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1.
In this study, 123 PM2.5 filter samples were collected in Wuhan, Hubei province from December 2014 to November 2015. Water- soluble inorganic ions (WSIIs), elemental carbon (EC), organic carbon (OC) and inorganic elements were measured. Source apportionment and back trajectory was investigated by the positive matrix factorization (PMF) model and the hybrid single particle lagrangian integrated trajectory (HYSPLIT) model, respectively. The annual PM2.5 concentration was 80.5?±?38.2 μg/m3, with higher PM2.5 in winter and lower in summer. WSIIs, OC, EC, as well as elements contributed 46.8%, 14.8%, 6.7% and 8% to PM2.5 mass concentration, respectively. SO42?, NO3? and NH4+ were the dominant components, accounting for 40.2% of PM2.5 concentrations. S, K, Cl, Ba, Fe, Ca and I were the main inorganic elements, and accounted for 65.2% of the elemental composition. The ratio of NO3?/SO42? was 0.86?±?0.72, indicating that stationary sources play dominant role on PM2.5 concentration. The ratio of OC/EC was 2.9?±?1.4, suggesting the existence of secondary organic carbon (SOC). Five sources were identified using PMF model, which included secondary inorganic aerosols (SIA), coal combustion, industry, vehicle emission, fugitive dust. SIA, coal combustion, as well as industry were the dominant contributors to PM2.5 pollution, accounting for 34.7%, 20.5%, 19.6%, respectively. 相似文献
2.
This study presents the chemical composition (carbonaceous and nitrogenous components) of aerosols (PM2.5 and PM10) along with stable isotopic composition (δ13C and δ15N) collected during winter and the summer months of 2015–16 to explore the possible sources of aerosols in megacity Delhi, India. The mean concentrations (mean?±?standard deviation at 1σ) of PM2.5 and PM10 were 223?±?69 µg m?3 and 328?±?65 µg m?3, respectively during winter season whereas the mean concentrations of PM2.5 and PM10 were 147?±?22 µg m?3 and 236?±?61 µg m?3, respectively during summer season. The mean value of δ13C (range: ??26.4 to ??23.4‰) and δ15N (range: 3.3 to 14.4‰) of PM2.5 were ??25.3?±?0.5‰ and 8.9?±?2.1‰, respectively during winter season whereas the mean value of δ13C (range: ??26.7 to ??25.3‰) and δ15N (range: 2.8 to 11.5‰) of PM2.5 were ??26.1?±?0.4‰ and 6.4?±?2.5‰, respectively during the summer season. Comparison of stable C and N isotopic fingerprints of major identical sources suggested that major portion of PM2.5 and PM10 at Delhi were mainly from fossil fuel combustion (FFC), biomass burning (BB) (C-3 and C-4 type vegitation), secondary aerosols (SAs) and road dust (SD). The correlation analysis of δ13C with other C (OC, TC, OC/EC and OC/WSOC) components and δ15N with other N components (TN, NH4+ and NO3?) are also support the source identification of isotopic signatures. 相似文献
3.
