Resuspended dust episodes as an urban air-quality problem in subarctic regions.
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This paper describes the resuspension of road dust in an urban subarctic environment and focuses especially on the effect of wind speed on the formation of resuspended dust episodes.The study was conducted in Kuopio, Finland, in the spring of 1995. There were 36 daily measurements of mass concentrations of fine particulate matter (PM2.5), thoracic particulate matter (PM10), total suspended particulate matter, black carbon and carbon monoxide; size-segregated number concentrations of particles (diameter range 0.01-10 microm); and meteorological parameters. Total elemental compositions of PM2.5 and PM10 samples were analyzed with inductively coupled plasma mass spectrometry.The mass and number concentrations of particles in all the size ranges and the concentrations of soil-derived (iron) and combustion-derived (vanadium and lead) elements in the PM2.5 and PM10 increased during the dust episodes. The daily average wind speed dually affected the episodes. The pollutant concentrations increased at wind speeds of <4 m/s and >5 m/s. The former was related to inversion-type conditions characterized by low wind speeds, while the latter was likely to be due to wind-blown resuspended dust. Resuspended lead accounted for an average of 27% of the total lead, and resuspended vanadium for 46% of the total vanadium in PM2.5.Resuspended dust episodes were related to both low and high wind speeds, and the relationship suggests that factors other than wind speed, such as turbulence induced by traffic, affect the emergence of such episodes. The contribution of elevated levels of crustal material and toxic metals in resuspended PM2.5 to human adverse health effects should be investigated.Keywords:
Mass concentration (chemistry)
Subarctic climate
Asian Dust
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The association between fine and ultrafine particles and respiratory health was studied in adults with a history of asthma in Erfurt, Eastern Germany. Twenty-seven nonsmoking asthmatics recorded their peak expiratory flow (PEF) and respiratory symptoms daily. The size distribution of ambient particles in the range of 0.01 to 2.5 microm was determined with an aerosol spectrometer during the winter season 1991-1992. Most of the particles (73%) were in the ultrafine fraction (smaller than 0.1 microm in diameter), whereas most of the mass (82%) was attributable to particles in the size range of 0.1 to 0.5 microm. Because these two fractions did not have similar time courses (correlation coefficient r = 0.51), a comparison of their health effects was possible. Both fractions were associated with a decrease of PEF and an increase in cough and feeling ill during the day. Health effects of the 5-d mean of the number of ultrafine particles were larger than those of the mass of the fine particles. In addition, the effects of the number of the ultrafine particles on PEF were stronger than those of particulate matter smaller than 10 microm (PM10). Therefore, the present study suggests that the size distribution of ambient particles helps to elucidate the properties of ambient aerosols responsible for health effects.
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To evaluate the chemical profiles and sources of spring aerosol over Xi'an,24 h a day fine particulate matter PM2.5 and inhalable particulate matter PM10 samples were collected at 4 urban sites simultaneously in 2 weeks using minival samplers. PM2.5 and PM10 mass concentrations,carbon analyses(organic and elemental carbon),water inorganic ion(NH4 +,Na+,K+,Ca2+,Mg2+,F-,Cl-,SO4 2-,NO3-) and trace elements(Ca and Fe) were determined by gravimetry, ion chromatography, thermal-optical carbon analyzer and ED-XRF spectrometry,respectively. The results show that the average mass concentration of PM10 is 3 times larger than that of PM2.5. Comparing with that in the non-dust period a sharp increase in organic carbon level is observed during the dust period. SO4 2--NO3--NH4 +concentration is much higher in dust storm events than in normal days, mainly due to dilution of enhanced particulates in dry dust storm. The transport pathways and sources of PM2.5 and PM10 in dust storm period are identified on the basis of the air mass trajectories and the ratio of Ca and Fe elements. CO3 2-concentration is estimated using the method of ion balance. A strong relationship is observed between evaluated CO3 2-and measured Ca2+, which indicates that CaCO3 is a main composition during dust storm period.
