The Effect of Traction Sanding on Urban Suspended Particles in Finland

Springtime urban road dust forms one of the most serious problems regarding air pollution in Finland. The composition and origin of springtime dust was studied in southern Finland with two different methods. Suspended particles (PM10 and TSP) were collected with high volume particle samplers and particle deposition was collected with moss bags. The composition of the PM1.5−10 fraction was studied using individual particle analysis with SEM/EDX. The deposition in the moss bags was analysed with ICP-MS. The results showed that during the study period, approximately 10% of both PM1.5−10 particles and the deposition originated from sanding. Other sources in the springtime PM1.5−10 were e.g. asphalt aggregate or soil and combustion processes. It can be concluded that sanding produced a relatively small amount of particulate matter under the investigated circumstances

Organic Aerosols and the Origin of Life : An Hypothesis

Recent experimental work has verified the prediction that marine aerosols could have an exterior film of amphiphiles; palmitic, stearic and oleic acids were predominant. Thermodynamic analysis has revealed that such aerosols are energetically capable of asymmetric division. In a prebiotic terrestrial environment, one of the products of such aerosol fission would have been bacterially sized (microns), the other would have been virally sized (tens of nanometers). Plausible avenues for chemical differentiation between the two particles are discussed, and the probabilities for the transition from geochemistry to biochemistry updated in light of recent palaeo fossil studies

Distribution of Airborne Particles from Multi-Emission Source

The purpose of this work was to study the distribution of airborne particles in the surroundings of an iron and steel factory in southern Finland. Several sources of particulate emissions are lying side by side, causing heavy dust loading to the environment. This complicated multi-pollutant situation was studied mainly by SEM/EDX methodology. Particles accumulated on Scots pine bark were identified and quantitatively measured according to their element content, size and shape. As a result, distribution maps of particulate elements were drawn and the amount of different particle types along the study lines was plotted. Particulate emissions from the industrial or energy production processes were not the main dust source. Most emissions were produced from the clinker crusher. Numerous stockpiles of the industrial wastes and raw materials also gave rise to particulate emissions as a result of wind erosion. It was concluded that SEM/EDXmethodology is a useful tool for studying the distribution of particulate pollutants

The effect of mineralogy, texture and mechanical properties of anti-skid and asphalt aggregates on urban dust

In northern latitudes mineral dust is formed when cars use studded tyres and roads are sanded to obtain more traction on the icy surfaces. Anti-skid and asphalt aggregates with different textural, mineralogical and mechanical properties were tested with an indoor road simulator fitted with studded and friction tyres. The particle size distribution and proportions of dust from pavement and anti-skid aggregate were analyzed using SEM-EDX. The wear on the road pavement depends on the properties of the anti-skid and asphalt aggregate (particle size distribution, mechanical/physical and textural properties). Antiskid aggregates, which contain mainly hard minerals (e.g. feldspars and quartz) and which have a low resistance to fragmentation, should be used with caution as they may break more easily into smaller particles and are likely to wear the pavement. By using high-quality anti-skid aggregates it is possible to reduce the amount of urban dust

Fatty acids on continental sulfate aerosol particles

Published 2005 American Geophysical Union. Reproduced by permission of American Geophysical Union.Surface analyses of atmospheric aerosols from different continental sources, such as forest fires and coal and straw burning, show that organic surfactants are found on such aerosols. The predominant organic species detected by time-of-flight secondary ion mass spectrometry on the sulfate aerosols are fatty acids of different carbon chain length up to the C32 acid. These observations are consistent with literature accounts of functional group analysis of bulk samples, but this is the first direct evidence of fatty acid films on the surface of sulfate aerosols. Surface analysis leads to the conclusion that fatty acid films on continental aerosols may be more common than has been previously suggested

Changes in background aerosol composition in Finland during polluted and clean periods studied by TEM/EDX individual particle analysis

