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1.
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
2.
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
3.
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
4.
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
5.
Ambient concentrations of organic carbon (OC), elemental carbon (EC) and water soluble inorganic ionic components (WSIC) of PM 10 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 PM 10 was recorded at the study site of Giridih. During winter 2011–12, the average concentrations of PM 10, 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 PM 10, 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 PM 10 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
6.
The seasonal variation of particulate matter and its relationship with meteorological parameters were measured at five different residential sites in Delhi. Sampling was carried out for one year including all three seasons (summer, monsoon, and winter). The yearly average concentration of particulate matter (PM2.5) was 135.16 ± 41.34 µg/m3. The highest average values were observed in winter (208.44 ± 43.67 µg/m3) and the lowest during monsoon season (80.29 ± 39.47 µg/m3). The annual average concentration of PM2.5 was found to be the highest at the Mukherjee Nagar site (242.16 µg/m3 ) during the winter and lowest at (Jawaharlal Nehru University) JNU (35.65 µg/m3) during the monsoon season. The strongest correlation between PM mass and a meteorological parameter was a strong negative correlation with temperature (R2=0.55). All other parameters were weakly correlated (R2<0.2) with PM mass. 相似文献
7.
In this study we present the seasonal chemical characteristics and potential sources of PM10 at an urban location of Delhi, India during 2010?2019. The concentrations of carbonaceous aerosols [organic carbon (OC), elemental carbon (EC), water soluble organic carbon (WSOC) and water insoluble organic carbon (WIOC)] and elements (Al, Fe, Ti, Cu, Zn, Mn, Pb, Cr, F, Cl, Br, P, S, K, As, Na, Mg, Ca, B, Ni, Mo, V, Sr, Zr and Rb) in PM10 were estimated to explore their possible sources. The annual average concentration (2010–2019) of PM10 was computed as 227?±?97 µg m?3 with a range of 34?734 µg m?3. The total carbonaceous aerosols in PM10 was accounted for 22.5% of PM10 mass concentration, whereas elements contribution to PM10 was estimated to be 17% of PM10. The statistical analysis of OC vs. EC and OC vs. WSOC of PM10 reveals their common sources (biomass burning and/or fossil fuel combustion) during all the seasons. Enrichment factors (EFs) of the elements and the relationship of Al with other crustal metals (Fe, Ca, Mg and Ti) of PM10 indicates the abundance of mineral dust over Delhi. Principal component analysis (PCA) extracted the five major sources [industrial emission (IE), biomass burning?+?fossil fuel combustion (BB?+?FFC), soil dust, vehicular emissions (VE) and sodium and magnesium salts (SMS)] of PM10 in Delhi, India. Back trajectory and cluster analysis of airmass parcel indicate that the pollutants approaching to Delhi are mainly from Pakistan, IGP region, Arabian Sea and Bay of Bengal. 相似文献
8.
Size-segregated aerosol particles were collected using a high volume MOUDI sampler at a coastal urban site in Xiamen Bay, China, from March 2018 to June 2020 to examine the seasonal characteristics of aerosol and water-soluble inorganic ions (WSIIs) and the dry deposition of nitrogen species. During the study period, the annual average concentrations of PM1, PM2.5, PM10, and TSP were 14.8?±?5.6, 21.1?±?9.0, 35.4?±?14.2 μg m?3, and 45.2?±?21.3 μg m?3, respectively. The seasonal variations of aerosol concentrations were impacted by the monsoon with the lowest value in summer and the higher values in other seasons. For WSIIs, the annual average concentrations were 6.3?±?3.3, 2.1?±?1.2, 3.3?±?1.5, and 1.6?±?0.8 μg m?3 in PM1, PM1-2.5, PM2.5–10, and PM>10, respectively. In addition, pronounced seasonal variations of WSIIs in PM1 and PM1-2.5 were observed, with the highest concentration in spring-winter and the lowest in summer. The size distribution showed that SO42?, NH4+ and K+ were consistently present in the submicron particles while Ca2+, Mg2+, Na+ and Cl? mainly accumulated in the size range of 2.5–10 μm, reflecting their different dominant sources. In spring, fall and winter, a bimodal distribution of NO3? was observed with one peak at 2.5–10 μm and another peak at 0.44–1 μm. In summer, however, the fine mode peak disappeared, likely due to the unfavorable conditions for the formation of NH4NO3. For NH4+ and SO42?, their dominant peak at 0.25–0.44 μm in summer and fall shifted to 0.44–1 μm in spring and winter. Although the concentration of NO3–N was lower than NH4–N, the dry deposition flux of NO3–N (35.77?±?24.49 μmol N m?2 d?1) was much higher than that of NH4–N (10.95?±?11.89 μmol N m?2 d?1), mainly due to the larger deposition velocities of NO3–N. The contribution of sea-salt particles to the total particulate inorganic N deposition was estimated to be 23.9—52.8%. Dry deposition of particulate inorganic N accounted for 0.95% of other terrestrial N influxes. The annual total N deposition can create a new productivity of 3.55 mgC m?2 d?1, accounting for 1.3–4.7% of the primary productivity in Xiamen Bay. In light of these results, atmospheric N deposition could have a significant influence on biogeochemistry cycle of nutrients with respect to projected increase of anthropogenic emissions from mobile sources in coastal region. 相似文献
9.