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Abstract. Trace element measurements in PM10–2.5, PM2.5–1.0 and PM1.0–0.3 aerosol were performed with 2 h time resolution at kerbside, urban background and rural sites during the ClearfLo winter 2012 campaign in London. The environment-dependent variability of emissions was characterized using the Multilinear Engine implementation of the positive matrix factorization model, conducted on data sets comprising all three sites but segregated by size. Combining the sites enabled separation of sources with high temporal covariance but significant spatial variability. Separation of sizes improved source resolution by preventing sources occurring in only a single size fraction from having too small a contribution for the model to resolve. Anchor profiles were retrieved internally by analysing data subsets, and these profiles were used in the analyses of the complete data sets of all sites for enhanced source apportionment. A total of nine different factors were resolved (notable elements in brackets): in PM10–2.5, brake wear (Cu, Zr, Sb, Ba), other traffic-related (Fe), resuspended dust (Si, Ca), sea/road salt (Cl), aged sea salt (Na, Mg) and industrial (Cr, Ni); in PM2.5–1.0, brake wear, other traffic-related, resuspended dust, sea/road salt, aged sea salt and S-rich (S); and in PM1.0–0.3, traffic-related (Fe, Cu, Zr, Sb, Ba), resuspended dust, sea/road salt, aged sea salt, reacted Cl (Cl), S-rich and solid fuel (K, Pb). Human activities enhance the kerb-to-rural concentration gradients of coarse aged sea salt, typically considered to have a natural source, by 1.7–2.2. These site-dependent concentration differences reflect the effect of local resuspension processes in London. The anthropogenically influenced factors traffic (brake wear and other traffic-related processes), dust and sea/road salt provide further kerb-to-rural concentration enhancements by direct source emissions by a factor of 3.5–12.7. The traffic and dust factors are mainly emitted in PM10–2.5 and show strong diurnal variations with concentrations up to 4 times higher during rush hour than during night-time. Regionally influenced S-rich and solid fuel factors, occurring primarily in PM1.0–0.3, have negligible resuspension influences, and concentrations are similar throughout the day and across the regions.
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Mineral dust
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The chemical composition and toxicity of wintertime urban-air particulate matter with an aerodynamic diameter of <10 microm (PM10), derived mostly from long-range transport and local combustion sources, were compared with those of springtime PM10 derived mostly from the resuspension of road dust.Water-soluble ions and elements and polycyclic aromatic hydrocarbons (PAH) were analyzed from seasonally pooled PM10 samples collected at a busy traffic site in Helsinki in 1999. These PM10 samples were also tested for cytotoxicity [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide test] and the production of proinflammatory cytokines [tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6)] and nitric oxide (NO) in the mouse macrophage cell line RAW 264.7. Their oxidative capacity and the associated DNA (deoxyribonucleic acid) damage were investigated by electron paramagnetic resonance and the formation of 8-hydroxy-2'-deoxyguanosine (8-OH-DG) in isolated calf thymus DNA, respectively.The late wintertime and springtime PM10 had similar compositions of water-soluble ions and elements, but the winter PM10 had a higher content of PAH. The spring PM10 was a much more potent inducer of TNF-alpha and IL-6 production than the winter PM10 was, but there were no consistent differences in cytotoxic potency. In contrast, the winter PM10 was a significantly more potent inducer of NO production and 8-OH-DG formation. The large cytokine responses to the spring PM10 were caused by its insoluble fraction and largely inhibited by the endotoxin antagonist polymyxin B. The transition metal chelator deferoxamine did not modify the proinflammatory or cytotoxic responses to the PM10 samples.The toxicity profile of urban-air PM10 changed with season in a subarctic climate. Particulate-bound endotoxin from soil gram-negative bacteria is suggested as a highly proinflammatory constituent of springtime resuspended road dust.
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Particle (ecology)
Ultrafine particle
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Mass concentrations of ambient particulate matter were measured in terms of daily average values of PM1, PM2.5, and PM10 for 6 months during the winter of 1996−1997 at a fixed sampling site in Helsinki, Finland, along with meteorological parameters and particle number concentra tions in the size range 0.01−1 μm. In addition, the PM filters were subjected to reflectometric analysis to determine absorption coefficients for the various fractions of urban particulate matter. The data were divided into two periods (winter and spring) in order to study more closely seasonal phenomena that have an effect on air pollution patterns. The variations in PM10 and PM2.5 concentrations differed in pattern during resuspended dust episodes, whereas those in PM1 concentrations followed those in PM2.5 fairly well throughout the 6-month measurement period. Thus it seems that PM1 does not provide much additional information on mass concentrations relative to PM2.5. Number concentrations in the ultrafine particle size range from 0.01 to 0.1 μm, especially in wintertime, were much better correlated with absorption coefficients than with any of the three PM mass-based concentrations, indicating that Black Smoke particles are related to that size range. The results also indicate that coarse particle concentrations in ambient air are affected more by seasonal factors than are fine particle concentrations.
Mass concentration (chemistry)
Particle (ecology)
Subarctic climate
Seasonality
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