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1.
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
2.
Secondary aerosol formation was studied at Allahabad in the Indo-Gangetic region during a field campaign called Land Campaign-II
in December 2004 (northern winter). Regional source locations of the ionic species in PM 10 were identified by using Potential Source Contribution Function (PSCF analysis). On an average, the concentration of water
soluble inorganic ions (sum of anions and cations) was 63.2 μgm −3. Amongst the water soluble ions, average NO 3− concentration was the highest (25.0 μgm −3) followed by SO 42− (15.8 μgm −3) and NH 4+ (13.8 μgm −3) concentrations. These species, contributed 87% of the total mass of water soluble species, indicating that most of the water
soluble PM 10 was composed of NH 4NO 3 and (NH 4) 2SO 4/NH 4HSO 4 or (NH 4) 3H(SO 4) 2 particles. Further, the concentrations of SO 42−, NO 3−, and NH4 + aerosols increased at high relative humidity levels up to the deliquescence point (∼63% RH) for salts of these species suggesting
that high humidity levels favor the conversion and partitioning of gaseous SO 2, NO x, and NH 3 to their aerosol phase. Additionally, lowering of ambient temperature as the winter progressed also resulted in an increase
of NO 3− and NH 4+ concentrations, probably due to the semi volatile nature of ammonium nitrate. PSCF analysis identified regions along the
Indo-Gangetic Plain (IGP) including Northern and Central Uttar Pradesh, Punjab, Haryana, Northern Pakistan, and parts of Rajasthan
as source regions of airborne nitrate. Similar source regions, along with Northeastern Madhya Pradesh were identified for
sulfate. 相似文献
3.
A study has been carried out on water soluble ions, trace elements, as well as PM 2.5 and PM 2.5–10 elemental and organic carbon samples collected daily from Central Taiwan over a one year period in 2005. A source apportionment
study was performed, employing a Gaussian trajectory transfer coefficient model (GTx) to the results from 141 sets of PM 2.5 and PM 2.5–10 samples. Two different types of PM 10 episodes, local pollution (LOP) and Asian dust storm (ADS) were observed in this study. The results revealed that relative
high concentrations of secondary aerosols (NO 3−, SO 42− and NH 4+) and the elements Cu, Zn, Cd, Pb and As were observed in PM 2.5 during LOP periods. However, sea salt species (Na + and Cl −) and crustal elements (e.g., Al, Fe, Mg, K, Ca and Ti) of PM 2.5–10 showed a sharp increase during ADS periods. Anthropogenic source metals, Cu, Zn, Cd, Pb and As, as well as coarse nitrate
also increased with ADS episodes. Moreover, reconstruction of aerosol compositions revealed that soil of PM 2.5–10 elevated approximately 12–14% in ADS periods than LOP and Clear periods. A significantly high ratio of non-sea salt sulfate
to elemental carbon (NSS-SO 42−/EC) of PM 2.5–10 during ADS periods was associated with higher concentrations of non-sea-salt sulfates from the industrial regions of China.
Source apportionment analysis showed that 39% of PM 10, 25% of PM 2.5, 50% of PM 2.5–10, 42% of sulfate and 30% of nitrate were attributable to the long range transport during ADS periods, respectively. 相似文献
4.
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
5.
An extensive aerosol sampling program was conducted during January-December 2006 over Kolkata (22o33?? N and 88o20?? E), a mega-city in eastern India in order to understand the sources, distributions and properties of atmospheric fine mode aerosol (PM 2.5). The primary focus of this study is to determine the relative contribution of natural and anthropogenic as well as local and transported components to the total fine mode aerosol loading and their seasonal distributions over the metropolis. The average concentrations of fine mode aerosol was found to be 71.2?±?25.2???gm -3 varying between 34.5???gm -3 in monsoon and 112.6???gm -3 in winter. The formation pathways of major secondary aerosol components like nitrate and sulphate in different seasons are discussed. A long range transport of dust aerosol from arid and semi-arid regions of western India and beyond was observed during pre-monsoon which significantly enriched the total aerosol concentration. Vehicular emissions, biomass burning and transported dust particles were the major sources of PM 2.5 from local and continental regions whereas sea-salt aerosol was the major source of PM 2.5 from marine source regions. 相似文献
6.
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
7.
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
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.
The contribution of emissions from agricultural facilities is rapidly becoming a major concern for local and regional air
quality. Characterization of particle properties such as physical size distribution and chemical composition can be valuable
in understanding the processes contributing to emissions and ultimate fate of particulate matter from agricultural facilities.