Aerosol samples were collected at a rural background site in southern Finland in May 2004 during pollution episode ( PM1 similar to 16 mu g m(-3), backward air mass trajectories from south-east), intermediate period (PM1 similar to 5 mu g m(-3), backtrajectories from north-east) and clean period (PM1 similar to 2 mu g m(-3), backtrajectories from northwest/ north). The elemental composition, morphology and mixing state of individual aerosol particles in three size fractions were studied using transmission electron microscopy (TEM) coupled with energy dispersive X-ray (EDX) microanalyses. The TEM/EDX results were complemented with the size-segregated bulk chemical measurements of selected ions and organic and elemental carbon. Many of the particles in PM0.2-1 and PM1-3.3 size fractions were strongly internally mixed with S, C and/or N. The major particle types in PM0.2-1 samples were 1) soot and 2) ( ammonium) sulphates and their mixtures with variable amounts of C, K, soot and/or other inclusions. Number proportions of those two particle groups in PM0.2-1 samples were 0 - 12% and 83 - 97%, respectively. During the pollution episode, the proportion of Ca-rich particles was very high ( 26 - 48%) in the PM1- 3.3 and PM3.3-11 samples, while the PM0.2-1 and PM1- 3.3 samples contained elevated proportions of silicates ( 22 - 33%), metal oxides/hydroxides ( 1 - 9%) and tar balls ( 1 - 4%). These aerosols originated mainly from polluted areas of Eastern Europe, and some open biomass burning smoke was also brought by long-range transport. During the clean period, when air masses arrived from the Arctic Ocean, PM1- 3.3 samples contained mainly sea salt particles ( 67 - 89%) with a variable rate of Cl substitution ( mainly by NO3-). During the intermediate period, the PM1- 3.3 sample contained porous (sponge-like) Na-rich particles (35%) with abundant S, K and O. They might originate from the burning of wood pulp wastes of paper industry. The proportion of biological particles and C-rich fragments ( probably also biological origin) were highest in the PM3.3-11 samples ( 0 - 81% and 0 - 22%, respectively). The origin of different particle types and the effect of aging processes on particle composition and their hygroscopic and optical properties are discussed.Aerosol samples were collected at a rural background site in southern Finland in May 2004 during pollution episode ( PM1 similar to 16 mu g m(-3), backward air mass trajectories from south-east), intermediate period (PM1 similar to 5 mu g m(-3), backtrajectories from north-east) and clean period (PM1 similar to 2 mu g m(-3), backtrajectories from northwest/ north). The elemental composition, morphology and mixing state of individual aerosol particles in three size fractions were studied using transmission electron microscopy (TEM) coupled with energy dispersive X-ray (EDX) microanalyses. The TEM/EDX results were complemented with the size-segregated bulk chemical measurements of selected ions and organic and elemental carbon. Many of the particles in PM0.2-1 and PM1-3.3 size fractions were strongly internally mixed with S, C and/or N. The major particle types in PM0.2-1 samples were 1) soot and 2) ( ammonium) sulphates and their mixtures with variable amounts of C, K, soot and/or other inclusions. Number proportions of those two particle groups in PM0.2-1 samples were 0 - 12% and 83 - 97%, respectively. During the pollution episode, the proportion of Ca-rich particles was very high ( 26 - 48%) in the PM1- 3.3 and PM3.3-11 samples, while the PM0.2-1 and PM1- 3.3 samples contained elevated proportions of silicates ( 22 - 33%), metal oxides/hydroxides ( 1 - 9%) and tar balls ( 1 - 4%). These aerosols originated mainly from polluted areas of Eastern Europe, and some open biomass burning smoke was also brought by long-range transport. During the clean period, when air masses arrived from the Arctic Ocean, PM1- 3.3 samples contained mainly sea salt particles ( 67 - 89%) with a variable rate of Cl substitution ( mainly by NO3-). During the intermediate period, the PM1- 3.3 sample contained porous (sponge-like) Na-rich particles (35%) with abundant S, K and O. They might originate from the burning of wood pulp wastes of paper industry. The proportion of biological particles and C-rich fragments ( probably also biological origin) were highest in the PM3.3-11 samples ( 0 - 81% and 0 - 22%, respectively). The origin of different particle types and the effect of aging processes on particle composition and their hygroscopic and optical properties are discussed.Aerosol samples were collected at a rural background site in southern Finland in May 2004 during pollution episode ( PM1 similar to 16 mu g m(-3), backward air mass trajectories from south-east), intermediate period (PM1 similar to 5 mu g m(-3), backtrajectories from north-east) and clean period (PM1 similar to 2 mu g m(-3), backtrajectories from northwest/ north). The elemental composition, morphology and mixing state of individual aerosol particles in three size fractions were studied using transmission electron microscopy (TEM) coupled with energy dispersive X-ray (EDX) microanalyses. The TEM/EDX results were complemented with the size-segregated bulk chemical measurements of selected ions and organic and elemental carbon. Many of the particles in PM0.2-1 and PM1-3.3 size fractions were strongly internally mixed with S, C and/or N. The major particle types in PM0.2-1 samples were 1) soot and 2) ( ammonium) sulphates and their mixtures with variable amounts of C, K, soot and/or other inclusions. Number proportions of those two particle groups in PM0.2-1 samples were 0 - 12% and 83 - 97%, respectively. During the pollution episode, the proportion of Ca-rich particles was very high ( 26 - 48%) in the PM1- 3.3 and PM3.3-11 samples, while the PM0.2-1 and PM1- 3.3 samples contained elevated proportions of silicates ( 22 - 33%), metal oxides/hydroxides ( 1 - 9%) and tar balls ( 1 - 4%). These aerosols originated mainly from polluted areas of Eastern Europe, and some open biomass burning smoke was also brought by long-range transport. During the clean period, when air masses arrived from the Arctic Ocean, PM1- 3.3 samples contained mainly sea salt particles ( 67 - 89%) with a variable rate of Cl substitution ( mainly by NO3-). During the intermediate period, the PM1- 3.3 sample contained porous (sponge-like) Na-rich particles (35%) with abundant S, K and O. They might originate from the burning of wood pulp wastes of paper industry. The proportion of biological particles and C-rich fragments ( probably also biological origin) were highest in the PM3.3-11 samples ( 0 - 81% and 0 - 22%, respectively). The origin of different particle types and the effect of aging processes on particle composition and their hygroscopic and optical properties are discussed.Peer reviewe