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
10.
Campaigns were conducted to measure Organic Carbon (OC) and Elemental Carbon (EC) in PM2.5 during winter and summer 2003 in Beijing. Modest differences of PM2.5 and PM10 mean concentrations were observed between the winter and summer campaigns. The mean PM2.5/PM10 ratio in both seasons was around 60%, indicating PM2.5 contributed significantly to PM10. The mean concentrations of OC and EC in PM2.5 were 11.2±7.5 and 6.0±5.0μg m-3 for the winter campaign, and 9.4±2.1 and 4.3±3.0 μg m-3 for the summer campaign, respectively. Diurnal concentrations of OC and EC in PM2.5 were found high at night and low during the daytime in winter, and characterized by an obvious minimum in the summer afternoon. The mean OC/EC ratio was 1.87±0.09 for winter and Z39±0.49 for summer. The higher OC/EC ratio in summer indicates some formation of Secondary Organic Carbon (SOC). The estimated SOC was 2.8 μg m-3 for winter and 4.2μg m-3 for summer. 相似文献
11.
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
12.
Size-segregated high-volume (HV) quartz filter samples were collected daily at the Melpitz rural site in Germany for PM 10 (November 1992 until April 2012), and for PM 2.5 and PM 1 (January 2003 until April 2012, PM 1 sampled every sixth day). The samples were analysed for mass concentration (gravimetrically), water-soluble ions (ion-chromatography) and since 2003 for organic carbon (OC) and elemental carbon (EC) (thermography). The long-term measurements first show a decreasing trend for PM 10 (1993–2000) followed by a second period (2001–2011) with a mean mass concentration of about 22.4 μgm ?3 and an inter-annual variation of about?±?2.9 μgm ?3 (13% fluctuation margin). The absolute sulphate and calcium concentration (for the full period), as well as the EC concentration (time after 2003) decrease by about 50, 75 and 30% for PM 10, respectively. The nitrate concentration remains constant all the time. For the daily objective weather type classification (OWTC, 1993–2002) the highest PM 10 concentration was found for South-East (SE) and the lowest for North-West (NW) wind direction with 44 and 24 μgm ?3, respectively. These concentrations decrease for 2003–2011 in comparison to 1993–2002 by about 21% and 26%, respectively. The highest PM 10, PM 2.5 and PM 1 concentrations (2003–2011) were found for SE and the lowest for NW wind direction with about 34 and 17 μgm ?3 (PM 10), 28 and 19 μgm ?3 (PM 2.5) and 22 and 11 μgm ?3 (PM 1), respectively. The relative content of sulphate, OC and EC was the highest for SE wind direction. A differentiation into four categories for winter (Wi) and summer (Su) and air mass inflow from West (W) and East (E) was carried out. The highest PM concentrations were observed for WiE with the highest inter-annual fluctuation. In this category sulphate contents are largest. The lowest concentrations where found for SuW. The means for WiE show the strongest relative decreases, e.g. in PM 10 sulphate (1993–2011) and EC (2003–2011) by about 60% and 40%, respectively. Nitrate is an indicator for NO x motor-car emissions. It shows a typical variation with maximum values in the middle of the week , especially for air mass inflow from West. In contrast, chloride mostly originating from sea spray doesn’t show such a concentration pattern. The PM 2.5/PM 10 as well the PM 1/PM 10-ratio have the highest median (0.878 and 0.654) during WiE and the lowest (0.718 and 0.578) during SuW, respectively. For the ratio PM 2.5/PM 10 a slightly increasing trend was found (about 0.71 and 0.83 for 1995 and 2011, respectively). The increase is stronger in summer than in winter. 相似文献
13.
