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1.
Agricultural waste burning is a widespread practice throughout the world but there is little information about its pollutant impact. This paper deals with a preliminary study of the pollution observed in Vitoria (Northern Spain) caused by cereal waste burning. The mean hourly flux of pollutants produced by cereal waste burning fires can reach values of 1.4 kt of CO 2, 13 t of TPM and 3 t of NO x in the area around Vitoria. Measurements obtained in the area of emission and inside fire plumes show high ratios (NO 2/NO x) indicating that nitrogen oxides emitted by the source undergo a rapid transformation in the same area of emission. Results relating to aerosol composition collected in Vitoria during burning periods show an increase in the concentration of K +, NO 3− and Cl − ions, that are inter-correlated. The modification of the ionic composition of aerosols also affects the chemistry of the rain collected in Vitoria. During the burning period, it is particularly noticeable that anthropogenic pollution (usually identifiable by the correlation between SO 42− and NO 3− concentrations) disappears, indicating the existence of an independent source of NO 3− not linked to the SO 42− source. Similar results were deduced studying BAPMON data collected in Spain during cereal waste burning. Finally, we note that ozone concentration measured at Vitoria is not affected by the pollution generated by the burning fires. 相似文献
2.
In this study, air pollutants, including ozone (O 3), nitrogen oxides (NO x = NO + NO 2), carbon monoxides (CO), sulfur dioxide (SO 2), and volatile organic compounds (VOCs) measured in the Yangtze River Delta (YRD) region during several air flights between September/30 and October/11 are analyzed. This measurement provides horizontal and vertical distributions of air pollutants in the YRD region. The analysis of the result shows that the measured O 3 concentrations range from 20 to 60 ppbv. These values are generally below the US national standard (84 ppbv), suggesting that at the present, the O 3 pollutions are modest in this region. The NO x concentrations have strong spatial and temporal variations, ranging from 3 to 40 ppbv. The SO 2 concentrations also have large spatial and temporal variations, ranging from 1 to 35 ppbv. The high concentrations of CO are measured with small variations, ranging from 3 to 7 ppmv. The concentrations of VOCs are relatively low, with the total VOC concentrations of less than 6 ppbv. The relative small VOC concentrations and the relative large NO x concentrations suggest that the O 3 chemical formation is under a strong VOC-limited regime in the YRD region. The measured O 3 and NO x concentrations are strongly anti-correlated, indicating that enhancement in NO x concentrations leads to decrease in O 3 concentrations. Moreover, the O 3 concentrations are more sensitive to NO x concentrations in the rural region than in the city region. The ratios of Δ[O 3]/Δ[NO x] are ?2.3 and ?0.25 in the rural and in the city region, respectively. In addition, the measured NO x and SO 2 concentrations are strongly correlated, highlighting that the NO x and SO 2 are probably originated from same emission sources. Because SO 2 emissions are significantly originated from coal burnings, the strong correlation between SO 2 and NO x concentrations suggests that the NO x emission sources are mostly from coal burned sources. As a result, the future automobile increases could lead to rapid enhancements in O 3 concentrations in the YRD region. 相似文献
3.
Measurements on size distribution of atmospheric aerosol were made at Dayalbagh, Agra during July to September 1998. A 4-stage cascade particle sampler (CPS - 105) which fractionates particles in sizes ranging between 0.7 and >10.9 μm, was used. Samples were collected on Whatman 41 filters. The filters were analyzed for the major water-soluble ions. The anions (F, Cl, NO 3 and SO 4) were analyzed by Dionex DX-500 ion chromatograph while atomic absorption and colorimetric techniques were used for the analysis of cations (Na, K, Ca and Mg) and NH 4, respectively. The average mass of aerosol was found to be 131.6 μg m −3 and aerosol composition was found to be influenced by terrigeneous sources. The mass size distribution of total aerosol and the ions NH 4, Cl, NO 3, K, Ca, Mg, SO 4 and Na was bimodal while that of F was unimodal. SO 4, F, K and NH 4 dominated in the fine mode while Ca, Mg, Cl and NO 3 were in abundance in coarse fraction. Na was found in both coarse as well as fine mode. Coarse mode SO 4 and NO 3 have been ascribed to contribution from re-suspension of soil and formation by heterogeneous oxidation on soil derived particles. Preponderance of K in fine mode is attributed to emissions from vegetation and from burning of plant materials. Ca, Mg, Cl and NO 3 are largely soil derived and hence dominate in coarse fraction. Equivalent ratios of NH 4/(SO 4+NO 3) were calculated for both fine and coarse aerosols. The coarse mode ratio varied between 0.7 and 1.4 while in fine mode it ranged between 1.4 and 1.9. It shows that aerosol is basic, the basicity of coarse mode is due to higher concentration of soil-derived alkaline components while the basicity in fine mode is due to neutralization of acidity by NH 3. 相似文献
4.