A measurement campaign was conducted at an Iowa, deep-pit, three-barn swine finishing facility to characterize near-source
ambient particulate matter. Size-specific mass concentrations were determined using minivol samplers, with additional size
distribution information obtain using optical particle counters. Particulate composition was determined via ion chromatographic
analysis of the collected filters. A thermal-CO 2 elemental/organic carbon analyzer measured particulate carbon. The chemical composition and size distribution of sub-micron
particles were determined via real-time aerosol mass spectrometry. Primary particulate was not found to be a major emission
from the examined facility, with filter-based impactor samples showing average near-source increases (~15–50 m) in ambient
PM 10 of 5.8 ± 2.9 μg m −3 above background levels. PM 2.5 also showed contribution attributable to the facility (1.7 ± 1.1 μg m −3). Optical particle counter analysis of the numerical size distributions showed bimodal distributions for both the upwind
and downwind conditions, with maximums around 2.5 μm and below the minimum quantified diameter of 0.3 μm. The distributions
showed increased numbers of coarse particles (PM 10) during periods when wind transport came from the barns, but the differences were not statistically significant at the 95%
confidence level. The PM 10 aerosols showed statistically increased concentrations of sulfate, nitrate, ammonium, calcium, organic carbon, and elemental
carbon when the samplers were downwind from the pig barns. Organic carbon was the major constituent of the barn-impacted particulate
matter in both sub-micron (54%) and coarse size (20%) ranges. The AMS PM 1 chemical speciation showed similar species increases, with the exception of and Ca +2, the latter not quantified by the AMS. 相似文献
10.
The new European Council Directive (PE-CONS 3696/07) frames the inhalable (PM 10) and fine particles (PM 2.5) on priority to chemically characterize these fractions in order to understand their possible relation with health effects.
Considering this, PM 2.5 was collected during four different seasons to evaluate the relative abundance of bulk elements (Cl, S, Si, Al, Br, Cu, Fe,
Ti, Ca, K, Pb, Zn, Ni, Mn, Cr and V) and water soluble ions (F −, Cl −, NO 2
−, NO 3
−, SO 4
2−, Na +, NH 4
+, Ca 2+ and Mg 2+) over Menen, a Belgian city near the French border. The air quality over Menen is influenced by industrialized regions on
both sides of the border. The most abundant ionic species were NO 3
−, SO 4
2− and NH 4
+, and they showed distinct seasonal variation. The elevated levels of NO 3
− during spring and summer were found to be related to the larger availability of the NO x precursor. The various elemental species analyzed were distinguished into crustal and anthropogenic source categories. The
dominating elements were S and Cl in the PM 2.5 particles. The anthropogenic fraction (e.g. Zn, Pb, and Cu) shows a more scattered abundance. Furthermore, the ions and elemental
data were also processed using principal component analysis and cluster analysis to identify their sources and chemistry.
These approach identifies anthropogenic (traffic and industrial) emissions as a major source for fine particles. The variations
in the natural/anthropogenic fractions of PM 2.5 were also found to be a function of meteorological conditions as well as of long-range transport of air masses from the industrialized
regions of the continent.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
11.
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
12.
Both aerosol and rainwater samples were collected and analyzed for ionic species at a coastal site in Southeast Asia over
a period of 9 months (January–September 2006) covering different monsoons. In general, the occurrence and distribution of
ionic species showed a distinct seasonal variation in response to changes in air mass origins. Real-time physical characterization
of aerosol particles during rain events showed changes in particle number distributions which were used to assess particle
removal processes associated with precipitation, or scavenging. The mean scavenging coefficients for particles in the range
10–500 nm and 500–10 μm were 7.0 × 10 −5 ± 2.8 × 10 −5 s −1 and 1.9 × 10 −4 ± 1.6 × 10 −5 s −1, respectively. A critical analysis of the scavenging coefficients obtained from this study suggested that the wet removal
of aerosol particles was greatly influenced by rain intensity, and was particle size-dependent as well. The scavenging ratios,
another parameter used to characterize particle removal processes by precipitation, for NH 4
+, Cl −, SO 4
2−, and NO 3
− were found to be higher than those of Na +, K +, and Ca 2+ of oceanic and crustal origins. This enrichment implied that gaseous species NH 3, HCl, and HNO 3 could also be washed out readily. These additional sources of ions in precipitation presumably counter-balanced the dilution
effect caused by high total precipitation volume in the marine and tropical area. 相似文献
13.
