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1.
Analysis of chemical characteristics of PM<Subscript>2.5</Subscript> in Beijing over a 1-year period
Zhanshan Wang Dawei Zhang Baoxian Liu Yunting Li Tian Chen Feng Sun Dongyan Yang Yunping Liang Miao Chang Liu Yang Anguo Lin 《Journal of Atmospheric Chemistry》2016,73(4):407-425
Beijing is one of the largest and most densely populated cities in China. PM2.5 (fine particulates with aerodynamic diameters less than 2.5 μm) pollution has been a serious problem in Beijing in recent years. To study the temporal and spatial variations in the chemical components of PM2.5 and to discuss the formation mechanisms of secondary particles, SO2, NO2, PM2.5, and chemical components of PM2.5 were measured at four sites in Beijing, Dingling (DL), Chegongzhuang (CG), Fangshan (FS), and Yufa (YF), over four seasons from 2012 to 2013. Fifteen chemical components, including organic carbon (OC), elemental carbon (EC), K+, NH4 +, NO3 ?, SO4 2?, Cl?, Al, Ca, Fe, Mg, Na, Pb, Si, and Zn, were selected for analysis. Overall, OC, SO4 2?, NO3 ?, and NH4 + were dominant among 15 components, the annual average concentrations of which were 22.62 ± 21.86, 19.39 ± 21.06, 18.89 ± 19.82, and 13.20 ± 12.80 μg·m?3, respectively. Compared with previous studies, the concentrations of NH4 + were significantly higher in this study. In winter, the average concentrations of OC and EC were, respectively, 3 and 2.5 times higher than in summer, a result of coal combustion during winter. The average OC/EC ratios over the four sites were 4.9, 7.0, 8.1, and 8.4 in spring, summer, autumn, and winter, respectively. The annual average [NO3 ?]/[SO4 2?] ratios in DL, CG, FS, and YF were 1.01, 1.25, 1.08, and 1.12, respectively, which were significantly higher than previous studies in Beijing, indicating that the contribution ratio of mobile source increased in recent years in Beijing. Analysis of correlations between temperature and relative humidity and between SOR ([SO4 2?]/([SO4 2?] + [SO2])) and NOR ([NO3 ?]/([NO3 ?] + [NO2])) indicated that gas-phase oxidation reactions were the major formation mechanism of SO4 2? in spring and summer in urban Beijing, whereas slow gas-phase oxidation reactions and heterogeneous reactions both occurred in autumn and winter. NO3 ? was mainly formed through year-round heterogeneous reactions in urban Beijing. 相似文献
2.
Suresh Tiwari Atul K. Srivastava Deewan S. Bisht Tarannum Bano Sachchidanand Singh Sudhamayee Behura Manoj K. Srivastava D. M. Chate B. Padmanabhamurty 《Journal of Atmospheric Chemistry》2009,62(3):193-209
The concentrations of PM10, PM2.5 and their water-soluble ionic species were determined for the samples collected during January to December, 2007 at New Delhi
(28.63° N, 77.18° E), India. The annual mean PM10 and PM2.5 concentrations (± standard deviation) were about 219 (± 84) and 97 (±56) μgm−3 respectively, about twice the prescribed Indian National Ambient Air Quality Standards values. The monthly average ratio
of PM2.5/PM10 varied between 0.18 (June) and 0.86 (February) with an annual mean of ∼0.48 (±0.2), suggesting the dominance of coarser in
summer and fine size particles in winter. The difference between the concentrations of PM10 and PM2.5, is deemed as the contribution of the coarse fraction (PM10−2.5). The analyzed coarse fractions mainly composed of secondary inorganic aerosols species (16.0 μgm−3, 13.07%), mineral matter (12.32 μgm−3, 10.06%) and salt particles (4.92 μgm−3, 4.02%). PM2.5 are mainly made up of undetermined fractions (39.46 μgm−3, 40.9%), secondary inorganic aerosols (26.15 μgm−3, 27.1%), salt aerosols (22.48 μgm−3, 23.3%) and mineral matter (8.41 μgm−3, 8.7%). The black carbon aerosols concentrations measured at a nearby (∼300 m) location to aerosol sampling site, registered
an annual mean of ∼14 (±12) μgm−3, which is significantly large compared to those observed at other locations in India. The source identifications are made
for the ionic species in PM10 and PM2.5. The results are discussed by way of correlations and factor analyses. The significant correlations of Cl−, SO42−, K+, Na+, Ca2+, NO3− and Mg2+ with PM2.5 on one hand and Mg2+ with PM10 on the other suggest the dominance of anthropogenic and soil origin aerosols in Delhi. 相似文献
3.
