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1.
Expedition data obtained in the coastal-shelf zone of the East Siberian Sea in September 2003, 2004, and 2008 are generalized.
Studies of carbonate system in water and CO2 fluxes between ocean and atmosphere in this region confirmed that it was reasonable to divide the water area studied into
two biogeochemical provinces and that the ecosystem of its coastal part is mainly of a heterotrophic nature. In different
years, the extent of water supersaturation in carbon dioxide in the East Siberian Sea and the area of the CO2 release significantly changed. Geographic localization of the atmosphere action centers over the Arctic and their intensity
were main determining factors; that told both on the formation of a basic character of the atmospheric and hydrological processes
and on the dynamics of the CO2 exchange between water and air. 相似文献
2.
MARKKU KULMALA VELI-MATTI KERMINEN ARI LAAKSONEN ILONA RIIPINEN MIKKO SIPILÄ TAINA M. RUUSKANEN LARISA SOGACHEVA PERTTI HARI JAANA BÄCK KARI E. J. LEHTINEN YRJÖ VIISANEN MERETE BILDE BIRGITTA SVENNINGSSON MIHALIS LAZARIDIS KJETIL TØRSETH PETER TUNVED E. DOUGLAS NILSSON SARA PRYOR LISE-LOTTE SØRENSEN URMAS HÕRRAK PAUL M. WINKLER ERIK SWIETLICKI MARJA-LIISA RIEKKOLA RADOVAN KREJCI CHRISTOPHER HOYLE ØYSTEIN HOV GUNNAR MYHRE HANS-CHRISTEN HANSSON 《Tellus. Series B, Chemical and physical meteorology》2008,60(3):300-317
3.
A box model is used to explore the detailed chemistry of C2 and C3 organic compounds in the marine troposphere by tracing the individual reaction paths resulting from the oxidation of ethane,
ethene, acetylene, propane, propene and acetic acid. The mechanisms include chemical reactions in the gas phase and in the
aqueous phase of clouds and aerosol particles at cloud level under conditions resembling those in the northern hemisphere.
Organic hydroperoxides are found to be important intermediate products, with subsequent reactions leading partly to the formation
of mixed hydroxy or carbonyl hydroperoxides that are readily absorbed into cloud water, where they contribute significantly
to the formation of multifunctional organic compounds and organic acids. Organic hydroperoxides add little to the oxidation
of sulfur dioxide dissolved in the aqueous phase, which is dominated by H2O2. Next to acetaldehyde and acetone, glycol aldehyde, glyoxal, methyl glyoxal and hydroxy propanone are prominent oxidation
products in the gas and the aqueous phase. Acetaldehyde is not efficiently converted to acetic acid in clouds; the major local
sources of acetic acid are gas-phase reactions. Other acids produced include hydroperoxy acetic, glycolic, glyoxylic, oxalic,
pyruvic, and lactic acid. The mechanism of Schuchmann et al. (1985), which derives glycolic and glyoxylic acid from the oxidation of acetate, is found unimportant in the marine atmosphere.
The principal precursors of glyoxylic acid are glyoxal and glycolic acid. The former derives mainly from acetylene and ethene,
the latter from glycolaldehyde, also an oxidation product of ethene. The oxidation of glyoxylic acid leads to oxalic acid,
which accumulates and is predicted to reach steady state concentrations in the range 30–90 ng m−3. This is greater, yet of the same magnitude, than the concentrations observed over the remote Pacific Ocean. 相似文献
4.