The influence of NO x (NO+NO 2) concentrations on the product distribution of the OH-initiated oxidation of DMS has been studied at room temperature using total NO x concentrations varying from 0 to ∼1800 ppbv (30–600 ppbv NO 2 and 140–1760 ppbv NO). Clear trends in the formation yields of the products SO 2, COS, MSA, MTF (methyl thiolformate), MSPN (methanesulphonyl peroxynitrate), DMSO and DMSO 2 have been observed with variation in NO x. The presence of low levels of NO reduces the yields of both MTF and COS to zero. The formation yields of MSA and DMSO 2 increase with increasing NO x concentration, whereas the yields of DMSO and SO 2 decrease. The following approximate changes in the yield, not corrected for possible loss processes, have been measured for variation of NO x between 0 and ∼1800 ppbv: DMSO decreases from 20 to 3%S; DMSO 2 increases from 3 to 15%S, SO 2 decreases from 70 to 30%S and MSA increases from 4 to 17%S. Under the experiments conditions NO x levels of several tens of ppbv are required before a perceptible change is observed in the MSA yield. If applicable to the atmosphere such a situation is only likely to be observed near coastal areas affected by pollution. MSPN (CH 3SO 2O 2NO 2) is observed as an oxidation product in the presence of NO 2 even at low levels (e.g. 60 ppbv). Its possible role as a NO x reservoir in the troposphere is considered. 相似文献
5.
In this study, we present ∼1 yr (October 1998–September 1999) of 12-hour mean ammonia (NH 3), ammonium (NH 4+), hydrochloric acid (HCl), chloride (Cl −), nitrate (NO 3−), nitric acid (HNO 3), nitrous acid (HONO), sulfate (SO 42−), and sulfur dioxide (SO 2) concentrations measured at an agricultural site in North Carolina's Coastal Plain region. Mean gas concentrations were 0.46, 1.21, 0.54, 5.55, and 4.15 μg m −3 for HCl, HNO 3, HONO, NH 3, and SO 2, respectively. Mean aerosol concentrations were 1.44, 1.23, 0.08, and 3.37 μg m −3 for NH 4+, NO 3−, Cl −, and SO 42−, respectively. Ammonia, NH 4+, HNO 3, and SO 42− exhibit higher concentrations during the summer, while higher SO 2 concentrations occur during winter. A meteorology-based multivariate regression model using temperature, wind speed, and wind direction explains 76% of the variation in 12-hour mean NH 3 concentrations ( n=601). Ammonia concentration increases exponentially with temperature, which explains the majority of variation (54%) in 12-hour mean NH 3 concentrations. Dependence of NH 3 concentration on wind direction suggests a local source influence. Ammonia accounts for >70% of NH x (NH x=NH 3+NH 4+) during all seasons. Ammonium nitrate and sulfate aerosol formation does not appear to be NH 3 limited. Sulfate is primarily associated ammonium sulfate, rather than bisulfate, except during the winter when the ratio of NO 3−–NH 4+ is ∼0.66. The annual average NO 3−–NH 4+ ratio is ∼0.25. 相似文献
6.
