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1
Karlik, J. "Lesser-Known Atmospheric Compounds". Journal of Chemical Education 72, nr 12 (grudzień 1995): 1075. http://dx.doi.org/10.1021/ed072p1075.
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Sukhapan, Jariya, i Peter Brimblecombe. "Ionic Surface Active Compounds in Atmospheric Aerosols". Scientific World JOURNAL 2 (2002): 1138–46. http://dx.doi.org/10.1100/tsw.2002.188.
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Surfactants in the atmosphere have several potential roles in atmospheric chemistry. They can form films on aqueous surfaces, which lowers the surface tension and possibly delays water evaporation and gaseous transportation across the aqueous interface. They can also increase the solubility of organic compounds in the aqueous phase. Recently, the decrease of surface tension in cloud growing droplets has been suggested as relevant to increases in the number of droplets of smaller size, potentially enhancing cloud albedo. Natural surfactants in the lung aid gas transfer and influence the dissolution rate of aerosol particles, so surfactants in atmospheric aerosols, once inhaled, may interact with pulmonary surfactants. Ambient aerosols were collected from the edge of Norwich, a small city in a largely agricultural region of England, and analysed for surfactants. Methylene blue, a conventional dye for detecting anionic surfactants, has been used as a colorimetric agent. The concentration of surfactants expressed as methylene blue active substances (MBAS) is in the range of 6–170 pmol m-3(air). A negative correlation with chloride aerosol indicates that these surfactants are probably not the well-known surfactants derived from marine spray. A more positive correlation with aerosol nitrate and gaseous NOxsupports an association with more polluted inland air masses. The surfactants found in aerosols seem to be relatively strong acids, compared with weaker acids such as the long-chain carboxylic acids previously proposed as atmospheric surfactants. Surfactants from the oxidation of organic materials (perhaps vegetation- or soil-derived) seem a likely source of these substances in the atmosphere.
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Faxon, C. B., i D. T. Allen. "Chlorine chemistry in urban atmospheres: a review". Environmental Chemistry 10, nr 3 (2013): 221. http://dx.doi.org/10.1071/en13026.
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Environmental context Atmospheric chlorine radicals can affect the chemical composition of the atmosphere through numerous reactions with trace species. In urban atmospheres, the reactions of chlorine radicals can lead to effects such as increases in ozone production, thus degrading local and regional air quality. This review summarises the current understanding of atmospheric chlorine chemistry in urban environments and identifies key unresolved issues. Abstract Gas phase chlorine radicals (Cl•), when present in the atmosphere, react by mechanisms analogous to those of the hydroxyl radical (OH•). However, the rates of the Cl•-initiated reactions are often much faster than the corresponding OH• reactions. The effects of the atmospheric reactions of Cl• within urban environments include the oxidation of volatile organic compounds and increases in ozone production rates. Although concentrations of chlorine radicals are typically low compared to other atmospheric radicals, the relatively rapid rates of the reactions associated with this species lead to observable changes in air quality. This is particularly evident in the case of chlorine radical-induced localised increases in ozone concentrations. This review covers five aspects of atmospheric chlorine chemistry: (1) gas phase reactions; (2) heterogeneous and multi-phase reactions; (3) observational evidence of chlorine species in urban atmospheres; (4) regional modelling studies and (5) areas of uncertainty in the current state of knowledge.
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Skarżyńska, K., Ż. Polkowska i J. Namieśnik. "Sampling of Atmospheric Precipitation and Deposits for Analysis of Atmospheric Pollution". Journal of Automated Methods and Management in Chemistry 2006 (2006): 1–19. http://dx.doi.org/10.1155/jammc/2006/26908.
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This paper reviews techniques and equipment for collecting precipitation samples from the atmosphere (fog and cloud water) and from atmospheric deposits (dew, hoarfrost, and rime) that are suitable for the evaluation of atmospheric pollution. It discusses the storage and preparation of samples for analysis and also presents bibliographic information on the concentration ranges of inorganic and organic compounds in the precipitation and atmospheric deposit samples.
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Resende, Stella M., i Fernando R. Ornellas. "Thermochemistry of atmospheric sulfur compounds". Chemical Physics Letters 367, nr 3-4 (styczeń 2003): 489–94. http://dx.doi.org/10.1016/s0009-2614(02)01738-4.
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Lavrinenko, R. "Nitrogen compounds in atmospheric precipitation". Water, Air, & Soil Pollution 85, nr 4 (grudzień 1995): 2149–54. http://dx.doi.org/10.1007/bf01186152.
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Torokova, L., V. Mazankova, N. J. Mason, F. Krcma, G. Morgan i S. Matejcik. "The Influence of CO2 Admixtures on Process in Titan's Atmospheric Chemistry". PLASMA PHYSICS AND TECHNOLOGY 3, nr 3 (14.02.2016): 163–67. http://dx.doi.org/10.14311/ppt.2016.3.163.
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The exploration of planetary atmosphere is being advanced by the exciting results of the Cassin-Huygens mission to Titan. The complex chemistry revealed in such atmospheres leading to the synthesis of bigger molecules is providing new insights into our understanding of how life on Earth developed. In our experiments Titan's atmosphere is simulated in a glow discharge formed from a mixture of N<sub>2</sub>:CH<sub>4</sub>:CO<sub>2</sub> gas. Samples of the discharge gas were analysed by GC-MS and FTIR. The major products identified in spectra were: hydrogen cyanide, acetylene and acetonitrile. The same compounds were detected in the FTIR: hydrogen cyanide, acetylene and ammonia. Whilst many of these compounds have been predicted and/or observed in the Titan atmosphere, the present plasma experiments provide evidence of both the chemical complexity of Titan atmospheric processes and the mechanisms by which larger species grow prior to form the dust that should cover much of the Titan's surface.
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Radmilović-Radjenović, Marija, Martin Sabo i Branislav Radjenović. "Transport Characteristics of the Electrification and Lightning of the Gas Mixture Representing the Atmospheres of the Solar System Planets". Atmosphere 12, nr 4 (29.03.2021): 438. http://dx.doi.org/10.3390/atmos12040438.
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Electrification represents a fundamental process in planetary atmospheres, widespread in the Solar System. The atmospheres of the terrestrial planets (Venus, Earth, and Mars) range from thin to thick are rich in heavier gases and gaseous compounds, such as carbon dioxide, nitrogen, oxygen, argon, sodium, sulfur dioxide, and carbon monoxide. The Jovian planets (Jupiter, Saturn, Uranus, and Neptune) have thick atmospheres mainly composed of hydrogen and helium involving. The electrical discharge processes occur in the planetary atmospheres leading to potential hazards due to arcing on landers and rovers. Lightning does not only affect the atmospheric chemical composition but also has been involved in the origin of life in the terrestrial atmosphere. This paper is dealing with the transport parameters and the breakdown voltage curves of the gas compositions representing atmospheres of the planets of the Solar System. Ionization coefficients, electron energy distribution functions, and the mean energy of the atmospheric gas mixtures have been calculated by BOLSIG+. Transport parameters of the carbon dioxide rich atmospheric compositions are similar but differ from those of the Earth’s atmosphere. Small differences between parameters of the Solar System’s outer planets can be explained by a small abundance of their constituent gases as compared to the abundance of hydrogen. Based on the fit of the reduced effective ionization coefficient, the breakdown voltage curves for atmospheric mixtures have been plotted. It was found that the breakdown voltage curves corresponding to the atmospheres of Solar System planets follow the standard scaling law. Results of calculations satisfactorily agree with the available data from the literature. The minimal and the maximal value of the voltage required to trigger electric breakdown is obtained for the Martian and Jupiter atmospheres, respectively.