Lucy J. Carpenter Stephen J. Andrews Richard T. Lidster Alfonso Saiz-Lopez Miguel Fernandez-Sanchez William J. Bloss Bin Ouyang Roderic L. Jones 《Journal of Atmospheric Chemistry》2017,74(2):145-156
Ocean emissions of inorganic and organic iodine compounds drive the biogeochemical cycle of iodine and produce reactive ozone-destroying iodine radicals that influence the oxidizing capacity of the atmosphere. Di-iodomethane (CH2I2) and chloro-iodomethane (CH2ICl) are the two most important organic iodine precursors in the marine boundary layer. Ship-borne measurements made during the TORERO (Tropical Ocean tRoposphere Exchange of Reactive halogens and Oxygenated VOC) field campaign in the east tropical Pacific Ocean in January/February 2012 revealed strong diurnal cycles of CH2I2 and CH2ICl in air and of CH2I2 in seawater. Both compounds are known to undergo rapid photolysis during the day, but models assume no night-time atmospheric losses. Surprisingly, the diurnal cycle of CH2I2 was lower in amplitude than that of CH2ICl, despite its faster photolysis rate. We speculate that night-time loss of CH2I2 occurs due to reaction with NO3 radicals. Indirect results from a laboratory study under ambient atmospheric boundary layer conditions indicate a k CH2I2+NO3 of ≤4 × 10?13 cm3 molecule?1 s?1; a previous kinetic study carried out at ≤100 Torr found k CH2I2+NO3 of 4 × 10?13 cm3 molecule?1 s?1. Using the 1-dimensional atmospheric THAMO model driven by sea-air fluxes calculated from the seawater and air measurements (averaging 1.8 +/? 0.8 nmol m?2 d?1 for CH2I2 and 3.7 +/? 0.8 nmol m?2 d?1 for CH2ICl), we show that the model overestimates night-time CH2I2 by >60 % but reaches good agreement with the measurements when the CH2I2 + NO3 reaction is included at 2–4 × 10?13 cm3 molecule?1 s?1. We conclude that the reaction has a significant effect on CH2I2 and helps reconcile observed and modeled concentrations. We recommend further direct measurements of this reaction under atmospheric conditions, including of product branching ratios. 相似文献
5.
6.
Using a single drop experiment, the uptake of NO3 radicals on aqueous solutions of the dye Alizarin Red S and NaCl was measured at 293 K. Uptake coefficients in the range
(1.7–3.1) ⋅ 10− 3 were measured on Alizarin Red S solutions. The uptake coefficients measured on NaCl solutions were in the range of (1.1–2.0)
⋅ 10−3 depending on the salt concentration. Both experiments lead to a consistent result for the mass accommodation coefficient
of αNO3 = (4.2− 1.7+2.2)⋅ 10−3.
The product H(Dl kCl−II)0.5 for the NO3 radical was determined to be (1.9 ± 0.2) M atm− 1 cm s−0.5 M−0.5 s−0.5 by fitting the uptake data for the NaCl solutions to the so-called resistance model.
The yield of the chemical NO3 radical source was characterized using UV-VIS and FT-IR spectroscopy. The amount of gas-phase NO3 radicals measured at elevated humidities was less than expected. Instead, a rise of the gas-phase HNO3 concentration was found indicating a conversion of gas-phase NO3 radicals to gas-phase HNO3 on the moist reactor walls. 相似文献
7.
A linear diagnostic equation for the nonhydrostatic vertical motion W in severe storms is derived in the Cartesian-earth-spherical coordinates. This W diagnostic equation reveals explicitly how forcing factors work together to exert influence on the nonhydrostatic vertical motion in severe storms. If high-resolution global data are available in Cartesian coordinates with guaranteed quality, the Lax-Crank-Nicolson scheme and the Thomas algorithm might provide a promising numerical solution of this diagnostic equation. As a result, quantitative analyses are expected for the evolution mechanisms of severe storms. 相似文献
8.
Products of the gas-phase reaction of the NO3 radical with thiophene have been investigated using different experimental systems. On the one hand, experiments have been conducted in our laboratory using two different methods, a Teflon static reactor coupled to a gas chromatograph combined with mass-spectrometry (GC-MS) and a discharge flow tube with direct MS spectroscopic detection. A qualitative analysis in these cases indicates that possible products for the reaction of thiophene+NO3 at room temperature include: sulphur dioxide, acetic and formic acids, a short-chain aldehyde, 2-nitrothiophene and 3-nitrothiophene. On the other hand, quantitative experiments have been performed in the European Photoreactor (EUPHORE) in Valencia, Spain. In this case, the major products were: HNO3 (≈80%), nitrothiophenes (≈30%), SO2 (≈20%), propanal (3%) and a fraction of particles (≈10%). The results obtained indicate that at least 70% of the reaction of NO3 with thiophene proceeds by an H-abstraction process at room temperature. The mechanism of the reaction studied is proposed on the basis of experimental results. 相似文献
9.
The estimate of the release of radioactive substances (133Xe, 131I, and 137Cs) into the atmosphere from the Fukushima Daiichi nuclear disaster is presented. It was obtained using the FLEXPART Lagrangian dispersion model and the data of local ground-based measurements of radiation dose rate. The computation period covers the active phase of the nuclear disaster that lasted 20 days after the tsunami. To get the quantitative characteristics of emissions of radioactive substances, the inverse modeling based on the Bayesian approach is used. The emissions were estimated for three altitudes. The total emissions are equal to 2.1 + 0.4 kg (14 000 + 2700 PBq) for 133Xe, (3.8 + 0.4) x 10-2 kg (174 + + 18 PBq) for 131I, and 5.7 + 1.2 kg (18 + 4 PBq) for 137Cs that is consistent with the results of other studies. Retrieved emissions were used to provide the forward modeling for mapping the areas of radionuclide deposition. The developed method of retrieving the emission of radioactive substances makes a useful instrument that operationally estimates and localizes the areas of potential pollution in case of nuclear accidents and could be used for making decisions on the population evacuation. 相似文献
10.