This study elucidates the characteristics of ambient PM 2.5 (fine) and PM 1 (submicron) samples collected between July 2009 and June 2010 in Raipur, India, in terms of water soluble ions, i.e. Na +, NH 4 + , K +, Mg 2+, Ca 2+, Cl ?, NO 3 ? and SO 4 2? . The total number of PM 2.5 and PM 1 samples collected with eight stage cascade impactor was 120. Annual mean concentrations of PM 2.5 and PM 1 were 150.9?±?78.6 μg/m 3 and 72.5?±?39.0 μg/m 3, respectively. The higher particulate matter (PM) mass concentrations during the winter season are essentially due to the increase of biomass burning and temperature inversion. Out of above 8 ions, the most abundant ions were SO 4 2? , NO 3 ? and NH 4 + for both PM 2.5 and PM 1 aerosols; their average concentrations were 7.86?±?5.86 μg/m 3, 3.12?±?2.63 μg/m 3 and 1.94?±?1.28 μg/m 3 for PM 2.5, and 5.61?±?3.79 μg/m 3, 1.81?±?1.21 μg/m 3 and 1.26?±?0.88 μg/m 3 for PM 1, respectively. The major secondary species SO 4 2? , NO 3 ? and NH 4 + accounted for 5.81%, 1.88% and 1.40% of the total mass of PM 2.5 and 11.10%, 2.68%, and 2.48% of the total mass of PM 1, respectively. The source identification was conducted for the ionic species in PM 2.5 and PM 1 aerosols. The results are discussed by the way of correlations and principal component analysis. Spearman correlation indicated that Cl ? and K + in PM 2.5 and PM 1 can be originated from similar type of sources. Principal component analysis reveals that there are two major sources (anthropogenic and natural such as soil derived particles) for PM 2.5 and PM 1 fractions. 相似文献
4.
Pre and Post-Monsoon levels of ambient SO2, NO2, PM2.5 and the trace metals Fe, Cu, etc. were measured at industrial and residential regions of the Kochi urban area in South India for a period of two years. The mean PM2.5, SO2 and NO2 concentrations across all sites were 38.98?±?1.38 µg/m3, 2.78?±?0.85 µg/m3 and 11.90?±?4.68 µg/m3 respectively, which is lower than many other Indian cities. There was little difference in any on the measured species between the seasons. A few sites exceeded the NAAQS (define acronym and state standard) and most of the sites exceeded WHO (define acronym and state standard) standard for PM2.5. The average trace metal concentrations (ng/m3) were found to be Fe (32.58)?>?Zn (31.93)?>?Ni (10.13)?>?Cr (5.48)?>?Pb (5.37)?>?Cu (3.24). The maximum concentration of trace metals except Pb were reported in industrial areas. The enrichment factor, of metals relative to crustal material, indicated anthropogenic dominance over natural sources for the trace metal concentration in Kochi’s atmosphere. This work demonstrates the importance of air quality monitoring in this area. 相似文献
5.
Aerosol (PM 10) samples were collected and its precursor gases, i.e., NH 3, NO, NO 2, and SO 2 measured over Bay of Bengal (BoB) during winter months of December 2008 to January 2009 to understand the relationship between particular matter (PM) and precursor gases. The observations were done under the winter phase of Integrated Campaign on Aerosols, gases and Radiation Budget (W_ICARB). The distribution of water-soluble inorganic ionic composition (WSIC) and its interaction with precursor gases over BoB are reported in present case. Average atmospheric concentration of NH 3, NO, NO 2, and SO 2 were recorded as 4.78?±?1.68, 1.89?±?1.26, 0.31?±?0.14, and 0.80?±?0.30?μg?m ?3, whereas WSIC component of PM 10, i.e., NH 4 +, SO 4 2?, NO 3 ?, and Cl ? were recorded as 1.96?±?1.66, 8.68?±?3.75, 1.92?±?1.75, and 2.48?±?0.78?μg?m ?3, respectively. In the present case, abundance of nss-SO 4 2? in the particulate matter is recorded as 18?%. It suggests the possibility of long-range transport as well as marine biogenic origin. Higher SO 4 2?/(SO 2?+?SO 4 2?) equivalent molar ratio during the campaign indicates the gas-to-particle conversion with great efficiency over the study region. 相似文献
6.
Beijing is one of the largest and most densely populated cities in China. PM 2.5 (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 PM 2.5 and to discuss the formation mechanisms of secondary particles, SO 2, NO 2, PM 2.5, and chemical components of PM 2.5 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 +, NH 4 +, NO 3 ?, SO 4 2?, Cl ?, Al, Ca, Fe, Mg, Na, Pb, Si, and Zn, were selected for analysis. Overall, OC, SO 4 2?, NO 3 ?, and NH 4 + 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 NH 4 + 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 [NO 3 ?]/[SO 4 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 ([SO 4 2?]/([SO 4 2?] + [SO 2])) and NOR ([NO 3 ?]/([NO 3 ?] + [NO 2])) indicated that gas-phase oxidation reactions were the major formation mechanism of SO 4 2? in spring and summer in urban Beijing, whereas slow gas-phase oxidation reactions and heterogeneous reactions both occurred in autumn and winter. NO 3 ? was mainly formed through year-round heterogeneous reactions in urban Beijing. 相似文献
7.