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Pasquini, Dalila, Antonella Gori, Francesco Ferrini i Cecilia Brunetti. "An Improvement of SPME-Based Sampling Technique to Collect Volatile Organic Compounds from Quercus ilex at the Environmental Level". Metabolites 11, nr 6 (14.06.2021): 388. http://dx.doi.org/10.3390/metabo11060388.
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Biogenic Volatile Organic Compounds (BVOCs) include many chemical compounds emitted by plants into the atmosphere. These compounds have a great effect on biosphere–atmosphere interactions and may affect the concentration of atmospheric pollutants, with further consequences on human health and forest ecosystems. Novel methods to measure and determine BVOCs in the atmosphere are of compelling importance considering the ongoing climate changes. In this study, we developed a fast and easy-to-handle analytical methodology to sample these compounds in field experiments using solid-phase microextraction (SPME) fibers at the atmospheric level. An improvement of BVOCs adsorption from SPME fibers was obtained by coupling the fibers with fans to create a dynamic sampling system. This innovative technique was tested sampling Q. ilex BVOCs in field conditions in comparison with the conventional static SPME sampling technique. The results showed a great potential of this dynamic sampling system to collect BVOCs at the atmosphere level, improving the efficiency and sensitivity of SPME fibers. Indeed, our novel device was able to reduce the sampling time, increase the amount of BVOCs collected through the fibers and add information regarding the emissions of these compounds at the environmental level.
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Grankin, Dmitry, Irina Mironova, Galina Bazilevskaya, Eugene Rozanov i Tatiana Egorova. "Atmospheric Response to EEP during Geomagnetic Disturbances". Atmosphere 14, nr 2 (30.01.2023): 273. http://dx.doi.org/10.3390/atmos14020273.
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Energetic electron precipitation (EEP) is associated with solar activity and space weather and plays an important role in the Earth’s polar atmosphere. Energetic electrons from the radiation belt precipitate into the atmosphere during geomagnetic disturbances and cause additional ionization rates in the polar middle atmosphere. These induced atmospheric ionization rates lead to the formation of radicals in ion-molecular reactions at the heights of the mesosphere and upper stratosphere with the formation of reactive compounds of odd nitrogen NOy and odd hydrogen HOx groups. These compounds are involved in catalytic reactions that destroy the ozone. In this paper, we present the calculation of atmospheric ionization rates during geomagnetic disturbances using reconstructed spectra of electron precipitation from balloon observations; estimation of ozone destruction during precipitation events using one-dimensional photochemical radiation-convective models, taking into account both parameterization and ion chemistry; as well as provide an estimation of electron density during these periods.
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Li, Zijun, Noora Hyttinen, Miika Vainikka, Olli-Pekka Tikkasalo, Siegfried Schobesberger i Taina Yli-Juuti. "Saturation vapor pressure characterization of selected low-volatility organic compounds using a residence time chamber". Atmospheric Chemistry and Physics 23, nr 12 (21.06.2023): 6863–77. http://dx.doi.org/10.5194/acp-23-6863-2023.
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Abstract. Saturation vapor pressure (psat) is an important thermodynamic property regulating the gas-to-particle partitioning of organic compounds in the atmosphere. Low-volatility organic compounds (LVOCs), with sufficiently low psat values, primarily stay in the particle phase and contribute to aerosol formation. Obtaining accurate information on the psat of LVOCs requires volatility measurements performed at temperatures relevant to atmospheric aerosol formation. Here, we present an isothermal evaporation method using a residence time chamber to measure psat for dry single-compound nanoparticles at 295 K. Our method is able to characterize organic compounds with psat spanning from 10−8 to 10−4 Pa at 295 K. The compounds included four polyethylene glycols (PEGs: PEG6, PEG7, PEG8, and PEG9), two monocarboxylic acids (palmitic acid and stearic acid), two dicarboxylic acids (azelaic acid and sebacic acid), two alcohols (meso-erythritol and xylitol), and one ester (di-2-ethylhexyl sebacate). There was a good agreement between our measured psat values and those reported by previous volatility studies using different measurement techniques, mostly within 1 order of magnitude. Additionally, quantum-chemistry-based COSMOtherm calculations were performed to estimate the psat values of the studied compounds. COSMOtherm predicted the psat values for most of the studied compounds within 1 order of magnitude difference between the experimental and computational estimates.
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Johnson, Jack S., i Coty N. Jen. "A sulfuric acid nucleation potential model for the atmosphere". Atmospheric Chemistry and Physics 22, nr 12 (27.06.2022): 8287–97. http://dx.doi.org/10.5194/acp-22-8287-2022.
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Abstract. Observations over the last decade have demonstrated that the atmosphere contains potentially hundreds of compounds that can react with sulfuric acid to nucleate stable aerosol particles. Consequently, modeling atmospheric nucleation requires detailed knowledge of nucleation reaction kinetics and spatially and temporally resolved measurements of numerous precursor compounds. This study introduces the Nucleation Potential Model (NPM), a novel nucleation model that dramatically simplifies the diverse reactions between sulfuric acid and any combination of precursor gases. The NPM predicts 1 nm nucleation rates from only two measurable gas concentrations, regardless of whether all precursor gases are known. The NPM describes sulfuric acid nucleating with a parameterized base compound at an effective base concentration, [Beff]. [Beff] captures the ability of a compound or mixture to form stable clusters with sulfuric acid and is estimated from measured 1 nm particle concentrations. The NPM is applied to experimental and field observations of sulfuric acid nucleation to demonstrate how [Beff] varies for different stabilizing compounds, mixtures, and sampling locations. Analysis of previous field observations shows distinct differences in [Beff] between locations that follow the emission sources and stabilizing compound concentrations for that region. Overall, the NPM allows researchers to easily model nucleation across diverse environments and estimate the concentration of non-sulfuric acid precursors using a condensation particle counter.
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Atkinson, Roger, i Janet Arey. "Atmospheric Degradation of Volatile Organic Compounds". Chemical Reviews 103, nr 12 (grudzień 2003): 4605–38. http://dx.doi.org/10.1021/cr0206420.
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Grosjean, Daniel. "Atmospheric fate of toxic aromatic compounds". Science of The Total Environment 100 (marzec 1991): 367–414. http://dx.doi.org/10.1016/0048-9697(91)90386-s.
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Atkinson, Roger, i Janet Arey. "Atmospheric Chemistry of Biogenic Organic Compounds". Accounts of Chemical Research 31, nr 9 (wrzesień 1998): 574–83. http://dx.doi.org/10.1021/ar970143z.
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Ariya, Parisa A., Oleg Nepotchatykh, Olga Ignatova i Marc Amyot. "Microbiological degradation of atmospheric organic compounds". Geophysical Research Letters 29, nr 22 (listopad 2002): 34–1. http://dx.doi.org/10.1029/2002gl015637.
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Jones, Colleen P., Seth N. Lyman, Daniel A. Jaffe, Tanner Allen i Trevor L. O'Neil. "Detection and quantification of gas-phase oxidized mercury compounds by GC/MS". Atmospheric Measurement Techniques 9, nr 5 (18.05.2016): 2195–205. http://dx.doi.org/10.5194/amt-9-2195-2016.
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Abstract. Most mercury pollution is emitted to the atmosphere, and the location and bioavailability of deposited mercury largely depends on poorly understood atmospheric chemical reactions that convert elemental mercury into oxidized mercury compounds. Current measurement methods do not speciate oxidized mercury, leading to uncertainty about which mercury compounds exist in the atmosphere and how oxidized mercury is formed. We have developed a gas chromatography/mass spectrometry (GC-MS)-based system for identification and quantification of atmospheric oxidized mercury compounds. The system consists of an ambient air collection device, a thermal desorption module, a cryofocusing system, a gas chromatograph, and an ultra-sensitive mass spectrometer. It was able to separate and identify mercury halides with detection limits low enough for ambient air collection (90 pg), but an improved ambient air collection device is needed. The GC/MS system was unable to quantify HgO or Hg(NO3)2, and data collected cast doubt upon the existence of HgO in the gas phase.
