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421.
Description and evaluation of a sampling system for long-time monitoring of PAHs wet deposition 总被引:2,自引:0,他引:2
In this paper a new electronically controlled year-round wet-only sampler for wet deposition of trace organic compounds (e.g. airborne PAHs) is described. The sampler provides in situ filtration of the precipitation as well as preconcentration of nonpolar organic compounds by means of a C18-PAH modified silica gel cartridge. The whole assembly is insulated and equipped with heating elements which permit collection of wet deposition as ice or snow and insure correct function of the sampling system even during cold weather. Concurrent chemical analysis of both the particulate and the dissolved phases is performed by high resolution gas chromatography with flame ionization detection or HPLC with fluorescence detection. The reliability of the method was proved by analyzing PAH spiked water (simulated rain) and using NIST SRM 1649 ('urban dust') as certified material for particle-bound PAHs in precipitation. This study proved satisfactorily recoveries of as both particle-bound and unbound aqueous PAH, with only small losses to collector surfaces. It was proved that this new wet-only precipitation sampler can successfully be used for long-time monitoring of PAH in wet depositions in urban areas. 相似文献
422.
In this study the environmental fate of amitrole in terrestrial and aquatic model ecosystems was investigated. Under aerobic conditions mineralization of amitrole is the main degradation pathway. The experiments revealed that the leaching behaviour is low in the presence or the absence of dissolved organic matter (DOM) despite the high water solubility due to a strong binding of amitrole to soil constituents. Under anaerobic conditions the addition of DOM increases the transport of amitrole in soil columns. The tests with water/sediment model ecosystems showed that the mineralization of amitrole is lower in comparison to aerobic soil experiments. Up to 80.6% of the applied 14C-labelled amitrole transfer into the sediment and about 1/3 of this amount formed bound residues, which are not extractable. 相似文献
423.
424.
Wittmaack K 《Journal of the Air & Waste Management Association (1995)》2004,54(9):1091-1098
Size-selected aerosol samples were analyzed by scanning electron microscopy (SEM) to explore (1) the relative concentration of individual and aggregated carbon nanoparticles (C-NPs) and (2) the combustion behavior of C-NP agglomerates. SEM analysis of low-coverage aerosol deposits showed that most of the C-NP matter is present in the form of chain-type agglomerates. The individual C-NPs in the agglomerates are remarkably similar in diameter (40+/-5 nm) and appear to be very tightly bound to the neighboring NPs. Comparison with literature data suggests that the agglomerates originated from diesel exhaust. After gently removing the water-soluble compounds from relatively thick layers of aerosol matter, the residues were exposed to increasing temperatures, for 1 hr at each step, followed by SEM analysis of the same sample area. C-NP agglomerates were found to disappear rapidly at temperatures exceeding approximately 470 degrees C. This observation constitutes the first direct visualization of the combustion of what appears to be the most important fraction of elemental carbon in ambient aerosol matter. The experimental studies were complemented by simple model calculations that aimed at assessing the size-dependent mass fraction of individual C-NPs in ambient aerosol matter. The results suggest that the mass fraction decreases from 20+/-10% at particle diameters of approximately 30-40 nm to less than 0.1% above 300 nm. 相似文献
425.
Dittmar C Pfaffelmoser K Rötzer T Elling W 《Environmental pollution (Barking, Essex : 1987)》2005,134(1):1-4
Stand level O(3) fluxes were calculated using water balance calculations for 21 Common beech (Fagus sylvatica L.) stands and O(3) data from 20 monitoring stations in Southern Germany. For this intention, the daily loss of water by evapotranspiration per stand area was set against the daily O(3) uptake. During the last 30 years, O(3) uptake ranges between 0 and 187 mmol ha(-1) d(-1) per stand area. Cumulative O(3) uptake (CUO(3)), ranging between 0.1 and 0.7 mmol m(-2) yr(-1) per stand area, shows increasing trends since 1971 with considerably greater values at high altitudes. Effects in radial growth were used to derive an initial approximate critical threshold value for O(3) impacts on the vitality and growth of mature beech stands in Southern Germany. It is concluded that this concept of O(3) flux estimation in combination with dendroecological analyses offers both a site specific and regional applicable approach to derive new critical levels for O(3). 相似文献
426.
427.
