Characteristics of Road Dust from Different Sampling Sites in Northern Taiwan

Abstract

Road dust contributes a large percentage of the atmosphere’s suspended particles in Taiwan. Three road dust samples were collected from downtown, electrical park, and freeway tunnel areas. A mechanical sieve separated the road dust in the initial stage. Particles >100 μm were 75%, 70%, and 60% (wt/wt), respectively, of the samples. Those particles <37 μm were resuspended in another mixing chamber and then collected by a Moudi particle sampler. The largest mass fraction of resuspended road dust was in the range of 1–10 μm. Ultrafine particles (<1 μm) composed 33.7, 17, and 7.4% of the particle samples (downtown, electrical park, and freeway tunnel, respectively). The road dust compositions were analyzed by inductively coupled plasma (ICP)-atomic emissions spectroscopy and ICP-mass spectrometry. The highest concentration fraction contained more aluminum (Al), iron (Fe), calcium (Ca), and potassium than other elements in the road dust particle samples. Additionally, the sulfur (S) content in the road dust from the electrical park and freeway tunnel areas was 2.1 and 3.4 times the downtown area sample, respectively. The sulfur originated from the vehicle and boiler oil combustion and industrial manufacturing processes. Furthermore, zinc (Zn) concentration in the tunnel dust was 2.6 times that of the downtown and electrical park samples, which can be attributed to vehicle tire wear and tear. Resuspended road dusts (<10 μm) from the downtown and freeway tunnel areas were principally 2.5–10 μm Al, barium (Ba), Ca, copper (Cu), Fe, magnesium (Mg), sodium (Na), antimony (Sb), and Zn, whereas arsenic (As), chromium (Cr), and nickel (Ni) were predominant in the ultrafine particle samples (<1 μm). Al, Ba, and Ca are the typical soil elements in coarse particles; and As, and Cr and Ni are the typical fingerprint of oil combustion and vehicle engine abrasion in ultrafine particles. There was a special characteristic of resuspension road dust at electrical park, that is, many elements, including As, Ba, Ca, cadmium, Cr, Cu, Fe, manganese (Mn), Ni, lead (Pb), S, vanadium (V), and Zn, were major in ultrafine particles. These elements should be attributed to the special manufacturing processes of electric products.     

Source characterization for atmospheric trace metals over Kiel Bight

Atmospheric concentrations of Na, Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Rb, Sr, Ba and Pb are reported for 59 weekly air filter samples collected over the Kiel Bight. The contributions of sea salt, mineral dust and anthropogenic emissions to each of these elements were assumed to be represented by the concentrations of indicator elements, which were Na, Al and Zn, respectively. Based on this assumption a multiple regression analysis was applied to the concentration data. The results showed that atmospheric sea salt contributed significantly only to Sr and, of course, Na. Considerable portions of Al, K, Ca, Ti, Cr, Mn, Fe, Rb, Sr and Ba were derived from mineral dust. Anthropogenic sources were responsible for total V, Ni, Cu, Zn, As and Pb, and there was an anthropogenic component for most of the other elements.Moreover, the anthropogenic contribution was characterized by a nearly constant composition with respect to Ca, Ti, Cr, Mn, Fe, Cu, Zn, As, Rb, Sr, Ba and Pb, indicating that trace metals over the Kiel Bight are mainly derived from one source area. This conclusion was confirmed by correlating anthropogenic trace metal concentrations with the wind direction. A 40° wind sector directed to the south of the sampling site was identified as the major pathway for the transport of anthropogenic trace metals to the Kiel Bight.     

Background aerosol composition in the namib desert,South West Africa (Namibia)

A remote site in the Namib Desert was selected for sampling background aerosols in southern Africa, as one of a wide network of stations spanning the Southern Hemisphere in a programme designed to measure the background concentrations of trace elements in the atmosphere. A series of samples was collected over a 6-month period using a single-orifice cascade impactor, which fractionated the particles into six size groups. Analysis was performed using particle-induced X-ray emission (PIXE), yielding results for S, Cl, K, Ca, Ti, Mn, Fe, Br and Sr, and occasionally also for V, Cr, Ni, Cu, Zn and Pb. No direct correlations with wind direction were observed excluding strong local or regional sources of particles. K, Ca, Ti, Mn and Fe can be identified with a dust dispersion source. Cl, large particle S and Br, and part of the K and Sr are derived from sea spray. Relative to the soil components small particle K is not enriched as it normally is in regions with less scarce vegetation. Cr, V, Ni, Cu, Zn and Pb concentrations and enrichments in the aerosol are lower than practically all values measured at any other location hitherto. The concentration of the small particle sulphur, 200 ng m⁻³, is believed to be related to anaerobic conditions and plankton blooms in the ocean upwelling zones off Namibia.     

