.
Ontogeny of dispersal distances in young Spanish imperial eagles 总被引:1,自引:0,他引:1
M. Ferrer 《Behavioral ecology and sociobiology》1993,32(4):259-263
Summary I studied factors influencing dispersal distances in 30 young Spanish imperial eagles (Aquila adalberti) radio-tagged in southwestern Spain in 1986–1990. The mean dispersal distance between the natal nest and the settling area was 138 km. Every young bird reached its maximum dispersal distance within 4 months of its departure from the natal population. No significant differences between the sexes were detected in maximum dispersal distance, but females spent more time in the more distant settling areas. Dispersal distance was not related to the date of departure from the natal population. Dispersal distance was significantly longer for birds that hatched earlier and that had lower blood urea levels, indicating that better-nourished young had longer displacements. These results are not in accordance with the competitive displacement hypothesis. 相似文献
40.
Pollutant dispersion in wetland systems: Mathematical modelling and numerical simulation 总被引:1,自引:0,他引:1
In this paper we present and justify an original use of a diffusive-advective partial differential equation model, its discretization procedures and resulting numerical simulations for the dispersal of pollutants in an air–water system, with distinct behaviours in water and in air. The authors believe that the relevance of the developed work lies in its potential use in practical environmental assessment processes for the definition of both preventive and clean-up strategies. 相似文献