Characterization of aerosol particle episodes in Finland caused by wildfires in Eastern Europe

We studied the sources, compositions and size distributions of aerosol particles during long-range transport (LRT) PM2.5 episodes which occurred on 12–15 August, 26– 28 August and 5–6 September 2002 in Finland. Backward air mass trajectories, satellite detections of fire areas and dispersion modelling results indicate that emissions from wild- fires in Russia and other Eastern European countries arrived in Finland during these episodes. Elemental analyses using scanning electron microscopy (SEM) coupled with energy dispersive X-ray microanalyses (EDX) showed that the proportions of S-rich particles and agglomerates (agglomeration was caused partly by the sampling method used) increased during the episodes, and they contained elevated fractions of K, indicating emissions from biomass burning. These aerosols were mixed with S-rich emissions from fossil fuel burning during transport since air masses came through polluted areas of Europe. Minor amounts of coarse Ca-rich particles were also brought by LRT during the episodes, and they probably originated from wildfires and/or from Estonian and Russian oil-shale-burning industrial areas. Ion chromatography analysis showed that concentrations of sulphate (SO2− 4 ), total nitrate (NO−3 +HNO3(g)) and total ammonium (NH+4 +NH3(g)) increased during the episodes, but the ratio of the total amount of these ions to PM10 concentration decreased, indicating unusually high fractions of other chemical components. Particle number size distribution measurements with differential mobility particle sizer (DMPS) revealed that concentrations of particles 90–500 nm increased during the episodes, while concentrations of particles smaller than 90 nm decreased. The reduction of the smallest particles was caused by suppressed new particle formation due to vapour and molecular cluster uptake of LRT particles. Our results show that emissions from wildfires in Russian and other Eastern European countries deteriorated air quality of very large areas, even at distances of over 1000 km from the fire areas

Experimental observation of two-photon photoelectric effect from silver aerosol nanoparticles

Peer reviewe

Characterization and source identification of a fine particle episode in Finland

A strong long-range transported (LRT) fine particle (PM2.5) episode occurred from March 17–22, 2002 over large areas of Finland. Most of the LRT particle mass was in the submicrometre size fraction. The number of concentrations of 90–500 nm particles increased by a factor of 5.6 during the episode, but the concentrations of particles smaller than 90 nm decreased. This reduction of the smallest particles was caused by suppressed gas-to-particle conversion due to the vapour uptake of LRT particles. Individual particle analyses using SEM/EDX showed that the proportion of sulphur-rich particles rose strongly during the episode and that the relative weight percentage of potassium was unusually high in these particles. The median S/K ratios of S-rich particles were 2.1 at the beginning of the episode, 5.2 at the peak stage of the episode and 8.9 during the reference days. The high proportion of K is a clear indication of emissions from biomass burning, because K is a good tracer of biomass-burning aerosols. Trajectories and satellite detections of fire areas indicated that the main source of biomass-burning aerosols was large-scale agricultural field burning in the Baltic countries, Belarus, Ukraine and Russia. The higher S/K ratio of S-rich particles during the peak stage was obviously due to the increased proportion of fossil fuel-burning emissions in the LRT particle mass, since air masses arrived from the more polluted areas of Europe at that time. The concentrations of sulphate, total nitrate and total ammonium increased during the episode. Our results suggest that large-scale agricultural field burning may substantially affect PM2.5 concentrations under unfavourable meteorological conditions even at distances over 1000 km from the burning areas

Experimental studies about the impact of traction sand on urban road dust composition

http://www.elsevier.com/locate/issn/00489697Traffic causes enhanced PM10 resuspension especially during spring in the US, Japan, Norway, Sweden and Finland, among other countries. The springtime PM10 consists primarily of mineral matter from tyre-induced paved road surface wear and traction sand. In some countries, the majority of vehicles are equipped with studded tyres to enhance traction, which additionally increases road surface wear. Because the traction sand and the mineral matter from the pavement aggregate can have a similar mineralogical composition, it has been difficult to determine the source of the mineral fraction in the PM10. In this study, homogenous traction sand and pavement aggregate with different mineralogical compositions were chosen to determine the sources of PM10 particles by single particle analysis (SEMyEDX). This study was conducted in a test facility, which made it possible to rule out dust contributions from other sources. The ambient PM10 concentrations were higher when traction sand was used, regardless of whether the tyres were studded or not. Surprisingly, the use of traction sand greatly increased the number of the particles originating from the pavement. It was concluded that sand must contribute to pavement wear. This phenomenon is called the sandpaper effect. An understanding of this is important to reduce harmful effects of springtime road dust in practical winter maintenance of urban roads