During the MILAGRO campaign, March 2006, eight-stage cut impactors were used to sample atmospheric particles at Tecámac (T1 supersite), towards the northeast edge of the Mexico City Metropolitan Area, collecting fresh local emissions and aged pollutants produced in Mexico City. Particle samples were analyzed to determine total mass concentrations of Ca 2+, Mg 2+, NH 4 +, K +, Cl ?, SO 4 2?, and NO 3 ?. Average concentrations were 22.1 ± 7.2 μg m ?3 for PM 10 and 18.3 ± 6.2 μg m ?3 for PM 1.8. A good correlation between PM 10 and PM 1.8, without influence from wind patterns, indicates that local emissions are more important than the city’s pollution transported to the site, despite the fact that Tecámac is just 40 km away from Mexico City. A lack of diurnal patterns in the PM 2.5/PM 1.8 ratio supports this conclusion. The inorganic composition of particles suggests that vehicles, soil resuspension, and industries are the main pollutant sources. Finally, the particles were found to be neutralized, in agreement with observations in the Mexico City Metropolitan Area. 相似文献
8.
The samples of water-soluble inorganic ions (WSIs), including anions (F ?, Cl ?, SO 42?, NO 3?) and cations (NH 4+, K +, Na +, Ca 2+, Mg 2+) in 8 size-segregated particle matter (PM), were collected using a sampler (with 8 nominal cut-sizes ranged from 0.43 to 9.0 μm) from October 2008 to September 2009 at five sites in both polluted and background regions of a coastal city, Xiamen. The results showed that particulate matters in the fine mode (PM 2.1, Dp < 2.1 μm) comprised large part of mass concentrations of aerosols, which accounted for 45.56–51.27%, 40.04–60.81%, 42.02–60.81%, and 40.46–57.07% of the total particulate mass in spring, summer, autumn, and winter, respectively. The water-soluble ionic species in the fine mode at five sampling sites varied from 15.33 to 33.82 (spring), 14.03 to 28.06 (summer), 33.47 to 72.52 (autumn), and 48.39 to 69.75 μg m ? 3 (winter), respectively, which accounted for 57.30 ± 6.51% of the PM 2.1 mass concentrations. Secondary pollutants of NH 4+, SO 42? and NO 3? were the dominant contributors of WSIs, which suggested that pollutants from anthropogenic activities, such as SO 2, NOx were formed in aerosols by photochemical reactions. The size distributions of Na +, Cl ?, SO 42? and NO 3? were bimodal, peaking at 0.43–0.65 μm and 3.3–5.8 μm. Although some ions, such as NH 4+ presented bimodal distributions, the coarse mode was insignificant compared to the fine mode. Ca 2+ and Mg 2+ exhibited unimodal distributions at all sampling sites, peaking at 2.1–3.3 μm, while K + having a bimodal distributions with a major peak at 0.43–0.65 μm and a minor one at 3.3–4.7 μm, were used in most of samples. Seasonal and spatial variations in the size-distribution profiles suggested that meteorological conditions (seasonal patterns) and sampling locations (geographical patterns) were the main factors determining the formation of secondary aerosols and characteristics of size distributions for WSIs. 相似文献
9.