High concentrations (>15 μm 3 cm ?3) of CaSO 4, Ca(NO 3) 2 and (NH 4) 2SO 4 were selected as surrogates of dry neutral, aqueous neutral and dry acidic inorganic seed aerosols, respectively, to study the effects of inorganic seeds on secondary organic aerosol (SOA) formation in irradiated m-xylene/NO x photooxidation systems. The results indicate that neither ozone formation nor SOA formation is significantly affected by the presence of neutral aerosols (both dry CaSO 4 and aqueous Ca(NO 3) 2), even at elevated concentrations. The presence of high concentrations of (NH 4) 2SO 4 aerosols (dry acidic) has no obvious effect on ozone formation, but it does enhance SOA generation and increase SOA yields. In addition, the effect of dry (NH 4) 2SO 4 on SOA yield is found to be positively correlated with the (NH 4) 2SO 4 surface concentration, and the effect is pronounced only when the surface concentration reaches a threshold value. Further, it is proposed that the SOA generation enhancement is achieved by particle-phase heterogeneous reactions induced and catalyzed by the acidity of dry (NH 4) 2SO 4 seed aerosols. 相似文献
7.
Ground-based ambient air monitoring was conducted to assess the contribution of crop residue burning of wheat (Triticum aestivum) and rice (Oriza sativa) at different locations in three districts (Kaithal, Kurukshetra, and Karnal) of the agricultural state of Haryana in India for two successive years (2016 and 2017). The Air Quality Index (AQI) and concentration of primary pollutants (SOx, NOx, and PM2.5) were determined in rice and wheat crop season, for burning and non-burning periods. During crop residue burning periods, concentrations of SOx, NOx, and PM2.5 were exceeded the NAAQS values by 78%, 71%, and 53%, respectively. A significant increase in SOx (4.5 times), NOx (3.8 times), and PM2.5 concentration (3.5 times) was observed in stubble burning periods as compared to pre-burning (p < 0.05). A positive and significant correlation among the three pollutant concentrations was observed (p < 0.01). The AQI of KA site in Karnal district fell in severely polluted category during 2016 for rice as well as wheat residue burning period, and of KK site in Kaithal during wheat residue burning in year 2017. Results of present study indicate a remarkable increase in pollutant concentration (SOx, NOx, and PM2.5) during the crop residue burning periods. To the best of our knowledge, the outcomes of present study in this region have not been reported in earlier reports. Hence, there is an urgent need to curb air pollution by adopting sustainable harvesting technologies and management of residues. 相似文献
8.
We present characteristics of the sulfur dioxide (SO 2) loading over Thessaloniki, Greece, and seven other selected sites around the world using SO 2 total column measurements from Brewer spectrophotometers together with satellite estimates of the Version 8 TOMS Sulfur Dioxide Index (SOI) over the same locations, retrieved from Nimbus 7 TOMS (1979–1993), Earth Probe TOMS (1996–2003) and OMI/Aura (2004–2006). Traditionally, the SOI has been used to quantify the SO 2 quantities emitted during great volcanic eruptions. Here, we investigate whether the SOI can give an indication of the total SO 2 load for areas and periods away from eruptive volcanic activity by studying its relative changes as a correlative measure to the SO 2 total column. We examined time series from Thessaloniki and another seven urban and non-urban stations, five in the European Union (Arosa, De Bilt, Hohenpeissenberg, Madrid, Rome) and two in India (Kodaikanal, New Delhi). Based on the Brewer data, Thessaloniki shows high SO 2 total columns for a European Union city but values are still low if compared to highly affected regions like those in India. For the time period 1983–2006 the SO 2 levels above Thessaloniki have generally decreased with a rate of 0.028 Dobson Units (DU) per annum, presumably due to the European Union's strict sulfur control policies. The seasonal variability of the SO 2 total column exhibits a double peak structure with two maxima, one during winter and the second during summer. The winter peak can be attributed to central heating while the summer peak is due to synoptic transport from sources west of the city and sources in the north of Greece. A moderate correlation was found between the seasonal levels of Brewer total SO 2 and SOI for Thessaloniki, Greece ( R = 0.710–0.763) and Madrid, Spain ( R = 0.691) which shows that under specific conditions the SOI might act as an indicator of the SO 2 total load. 相似文献
9.
