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31.
In this study the emissions of polycyclic aromatic hydrocarbons (PAH) and their nitro-derivates (NPAH) from a modern heavy duty engine were analysed. Focus was on the effects of the aftertreatment system. It consisted of an oxidation catalyst coupled to a diesel particulate filter (DPF). In such systems the process of PAH and NPAH degradation may compete with the NPAH formation. Scope of the study was to explain to which extent modern DPF could support the formation of highly mutagenic NPAH by nitration of pre-existing PAH. It was found that the diesel trap reduced the total amount of PAH and NPAH emitted both at low load and high load. Nevertheless, at low load the lower temperatures and the higher NO(2) concentration furnished better conditions for PAH nitration while they were more adverse to NPAH degradation. These effects were NPAH-specific. For these reasons, some NPAH like 3-nitrophenanthrene were still efficiently degraded but others were newly formed. For instance emissions of the highly toxic 1-benzo(a)pyrene and 6-nitrobenzo(a)pyrene where increased by a factor 15 at low load and, even if in lower amount, were formed also at high load. The super-mutagen 1,6-dinitropyrene, which was not present in raw exhaust, could be found only after the DPF, indicating a new formation. In regard to emissions from the active regeneration mode, tremendous high emissions of 1-nitropyrene were reported. More accurate investigation of such a regeneration mode would be of great interest for the future. 相似文献
32.
Federica Pognant Matteo Bo Chi Vuong Nguyen Pietro Salizzoni Marina Clerico 《Environmental Modeling and Assessment》2018,23(2):157-164
The use of wood biomass as a fuel for domestic and industrial heating systems allows for a reduction of CO2 emissions at a global scale, but it may also result in worse local air quality conditions, due to their emissions of particulate matter. The aim of this study is to assess the actual trend of atmospheric pollution in a study area, assuming that all heating systems are replaced by small size biomass boilers linked to the buildings through district heating network. Ground level concentrations of particulate matter, emitted by different heating systems, are therefore evaluated through numerical simulations performed by means of an atmospheric dispersion model (Sirane). As a first step, we have compared the environmental impact of a woodchip boilers network with that given by the use of traditional heating systems, i.e. wood stoves and natural gas boilers. As a second step, we have analysed the impact of such a network taking into account different emission scenarios, related to different boilers operating conditions. Results show that the environmental performances of a woodchip boilers network can be optimized by combining it with other renewable sources of energy devoted to the supply of hot water. The adopted analysis methodology can be applied to other real or hypothetic punctual sources on the territory. 相似文献
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Conedera Marco Wohlgemuth Thomas Tanadini Matteo Pezzatti Gianni Boris 《Regional Environmental Change》2018,18(2):425-436
Regional Environmental Change - The spread of non-native species into natural communities is a noticeable phenomenon linked to global change. Drivers of such invasions, however, may differ... 相似文献
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Hertwig Denise Soulhac Lionel Fuka Vladimír Auerswald Torsten Carpentieri Matteo Hayden Paul Robins Alan Xie Zheng-Tong Coceal Omduth 《Environmental Fluid Mechanics》2018,18(4):1007-1044
Environmental Fluid Mechanics - The need to balance computational speed and simulation accuracy is a key challenge in designing atmospheric dispersion models that can be used in scenarios where... 相似文献
37.
Rapid analysis of neonicotinoid insecticides in guttation drops of corn seedlings obtained from coated seeds 总被引:1,自引:0,他引:1
Tapparo A Giorio C Marzaro M Marton D Soldà L Girolami V 《Journal of environmental monitoring : JEM》2011,13(6):1564-1568
Regarding the hypothesis that neonicotinoid insecticides used for seed coating of agricultural crops - mainly corn, sunflower and seed rape - are related to the extensive death of honey bees, the phenomenon of corn seedling guttation has been recently considered as a possible route of exposure of bees to these systemic insecticides. In the present study, guttation drops of corn plants obtained from commercial seeds coated with thiamethoxam, clothianidin, imidacloprid and fipronil have been analyzed by an optimized fast UHPLC-DAD procedure showing excellent detection limits and accuracy, both adequate for the purpose. The young plants grown both in pots - in greenhouse - and in open field from coated seeds, produced guttation solutions containing high levels of the neonicotinoid insecticides (up to 346 mg L(-1) for imidacloprid, 102 mg L(-1) for clothianidin and 146 mg L(-1) for thiamethoxam). These concentration levels may represent lethal doses for bees that use guttation drops as a source of water. The neonicotinoid concentrations in guttation drops progressively decrease during the first 10-15 days after the emergence of the plant from the soil. Otherwise fipronil, which is a non-systemic phenylpyrazole insecticide, was never detected into guttation drops. Current results confirm that the physiological fluids of the corn plant can effectively transfer neonicotinoid insecticides from the seed onto the surface of the leaves, where guttation drops may expose bees and other insects to elevated doses of neurotoxic insecticides. 相似文献
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J. Büsch P. Huber E. Pflüger St. Miltenyi J. Holtz Professor Dr. A. Radbruch 《黑龙江环境通报》1994,14(12):1129-1140
For simple and effective isolation of fetal cells from peripheral maternal blood, we combined depletion of maternal cells and enrichment of fetal cells by high-gradient magnetic cell separation (MACS). First CD45+ and CD14+ cells were depleted from maternal peripheral blood mononuclear cells by MACS. From the depleted fraction, CD71+ erythroid cells were enriched up to 80 per cent by MACS. This ‘double-MACS’ procedure yielded an average depletion rate of 780-fold and an average enrichment rate of 500-fold, with approximate recovery rates of 40–55 per cent. For paternity testing, cells from unseparated blood and the various fractions were analysed for polymorphism of the HLA-DQ-A1 locus and D1S80 locus by the polymerase chain reaction (PCR). In CD45−/CD71+ sorted cells from maternal blood, but not in unfractionated cells from maternal blood or CD45−/CD14− cells, paternal alleles could be detected. In the CD45−/CD71+ fraction, the relative frequency of paternal alleles compared with maternal alleles ranged from 1 in 20 to 1 in 200 (determined by titration and depending on the quality of separation and biological variation). In 7 out of 11 cases, between weeks 12 and 25 of gestation, we could identify paternal alleles by PCR, either HLA-DQ-A1 or D1S80. This double-MACS procedure is simple, fast, efficient, and reliable for non-invasive prenatal diagnosis. 相似文献
40.
In repeat amniotic fluid cultures mosaicism due to trisomy 9 was noted. Autopsy of the aborted female fetus showed a sinus urogenitalis and gonadal dysgenesis with absence of germ cells only. Fetal lymphocytes and skin fibroblasts had a normal karyotype but trisomy 9 was found in cells grown from placenta. It is likely that trisomic cells were limited to fetal membranes. 相似文献