Detection of nitric acid (HNO<Subscript>3</Subscript>) in the atmosphere using the LOPAP technique 总被引：1，自引：0，他引：1
Jörg Kleffmann Traian Gavriloaiei Yasin Elshorbany Milagros Ródenas Peter Wiesen 《Journal of Atmospheric Chemistry》2007,58(2):131-149
A new instrument (LOPAP: LOng Path liquid Absorption Photometer) for the sensitive detection of nitric acid (HNO3) in the atmosphere is described. HNO3 is sampled in a temperature controlled stripping coil mounted in an external sampling module to minimize sampling artefacts in sampling lines. After conversion into a strongly absorbing dye, HNO3 is detected in long path absorption in special Teflon® AF 2400 tubes used as liquid core wave guides. For the correction of some interferences, due to for example HONO and particle nitrate, two channels are used in series. The interferences from several potential interfering compounds including particle nitrate were quantified in the laboratory and in a large outdoor simulation chamber. With the exception of the interference caused by N2O5, which is quantitatively measured by the instrument, all tested interferences can be corrected under atmospheric conditions. Thus, in the instrument only the sum of N(V) from HNO3 and N2O5 is determined, which is expected to be a common problem of wet chemical HNO3 instruments. The instrument has a detection limit of 5–30 pptv for a time response of 6–2 min, respectively and was validated against the FTIR technique in a large outdoor simulation chamber. In addition, the applicability of the instrument was demonstrated in a field campaign. 相似文献
11.
An instrument is developed for the measurement of peroxy radical using chemical amplification coupled with NO2-luminol chemiluminescence detection. The chain length of 147 ± 10 (1σ) is determined by an HO2 source that uses the photolysis of water vapor under 184.9 nm in air. A Nafion system equipped with a Nafion tube of ~2.2 mm external diameter and 350 mm length is employed in the PERCA instrument (Nafion-PERCA system). When flowing an air sample containing HO2 through the Nafion system, it is found that - 94.6 % of HO2 is removed. In contrast, only 17.8 % of RO2 radicals (a mixtures of CH3O2 and CH3C(O)O2 with a ratio of 1.1:0.9) are removed. The results indicate the Nafion system has a good selective removing performance of HO2 radical during the PERCA measurement. Therefore, the method could be applied to ambient and laboratory measurements of absolute concentrations of RO2 as well as the sum of HO2 and RO2. 相似文献
12.
S. V. Vasilenkov 《Russian Meteorology and Hydrology》2010,35(6):401-405
Experimental investigations under field and laboratory conditions of 137Cs washout from the periodically frozen and thawed soils were carried out. The experiments demonstrated that the amount of
cesium washed out from the soil after freezing was much larger than from the non-frozen soils and by its intensity it corresponds
to the washout under the influence of intensifiers. This fact allows recommending cheap and technologically simple measures
for the in-snow runoff control to rehabilitate the contaminated lands. 相似文献
13.
The air quality analyses for nitrogen dioxide (NO2) were conducted in Tehran, capital of Iran. Daily and annual variations in its average concentrations were calculated using measurements from four sampling stations. Multiple linear and nonlinear regression equations for relationships between concentration of pollutant and meteorological parameters were obtained from average data. The RMSE test showed that the stepwise model is the best option among the considered prediction models. 相似文献
14.