The annular denuder system (ADS) was used to characterize seasonal variations of acidic air pollutants in Seoul, South Korea. Fifty- four 24 h samples were collected over four seasons from October 1996 to September 1997. The annual mean concentrations of HNO 3, HNO 2, SO 2 and NH 3 in the gas phase were 1.09, 4.51, 17.3 and 4.34 μg m -3, respectively. The annual mean concentrations of PM 2.5( dp≤2.5 μm in aerodynamic diameter, 50% cutoff), SO 2-4, NO -3 and NH +4 in the particulate phase were 56.9, 8.70, 5.97 and 4.19 μg m -3, respectively. All chemical species monitored from this study showed statistical seasonal variations. Nitric acid (HNO 3) and ammonia (NH 3) exhibited substantially higher concentrations during the summer, while nitrous acid (HNO 2) and sulfur dioxide(SO 2) were higher during the winter. Concentrations of PM 2.5, SO 2-4, NO -3 and NH +4 in the particulate phase were higher during the winter months. SO 2-4, NO -3 and NH +4 accounted for 26–38% of PM 2.5. High correlations were found among PM 2.5, SO 2-4, NO -3 and NH +4. The mean H + concentration measured only in the fall was 5.19 nmole m -3. 相似文献
10.
This paper evaluates the relative impact on air quality of harbour emissions, with respect to other emission sources located in the same area. The impact assessment study was conducted in the city of Taranto, Italy. This area was considered as representative of a typical Mediterranean harbour region, where shipping, industries and urban activities co-exist at a short distance, producing an ideal case to study the interaction among these different sources. Chemical and meteorological field campaigns were carried out to provide data to this study. An emission inventory has been developed taking into account industrial sources, traffic, domestic heating, fugitive and harbour emissions. A 3D Lagrangian particle dispersion model (SPRAY) has then been applied to the study area using reconstructed meteorological fields calculated by the diagnostic meteorological model MINERVE. 3D short term hourly concentrations have been computed for both all and specific sources. Industrial activities are found to be the main contributor to SO 2. Industry and traffic emissions are mainly responsible for NO x simulated concentrations. CO concentrations are found to be mainly related to traffic emissions, while primary PM 10 simulated concentrations tend to be linked to industrial and fugitive emissions. Contributions of harbour activities to the seasonal average concentrations of SO 2 and NO x are predicted to be up to 5 and 30 μg m −3, respectively to be compared to a overall peak values of 60 μg m −3 for SO 2 and 70 μg m −3 for NO x. At selected urban monitoring stations, SO 2 and NO x average source contributions are predicted to be both of about 9% from harbour activities, while 87% and 41% respectively of total concentrations are predicted to be of industrial origin. 相似文献
11.
Long-range transport of mineral dust such as Yellow sand (YS) is not restricted to the springtime periods in Northeast Asia. A YS phenomenon was observed during 25–27 January 1999, which was a remarkably distinctive episode in the occurrence time and intensity that had ever observed in the wintertime in Korea. This YS event was traced to be originated from the arid region of central and eastern Asia; the Gobi desert and Loess plateau. The traveling speed of the dust storm was found to be about 70 km h −1 with it's horizontal size of larger than the whole Korean peninsula during this episode. Aerosol mass loadings changed by an order of magnitude within a few hours. The dominant ion components were SO 42−, NO 3−, Ca 2+ and Na + during the passage of YS. The mode diameter of these compounds of YS was around 4 μm, compared to 0.4–0.9 μm after the passage of YS. SO 42− and NO 3− concentrations were found to be well correlated with Ca 2+ concentration in the coarse mode during the YS event, whereas they were well correlated with NH 4+ concentration during the non-YS period, indicating a significant amount of SO 42− and NO 3− formations on the Ca 2+-rich coarse aerosol during the long-range transport of YS. 相似文献
12.