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Derendorp, Leonie, Rupert Holzinger i Thomas Röckmann. "UV-induced emissions of C2 - C5 hydrocarbons from leaf litter". Environmental Chemistry 8, nr 6 (2011): 602. http://dx.doi.org/10.1071/en11024.
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Environmental contextLeaf litter can be found at the Earth’s surface in large quantities, and has the potential to release significant amounts of volatile compounds into the atmosphere where they influence atmospheric chemistry and local air quality. This study investigates the influence of UV radiation on the emission of C2–C5 hydrocarbons from leaf litter. Research on volatile compound emissions from leaf litter is limited, but essential for establishing their global budgets and understanding atmospheric chemistry. AbstractLeaf litter is available at many locations at the Earth’s surface. It has the potential to emit many different types of volatile organic compounds (VOCs) into the atmosphere, which may influence local atmospheric chemistry and air quality. In this study, emissions of several C2–C5 hydrocarbons from leaf litter were measured for different plant species and the influence of ultraviolet (UV) radiation on the emissions was determined. Within the ambient range of UV intensities, the emission rates increased linearly with the intensity of the UV radiation. UVB radiation (280–320 nm) was more efficient in the generation of hydrocarbons from leaf litter than UVA (320–400 nm). In the absence of oxygen, no emissions of C2–C5 hydrocarbons were observed. When leaf litter was placed in humid air, emission rates approximately tripled compared with emissions from leaf litter in dry air. Decay of the emission rates was visible on a timescale of months. A simple upscaling showed that UV-induced hydrocarbon emissions from leaf litter might have a small influence on atmospheric chemistry on the local scale, but do not contribute significantly to their global budgets.
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Jenkin, Michael E., Richard Valorso, Bernard Aumont, Andrew R. Rickard i Timothy J. Wallington. "Estimation of rate coefficients and branching ratios for gas-phase reactions of OH with aliphatic organic compounds for use in automated mechanism construction". Atmospheric Chemistry and Physics 18, nr 13 (4.07.2018): 9297–328. http://dx.doi.org/10.5194/acp-18-9297-2018.
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Abstract. Reaction with the hydroxyl (OH) radical is the dominant removal process for volatile organic compounds (VOCs) in the atmosphere. Rate coefficients for reactions of OH with VOCs are therefore essential parameters for chemical mechanisms used in chemistry transport models, and are required more generally for impact assessments involving the estimation of atmospheric lifetimes or oxidation rates for VOCs. Updated and extended structure–activity relationship (SAR) methods are presented for the reactions of OH with aliphatic organic compounds, with the reactions of aromatic organic compounds considered in a companion paper. The methods are optimized using a preferred set of data including reactions of OH with 489 aliphatic hydrocarbons and oxygenated organic compounds. In each case, the rate coefficient is defined in terms of a summation of partial rate coefficients for H abstraction or OH addition at each relevant site in the given organic compound, so that the attack distribution is defined. The information can therefore guide the representation of the OH reactions in the next generation of explicit detailed chemical mechanisms. Rules governing the representation of the subsequent reactions of the product radicals under tropospheric conditions are also summarized, specifically their reactions with O2 and competing processes.
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Jenkin, Michael E., Richard Valorso, Bernard Aumont, Andrew R. Rickard i Timothy J. Wallington. "Estimation of rate coefficients and branching ratios for gas-phase reactions of OH with aromatic organic compounds for use in automated mechanism construction". Atmospheric Chemistry and Physics 18, nr 13 (4.07.2018): 9329–49. http://dx.doi.org/10.5194/acp-18-9329-2018.
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Abstract. Reaction with the hydroxyl (OH) radical is the dominant removal process for volatile organic compounds (VOCs) in the atmosphere. Rate coefficients for the reactions of OH with VOCs are therefore essential parameters for chemical mechanisms used in chemistry transport models, and are required more generally for impact assessments involving estimation of atmospheric lifetimes or oxidation rates for VOCs. A structure–activity relationship (SAR) method is presented for the reactions of OH with aromatic organic compounds, with the reactions of aliphatic organic compounds considered in the preceding companion paper. The SAR is optimized using a preferred set of data including reactions of OH with 67 monocyclic aromatic hydrocarbons and oxygenated organic compounds. In each case, the rate coefficient is defined in terms of a summation of partial rate coefficients for H abstraction or OH addition at each relevant site in the given organic compound, so that the attack distribution is defined. The SAR can therefore guide the representation of the OH reactions in the next generation of explicit detailed chemical mechanisms. Rules governing the representation of the reactions of the product radicals under tropospheric conditions are also summarized, specifically the rapid reaction sequences initiated by their reactions with O2.
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Mariano-Nasser, Flávia Aparecida de Carvalho, Cristine Vanz Borges, Juliana Arruda Ramos, Maurício Dominguez Nasser, Giovanna Alencar Lundgren, Karina Aparecida Furlaneto, Tânia Regina Kovalski i Rogério Lopes Vieites. "Bioactive compounds and enzymatic activity in minimally processed eggplant packedunderactive modified atmosphere". Semina: Ciências Agrárias 40, nr 1 (15.02.2019): 139. http://dx.doi.org/10.5433/1679-0359.2019v40n1p139.
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The study aimed to assess bioactive compounds and polyphenoloxidase activity of minimally processed eggplants stored in different atmospheres. Eggplants (Solanum melongena L.; cv. Ciça) were minimally processed (MP), sanitized and treated with a 2% citric acid solution. They were packed in plastic containers (vacuum) of nylon + transparent polyethylene and submitted to modified atmospheres with the following concentrations of gases: control (atmospheric air), vacuum, 4% O2 + 5% CO2,4% O2 + 6% CO2, 4% O2 + 7% CO2, and 4% O2 + 8% CO2, being stored in a cold chamber (5 ± 1 °C and 90 ± 1% relative humidity) for 10 days. The analyses consisted of the total phenolic compounds, total antioxidant activity, flavonoids, and polyphenoloxidase activity. The experimental design was a completely randomized design in a 6 × 6 factorial scheme (treatment vs. storage period). The data were submitted to analysis of variance and a regression analysis was performed for storage time. The active modified atmosphere with 8% CO2 is effective in reducing the polyphenoloxidase activity in minimally processed eggplant. The contents of phenolic compounds and flavonoids of minimally processed eggplant decrease with storage.
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Sellegri, K., B. Umann, M. Hanke i F. Arnold. "Deployment of a ground-based CIMS apparatus for the detection of organic gases in the boreal forest during the QUEST campaign". Atmospheric Chemistry and Physics 5, nr 2 (8.02.2005): 357–72. http://dx.doi.org/10.5194/acp-5-357-2005.
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Abstract. Measurements of atmospheric volatile organic compounds were performed in the Finnish Boreal forest atmosphere during spring 2003, as part of the project QUEST (Quantification of Aerosol Nucleation in the European Boundary Layer), using a ground-based Chemical Ionization Mass Spectrometer (CIMS) instrument. Based on the study of their hydrate distribution, methanol, acetonitrile, acetaldehyde, dimethyl amine (DMA), ethanol/formic acid, acetone, trimethyl amine (TMA), propanol/acetic acid, isoprene, methyl vinyl ketone (MVK) and metacrolein (MaCR), monoterpenes and monoterpene oxidation product (MTOP) are proposed as candidates for masses 32, 41, 44, 45, 46, 58, 59, 60, 68, 70, 136, and 168amu, respectively. It would be, to our knowledge, the first time DMA, TMA and MTOP are measured with this method. Most compounds show a clear diurnal variation with a maximum in the early night, corresponding to the onset of the noctural inversion and in agreement with independant measurements of CO. Biogenic compounds are highly correlated with each other and the ratio monoterpene/oxidation product shows a typical daily pattern of nightime maxima. However, because isoprene mixing ratios are also maximum during the early night, it is likely that it suffers of the interference from another unidentified biogenic compound. Hence mass 68amu is identified as isoprene+compound X.