A sampling campaign of aerosols over Urumqi from 2001–2007 and soil samples in the surrounding areas were carried out to investigate
the severe air pollution in Urumqi, a typical inland city, located in the center of Asia. Urumqi is one of the heavy polluted
cities in the world, as the days of haze spanned over one third of the year and accounted for 60–80% of the heating period
for the past 6 years. High concentration of fine aerosols, frequent occurrence, and rapid formation of heavy haze were the
three main characteristics. With comparison of the pollution elements, As, Cd, and S, and the ratio of Ca/Al in aerosols and
soils in those sites located on the south of Jungger Basin as tracers, it was found that As, Cd, and S highly enriched in
the aerosols over urban Urumqi were not only from the re-suspended road dust but also from the soil transported from south
of the Jungger Basin. Different from the most cities in China, the high concentration of sulfate in Urumqi was partially from
the primary soil dust transported from the surrounding areas. The mixing of the local anthropogenic aerosols with the soil
transported from outside the city was the main source of the high sulfate concentration. Ammonium salts were higher than the
summed equivalents of SO 42−, NO 3−, and Cl − in Urumqi and much higher than that in other Chinese cities. The total water soluble ions and the total ammonium salts were
as high as 57.8% and 51.0% in PM 2.5. The high concentration of soluble salts with high hygroscopicity, especially ammonium and sulfate salts, were the main factors
contributing to the heavy haze over Urumqi. 相似文献
14.
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
15.
The indoor PM 2.5 aerosol samples for charcoal broiling source under Chinese traditional charbroiling and the ambient fine aerosols samples
(PM 2.5) were collected in Beijing to investigate the characteristics of the charcoal broiling source and its impact on the fine
organic aerosols in the atmosphere. The concentrations of 20 species of the trace organic compounds, including polycyclic
aromatic hydrocarbons (PAHs), fatty acids, levoglucosan, and cholesterol in PM 2.5 were identified and quantified by GC/MS. The total PAHs and fatty acids emitted from charcoal broiling to PM 2.5 were 8.97 and 87,000 ng mg −1 respectively. The concentrations of the light molecular weight (LMW) 3- and 4-ring PAHs were much higher than those of the
high molecular weight (HMW) 5- and 6-ring PAHs. Fatty acids were the most abundant species in source profile, accounting for
over 90% of all identified organic compounds. More polyunsaturated fatty acid (linoleic acids) than the saturated fatty acid
(stearic acids) emitted in the cooking. Charcoal broiling is a minor source of PAHs compared to the source of biomass burning.
Comparing the ratios of levoglucosan/fatty acid and levoglucosan/cholesterol in the charcoal broiling samples to the ambient
samples, it is evident that meat cooking is an important source of fatty acids, but a less important source of cholesterol.
Cooking, as one of the source of fine organic particles, plus other anthropogenic sources would be related to the formation
of the severe haze occurred and spread over the urban atmosphere in most of the cities of China in the past several years. 相似文献
16.
气候变化引起的地面气溶胶浓度变化与区域空气质量密切相关。本文利用“国际大气化学—气候模式比较计划”(Atmospheric Chemistry and Climate Model Intercomparison Project, ACCMIP)中4个模式的试验数据分析了RCP8.5情景下2000~2100年气候变化对中国气溶胶浓度的影响。结果显示,在人为气溶胶排放固定在2000年、仅考虑气候变化的影响时,2000~2100年气候变化导致中国北部地区(31°N~45°N, 105°E~122°E)硫酸盐、有机碳和黑碳气溶胶分别增加28%、21%和9%,硝酸盐气溶胶在中国东部地区减少30%。气候变化对细颗粒物(PM 2.5)浓度的影响有显著的季节变化特征,冬季PM 2.5浓度在中国东部减少15%,这主要是由硝酸盐气溶胶在冬季的显著减少造成的;夏季PM 2.5浓度在中国北部地区增加16%,而长江以南地区减少为9%,这可能与模式模拟的未来东亚夏季风环流的增强有关。 相似文献
17.
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
18.