To characterize atmospheric particulate matter equal or less than 2.5 μm in diameter (PM2.5) over the Tropical Atlantic Ocean, aerosol sampling was carried out in Puerto Rico during August and September, 2006. Aerosols were analyzed by ion chromatography for water-soluble inorganic and organic ions (including Na+, NH4 +, Mg2+, Ca2+, K+, Cl?, SO4 2?, NH4 +, F?, methanesulfonate (MSA), and oxalate), by inductive coupled plasma mass spectrometry (ICPMS) for trace elements (Al, Fe, Zn, Mn, Cu, Ni, V, Pb, Cr, Sb, Co, Sc, Cd), and by scanning electron microscopy for individual aerosol particle composition and morphology. The results show that the dominant cations in aerosols were Na+, (mean: 631 ng m?3), accounting for 63.8 % of the total cation and NH4 + (mean: 164 ng m?3), accounting for 13.8 % of the total cation measured in this study. The main inorganic anions were Cl? (576 ng m?3, 54.1 %) and SO4 2? (596 ng m?3, 38.0 %). The main organic anion was oxalate (18 ng m?3). Crustal enrichment factor calculations identified 62 % of the trace elements measured (Cu, Ni, V, Co, Al, Mn, Fe, Sc, and Cr) with crustal origin. Single particle analysis demonstrated that 40 % of the aerosol particles examined were Cl? rich particles as sodium chloride from seawater and 34 % of the total particles were Si-rich particles, mainly in the form of aluminosilicates from dust material. Based on the combination of air-mass trajectories, cluster analysis and principal component analysis, the major sources of these PM2.5 particles include marine, Saharan dust and biomass burning from West Africa; however, volcanic emissions from the Soufriere Hills in Montserrat had significant impact on aerosol composition in this region at the time of sample collection. 相似文献
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17.
Urban Atmospheric Chemistry During the PUMA Campaign 2: Radical Budgets for OH,HO<Subscript>2</Subscript> and RO<Subscript>2</Subscript> 总被引：1，自引：0，他引：1
A detailed photochemical box model was used to investigate the key reaction pathways between OH, HO2 and RO2 radicals during the summer and winter PUMA field campaigns in the urban city-centre of Birmingham in the UK. The model employed
the most recent version of the Master Chemical Mechanism and was constrained to 15-minute average measurements of long-lived
species determined in situ at the site. The results showed that in the summer, OH initiation was dominated by the reactions of ozone with alkenes, nitrous
acid (HONO) photolysis and the reaction of excited oxygen atoms atoms with water. In the winter, ozone+alkene reactions were
the primary initiation route, with a minor contribution from HONO photolysis. Photolysis of aldehydes was the main initiation
route for HO2, in both summer and winter. RO2 initiation was dominated by the photolysis of aldehydes in the summer with a smaller contribution from ozone+alkenes, a situation
that was reversed in the winter. At night, ozone+alkene reactions were the main radical source. Termination, under all conditions,
primarily involved reactions with NO (OH) and NO2 (OH and RCO3). These results demonstrate the importance of ozone+alkene reactions in urban atmospheres, particularly when photolysis reactions
were less important during winter and at nighttime. The implications for urban atmospheric chemistry are discussed. 相似文献
18.
Since the late 1950s, production of both cash-crop cotton and food crops has increased immensely in the Malian cotton zone. The response of farmers to external incentives or obstacles has been swift. In an opportunistic way, farmers seem to seek immediate and maximum profits. This has been particularly evident with the boom in both cotton and food crop production after the devaluation of the CFA franc in January 1994. Such reactions support the idea that it is not only African pastoral production systems which are non-equilibrial and opportunistic, but that this also characterises farming communities. Furthermore, the agricultural development in the cotton zone is regularly said to cause serious environmental degradation mainly through deforestation and soil depletion. The paper questions this view. The environmental transformation taking place is analysed, but whether this transformation represents ‘degradation’ or ‘improvement’ is largely a normative question subject to the values and environmental perceptions of the individual actors. 相似文献
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20.
Anoop S. Mahajan Lisa K. Whalley Elena Kozlova Hilke Oetjen Luis Mendez Kate L. Furneaux Andrew Goddard Dwayne E. Heard John M. C. Plane Alfonso Saiz-Lopez 《Journal of Atmospheric Chemistry》2010,66(3):167-178
Measurements of formaldehyde (HCHO) were made at the Cape Verde Atmospheric Observatory between November 2006 and June 2007 using the Long-Path Differential Optical Absorption Spectroscopy (LP-DOAS) technique. Observations show that typical HCHO mixing ratios ranged between 350 and 550 pptv (with typical 2-σ uncertainties of ~110 pptv), with several events of high HCHO, the maximum being 1,885?±?149 pptv. The observations indicate a lack of strong seasonal or diurnal variations, within the uncertainty of the measurements. A box model is employed to test whether the observations can be explained using known hydrocarbon photochemistry; the model replicates well the typical diurnal profile and monthly mean values. The model results indicate that on average 20% of HO2 production and 10% of OH destruction can be attributed to the mean HCHO levels, suggesting that even at these low average mixing ratios HCHO plays an important role in determining the HOx (HO2+OH) balance of the remote marine boundary layer. 相似文献