Khaiwal Ravindra Marianne Stranger Rene Van Grieken 《Journal of Atmospheric Chemistry》2008,59(3):199-218
The new European Council Directive (PE-CONS 3696/07) frames the inhalable (PM10) and fine particles (PM2.5) on priority to chemically characterize these fractions in order to understand their possible relation with health effects.
Considering this, PM2.5 was collected during four different seasons to evaluate the relative abundance of bulk elements (Cl, S, Si, Al, Br, Cu, Fe,
Ti, Ca, K, Pb, Zn, Ni, Mn, Cr and V) and water soluble ions (F−, Cl−, NO2
−, NO3
−, SO4
2−, Na+, NH4
+, Ca2+ and Mg2+) over Menen, a Belgian city near the French border. The air quality over Menen is influenced by industrialized regions on
both sides of the border. The most abundant ionic species were NO3
−, SO4
2− and NH4
+, and they showed distinct seasonal variation. The elevated levels of NO3
− during spring and summer were found to be related to the larger availability of the NOx precursor. The various elemental species analyzed were distinguished into crustal and anthropogenic source categories. The
dominating elements were S and Cl in the PM2.5 particles. The anthropogenic fraction (e.g. Zn, Pb, and Cu) shows a more scattered abundance. Furthermore, the ions and elemental
data were also processed using principal component analysis and cluster analysis to identify their sources and chemistry.
These approach identifies anthropogenic (traffic and industrial) emissions as a major source for fine particles. The variations
in the natural/anthropogenic fractions of PM2.5 were also found to be a function of meteorological conditions as well as of long-range transport of air masses from the industrialized
regions of the continent.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
4.
A total of 11 PM2.5 samples were collected from October 2003 to October 2004 at 8 sampling sites in Beijing city. The PM2.5 concentrations are all above the PM2.5 pollution standard (65 μg m^-3) established by Environmental Protection Agency, USA (USEPA) in 1997 except for the Ming Tombs site. PM2.5 concentrations in winter are much higher than in summer. The 16 Polycyclic aromatic hydrocarbons (PAHs) listed as priority pollutants by USEPA in PM2.5 were completely identified and quantified by high performance liquid chromatography (HPLC) with variable wavelength detector (VWD) and fluorescence detector (FLD) employed. The PM2.5 concentrations indicate that the pollution situation is still serious in Beijing. The sum of 16 PAHs concentrations ranged from 22.17 to 5366 ng m^-3. The concentrations of the heavier molecular weight PAHs have a different pollution trend from the lower PAHs. Seasonal variations were mainly attributed to the difference in coal combustion emission and meteorological conditions. The source apportionment analysis suggests that PAHs from PM2.5 in Beijing city mainly come from coal combustion and vehicle exhaust emission. New measures about restricting coal combustion and vehicle exhaust must be established as soon as possible to improve the air pollution situation in Beijing city. 相似文献
5.