Ozone and related trace gases (CO, NO x, and SO 2) were measured from June 1999 to July 2000 at a rural site in the Yangtze Delta of China, a region of intensive anthropogenic activity. Elevated ozone levels were frequently observed during the study period, with the highest frequency in late spring and early summer. Over a 1 yr period, 21 d were found to have ozone concentrations exceeding the new US 8-h 80 ppb health standard. Calculation of the “SUM06” exposure index also shows relatively high (>15 ppm h) values for each season except winter. At these levels ozone may have adverse effects on human health as well as agricultural crops. Analysis of meteorological data shows that the high ozone days were associated with large-scale stagnation, intense solar radiation, and minimum rainfall. Large-scale back trajectories indicate a slow-moving/re-circulating airmass during the episodic days. Examination of chemical data shows that the observed daytime high ozone concentrations were due to downward mixing of ozone-rich air, in situ photochemical formation, and in some cases, advection to the site of aged plumes. The very high CO levels (and high CO to NO x ratios) were found to coincide with many of the ozone episodes, suggesting a contribution from sources of emission involving incomplete combustion. It is suggested that the burning of biomass (e.g., biofeuls and crop residues) may be an important source for the observed high CO and O 3 values. 相似文献
13.
A spatially resolved biomass burning data set, and related emissions of sulphur dioxide and aerosol chemical constituents was constructed for India, for 1996–1997 and extrapolated to the INDOEX period (1998–1999). Sources include biofuels (wood, crop waste and dung-cake) and forest fires (accidental, shifting cultivation and controlled burning). Particulate matter (PM) emission factors were compiled from studies of Indian cooking stoves and from literature for open burning. Black carbon (BC) and organic matter (OM) emissions were estimated from these, accounting for combustion temperatures in cooking stoves. Sulphur dioxide emission factors were based on fuel sulphur content and reported literature measurements. Biofuels accounted 93% of total biomass consumption (577 MT yr −1), with forest fires contributing only 7%. The national average biofuel mix was 56 : 21 : 23% of fuelwood, crop waste and dung-cake, respectively. Compared to fossil fuels, biomass combustion was a minor source of SO 2 (7% of total), with higher emissions from dung-cake because of its higher sulphur content. PM 2.5 emissions of 2.04 Tg yr −1 with an “inorganic fraction” of 0.86 Tg yr −1 were estimated. Biomass combustion was the major source of carbonaceous aerosols, accounting 0.25 Tg yr −1 of BC (72% of total) and 0.94 Tg yr −1 of OM (76% of total). Among biomass, fuelwood and crop waste were primary contributors to BC emissions, while dung-cake and forest fires were primary contributors to OM emissions. Northern and the east-coast India had high densities of biomass consumption and related emissions. Measurements of emission factors of SO 2, size resolved aerosols and their chemical constituents for Indian cooking stoves are needed to refine the present estimates. 相似文献
14.
Marine background levels of non-sea-salt- (nss-) SO 42− (5.0–9.7 neq m −3), NH 4+ (2.1–4.4 neq m −3) and elemental carbon (EC) (40–80 ngC m −3) in aerosol samples were measured over the equatorial and South Pacific during a cruise by the R/V Hakuho-maru from November 2001 to March 2002. High concentrations of nss-SO 42− (47–94 neq m −3), NH 4+ (35–94 neq m −3) and EC (130–460 ngC m −3) were found in the western North Pacific near the coast of the Asian continent under the influence of the Asian winter monsoon. Particle size distributions of ionic components showed that the equivalent concentrations of nss-SO 42− were balanced with those of NH 4+ in the size range of 0.06< D<0.22 μm, whereas the concentration ratios of NH 4+ to nss-SO 42− in the size range of D>0.22 μm were decreased with increase in particle size. We estimated the source contributions of those aerosol components in the marine background air over the equatorial and South Pacific. Biomass burning accounted for the large fraction (80–98% in weight) of EC and the minor fraction (2–4% in weight) of nss-SO 42−. Marine biogenic source accounted for several tens percents of NH 4+ and nss-SO 42−. In the accumulation mode, 70% of particle number existed in the size range of 0.1< D<0.2 μm. In the size rage of 0.06< D<0.22 μm, the dominant aerosol component of (NH 4) 2SO 4 would be mainly derived from the marine biogenic sources. 相似文献
15.