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Baker, A. K., F. Slemr i C. A. M. Brenninkmeijer. "Analysis of non-methane hydrocarbons in air samples collected aboard the CARIBIC passenger aircraft". Atmospheric Measurement Techniques Discussions 2, nr 5 (6.10.2009): 2377–401. http://dx.doi.org/10.5194/amtd-2-2377-2009.
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Abstract. The CARIBIC project (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) is a long-term monitoring program making regular atmospheric measurements from an instrument container installed monthly aboard a passenger aircraft. Typical cruising altitudes of the aircraft allow for the study of the free troposphere and the extra-tropical upper troposphere as well as the lowermost stratosphere. CARIBIC measurements include a number of real time analyses as well as the collection of aerosol and whole air samples. These whole air samples are analyzed post-flight for a suite of trace gases, which includes non-methane hydrocarbons (NMHC). The NMHC measurement system and its analytical performance are described here. Precision was found to vary slightly by compound, and is less than 2% for the C2–C6 alkanes and ethyne, and between 1 and 6% for C7–C8 alkanes and aromatic compounds. Preliminary results from participation in a Global Atmospheric Watch (WMO) VOC audit indicate accuracies within the precision of the system. Limits of detection are 1 pptv for most compounds, and up to 3 pptv for some aromatics. These are sufficiently low to measure mixing ratios typically observed in the upper troposphere and lowermost stratosphere for the longer-lived NMHC, however, in air samples from these regions many of the compounds with shorter lifetimes (<5 d) were frequently below the detection limit. Observed NMHC concentrations span many orders of magnitude, dependent on atmospheric region and air mass history, with concentrations typically decreasing with shorter chemical lifetimes.
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Baker, A. K., F. Slemr i C. A. M. Brenninkmeijer. "Analysis of non-methane hydrocarbons in air samples collected aboard the CARIBIC passenger aircraft". Atmospheric Measurement Techniques 3, nr 1 (26.02.2010): 311–21. http://dx.doi.org/10.5194/amt-3-311-2010.
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Abstract. The CARIBIC project (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) is a long-term monitoring program making regular atmospheric measurements from an instrument container installed monthly aboard a passenger aircraft. Typical cruising altitudes of the aircraft allow for the study of the free troposphere and the extra-tropical upper troposphere as well as the lowermost stratosphere. CARIBIC measurements include a number of real time analyses as well as the collection of aerosol and whole air samples. These whole air samples are analyzed post-flight for a suite of trace gases, which includes non-methane hydrocarbons (NMHC). The NMHC measurement system and its analytical performance are described here. Precision was found to vary slightly by compound, and is less than 2% for the C2–C6 alkanes and ethyne, and between 1% and 6% for C7–C8 alkanes and aromatic compounds. Preliminary results from participation in a Global Atmospheric Watch (WMO) VOC audit indicate accuracies within the precision of the system. Limits of detection are 1 pptv for most compounds, and up to 3 pptv for some aromatics. These are sufficiently low to measure mixing ratios typically observed in the upper troposphere and lowermost stratosphere for the longer-lived NMHC, however, in air samples from these regions many of the compounds with shorter lifetimes (<5 days) were frequently below the detection limit. Observed NMHC concentrations span several orders of magnitude, dependent on atmospheric region and air mass history, with concentrations typically decreasing with shorter chemical lifetimes.
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Prather, M. J. "Photolysis rates in correlated overlapping cloud fields: Cloud-J 7.3c". Geoscientific Model Development 8, nr 8 (14.08.2015): 2587–95. http://dx.doi.org/10.5194/gmd-8-2587-2015.
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Abstract. A new approach for modeling photolysis rates (J values) in atmospheres with fractional cloud cover has been developed and is implemented as Cloud-J – a multi-scattering eight-stream radiative transfer model for solar radiation based on Fast-J. Using observations of the vertical correlation of cloud layers, Cloud-J 7.3c provides a practical and accurate method for modeling atmospheric chemistry. The combination of the new maximum-correlated cloud groups with the integration over all cloud combinations by four quadrature atmospheres produces mean J values in an atmospheric column with root mean square (rms) errors of 4 % or less compared with 10–20 % errors using simpler approximations. Cloud-J is practical for chemistry–climate models, requiring only an average of 2.8 Fast-J calls per atmosphere vs. hundreds of calls with the correlated cloud groups, or 1 call with the simplest cloud approximations. Another improvement in modeling J values, the treatment of volatile organic compounds with pressure-dependent cross sections, is also incorporated into Cloud-J.
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Prather, M. J. "Photolysis rates in correlated overlapping cloud fields: Cloud-J 7.3". Geoscientific Model Development Discussions 8, nr 5 (27.05.2015): 4051–73. http://dx.doi.org/10.5194/gmdd-8-4051-2015.
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Abstract. A new approach for modeling photolysis rates (J values) in atmospheres with fractional cloud cover has been developed and implemented as Cloud-J – a multi-scattering eight-stream radiative transfer model for solar radiation based on Fast-J. Using observed statistics for the vertical correlation of cloud layers, Cloud-J 7.3 provides a practical and accurate method for modeling atmospheric chemistry. The combination of the new maximum-correlated cloud groups with the integration over all cloud combinations represented by four quadrature atmospheres produces mean J values in an atmospheric column with root-mean-square errors of 4% or less compared with 10–20% errors using simpler approximations. Cloud-J is practical for chemistry-climate models, requiring only an average of 2.8 Fast-J calls per atmosphere, vs. hundreds of calls with the correlated cloud groups, or 1 call with the simplest cloud approximations. Another improvement in modeling J values, the treatment of volatile organic compounds with pressure-dependent cross sections is also incorporated into Cloud-J.
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Epstein, S. A., E. Tapavicza, F. Furche i S. A. Nizkorodov. "Direct photolysis of carbonyl compounds dissolved in cloud and fog~droplets". Atmospheric Chemistry and Physics 13, nr 18 (26.09.2013): 9461–77. http://dx.doi.org/10.5194/acp-13-9461-2013.
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Abstract. Gas-phase photolysis is an important tropospheric sink for many carbonyl compounds; however the significance of direct photolysis of these compounds dissolved in cloud and fog droplets is uncertain. We develop a theoretical approach to assess the importance of aqueous photolysis for a series of carbonyls that possess carboxyl and hydroxyl functional groups by comparison with rates of other atmospheric processes. We use computationally and experimentally derived effective Henry's law constants, hydration equilibrium parameters, aqueous hydroxyl radical (OH) rate constants, and optical extinction coefficients to identify types of compounds that will (or will not) have competitive aqueous photolysis rates. We also present molecular dynamics simulations designed to estimate gas- and aqueous-phase extinction coefficients of unstudied atmospherically relevant compounds found in d-limonene and isoprene secondary organic aerosol. In addition, experiments designed to measure the photolysis rate of glyceraldehyde, an atmospherically relevant water-soluble organic compound, reveal that aqueous quantum yields are highly molecule-specific and cannot be extrapolated from measurements of structurally similar compounds. We find that only two out of the 92 carbonyl compounds investigated, pyruvic acid and acetoacetic acid, may have aqueous photolysis rates that exceed the rate of oxidation by dissolved OH. For almost all carbonyl compounds lacking α,β-conjugation that were investigated, atmospheric removal by direct photolysis in cloud and fog droplets can be neglected under typical atmospheric conditions.