Xidan Feng Zhi Dang Weilin Huang Longyi Shao Weijun Li 《Journal of Atmospheric Chemistry》2009,64(1):37-51
Samples of airborne PM2.5 particles in Guangzhou urban area were collected during the autumn of 2006 and the spring of 2007. The morphologies and elemental
compositions of individual particles were determined by Scanning Electron Microscopy coupled with Energy Dispersive X-ray
Spectrometer (SEM-EDX). The obtained images were further analyzed for size distribution by an image analysis system. Based
on the morphology, particles in PM2.5 were classified into four groups: soot aggregates, minerals, fly ash and others. The amount of soot aggregates and minerals
were higher than that of fly ashes. The distributions of particles by number and size in two seasons were bimodal with 90%
less than 1.0 μm in diameter. The primary peak from the autumn samples was in the size range of 0.4 ~ 0.5 μm, and 0.3 ~ 0.4 μm
for the spring samples. More soot aggregates (36.1%) and minerals (61.5%) were found than fly ash (2.4%) in autumn, but soot
aggregates (89.9%) was the dominant particle type in spring. The size distribution of particles according to the volume was
generally opposite to that according to the number. Particles less than 1.0 μm were as high as 89.5% in number but contributed
only 18.9% in volume, indicating that fine particles contributed relatively little in volume although existing in large numbers. 相似文献
6.
Long-term measurements of atmospheric PM<Subscript>2.5</Subscript> and its chemical composition in rural Korea 总被引:4,自引:0,他引:4
Long-term measurements of ambient particulate matter less than 2.5 μm in diameter (PM2.5) and its chemical compositions were performed at a rural site in Korea from December 2005 to August 2009. The average PM2.5 concentration was 31 μg m−3 for the whole sampling period, and showed a slightly downward annual trend. The major components of PM2.5 were organic carbon, SO42−, NO3−, and NH4+, which accounted for 55 % of total PM2.5 mass on average. For the top 10 % of PM2.5 samples, anionic constituents and trace elements clearly increased while carbonaceous constituents and NH4+ remained relatively constant. Both Asian dust and fog events clearly increased PM2.5 concentrations, but affected its chemical composition differently. While trace elements significantly increased during Asian
dust events, NO3−, NH4+ and Cl were dramatically enhanced during fog events due to the formation of saturated or supersaturated salt solution. The
back-trajectory based model, PSCF (Potential Source Contribution Function) identified the major industrial areas in Eastern
China as the possible source areas for the high PM2.5 concentrations at the sampling site. Using factor analysis, soil, combustion processes, non-metal manufacture, and secondary
PM2.5 sources accounted for 77 % of the total explained variance. 相似文献
7.
The Atmospheric Environmental Monitoring Network successfully undertook the task of monitoring the atmospheric quality of Beijing and its surrounding area during the 2008 Olympics.The results of this monitoring show that high concentrations of PM2.5 pollution exhibited a regional pattern during the monitoring period(1 June-30 October 2008).The PM2.5 mass concentrations were 53 μg m 3,66 μg m 3,and 82 μg m 3 at the background site,in Beijing,and in the Beijing-Tianjin-Hebei urban agglomerations,respectively.The PM2.5 levels were lowest during the 2008 Olympic Games(8-24 August):35 μg m 3 at the background site,42 μg m 3 in Beijing and 57 μg m 3 in the region.These levels represent decreases of 49%,48%,and 56%,respectively,compared to the prophase mean concentration before the Olympic Games.Emission control measures contributed 62%-82% of the declines observed in Beijing,and meteorological conditions represented 18%-38%.The concentration of fine particles met the goals set for a "Green Olympics." 相似文献
8.
Zhaobin Sun Xiaoling Zhang Xiujuan Zhao Xiangao Xia Shiguang Miao Ziming Li Zhigang Cheng Wei Wen Yixi Tang 《Acta Meteorologica Sinica》2018,32(2):288-301
We used simultaneous measurements of surface PM2.5 concentration and vertical profiles of aerosol concentration, temperature, and humidity, together with regional air quality model simulations, to study an episode of aerosol pollution in Beijing from 15 to 19 November 2016. The potential effects of easterly and southerly winds on the surface concentrations and vertical profiles of the PM2.5 pollution were investigated. Favorable easterly winds produced strong upward motion and were able to transport the PM2.5 pollution at the surface to the upper levels of the atmosphere. The amount of surface PM2.5 pollution transported by the easterly winds was determined by the strength and height of the upward motion produced by the easterly winds and the initial height of the upward wind. A greater amount of PM2.5 pollution was transported to upper levels of the atmosphere by upward winds with a lower initial height. The pollutants were diluted by easterly winds from clean ocean air masses. The inversion layer was destroyed by the easterly winds and the surface pollutants and warm air masses were then lifted to the upper levels of the atmosphere, where they re-established a multi-layer inversion. This region of inversion was strengthened by the southerly winds, increasing the severity of pollution. A vortex was produced by southerly winds that led to the convergence of air along the Taihang Mountains. Pollutants were transported from southern–central Hebei Province to Beijing in the boundary layer. Warm advection associated with the southerly winds intensified the inversion produced by the easterly winds and a more stable boundary layer was formed. The layer with high PM2.5 concentration became dee-per with persistent southerly winds of a certain depth. The polluted air masses then rose over the northern Taihang Mountains to the northern mountainous regions of Hebei Province. 相似文献
9.