This paper reports aerosol chemical properties for the first time over a Korean Global Atmosphere Watch (GAW) supersite, Anmyeon (36°32′N; 126° 19′E), during 2003–2004 period. Total suspended Particulates (TSP) showed significant seasonal variation with consistent higher mass concentrations during spring season (average of up to 230?±?190 μg/m 3). PM 10 also followed similar trend with higher concentrations during spring (average of up to 170?±?130 μg/m 3) and showed reduced concentrations during summer. PM 2.5 showed a significant increase during summer (average of up to 60?±?25 μg/m 3), which could be due to the influx of fine mode sea salt aerosols associated with the Changma front (summer monsoon). Chemical composition analysis showed enhanced presence of acidic fractions, majorly contributed by sulphates (SO 4 2- ) and nitrates (NO 3 - ) in TSP, PM 10 and PM 2.5 during different seasons. Enhanced presence of Calcium (Ca 2+) was observed during sand storm days during spring. The high correlation obtained on matrix analysis between crustal ions and acidic ions suggests that the ionic compositions over the site are mainly contributed by terrestrial sources of similar origin. The neutralization factors has been estimated to find the extend of neutralization of acidicity by main basic components, and found to have higher value for Ammonium (up to 1.1) in different seasons, indicating significant neutralization of acidic components over the region by NH 4 + . Back trajectory analysis has been performed during different seasons to constrain the possible sources of aerosol origin and the results are discussed in detail. 相似文献
10.
Severe air pollution with visibility deterioration has long been a focus in the North China Plain (NCP). In this study, concentration and light extinction analysis of PM 2.5 chemical components were carried out from 2014 to 2017 to study the pollution characteristics in Baoding, a case city of the NCP. The annual average concentration of total PM 2.5 components showed a declining trend, decreasing by 11 µg m −3 (water-soluble inorganic ions), 23 µg m −3 (carbonaceous aerosols), and 1796 ng m −3 (inorganic elements). Contributing 82.9% to the concentration of total ions, the dominant components, NH 4+, NO 3−, and SO 42− became the main pollutants in PM 2.5 pollution. Based on the IMPROVE algorithm, the average reconstructed PM 2.5 mass concentration was 93 ± 69 µg m −3 during the observation period. Meanwhile, the light extinction coefficients were 373.8 ± 233.6 M m −1, 405.3 ± 300.1 M m −1, 554.3 ± 378.2 M m −1 and 1005.2 ± 750.3 M m −1, in spring, summer, autumn, and winter, respectively. Ammonium sulfate, ammonium nitrate, and organic matter were the largest contributors to light extinction, accounting for a total of 55%–77% in the four seasons. The bsca (light scattering by particles and gases) reconstructed from PM 2.5 components (R bsca) and the bsca converted from visibility (V bsca) were compared to evaluate the performance of the IMPROVE algorithm, revealing a high correlation coefficient of 0.84. The high values of V bsca were underestimated while the low values were overestimated, as determined through comparison with the one-to-ne line. Especially, when R bsca > 1123 M m −1 (corresponding to < 2.0 km, approximately), V bsca was underestimated by 17.6%. PM 2.5 mass concentration and relative humidity also had an impact on the estimation.摘要华北平原大气污染与低能见度状况一直是人们关切的问题.本文通过分析2014 - 2017年PM 2.5化学成分的浓度和消光效果, 研究了华北平原典型城市保定市的大气污染特征.结果表明, PM 2.5组分的年均浓度显示下降趋势, 水溶性无机离子,碳质气溶胶和金属元素分别减少了11 µg m −3, 23 µg m −3和1796 ng m −3.NH 4+,NO 3−和SO 42−是PM 2.5污染的主要污染物, 三者之和占总离子浓度的82.9%.基于IMPROVE方程对细颗粒物进行重构, 在观测期间PM 2.5质量浓度平均为93 ± 69 µg m −3, 春季,夏季,秋季和冬季的消光系数分别为373.8 ± 233.6 M m −1,405.3 ± 300.1 M m −1,554.3 ± 378.2 M m −1和1005.2 ± 750.3 M m −1.硫酸铵,硝酸铵和有机物对消光的贡献最大, 不同季节下占比达55% ~77%.通过PM 2.5组分进行重构, 利用IMPROVE算法计算得到R bsca, 用能见度测量值转换得到V bsca, 二者具有较高的相关性 (r 2=0.84) ;但存在V bsca的高值被低估, V bsca的低值被高估的现象;特别是当R bsca > 1123 M m −1 (对应能见度约小于2.0 km) 时, V bsca的值被低估了17.6%.高浓度PM 2.5和高湿度对IMPROVE算法结果有显著的影响. 相似文献
11.