The addition of N2O5 to 1-hexene in synthetic air results in 1,2-hexanedioldinitrate and 2-hexanon-1-ol-nitrate as the main products and some -hydroxy-1-ol-nitrate. In the reaction with cyclohexene, cis/trans-1,2-cyclohexanediol-dinitrate and cyclohexene-1-on-2-ol-nitrate have been detected. The addition of NO3 to isoprene produces 4-nitrato-3-methylbutenal-2. The reaction of NO3 with methylenecyclohexane and sabinene in air results in 1-(methylnitrate) cyclohexane-1-ol and both epimers of 1-(methylnitrate)-4-(isopropyl) cyclo-hexene-4-ol, respectively. The main products of the addition of NO3 to - and β-pinene were probably rearranged compounds of the limonene type: -pinene produces 1-(methyl)-2-(nitrato)-4-(2-propane-2-ol)-cyclohex-1-ene and β-pinene produces 1-(methylnitrate)-4-(2-propane-2-ol)cyclohex-1-ene. Other rearrangements give rise to a variety of nitrates and ketonitrates of structures as yet unknown in the - and β-pinene systems.
The probably particle-borne addition of NO2 to -pinene, β-pinene and camphene in air produces 2-nitrolimonene, 7-nitrolimonene and nitrocamphene as the main reaction products. 相似文献
428.
Richter S Steinhäuser KG 《Environmental science and pollution research international》2003,10(4):265-270
The 6th Intergovernmental Negotiating Committee (INC 6), under the Stockholm Convention on POPs, gave an expert group the mandate to develop guidelines for the application and implementation of best available techniques (BAT) and best environmental practices (BEP) for the prevention and reduction of unintentionally produced and emitted POPs, including polychlorinated dibenzodioxins/-furans (PCDD/Fs), polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB). Measures to reduce or eliminate the release of these POPs to the environment can be found in Article 5 of the Convention. BAT and BEP are already being applied as emission reduction instruments in a number of industrialised countries and are elements of other major international treaties, e.g. the UN ECE Protocol on POPs and the Marine Convention's OSPAR and HELCOM, and of the EU Directive for Integrated Pollution Prevention and Control (IPPC Directive). Existing concepts are presented and compared with the requirements of the Stockholm Convention. Consequences, perspectives and questions for the future intersessional work of the above-mentioned Expert Group are discussed. 相似文献
429.
Infrared spectrometry is a versatile basis to analyse greenhouse gases in the atmosphere. A multicomponent air pollution software (MAPS) was developed for retrieval of gas concentrations from radiation emission as well as absorption measurements. Concentrations of CO, CH4, N2O, and H2O as well as CO2, NO, NO2, NH3, SO2, HCl, HCHO, and the temperature of warm gases are determined on-line. The analyses of greenhouse gases in gaseous emission sources and in ambient air are performed by a mobile remote sensing system using the double-pendulum interferometer K300 of the Munich company Kayser-Threde. Passive radiation measurements are performed to retrieve CO, N2O, and H2O as well as CO2, NO, SO2, and HCl concentrations in smoke stack effluents of thermal power plants and municipal incinerators and CO and H2O as well as CO2 and NO in exhausts of aircraft engines. Open-path radiation measurements are used to determine greenhouse gas concentrations at different ambient air conditions and greenhouse gas emission rates of diffusive sources as garbage deposits, open coal mining, stock farming together with additional compounds (e.g. NH3), and from road traffic together with HCHO. Some results of measurements are shown. A future task is the verification of emission cadastres by these inspection measurements. 相似文献
430.
Karl-Werner Schramm Petra Marth Alexander Wolf Klaus Hahn Konstantin Oxynos Johannes Schmitzer und Antonius Kettrup 《Umweltwissenschaften und Schadstoff-Forschung》1999,11(5):277-280
Zusammenfassung Lipidbezogene Verteilungskoeffizienten (KLM/L) zwischen Muskelkonzentrationen-(CML) und Leberkonzentrationen (CLL) zweier Friedfischarten Brassen (Abramis brama) und Aalmutter (Zoarces viviparus) ergeben theoriekonform (KLM/L=CML/CLL=1) nominale Werte um 1 für persistente (hochchlorierte PCB) und Werte über 1 für metabolisierbare lipophile Umweltchemikalien
wie chlorierte Cyclohexane oder DDT.
相似文献