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
10.
Jae-Seok Kim Anna Liza Bais Sun-hee Kang Jaehoon Lee Kihong Park 《Journal of Atmospheric Chemistry》2011,68(3):251-263
Ammonia has a short residence time in the atmosphere and rapidly neutralizes acid gases that occur near its source, requiring a rapid measurement system for ammonia and particulate ammonium concentrations to better understand their sources, temporal variation of ammonia emissions, and the formation of secondary ammonium aerosols. A semi-continuous measurement system, consisting of a diffusion scrubber, a particle growth chamber, an air-liquid separator, and a fluorescent detector, was developed to determine both gaseous ammonia (NH3) and particulate ammonium (NH 4 + ) in PM2.5 in the ambient atmosphere of Gwangju, South Korea, during the months of March, April, July, and September of 2007. During the sampling periods, the average concentrations of ammonia and ammonium were found to be 2.33?±?1.29 μg/m3 and 1.89?±?0.99 μg/m3, respectively. Although the average gaseous ammonia concentration was highest in March, the particulate ammonium concentration was higher during the warmer season, reaching 2.08?±?1.07 μg/m3 and 2.32?±?0.94 μg/m3 in April and July, respectively, while only 1.68?±?0.61 μg/m3 in March and 1.24?±?0.99 μg/m3 in September. It is proposed that the higher availability of acid species during the warmer months produced a significant amount of particulate ammonium sulfate. Diurnal fluctuation of ammonia and ammonium during the warmer months showed that their peak time occurred at approximately 10:00 am. Both ammonia and ammonium concentrations were better correlated during the warmer months than during the cooler months. Further, the data suggest that the ammonia and ammonium were measured under well dispersed conditions, and multiple sources contributed to the ammonia at the sampling site. 相似文献
11.
Reconstructed light extinction coefficients using chemical compositions of PM<Subscript>2.5</Subscript> in winter in Urban Guangzhou,China 总被引:8,自引:0,他引:8
The objective of this study was to reconstruct light extinction coefficients (b ext ) according to chemical composition components of particulate matter up to 2.5 μm in size (PM 2.5 ). PM 2.5 samples were collected at the monitoring station of the South China of Institute of Environmental Science (SCIES, Guangzhou, China) during January 2010, and the online absorbing and scattering coefficients were obtained using an aethalometer and a nephelometer. The measured values of light absorption coefficient by particle (b ap ) and light scattering coefficient by particle (b sp ) significantly correlated (R 2 > 0.95) with values of b ap and b sp that were reconstructed using the Interagency Monitoring of Protected Visual Environments (IMPROVE) formula when RH was <70%. The measured b ext had a good correlation (R 2 > 0.83) with the calculated b ext under ambient RH conditions. The result of source apportionment of b ext showed that ammonium sulfate [(NH 4 ) 2 SO 4 ] was the largest contributor (35.0%) to b ext , followed by ammonium nitrate (NH 4 NO 3 , 22.9%), organic matter (16.1%), elemental carbon (11.8%), sea salt (4.7%), and nitrogen dioxide (NO 2 , 9.6%). To improve visibility in Guangzhou, the effective control of secondary particles like sulfates, nitrates, and ammonia should be given more attention in urban environmental management. 相似文献
12.