The interaction of NO 2 on carbonaceous aerosol particles in an NO 2 concentration range relevant for the troposphere was studied. The adsorption as a function of NO 2 concentration (2.5–65 ppb) was investigated along with the dependence on time (1–600 s) and particle concentration. The results exhibit a zero-order process in NO 2 for the chemisorption over the measured time and concentration range. The results suggest that the chemisorption reaction is limited by a rapidly established steady-state coverage of a precursor in the form of reversibly adsorbed NO 2 which seems to be constant over the whole investigated NO 2 concentration range. Within the first 20 s, a chemisorption rate of 2.5×10 11 molecules cm -2 s -1 was calculated. To estimate a saturation value for the NO 2 adsorption on carbonaceous aerosol particles, bulk experiments were performed where the aerosol was deposited on a filter before exposure to NO 2. This gives a lower limit for the total NO 2 adsorption of about 1×10 14 molecules cm -2 of particle surface area. The measurements show that the concept of the often used sticking coefficient γ (i.e. the number of adsorbed molecules per number of the total gas–surface collisions) is not a useful parameter to describe the chemisorption of NO 2 at low ppb concentration on such complex surfaces as carbonaceous aerosol particles. 相似文献
16.
Ozone was measured in six- and NO x in five sampling periods in 1996–97, mostly during summer, at a 1070 m altitude site in northern Peloponnese. Mean values in each sampling period ranged from 43–48 ppb exceeding the European Union 24 h plant protection standard. The background ozone concentration of 43 ppb derived from the correlation of ozone with NO ′x also exceeded the EU plant protection standard. Ozone exhibited maxima in the afternoon and minima during the night; in certain 24–48 h periods, however, the ozone concentrations remained practically constant; in these short periods air mass back trajectories indicated air masses which originated in north Africa. NO ′x concentrations had maximum of 24 h around noon. Their mean concentrations ranged from 0.5–0.7 ppb, smaller than respective concentrations in north-central Europe. 相似文献
17.
The influence of soluble compounds leached from real atmospheric aerosol particles (size range Dae: 0.17–1.6 μm) and dissolved NO 2 on S(IV) oxidation in aqueous solution is presented. Experiments were conducted with aerosol particles of two different origins (i.e., urban and industrial) and at concentrations of trace gases in the gas mixtures (SO 2/air and SO 2/NO 2/air) typical for a polluted atmosphere. During the introduction of SO 2/air into the aqueous aerosol suspensions under dark conditions at pH 4, the formation of SO 42− was very slow with a long induction period. However, in the presence of NO 2 the oxidation rate of dissolved SO 2 in suspensions of aerosols from both origins increased substantially (about 10 times). The results suggest that soluble compounds eluted from atmospheric aerosols have not only a catalytic (e.g. Fe, Mn), but also a pronounced inhibiting effect (e.g., oxalate, formate, acetate, glycolate) on S(IV) autoxidation. When NO 2 was also introduced into the aerosol suspensions, the inhibition was not so highly expressed. An explanation for this is that the radical chain mechanism is mainly initiated by the interaction of dissolved NO 2 and HSO 3−. Therefore, at conditions typical for a polluted atmosphere dissolved NO 2 can have a significant influence on the secondary formation of SO 42−. 相似文献
18.