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
14.
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
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.
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
17.
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
18.
Continuous observations of mass concentration and elemental composition of aerosol particles （PM2.5） were conducted at Tongyu, a semi-arid site in Northeast China in the spring of 2006. The average mass concentration of PM2.5 at Tongyu station was 260.9±274.4 μg m^-3 during the observation period. Nine dust events were monitored with a mean concentration of 528.0±302.7 μgm^-3. The PM2.5 level during non- dust storm （NDS） period was 111.65±63.37 μg m^-3. High mass concentration shows that fine-size particles pollution was very serious in the semi-arid area in Northeast China. The enrichment factor values for crust elements during the dust storm （DS） period are close to those in the NDS period, while the enrichment factor values for pollution elements during the NDS period are much higher than those in the DS period, showing these elements were from anthropogenic sources. The ratios of dust elements to Fe were relative constant during the DS period. The Ca/Fe ratio in dust aerosols at Tongyu is remarkably different from that observed in other source regions and downwind regions. Meteorological analysis shows that dust events at Tongyu are usually associated with dry, low pressure and high wind speed weather conditions. Air mass back-trajectory analysis identified three kinds of general pathways were associated with the aerosol particle transport to Tongyu, and the northwest direction pathway was the main transport route. 相似文献
19.
Results are presented of monitoring measurements of the mass concentration of PM 10 (particles with the size of less than 10 μm) and PM 2.5 (less than 2.5 μm) fine-dispersed aerosol fractions at the Sainshand and Zamyn-Üüd stations located in the Gobi Desert of Mongolia. Revealed are the annual variations of the mass concentration of PM 10 and PM 2.5 fine-dispersed aerosol fractions at these stations in 2008. The maximum values of monthly mean concentration during the year were observed in May in the period of dust storms. On the days with the steady calm weather, the mass concentrations of PM 10 and PM 2.5 varied within 5–8 μg/m 3 (PM 10) and 3–5 μg/m 3 (PM 2.5) at the Sainshand station. During the dust storms, the maximum values of concentration exceeded 1400 μg/m 3 (PM 10) and 380 μg/m 3 (PM 2.5) that is by 28 (PM 10) and 15 (PM 2.5) times higher than the maximum permissible concentration for the European Union. Results are given of studying the frequency and duration of dust storms in recent 20 years (1991–2010) in the Eastern Gobi Desert. 相似文献
20.
Atmospheric particle-bound mercury levels were measured in PM 10 aerosols (HgP) at a rural site (Mahasar, Haryana) during winter 2014–15 and summer 2015. The PM 10 HgP was determined by using Differential Pulse Anodic Stripping Voltammetry through standard addition methods while the trace metals were determined by using an Atomic Absorption Spectroscopy. The mass concentrations of HgP varied from 591 to 1533 pg/m 3 with an average of 1009?±?306 pg/m 3 during the winter, while the mass concentrations of HgP varied from 43 to 826 pg/m 3 with an average of 320?±?228 pg/m 3 during the summer. However, it is difficult to assess whether these levels are harmful or not because there is no standard value available as National Ambient Air Quality Standard. The higher concentrations of HgP during winters were possibly due to favourable local meteorological conditions for the stagnation of particulate matter in the lower atmosphere and the increased emissions from existing natural or anthropogenic sources, regional sources and long-range transportation. Relatively low concentrations of HgP during summer might be due to increased mixing heights as well as scavenging effect because some light to heavy rain events were observed during summer time sampling. However, among other metals determined, the concentration of HgP was the lowest during both the seasons. The study may be useful in assessing the health impacts of PM 10 HgP and other metals. 相似文献
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