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Altieri, K. E., B. J. Turpin i S. P. Seitzinger. "Oligomers, organosulfates, and nitrooxy organosulfates in rainwater identified by ultra-high resolution electrospray ionization FT-ICR mass spectrometry". Atmospheric Chemistry and Physics 9, nr 7 (7.04.2009): 2533–42. http://dx.doi.org/10.5194/acp-9-2533-2009.
Pełny tekst źródłaStreszczenie:
Abstract. Wet deposition is an important removal mechanism for atmospheric organic matter, and a potentially important input for receiving ecosystems, yet less than 50% of rainwater organic matter is considered chemically characterized. Precipitation samples collected in New Jersey, USA, were analyzed by negative ion ultra-high resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Elemental compositions of 552 unique molecular species were determined in the mass range 50–500 Da in the rainwater. Four main groups of organic compounds were identified: compounds containing carbon, hydrogen, and oxygen (CHO) only, sulfur (S) containing CHOS compounds, nitrogen (N) containing CHON compounds, and S- and N- containing CHONS compounds. Organic acids commonly identified in precipitation were detected in the rainwater. Within the four main groups of compounds detected in the rainwater, oligomers, organosulfates, and nitrooxy-organosulfates were assigned based on elemental formula comparisons. The majority of the compounds identified are products of atmospheric reactions and are known contributors to secondary organic aerosol (SOA) formed from gas phase, aerosol phase, and in-cloud reactions in the atmosphere. It is suggested that the large uncharacterized component of SOA is the main contributor to the large uncharacterized component of rainwater organic matter.
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Scalabrin, E., R. Zangrando, E. Barbaro, N. M. Kehrwald, J. Gabrieli, C. Barbante i A. Gambaro. "Amino acids in Arctic aerosols". Atmospheric Chemistry and Physics Discussions 12, nr 7 (13.07.2012): 17367–96. http://dx.doi.org/10.5194/acpd-12-17367-2012.
Pełny tekst źródłaStreszczenie:
Abstract. Amino acids are significant components of atmospheric aerosols, affecting organic nitrogen input to marine ecosystems, atmospheric radiation balance, and the global water cycle. The wide range of amino acid reactivities suggest that amino acids may serve as markers of atmospheric transport and deposition of particles. Despite this potential, few measurements have been conducted in remote areas to assess amino acid concentrations and potential sources. Polar regions offer a unique opportunity to investigate atmospheric processes and to conduct source apportionment studies of such compounds. In order to better understand the importance of amino acid compounds in the global atmosphere, we determined free amino acids (FAAs) in seventeen size-segregated aerosol samples collected in a polar station in the Svalbard Islands from 19 April until 14 September 2010. We used an HPLC coupled with a tandem mass spectrometer (ESI-MS/MS) to analyze 20 amino acids to quantify compounds at fmol m−3 levels. Mean total FAA concentration was 1070 fmol m−3 where serine and glycine were the most abundant compounds in almost all samples and accounted for 45–60% of the total amino acid relative abundance. The other eighteen compounds had average concentrations between 0.3 and 98 fmol m−3. The higher amino acid concentrations were present in the ultrafine aerosol fraction (<0.49 μm) and accounted for the majority of the total amino acid content. Local marine sources dominate the boreal summer amino acid concentrations, with the exception of the regional input from Icelandic volcanics.
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Li, Pingyang, Jens Mühle, Stephen A. Montzka, David E. Oram, Benjamin R. Miller, Ray F. Weiss, Paul J. Fraser i Toste Tanhua. "Atmospheric histories, growth rates and solubilities in seawater and other natural waters of the potential transient tracers HCFC-22, HCFC-141b, HCFC-142b, HFC-134a, HFC-125, HFC-23, PFC-14 and PFC-116". Ocean Science 15, nr 1 (11.01.2019): 33–60. http://dx.doi.org/10.5194/os-15-33-2019.
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Abstract. We present consistent annual mean atmospheric histories and growth rates for the mainly anthropogenic halogenated compounds HCFC-22, HCFC-141b, HCFC-142b, HFC-134a, HFC-125, HFC-23, PFC-14 and PFC-116, which are all potentially useful oceanic transient tracers (tracers of water transport within the ocean), for the Northern and Southern Hemisphere with the aim of providing input histories of these compounds for the equilibrium between the atmosphere and surface ocean. We use observations of these halogenated compounds made by the Advanced Global Atmospheric Gases Experiment (AGAGE), the Scripps Institution of Oceanography (SIO), the Commonwealth Scientific and Industrial Research Organization (CSIRO), the National Oceanic and Atmospheric Administration (NOAA) and the University of East Anglia (UEA). Prior to the direct observational record, we use archived air measurements, firn air measurements and published model calculations to estimate the atmospheric mole fraction histories. The results show that the atmospheric mole fractions for each species, except HCFC-141b and HCFC-142b, have been increasing since they were initially produced. Recently, the atmospheric growth rates have been decreasing for the HCFCs (HCFC-22, HCFC-141b and HCFC-142b), increasing for the HFCs (HFC-134a, HFC-125, HFC-23) and stable with little fluctuation for the PFCs (PFC-14 and PFC-116) investigated here. The atmospheric histories (source functions) and natural background mole fractions show that HCFC-22, HCFC-141b, HCFC-142b, HFC-134a, HFC-125 and HFC-23 have the potential to be oceanic transient tracers for the next few decades only because of the recently imposed bans on production and consumption. When the atmospheric histories of the compounds are not monotonically changing, the equilibrium atmospheric mole fraction (and ultimately the age associated with that mole fraction) calculated from their concentration in the ocean is not unique, reducing their potential as transient tracers. Moreover, HFCs have potential to be oceanic transient tracers for a longer period in the future than HCFCs as the growth rates of HFCs are increasing and those of HCFCs are decreasing in the background atmosphere. PFC-14 and PFC-116, however, have the potential to be tracers for longer periods into the future due to their extremely long lifetimes, steady atmospheric growth rates and no explicit ban on their emissions. In this work, we also derive solubility functions for HCFC-22, HCFC-141b, HCFC-142b, HFC-134a, HFC-125, HFC-23, PFC-14 and PFC-116 in water and seawater to facilitate their use as oceanic transient tracers. These functions are based on the Clark–Glew–Weiss (CGW) water solubility function fit and salting-out coefficients estimated by the poly-parameter linear free-energy relationships (pp-LFERs). Here we also provide three methods of seawater solubility estimation for more compounds. Even though our intention is for application in oceanic research, the work described in this paper is potentially useful for tracer studies in a wide range of natural waters, including freshwater and saline lakes, and, for the more stable compounds, groundwaters.
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Finlayson-Pitts, Barbara J. "Introductory lecture: atmospheric chemistry in the Anthropocene". Faraday Discussions 200 (2017): 11–58. http://dx.doi.org/10.1039/c7fd00161d.