The concentrations of PM 10, PM 2.5 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 PM 10 and PM 2.5 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 PM 2.5/PM 10 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 PM 10 and PM 2.5, is deemed as the contribution of the coarse fraction (PM 10−2.5). 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%). PM 2.5 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 PM 10 and PM 2.5. The results are discussed by way of correlations and factor analyses. The significant correlations of Cl −, SO 42−, K +, Na +, Ca 2+, NO 3− and Mg 2+ with PM 2.5 on one hand and Mg 2+ with PM 10 on the other suggest the dominance of anthropogenic and soil origin aerosols in Delhi. 相似文献
12.
PM 10 samples were collected to characterize the seasonal and annual trends of carbonaceous content in PM 10 at an urban site of megacity Delhi, India from January 2010 to December 2017. Organic carbon (OC) and elemental carbon (EC) concentrations were quantified by thermal-optical transmission (TOT) method of PM 10 samples collected at Delhi. The average concentrations of PM 10, OC, EC and TCA (total carbonaceous aerosol) were 222?±?87 (range: 48.2–583.8 μg m ?3), 25.6?±?14.0 (range: 4.2–82.5 μg m ?3), 8.7?±?5.8 (range: 0.8–35.6 μg m ?3) and 54.7?±?30.6 μg m ?3 (range: 8.4–175.2 μg m ?3), respectively during entire sampling period. The average secondary organic carbon (SOC) concentration ranged from 2.5–9.1 μg m ?3 in PM 10, accounting from 14 to 28% of total OC mass concentration of PM 10. Significant seasonal variations were recorded in concentrations of PM 10, OC, EC and TCA with maxima during winter and minima during monsoon seasons. In the present study, the positive linear trend between OC and EC were recorded during winter ( R2?=?0.53), summer ( R2?=?0.59) and monsoon ( R2?=?0.78) seasons. This behaviour suggests the contribution of similar sources and common atmospheric processes in both the fractions. OC/EC weight ratio suggested that vehicular emissions, fossil fuel combustion and biomass burning could be the major sources of carbonaceous aerosols of PM 10 at the megacity Delhi, India. Trajectory analysis indicates that the air mass approches to the sampling site is mainly from Indo Gangetic plain (IGP) region (Uttar Pradesh, Haryana and Punjab etc.), Thar desert, Afghanistan, Pakistan and surrounding areas. 相似文献
13.
Haze-fog conditions over northern India are associated with visibility degradation and severe attenuation of solar radiation by airborne particles with various chemical compositions. PM 2.5 samples have been collected in Delhi, India from December 2011 to November 2012 and analyzed for carbonaceous and inorganic species. PM 10 measurements were made simultaneously such that PM 10–2.5 could be estimated by difference. This study analyzes the temporal variation of PM 2.5 and carbonaceous particles (CP), focusing on identification of the primary and secondary aerosol emissions, estimations of light extinction coefficient (b ext) and the contributions by the major PM 2.5 chemical components. The annual mean concentrations of PM 2.5, organic carbon (OC), elemental carbon (EC) and PM 10–2.5 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., SO 4 2? and NO 3 ?) maximize during the post-monsoon and winter due to fossil fuel combustion and biomass burning. PM 10–2.5 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 b ext 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 b ext, followed by (NH 4) 2SO 4 (~21 % and ~24 %) and EC (~13 % and ~10 %), according to the original and revised algorithms, respectively. The b ext estimates via the two IMPROVE versions are highly correlated (R 2 = 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
14.