Junting Zhong Xiaoye Zhang Yaqiang Wang Junying Sun Yangmei Zhang Jizhi Wang Kaiyan Tan Xiaojing Shen Haochi Che Lu Zhang Zhouxiang Zhang Xuefei Qi Huarong Zhao Sanxue Ren Yang Li 《Acta Meteorologica Sinica》2017,31(5):809-819
Based on observations of urban mass concentration of fine particulate matter smaller than 2.5 μm in diameter (PM2.5), ground meteorological data, vertical measurements of winds, temperature, and relative humidity (RH), and ECMWF reanalysis data, the major changes in the vertical structures of meteorological factors in the boundary layer (BL) during the heavy aerosol pollution episodes (HPEs) that occurred in winter 2016 in the urban Beijing area were analyzed. The HPEs are divided into two stages: the transport of pollutants under prevailing southerly winds, known as the transport stage (TS), and the PM2.5 explosive growth and pollution accumulation period characterized by a temperature inversion with low winds and high RH in the lower BL, known as the cumulative stage (CS). During the TS, a surface high lies south of Beijing, and pollutants are transported northwards. During the CS, a stable BL forms and is characterized by weak winds, temperature inversion, and moisture accumulation. Stable atmospheric stratification featured with light/calm winds and accumulated moisture (RH > 80%) below 250 m at the beginning of the CS is closely associated with the inversion, which is strengthened by the considerable decrease in near-surface air temperature due to the interaction between aerosols and radiation after the aerosol pollution occurs. A significant increase in the PLAM (Parameter Linking Aerosol Pollution and Meteorological Elements) index is found, which is linearly related to PM mass change. During the first 10 h of the CS, the more stable BL contributes approximately 84% of the explosive growth of PM2.5 mass. Additional accumulated near-surface moisture caused by the ground temperature decrease, weak turbulent diffusion, low BL height, and inhibited vertical mixing of water vapor is conducive to the secondary aerosol formation through chemical reactions, including liquid phase and heterogeneous reactions, which further increases the PM2.5 concentration levels. The contribution of these reaction mechanisms to the explosive growth of PM2.5 mass during the early CS and subsequent pollution accumulation requires further investigation. 相似文献
13.
We present mobile vehicle lidar observations in Tianjin, China during the spring, summer, and winter of 2016. Mobile observations were carried out along the city border road of Tianjin to obtain the vertical distribution characteristics of PM2.5. Hygroscopic growth was not considered since relative humidity was less than 60% during the observation experiments. PM2.5 profile was obtained with the linear regression equation between the particle extinction coefficient and PM2.5 mass concentration. In spring, the vertical distribution of PM2.5 exhibited a hierarchical structure. In addition to a layer of particles that gathered near the ground, a portion of particles floated at 0.6–2.5-km height. In summer and winter, the fine particles basically gathered below 1 km near the ground. In spring and summer, the concentration of fine particles in the south was higher than that in the north because of the influence of south wind. In winter, the distribution of fine particles was opposite to that measured during spring and summer. High concentrations of PM2.5 were observed in the rural areas of North Tianjin with a maximum of 350 μg m–3 on 13 December 2016. It is shown that industrial and ship emissions in spring and summer and coal combustion in winter were the major sources of fine particles that polluted Tianjin. The results provide insights into the mechanisms of haze formation and the effects of meteorological conditions during haze–fog pollution episodes in the Tianjin area. 相似文献
14.