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The term “Anthropocene” was coined by Professor Paul Crutzen in 2000 to describe an unprecedented era in which anthropogenic activities are impacting planet Earth on a global scale. Greatly increased emissions into the atmosphere, reflecting the advent of the Industrial Revolution, have caused significant changes in both the lower and upper atmosphere. Atmospheric reactions of the anthropogenic emissions and of those with biogenic compounds have significant impacts on human health, visibility, climate and weather. Two activities that have had particularly large impacts on the troposphere are fossil fuel combustion and agriculture, both associated with a burgeoning population. Emissions are also changing due to alterations in land use. This paper describes some of the tropospheric chemistry associated with the Anthropocene, with emphasis on areas having large uncertainties. These include heterogeneous chemistry such as those of oxides of nitrogen and the neonicotinoid pesticides, reactions at liquid interfaces, organic oxidations and particle formation, the role of sulfur compounds in the Anthropocene and biogenic–anthropogenic interactions. A clear and quantitative understanding of the connections between emissions, reactions, deposition and atmospheric composition is central to developing appropriate cost-effective strategies for minimizing the impacts of anthropogenic activities. The evolving nature of emissions in the Anthropocene places atmospheric chemistry at the fulcrum of determining human health and welfare in the future.
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Timperley, M. H., R. J. Vigor-Brown, M. Kawashima i M. Ishigami. "Organic Nitrogen Compounds in Atmospheric Precipitation: Their Chemistry and Availability to Phytoplankton". Canadian Journal of Fisheries and Aquatic Sciences 42, nr 6 (1.06.1985): 1171–77. http://dx.doi.org/10.1139/f85-145.
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Urea accounted for 30, 36, and 56%, respectively, of the water-soluble organic nitrogen (DON) compounds deposited from the atmosphere at two sites in New Zealand and one site in japan. The other DON compounds were not identified but they were all of low molecular size, apparently anionic, and did not include detectable quantities of amino acids or uric acid. In axenic culture, Chlorella spp. grew successfully using DON from New Zealand precipitation as its only source of N; Pediastrum biwae, a phytoplankton endemic to Lake Biwa in Japan, also achieved successful growth using DON separated from Japanese precipitation. Ammonium-N and DON were deposited from the atmosphere in the absence of rain or snow, and we suggest that particulate matter, possibly soil, is a major source of these N compounds in atmospheric precipitation.
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Lyu, Ruihe, Zongbo Shi, Mohammed Salim Alam, Xuefang Wu, Di Liu, Tuan V. Vu, Christopher Stark, Pingqing Fu, Yinchang Feng i Roy M. Harrison. "Insight into the composition of organic compounds ( ≥ C<sub>6</sub>) in PM<sub>2.5</sub> in wintertime in Beijing, China". Atmospheric Chemistry and Physics 19, nr 16 (29.08.2019): 10865–81. http://dx.doi.org/10.5194/acp-19-10865-2019.
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Abstract. Organic matter is a major component of PM2.5 in megacities. In order to understand the detailed characteristics of organic compounds (≥ C6) at a molecular level on non-haze and haze days, we determined more than 300 organic compounds in the PM2.5 from an urban area of Beijing collected in November–December 2016 using two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC-ToF-MS). The identified organic compounds have been classified into groups, and quantitative methods were used to calculate their concentrations. Primary emission sources make significant contributions to the atmospheric organic compounds, and six groups (including n-alkanes, polycyclic aromatic hydrocarbons – PAHs, levoglucosan, branched alkanes, n-alkenes and alkyl-benzenes) account for 66 % of total identified organic compound mass. In addition, PAHs and oxygenated PAHs (O-PAHs) were abundant amongst the atmospheric organic compounds on both haze and non-haze days. The most abundant hydrocarbon groups were observed with a carbon atom range of C19–C28. In addition, the total concentration of unidentified compounds present in the chromatogram was estimated in the present study. The total identified compounds account for approximately 47 % of total organic compounds (≥ C6) in the chromatogram on both the non-haze and haze days. The total mass concentrations of organic compounds (≥ C6) in the chromatogram were 4.0 and 7.4 µg m−3 on the non-haze and haze days, respectively, accounting for 26.4 % and 18.5 % of organic matter, respectively, on those days estimated from the total organic carbon concentration. Ratios of individual compound concentrations between haze and non-haze days do not give a clear indication of the degree of oxidation, but the overall distribution of organic compounds in the chromatogram provides strong evidence that the organic aerosol is less GC volatile and hence more highly oxidized on haze days.
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Altieri, K. E., B. J. Turpin i S. P. Seitzinger. "Oligomers, organosulfates, and nitroxy organosulfates in rainwater identified by ultra-high resolution electrospray ionization FT-ICR mass spectrometry". Atmospheric Chemistry and Physics Discussions 8, nr 5 (23.09.2008): 17439–66. http://dx.doi.org/10.5194/acpd-8-17439-2008.
Pełny tekst źródłaStreszczenie:
Abstract. Wet deposition is an important removal mechanism for atmospheric organic matter, and a potentially important input for receiving ecosystems, yet less than 50% of rainwater organic matter is considered chemically characterized. Precipitation samples collected in New Jersey, USA, were analyzed by negative ion ultra-high resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Elemental compositions of 552 unique molecular species were determined in the mass range 50–500 Da in the rainwater. Three main groups of organic compounds were identified: compounds containing carbon, hydrogen, and oxygen (CHO) only, sulfur (S) containing CHOS compounds, and S- and nitrogen containing CHONS compounds. Organic acids commonly identified in precipitation were detected, as well as linear alkylbenzene sulfonates, which are persistent pollutants commonly measured in river water, seawater, and sediments, but to our knowledge, not previously documented in atmospheric samples. Within the three main groups of compounds detected in the rainwater, oligomers, organosulfates, and nitroxy-organosulfates were identified. The majority of the compounds identified are products of atmospheric reactions and are known contributors to secondary organic aerosol (SOA) formed from gas phase, aerosol phase, and in-cloud reactions in the atmosphere. It is suggested that the large uncharacterized component of SOA is the main contributor to the large uncharacterized component of rainwater organic matter.
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Scalabrin, E., R. Zangrando, E. Barbaro, N. M. Kehrwald, J. Gabrieli, C. Barbante i A. Gambaro. "Amino acids in Arctic aerosols". Atmospheric Chemistry and Physics 12, nr 21 (8.11.2012): 10453–63. http://dx.doi.org/10.5194/acp-12-10453-2012.
Pełny tekst źródłaStreszczenie:
Abstract. Amino acids are significant components of atmospheric aerosols, affecting organic nitrogen input to marine ecosystems, atmospheric radiation balance, and the global water cycle. The wide range of amino acid reactivities suggest that amino acids may serve as markers of atmospheric transport and deposition of particles. Despite this potential, few measurements have been conducted in remote areas to assess amino acid concentrations and potential sources. Polar regions offer a unique opportunity to investigate atmospheric processes and to conduct source apportionment studies of such compounds. In order to better understand the importance of amino acid compounds in the global atmosphere, we determined free amino acids (FAAs) in seventeen size-segregated aerosol samples collected in a polar station in the Svalbard Islands from 19 April until 14 September 2010. We used an HPLC coupled with a tandem mass spectrometer (ESI-MS/MS) to analyze 20 amino acids and quantify compounds at fmol m−3 levels. Mean total FAA concentration was 1070 fmol m−3 where serine and glycine were the most abundant compounds in almost all samples and accounted for 45–60% of the total amino acid relative abundance. The other eighteen compounds had average concentrations between 0.3 and 98 fmol m−3. The higher amino acid concentrations were present in the ultrafine aerosol fraction (< 0.49 μm) and accounted for the majority of the total amino acid content. Local marine sources dominate the boreal summer amino acid concentrations, with the exception of the regional input from Icelandic volcanic emissions.
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Amato, P., F. Demeer, A. Melaouhi, S. Fontanella, A. S. Martin-Biesse, M. Sancelme, P. Laj i A. M. Delort. "A fate for organic acids, formaldehyde and methanol in cloud water: their biotransformation by micro-organisms". Atmospheric Chemistry and Physics 7, nr 15 (9.08.2007): 4159–69. http://dx.doi.org/10.5194/acp-7-4159-2007.