Gaseous pollutants and PM 2.5 aerosol particles were investigated during a tropical storm and an air pollution episode in southern Taiwan. Field sampling and chemical analysis of particulate matter and gaseous pollutants were conducted in Daliao and Tzouying in the Kaohsiung area, using a denuder-filter pack system during the period of 22 October to 3 November 2004. Sulfate, nitrate and ammonium were the major ionic species in the PM 2.5, accounting for 46 and 39% of the PM 2.5 for Daliao and Tzouying, respectively. Higher PM 2.5, Cl ?, NO 3? and NH 4+, HNO 2 and NH 3 concentrations were found at night in both stations, whereas higher HNO 3 was found during the day. In general, higher PM 2.5, HCl, NH 3, SO 2, Cl ?, NO 3?, SO 42? and NH 4+ concentrations were found in Daliao. The synoptic weather during the experiment was first influenced by Typhoon NOCK-TEN, which resulted in the pollutant concentrations decreasing by about two-thirds. After the tropical thunderstorm system passed, the ambient air quality returned to the previous condition in 12 to 24 h. When there was a strong subsidence accompanied by a high-pressure system, a more stable environment with lower wind speed and mixing height resulted in higher PM 2.5, as well as HNO 2, NH 3, SO 42?, Cl ?, NO 3?, NH 4+ and K + concentrations during the episode days. The rainfall is mainly a scavenger of air pollutants in this study, and the stable atmospheric system and the high emission loading are the major reasons for high air pollutant concentrations. 相似文献
15.
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 (NH 3) and particulate ammonium (NH 4 + ) in PM 2.5 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/m 3 and 1.89?±?0.99 μg/m 3, 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/m 3 and 2.32?±?0.94 μg/m 3 in April and July, respectively, while only 1.68?±?0.61 μg/m 3 in March and 1.24?±?0.99 μg/m 3 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
16.
Long-term measurements of ambient particulate matter less than 2.5 μm in diameter (PM 2.5) and its chemical compositions were performed at a rural site in Korea from December 2005 to August 2009. The average PM 2.5 concentration was 31 μg m −3 for the whole sampling period, and showed a slightly downward annual trend. The major components of PM 2.5 were organic carbon, SO 42−, NO 3−, and NH 4+, which accounted for 55 % of total PM 2.5 mass on average. For the top 10 % of PM 2.5 samples, anionic constituents and trace elements clearly increased while carbonaceous constituents and NH 4+ remained relatively constant. Both Asian dust and fog events clearly increased PM 2.5 concentrations, but affected its chemical composition differently. While trace elements significantly increased during Asian
dust events, NO 3−, NH 4+ 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 PM 2.5 concentrations at the sampling site. Using factor analysis, soil, combustion processes, non-metal manufacture, and secondary
PM 2.5 sources accounted for 77 % of the total explained variance. 相似文献
17.
Cloud/fog samples were collected during spring of 2007 in the highly polluted North China Plain in order to examine the impact of pollution and dust particles on cloud water chemistry. The volume weighted mean pH of cloud water was 3.68. The cloud acidity was shown to be associated with air mass origins. Cloud water with its air mass trajectories originating from the southern part of China was more acidic than those from northern China. Anthropogenic source and dust had obvious impact on cloud water composition as indicated by the very high mean concentrations of SO 42? (1331.65 μeq L ? 1), NO 3? (772.44 μeq L ? 1), NH 4+ (1375.92 μeq L ? 1) and Ca 2+ (625.81 μeq L ? 1) in the observation periods. During sandstorm days, cloud pH values were relatively high, and the concentrations of all the ions in cloud water reached unusual high levels. Significant decreases in the mass concentrations of PM 2.5 and PM 10 were observed during cloud events. The average scavenging ratio for PM 2.5 and PM 10 was 52.0% and 55.7%, respectively. Among the soluble ions in fine particles, NO 3?, K + and NH 4+ tend to be more easily scavenged than Ca 2+ and Na +. 相似文献
18.