PM 10 samples were collected over three years at Monzenmachi, the Japan Sea coast, the Noto Peninsula, Ishikawa, Japan from January
17, 2001 to December 18, 2003, using a high volume air sampler with quartz filters. The concentrations of the water-soluble
inorganic ions in PM 10 were determined with using ion chromatography. By analyzing the characteristics of these, the evidences were found that the
Asian outflow had an obviously influence on the air quality at our study site. The results were as follows: the secondary
pollutants SO 42−, NO 3− and NH 4+ were the primary water-soluble inorganic ions at our study site. The monthly mean concentrations of SO 42−, NH 4+, NO 3− and Ca 2+ have prominent peak in spring due to the strong influence of the Asian continent outflow—these according to backward air
trajectory analysis, the maximum of which were 6.09 for nss-SO 42− in May, 2.87 for NO 3− and 0.68 μg m −3 for nss-Ca 2+ in April, respectively. Comparable to similar data reported from various points around East Asia, it had the characteristics
of a polluted coastal area at our study site. The concentration of nss-Ca 2+ in PM 10 drastically increased when the Asian dust invaded, the mean value during the Asian dust days(AD) was 0.86 μg m −3, about 4 times higher than those of normal days (NAD). Meanwhile, the mean concentrations of nss-SO 42−, NO 3− and NH 4+ in AD periods were higher than those in NAD periods which were 5.87, 1.76 and 1.82 μg m −3, respectively, it is due to the interaction between dust and secondary particles during the long-range transport of dust
storms. Finally, according to the source apportionment with positive matrix factorization (PMF) method in this study, the
major source profiles of PM 10 at our study site were categorized as (1) marine salt, (2) secondary sulfate, (3) secondary nitrate and (4) crustal source. 相似文献
19.
Near real-time measurements of PM 2.5 ionic compositions were performed at the summit of the highest mountain in the central-eastern plains in the spring and summer of 2007 in order to characterize aerosol composition and its interaction with clouds. The average concentrations of total water soluble ions were 27.5 and 36.7 μg?m ?3, accounting for 44% and 62% of the PM 2.5 mass concentration in the spring and summer, respectively. A diurnal pattern of SO 4 2- , NH 4 + and NO 3 - was observed in both campaigns and attributed to the upslope/downslope transport of air mass and the development of the planetary boundary layer (PBL). The average SO 2 oxidation ratio (SOR) in summer was 57% (±27%), more than twice that in spring 24% (±16%); the fine nitrate oxidation ratio (NOR) was comparable in the two seasons (9?±?6% and 11?±?10% in summer and spring, respectively). This result indicates strong summertime production of sulfate aerosol. A principal component analysis shows that short-range and long-range transport of pollution, cloud processing, and crustal source were the main factors affecting the variability of the measured ions (and other trace gases and aerosols) at Mt. Tai. Strong indications of biomass burning were observed in summer. Cloud scavenging rates showed larger variations for different ions and in different cloud events. The elevated concentrations of the water soluble ions at Mt. Tai indicate serious aerosol pollution over the North China plain of eastern China. 相似文献
20.
Ambient respirable particles (PM 10; aerodynamic diameter ≤10 μm) collected in a tropical urban environment (Delhi, India) during December 2008-November 2009
were characterized with respect to 16 US EPA priority polycyclic aromatic hydrocarbons (PAHs) and 8 major and trace metals
(Fe, Mn, Cd, Cu, Ni, Pb, Zn and Cr). Concentrations of Σ 16PAHs (annual mean: 74.7 ± 50.7 ng m −3, range 22.1–258.4 ng m −3) and most metallic species were at least an order of magnitude greater than values reported from similar locations worldwide.
Seasonal variations in Σ 16PAHs were significant ( p < 0.001) with highest levels in winter while crustal and anthropogenic metals showed significant but mutually opposite seasonal
dependence. Statistically significant associations were observed between chemical species and various meteorological parameters.
The PAH profile was dominated by combustion-derived large-ring species (~85%) that were essentially local in origin. Principal
component analysis–multiple linear regression (PCA-MLR) apportioned four sources: crustal dust (73%), vehicular emission (21%),
coal combustion (4%) and industrial emission (2%) that was further validated by hierarchical cluster analysis (HCA). Temporal
trend analysis showed that crustal sources were predominant in summer ( p < 0.05) while the remaining sources were most active in winter. Summertime intrusions of Saharan dust were identified with
the help of aerosol maps and air parcel backward trajectories. Inhalation cancer risk assessment showed that up to 3,907 excess
cancer cases (357 for PAHs, 122 for Cd, 2040 for Cr (VI) and 1387 for Ni) are likely in Delhi considering lifetime inhalation
exposure to these chemicals at their current concentrations. 相似文献
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