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Abstract. The interactions between microbial and chemical contents of cloud water were investigated. First, we observe that the bulk cloud water solution provides a substantial environment where bacteria can develop significantly. Then, a total number of 60 microbial strains originating from seven distinct samples of cloud water and affiliated to various taxonomic groups were examined for their ability to degrade some of the main atmospheric carboxylic compounds: formate, acetate, lactate, succinate, as well as formaldehyde and methanol. Biodegradation tests show that all these compounds can be transformed when used as single carbonaceous substrates, with activities depending on both the strain and the compound. The highest capacities of biodegradation are observed towards formaldehyde, formate and acetate, which are also the more concentrated compounds typically measured in cloud water. Hence, analyses by 1H NMR permitted to establish for instance that compounds like pyruvate or fumarate can be produced and released in the media in relation to the transformation of lactate or succinate. In addition, utilization of 13C labelled formaldehyde showed that it can be transformed through many metabolic pathways, similar to those induced by photochemistry and leading to the production of formate and/or methanol. These results suggest that microorganisms of cloud water can have various behaviours towards the chemical compounds present in the atmosphere: they can represent either a sink or source for organic carbon, and may have to be considered as actors of cloud chemistry.
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Schwarz, Marián, i Josef Kuthan. "Alkylation of 2,4,4,6-tetraphenyl-1,4-dihydropyridine". Collection of Czechoslovak Chemical Communications 54, nr 7 (1989): 1870–79. http://dx.doi.org/10.1135/cccc19891870.
Pełny tekst źródłaStreszczenie:
A series of photochromic N-methyl derivatives IIIa-IIIh was synthesized by alkylation of 1-sodio-2,4,4,6-tetraphenyl-1,4-dihydropyridine (II) in an inert atmosphere. On the other hand, the starting material II afforded products IVa and IVb in the presence of atmospheric oxygen. Mechanisms of acidobasic transformations of compounds IVa and IVb are discussed and spectral characteristics of new compounds are interpreted.
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Tsimpidi, Alexandra P., Vlassis A. Karydis, Spyros N. Pandis i Jos Lelieveld. "Global-scale combustion sources of organic aerosols: sensitivity to formation and removal mechanisms". Atmospheric Chemistry and Physics 17, nr 12 (20.06.2017): 7345–64. http://dx.doi.org/10.5194/acp-17-7345-2017.
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Abstract. Organic compounds from combustion sources such as biomass burning and fossil fuel use are major contributors to the global atmospheric load of aerosols. We analyzed the sensitivity of model-predicted global-scale organic aerosols (OA) to parameters that control primary emissions, photochemical aging, and the scavenging efficiency of organic vapors. We used a computationally efficient module for the description of OA composition and evolution in the atmosphere (ORACLE) of the global chemistry–climate model EMAC (ECHAM/MESSy Atmospheric Chemistry). A global dataset of aerosol mass spectrometer (AMS) measurements was used to evaluate simulated primary (POA) and secondary (SOA) OA concentrations. Model results are sensitive to the emission rates of intermediate-volatility organic compounds (IVOCs) and POA. Assuming enhanced reactivity of semi-volatile organic compounds (SVOCs) and IVOCs with OH substantially improved the model performance for SOA. The use of a hybrid approach for the parameterization of the aging of IVOCs had a small effect on predicted SOA levels. The model performance improved by assuming that freshly emitted organic compounds are relatively hydrophobic and become increasingly hygroscopic due to oxidation.
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Ronneau, C. "Atmospheric Chemical Compounds: Sources, Occurrence and Bioassay". Eos, Transactions American Geophysical Union 68, nr 49 (1987): 1643. http://dx.doi.org/10.1029/eo068i049p01643-02.
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Watts, Simon F. "Separation and trapping of atmospheric sulphur compounds". Environmental Technology Letters 10, nr 8 (sierpień 1989): 777–83. http://dx.doi.org/10.1080/09593338909384797.
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Tuazon, Ernesto C., Sara M. Aschmann i Roger Atkinson. "Atmospheric Degradation of Volatile Methyl-Silicon Compounds". Environmental Science & Technology 34, nr 10 (maj 2000): 1970–76. http://dx.doi.org/10.1021/es9910053.
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Heathfield, A. E., C. Anastasi, P. Pagsberg i A. McCulloch. "Atmospheric lifetimes of selected fluorinated ether compounds". Atmospheric Environment 32, nr 4 (luty 1998): 711–17. http://dx.doi.org/10.1016/s1352-2310(97)00330-0.
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Schmidt, U. "Atmospheric chemical compounds. Sources, occurrence and bioassay". Atmospheric Research 22, nr 1 (czerwiec 1988): 85–86. http://dx.doi.org/10.1016/0169-8095(88)90014-2.
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Nielsen, Torben, Kim Pilegaard, Axel H. Egeløv, Kit Granby, Poul Hummelshøj, Niels O. Jensen i Henrik Skov. "Atmospheric nitrogen compounds: occurrence, composition and deposition". Science of The Total Environment 189-190 (październik 1996): 459–65. http://dx.doi.org/10.1016/0048-9697(96)05246-1.
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Lodge, James P. "Atmospheric chemical compounds, sources, occurrence and bioassay". Atmospheric Environment (1967) 21, nr 3 (styczeń 1987): 722. http://dx.doi.org/10.1016/0004-6981(87)90057-6.
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Prodjosantoso, Antikolonial, Wahyu Widiyati, Wafin Wafin, Ani Widyawati i Maximus Pranjoto Utomo. "Cement Chemisrty: Hydration of Ca2-Xsrxsio4 Compound". Oriental Journal Of Chemistry 37, nr 3 (30.06.2021): 589–93. http://dx.doi.org/10.13005/ojc/370310.
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Dicalcium silicate (Ca2SiO4) isan importantcomponent of cement. The compound ofCa2-xSrxSiO4 can be formed if the Sr containing precursorsare used to synthesize the cement. The presence of Sr may alter the hydrationof the product. The hydration chemistry ofCa2-xSrxSiO4 compounds is reported. The hydration of Ca2-xSrxSiO4was conducted uder nitrogen atmosphere for about 6 months. The dry samples were characterized usingXRD, FTIR, TGA-DSC, andSEM-EDXmethods. It is confirmed that the hydration ofCa2-xSrxSiO4produces mainlyCa3Si2O7.3H2O and Ca(OH)2. However, the Sr doped Ca3Si2O7.3H2O andCa(OH)2 are possibly formed.The compound of CaCO3,as the result ofinteractions between Ca(OH)2 and atmospheric CO2gas during the sample handling,is also observed.
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Tost, H., M. G. Lawrence, C. Brühl i P. Jöckel. "Uncertainties in atmospheric chemistry modelling due to convection parameterisations and subsequent scavenging". Atmospheric Chemistry and Physics 10, nr 4 (19.02.2010): 1931–51. http://dx.doi.org/10.5194/acp-10-1931-2010.