Airborne particulates were monitored at an urban location of middle Indo-Gangetic Plain (IGP) and subsequently analyzed for particulate diversity and mixing states. Exceptionally high particulate loadings were found both in case of coarser (PM 10: 157.5 ± 102.9 μgm ?3, n = 46) and finer particulates (PM 2.5: 92.5 ± 49.8 μgm ?3). Based on particulate morphology and elemental composition, five different clusters of particulates namely tarball, soot, sulphur-rich, aluminosilicate and mineral species were found to dominate. Soot particles (0.1–5 μm) were found to be partly coated, having voids filled by coating material without being completely engulfed. A specific type of amorphous, carbonaceous spherules was evident in wintertime fine particulates signifying emissions from biomass burning and wild fire. Traces of S, Na and Ca were found associated with carbonaceous agglomerates suggesting its metal scavenging behavior. Particle laden filters were further processed for metallic and water soluble ionic species to constitute aerosol composition. Coarser particulates were characterized with higher metallic species (9.2–17.8 %), mostly of crustal origin (Ca: 5.5 %; Fe: 1.6 %; Zn: 1.3 % and Na: 3.8 %) while PM 2.5 also revealed their association with metallic components (6.0–14.9 %) having Ca (4.6 %), Fe (0.9 %) and K (0.8 %) as principle constituents. Ca, Na and NH 4 + found to generate chloride and sulphate salts thus affecting particulate hygroscopicity. Elevated fractions of NO 3 ? and K + in PM 2.5 signified contribution of biomass burning while presence of Cl ? with carbonaceous aerosols having traces of Si and K denoted contribution of farming and burning practices. Black carbon aerosol exhibited significant seasonal variability (6.9?21.9 μgm ?3) which support larger association of carbonaceous aerosols in particle micrograph. 相似文献
19.
Aerosol size distributions were measured with Micro Orifice Uniform Deposit Impactor (MOUDI) cascade impactors at the rural Angiola and urban Fresno Supersites in California's San Joaquin Valley during the California Regional PM 10/PM 2.5 Air Quality Study (CRPAQS) winter campaign from December 15, 2000 to February 3, 2001. PM 2.5 filter samples were collected concurrently at both sites with Sequential Filter Samplers (SFS). MOUDI nitrate (NO 3−) concentrations reached 66 μg/m 3 on January 6, 2001 during the 1000–1600 PST (GMT-8) period. Pair-wise comparisons between PM 2.5 MOUDI and SFS concentrations revealed high correlations at the Angiola site ( r > 0.93) but more variability ( r < 0.85) at the Fresno site for NO 3−, sulfate (SO 4=), and ammonium (NH 4+). Correlations were higher at Fresno ( r > 0.87) than at Angiola ( r < 0.7) for organic carbon (OC), elemental carbon (EC), and total carbon (TC). NO 3− and SO 4= size distributions in Fresno were multi-modal and wider than the uni-modal distributions observed at Angiola. Geometric mean diameters (GMD) were smaller for OC and EC than for NO 3− and SO 4= at both sites. OC and EC were more concentrated on the lowest MOUDI stage (0.056 µm) at Angiola than at Fresno. The NO 3− GMD increased from 0.97 to 1.02 µm as the NO 3− concentration at Angiola increased from 43 to 66 µg m − 3 during a PM 2.5 episode from January 4–7, 2001. There was a direct relationship between GMD and NO 3− and SO 4= concentrations at Angiola but no such relationships for OC or EC. This demonstrates that secondary aerosol formation increases both concentration and particle size for the rural California environment. 相似文献
20.
To characterize atmospheric particulate matter equal or less than 2.5 μm in diameter (PM 2.5) 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 +, NH 4 +, Mg 2+, Ca 2+, K +, Cl ?, SO 4 2?, NH 4 +, 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 NH 4 + (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 SO 4 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 PM 2.5 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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