U.C. Dumka S. Tiwari D.G. Kaskaoutis P.K. Hopke Jagvir Singh A.K. Srivastava D.S. Bisht S.D. Attri S. Tyagi A. Misra G.S. Munawar Pasha 《Journal of Atmospheric Chemistry》2017,74(4):423-450
Haze-fog conditions over northern India are associated with visibility degradation and severe attenuation of solar radiation by airborne particles with various chemical compositions. PM2.5 samples have been collected in Delhi, India from December 2011 to November 2012 and analyzed for carbonaceous and inorganic species. PM10 measurements were made simultaneously such that PM10–2.5 could be estimated by difference. This study analyzes the temporal variation of PM2.5 and carbonaceous particles (CP), focusing on identification of the primary and secondary aerosol emissions, estimations of light extinction coefficient (bext) and the contributions by the major PM2.5 chemical components. The annual mean concentrations of PM2.5, organic carbon (OC), elemental carbon (EC) and PM10–2.5 were found to be 153.6 ± 59.8, 33.5 ± 15.9, 6.9 ± 3.9 and 91.1 ± 99.9 μg m?3, respectively. Total CP, secondary organic aerosols and major anions (e.g., SO4 2? and NO3 ?) maximize during the post-monsoon and winter due to fossil fuel combustion and biomass burning. PM10–2.5 is more abundant during the pre-monsoon and post-monsoon. The OC/EC varies from 2.45 to 9.26 (mean of 5.18 ± 1.47), indicating the influence of multiple combustion sources. The bext exhibits highest values (910 ± 280 and 1221 ± 371 Mm?1) in post-monsoon and winter and lowest in monsoon (363 ± 110 and 457 ± 133 Mm?1) as estimated via the original and revised IMPROVE algorithms, respectively. Organic matter (OM =1.6 × OC) accounts for ~39 % and ~48 % of the bext, followed by (NH4)2SO4 (~21 % and ~24 %) and EC (~13 % and ~10 %), according to the original and revised algorithms, respectively. The bext estimates via the two IMPROVE versions are highly correlated (R2 = 0.95, root mean square error = 38 % and mean bias error = 28 %) and are strongly related to visibility impairment (r = ?0.72), mostly associated with anthropogenic rather than natural PM contributions. Therefore, reduction of CP and precursor gas emissions represents an urgent opportunity for air quality improvement across Delhi. 相似文献
15.
S. K. Sharma T. K. Mandal A. K. De N. C. Deb Srishti Jain Mohit Saxena S. Pal A. K. Choudhuri Saraswati 《Journal of Atmospheric Chemistry》2018,75(2):219-233
Ambient concentrations of organic carbon (OC), elemental carbon (EC) and water soluble inorganic ionic components (WSIC) of PM10 were studied at Giridih, Jharkhand, a sub-urban site near the Indo Gangatic Plain (IGP) of India during two consecutive winter seasons (November 2011–February 2012 and November 2012–February 2013). The abundance of carbonaceous and water soluble inorganic species of PM10 was recorded at the study site of Giridih. During winter 2011–12, the average concentrations of PM10, OC, EC and WSIC were 180.2?±?46.4; 37.2?±?6.2; 15.2?±?5.4 and 18.0?±?5.1 μg m?3, respectively. Similar concentrations of PM10, OC, EC and WSIC were also recorded during winter 2012–13. In the present case, a positive linear trend is observed between OC and EC at sampling site of Giridih indicates the coal burning, as well as dispersed coal powder and vehicular emissions may be the source of carbonaceous aerosols. The principal components analysis (PCA) also identifies the contribution of coal burning? +?soil dust, vehicular emissions?+?biomass burning and seconday aerosol to PM10 mass concentration at the study site. Backward trajectoy and potential source contributing function (PSCF) analysis indicated that the aerosols being transported to Giridih from upwind IGP (Punjab, Haryana, Uttar Pradesh and Bihar) and surrounding region. 相似文献
16.