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Abstract. Moist convection in global modelling contributes significantly to the transport of energy, momentum, water and trace gases and aerosols within the troposphere. Since convective clouds are on a scale too small to be resolved in a global model their effects have to be parameterised. However, the whole process of moist convection and especially its parameterisations are associated with uncertainties. In contrast to previous studies on the impact of convection on trace gases, which had commonly neglected the convective transport for some or all compounds, we investigate this issue by examining simulations with five different convection schemes. This permits an uncertainty analysis due to the process formulation, without the inconsistencies inherent in entirely neglecting deep convection or convective tracer transport for one or more tracers. Both the simulated mass fluxes and tracer distributions are analysed. Investigating the distributions of compounds with different characteristics, e.g., lifetime, chemical reactivity, solubility and source distributions, some differences can be attributed directly to the transport of these compounds, whereas others are more related to indirect effects, such as the transport of precursors, chemical reactivity in certain regions, and sink processes. The model simulation data are compared with the average regional profiles of several measurement campaigns, and in detail with two campaigns in fall and winter 2005 in Suriname and Australia, respectively. The shorter-lived a compound is, the larger the differences and consequently the uncertainty due to the convection parameterisation are, as long as it is not completely controlled by local production that is independent of convection and its impacts (e.g. water vapour changes). Whereas for long-lived compounds like CO or O3 the mean differences between the simulations are less than 25%), differences for short-lived compounds reach up to ±100% with different convection schemes. A rating of an overall "best" performing scheme is difficult, since the optimal performance depends on the region and compound.
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Raventos-Duran, T., M. Camredon, R. Valorso, C. Mouchel-Vallon i B. Aumont. "Structure-activity relationships to estimate the effective Henry's law constants of organics of atmospheric interest". Atmospheric Chemistry and Physics 10, nr 16 (17.08.2010): 7643–54. http://dx.doi.org/10.5194/acp-10-7643-2010.
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Abstract. The Henry's law constant is a key property needed to address the multiphase behaviour of organics in the atmosphere. Methods that can reliably predict the values for the vast number of organic compounds of atmospheric interest are therefore required. The effective Henry's law constant H* in air-water systems at 298 K was compiled from literature for 488 organic compounds bearing functional groups of atmospheric relevance. This data set was used to assess the reliability of the HENRYWIN bond contribution method and the SPARC approach for the determination of H*. Moreover, this data set was used to develop GROMHE, a new Structure Activity Relationship (SAR) based on a group contribution approach. These methods estimate logH* with a Root Mean Square Error (RMSE) of 0.38, 0.61, and 0.73 log units for GROMHE, SPARC and HENRYWIN respectively. The results show that for all these methods the reliability of the estimates decreases with increasing solubility. The main differences among these methods lie in H* prediction for compounds with H* greater than 103 M atm−1. For these compounds, the predicted values of logH* using GROMHE are more accurate (RMSE = 0.53) than the estimates from SPARC or HENRYWIN.
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Röhler, Laura, Martin Schlabach, Peter Haglund, Knut Breivik, Roland Kallenborn i Pernilla Bohlin-Nizzetto. "Non-target and suspect characterisation of organic contaminants in Arctic air – Part 2: Application of a new tool for identification and prioritisation of chemicals of emerging Arctic concern in air". Atmospheric Chemistry and Physics 20, nr 14 (29.07.2020): 9031–49. http://dx.doi.org/10.5194/acp-20-9031-2020.
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Abstract. The Norwegian Arctic possesses a unique environment for the detection of new potential chemicals of emerging Arctic concern (CEACs) due to remoteness, sparse population and the low number of local contamination sources. Hence, a contaminant present in Arctic air is still considered a priority indication for its environmental stability and environmental mobility. Today, legacy persistent organic pollutants (POPs) and related conventional environmental pollutants are already well-studied because of their identification as Arctic pollutants in the 1980s. Many of them are implemented and reported in various national and international monitoring activities including the Arctic Monitoring and Assessment Programme (AMAP). These standard monitoring schemes, however, are based on compound-specific quantitative analytical methods. Under such conditions, the possibility for the identification of hitherto unidentified contaminants is limited and random at best. Today, new and advanced technological developments allow a broader, unspecific analytical approach as either targeted multicomponent analysis or suspect and non-target screening strategies. In order to facilitate such a wide range of compounds, a wide-scope sample clean-up method for high-volume air samples based on a combination of adsorbents was applied, followed by comprehensive two-dimensional gas chromatography separation and low-resolution time-of-flight mass spectrometric detection (GC × GC-LRMS). During the study reported here, simultaneous non-target and suspect screening were applied. The detection of over 700 compounds of interest in the particle phase and over 1200 compounds in the gaseous phase is reported. Of those, 62 compounds were confirmed with reference standards and 90 compounds with a probable structure (based upon mass spectrometric interpretation and library spectrum comparison). These included compounds already detected in Arctic matrices and compounds not detected previously (see also Fig. 1). In addition, 241 compounds were assigned a tentative structure or compound class. Hitherto unknown halogenated compounds, which are not listed in the mass spectral libraries used, were also detected and partly identified.
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van Pinxteren, Manuela, Khanneh Wadinga Fomba, Nadja Triesch, Christian Stolle, Oliver Wurl, Enno Bahlmann, Xianda Gong i in. "Marine organic matter in the remote environment of the Cape Verde islands – an introduction and overview to the MarParCloud campaign". Atmospheric Chemistry and Physics 20, nr 11 (12.06.2020): 6921–51. http://dx.doi.org/10.5194/acp-20-6921-2020.
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Abstract. The project MarParCloud (Marine biological production, organic aerosol Particles and marine Clouds: a process chain) aims to improve our understanding of the genesis, modification and impact of marine organic matter (OM) from its biological production, to its export to marine aerosol particles and, finally, to its ability to act as ice-nucleating particles (INPs) and cloud condensation nuclei (CCN). A field campaign at the Cape Verde Atmospheric Observatory (CVAO) in the tropics in September–October 2017 formed the core of this project that was jointly performed with the project MARSU (MARine atmospheric Science Unravelled). A suite of chemical, physical, biological and meteorological techniques was applied, and comprehensive measurements of bulk water, the sea surface microlayer (SML), cloud water and ambient aerosol particles collected at a ground-based and a mountain station took place. Key variables comprised the chemical characterization of the atmospherically relevant OM components in the ocean and the atmosphere as well as measurements of INPs and CCN. Moreover, bacterial cell counts, mercury species and trace gases were analyzed. To interpret the results, the measurements were accompanied by various auxiliary parameters such as air mass back-trajectory analysis, vertical atmospheric profile analysis, cloud observations and pigment measurements in seawater. Additional modeling studies supported the experimental analysis. During the campaign, the CVAO exhibited marine air masses with low and partly moderate dust influences. The marine boundary layer was well mixed as indicated by an almost uniform particle number size distribution within the boundary layer. Lipid biomarkers were present in the aerosol particles in typical concentrations of marine background conditions. Accumulation- and coarse-mode particles served as CCN and were efficiently transferred to the cloud water. The ascent of ocean-derived compounds, such as sea salt and sugar-like compounds, to the cloud level, as derived from chemical analysis and atmospheric transfer modeling results, denotes an influence of marine emissions on cloud formation. Organic nitrogen compounds (free amino acids) were enriched by several orders of magnitude in submicron aerosol particles and in cloud water compared to seawater. However, INP measurements also indicated a significant contribution of other non-marine sources to the local INP concentration, as (biologically active) INPs were mainly present in supermicron aerosol particles that are not suggested to undergo strong enrichment during ocean–atmosphere transfer. In addition, the number of CCN at the supersaturation of 0.30 % was about 2.5 times higher during dust periods compared to marine periods. Lipids, sugar-like compounds, UV-absorbing (UV: ultraviolet) humic-like substances and low-molecular-weight neutral components were important organic compounds in the seawater, and highly surface-active lipids were enriched within the SML. The selective enrichment of specific organic compounds in the SML needs to be studied in further detail and implemented in an OM source function for emission modeling to better understand transfer patterns, the mechanisms of marine OM transformation in the atmosphere and the role of additional sources. In summary, when looking at particulate mass, we see oceanic compounds transferred to the atmospheric aerosol and to the cloud level, while from a perspective of particle number concentrations, sea spray aerosol (i.e., primary marine aerosol) contributions to both CCN and INPs are rather limited.