We present two years (January 2007–December 2008) of atmospheric SO 2, NO 2 and NH 3 measurements from ten background or rural sites in nine provinces in China. The measurements were made on a monthly basis using passive samplers under careful quality control. The results show large geographical and seasonal variations in the concentrations of these gases. The mean SO 2 concentration varied from 0.7 ± 0.4 ppb at Waliguan on Qinghai Plateau to 67.3 ± 31.1 ppb at Kaili in Guizhou province. The mean NO 2 concentration ranged from 0.6 ± 0.4 ppb at Waliguan to 23.9 ± 6.9 ppb at Houma in southern Shanxi. The mean NH 3 concentration ranged from 2.8 ± 3.0 ppb at Shangdianzi in northeastern Beijing to 13.7 ± 8.4 ppb at Houma. At most sites, SO 2 and NO 2 peaked in winter and reached minima in summer, while NH 3 showed maximum values in summer and lower values in cold seasons. On the whole, the geographical distributions of the observed gas concentrations are consistent with those of emissions. The ground measurements of SO 2 and NO 2 are contrasted to the SCIAMACHY SO 2 and OMI NO 2 tropospheric columns, respectively. Although the satellite data can capture the main features of emissions and concentrations of SO 2, they do not reflect the variations of SO 2 in the surface layer. The situation is better for the case of NO 2. The OMI NO 2 columns capture the geographical differences in the ground NO 2 and correlate fairly well with the ground levels of NO 2 at six of the ten sites. 相似文献
19.
Following the meteorological evaluation in Part I, this Part II paper presents the statistical evaluation of air quality predictions by the U.S. Environmental Protection Agency (U.S. EPA)’s Community Multi-Scale Air Quality (Models-3/CMAQ) model for the four simulated months in the base year 2005. The surface predictions were evaluated using the Air Pollution Index (API) data published by the China Ministry of Environmental Protection (MEP) for 31 capital cities and daily fine particulate matter (PM 2.5, particles with aerodiameter less than or equal to 2.5 μm) observations of an individual site in Tsinghua University (THU). To overcome the shortage in surface observations, satellite data are used to assess the column predictions including tropospheric nitrogen dioxide (NO 2) column abundance and aerosol optical depth (AOD). The result shows that CMAQ gives reasonably good predictions for the air quality.The air quality improvement that would result from the targeted sulfur dioxide (SO 2) and nitrogen oxides (NO x) emission controls in China were assessed for the objective year 2010. The results show that the emission controls can lead to significant air quality benefits. SO 2 concentrations in highly polluted areas of East China in 2010 are estimated to be decreased by 30–60% compared to the levels in the 2010 Business-As-Usual (BAU) case. The annual PM 2.5 can also decline by 3–15 μg m ?3 (4–25%) due to the lower SO 2 and sulfate concentrations. If similar controls are implemented for NO x emissions, NO x concentrations are estimated to decrease by 30–60% as compared with the 2010 BAU scenario. The annual mean PM 2.5 concentrations will also decline by 2–14 μg m ?3 (3–12%). In addition, the number of ozone (O 3) non-attainment areas in the northern China is projected to be much lower, with the maximum 1-h average O 3 concentrations in the summer reduced by 8–30 ppb. 相似文献
20.
Aircraft measurements of air pollutants were made to investigate the characteristic features of long-range transport of sulfur compounds over the Yellow Sea for the periods of 26–27 April and 7–10 November in 1998, and 9–11 April and 19 June in 1999, together with aerosol measurements at the Taean background station in Korea. The overall mean concentrations of SO 2, O 3 and aerosol number in the boundary layer for the observation period ranged 0.1–7.4 ppb 32.1–64.1 ppb and 1.0–143.6 cm −3, respectively. It was found that the air mass over the Yellow Sea had a character of both the polluted continental air and clean background air, and the sulfur transport was mainly confined in the atmospheric boundary layer. The median of SO 2 concentration within the boundary layer was about 0.1–2.2 ppb. However, on 8 November, 1998, the mean concentrations of SO 2 and aerosol number increased up to 7.4 ppb and 109.5 cm −3, respectively, in the boundary layer, whereas O 3 concentration decreased remarkably. This enhanced SO 2 concentration occurred in low level westerly air stream from China to Korea. Aerosol analyses at the downstream site of Taean in Korea showed 2–3 times higher sulfate concentration than that of other sampling days, indicating a significant amount of SO 2 conversion to non sea-salt sulfate during the long-range transport. 相似文献
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