Long-term characterization of major water-soluble inorganic ions in PM<Subscript>10</Subscript> in coastal site on the Japan Sea 总被引:1,自引:0,他引:1
Yong-tao Guo Jing Zhang Shi-gong Wang Feng She Xu Li 《Journal of Atmospheric Chemistry》2011,68(4):299-316
PM10 samples were collected over three years at Monzenmachi, the Japan Sea coast, the Noto Peninsula, Ishikawa, Japan from January
17, 2001 to December 18, 2003, using a high volume air sampler with quartz filters. The concentrations of the water-soluble
inorganic ions in PM10 were determined with using ion chromatography. By analyzing the characteristics of these, the evidences were found that the
Asian outflow had an obviously influence on the air quality at our study site. The results were as follows: the secondary
pollutants SO42−, NO3− and NH4+ were the primary water-soluble inorganic ions at our study site. The monthly mean concentrations of SO42−, NH4+, NO3− and Ca2+ have prominent peak in spring due to the strong influence of the Asian continent outflow—these according to backward air
trajectory analysis, the maximum of which were 6.09 for nss-SO42− in May, 2.87 for NO3− and 0.68 μg m−3 for nss-Ca2+ in April, respectively. Comparable to similar data reported from various points around East Asia, it had the characteristics
of a polluted coastal area at our study site. The concentration of nss-Ca2+ in PM10 drastically increased when the Asian dust invaded, the mean value during the Asian dust days(AD) was 0.86 μg m−3, about 4 times higher than those of normal days (NAD). Meanwhile, the mean concentrations of nss-SO42−, NO3− and NH4+ in AD periods were higher than those in NAD periods which were 5.87, 1.76 and 1.82 μg m−3, respectively, it is due to the interaction between dust and secondary particles during the long-range transport of dust
storms. Finally, according to the source apportionment with positive matrix factorization (PMF) method in this study, the
major source profiles of PM10 at our study site were categorized as (1) marine salt, (2) secondary sulfate, (3) secondary nitrate and (4) crustal source. 相似文献
17.
Quick measurement of CH<Subscript>4</Subscript>, CO<Subscript>2</Subscript> and N<Subscript>2</Subscript>O emissions from a short-plant ecosystem 总被引:43,自引:0,他引:43
Combining improved injector, gas line and valve-driving models, a gas chromatograph (GC) equipped with Hydrogen Flame Ionization Detector (FID) and Electron Capture Detector (ECD), can measure CH4, CO2, and N2O simultaneously in an air sample in four minutes. Test results show that the system has high sensitivity, resolution, and precision; the linear response range of the system meets the requirement of flux measurements in situ. The system is suitable for monitoring fluxes of the main greenhouse gases in a short-plant field since it is easy to use, efficacious, and constant and reliable in collecting data. 相似文献
18.
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
19.
The heterogeneous interaction of nitrogen dioxide with ammonium chloride was investigated in a molecular diffusion tube experiment
at 295–335 K and interpreted using Monte Carlo trajectory calculations. The surface residence time (τsurf) of NO2 on NH4Cl is equal to 15 μs at 295 K, increases with temperature up to 323 K (τsurf = 45 μs) and probably decreases beyond 323 K. The same experiment also yields uptake coefficients, γ, which are derived from
the absolute number of surviving molecules effusing out of the diffusion tube. The rate of uptake of NO2 on NH4Cl followed a rate law first order in [NO2] and the uptake coefficient γ is equal to 7 × 10−5 at 295 K, increases with temperature up to 323 K (γ = 2.1 × 10−4) and probably decreases beyond 323 K. Nitrous acid, water and nitrogen were detected as products. From these products, it
is concluded that the reaction of NO2 with NH4Cl is a reverse disproportionation reaction where two moles of NO2 result in ammonium nitrite, NH4NO2, as an intermediate, and nitryl chloride, NO2Cl. NH4NO2 decomposes in two pathways, one to nitrous acid, HONO and NH3, the other to nitrogen and water. The branching ratio for the production of HONO + NH3 to that of N2 + H2O is approximately 20 at 298 K and increases with increasing temperature. 相似文献
20.
Climate is simulated for reference and mitigation emissions scenarios from Integrated Assessment Models using the Bern2.5CC
carbon cycle–climate model. Mitigation options encompass all major radiative forcing agents. Temperature change is attributed
to forcings using an impulse–response substitute of Bern2.5CC. The contribution of CO2 to global warming increases over the century in all scenarios. Non-CO2 mitigation measures add to the abatement of global warming. The share of mitigation carried by CO2, however, increases when radiative forcing targets are lowered, and increases after 2000 in all mitigation scenarios. Thus,
non-CO2 mitigation is limited and net CO2 emissions must eventually subside. Mitigation rapidly reduces the sulfate aerosol loading and associated cooling, partly
masking Greenhouse Gas mitigation over the coming decades. A profound effect of mitigation on CO2 concentration, radiative forcing, temperatures and the rate of climate change emerges in the second half of the century. 相似文献