Atmospheric trace element deposition: principal component analysis of ICP-MS data from moss samples

Data from a Norwegian survey on atmospheric deposition, including 33 elements in 495 moss samples collected in 1990, are presented. The biomonitor moss used was Hylocomium splendens, and the analyses were carried out by ICP-MS. Principal component analysis is used to identify possible sources of the elements determined in the mosses. Dominant factors represent long-range atmospheric transported elements (Bi, Pb, Sb, Mo, Cd, V, As, Zn, Tl, Hg, Ga), windblown mineral particles (Y, La, Al, Li, U, Th, Ga, Fe, V, Cr), local emission sources (Ni, Cu, Co, and As; Zn, Cd, and Hg; Fe, Cr, and Al), transport from the marine environment (Mg, B, Na, Sr, Ca), and contribution from higher plants (Cs, Rb, Ba, Mn). Comparison of the results with similar surveys from 1977 and 1985 show a decreasing contribution of most long-range transported elements to southern Norway.     

Influence of angular exposure and proximity to vehicular traffic on the diversity of epiphytic lichens and the bioaccumulation of traffic-related elements

This study investigated the influence of angular exposure and distance from vehicular traffic on the diversity of epiphytic lichens and the bioaccumulation of traffic-related elements in a town of central Italy. An Index of Lichen Diversity (ILD) was calculated on the street-facing and the opposite side of road-lining trees and in a urban park 250 m away, and the content of selected trace elements (Al, Ba, Ce, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, V, and Zn) was determined in samples of the lichen Punctelia borreri (Sm.) Krog growing on tree bark, both on the exposed and opposite sides. ILD increases with distance from traffic emissions. However, at the site with vehicle traffic, non-nitrophilous lichens decreased while nitrophilous ones increased. The concentration of the traffic-related elements Ba, Cr, Cu, Mn, Sb, and Zn accumulated in thalli of P. borreri was higher on roadside trees than in trees from the urban park. ILD was not affected by the angular exposure to the road and the bioaccumulation of traffic-related elements was similar in lichens from the side of the bole exposed to traffic emissions and particulate resuspension and from the opposite side. The angular exposure in respect to the traffic source does not influence trace element accumulation. These results are important when using lichens for biomonitoring purposes, both for planning future studies and for the reliability of the interpretation of past surveys that do not report information about the angular exposure of the collected lichen material.     

Identification of particles containing chromium and lead in road dust and soakaway sediment by electron probe microanalyser

Individual particles containing Cr and/or Pb and other major components were identified in road dust from a heavily used road (hereinafter 'heavy traffic road dust'), road dust from a residential area and soakaway sediment by electron probe microanalyser to locate their sources and carrier particles. Individual particles containing high levels of Cr and/or Pb (>or=0.2%) were identified using wavelength dispersive spectrometry (WDS) map analysis. Chromium, Pb and other major elements were then determined by means of a combination of WDS and energy-dispersive spectrometry in all identified particles, 50 particles containing neither Cr nor Pb from each type of road dust and soakaway sediment, and yellow road line markings. WDS map analysis revealed that many particles containing both Cr and Pb were present among the identified particles in heavy traffic road dust, whereas they were minor components in road dust from the residential area and soakaway sediment. The plots of X-ray intensities of Cr vs. Pb were linear for the identified particles containing both Cr and Pb in heavy traffic road dust, and the line closely fitted the plots for the three yellow road line marking samples. Individual particles were then classified using cluster analysis of element components. The results revealed that the adsorption of source materials or released metals onto soil minerals occurred in road dust and soakaway sediment, that the yellow road line markings were sources of Cr and Pb in heavy traffic road dust, and that materials containing Fe as a major component, such as stainless steel, were additional sources of Cr in both road dust and soakaway sediment.     

The study of fine and coarse particles, and metallic elements for the daytime and night-time in a suburban area of central Taiwan, Taichung

Daily average concentrations of fine and coarse particulates, and TSP samples have been measured simultaneously at daytime and night-time periods by using Universal and PS-1 sampler in a suburban area of central Taiwan from June to August 1998. The samples were analyzed by atomic absorption spectrometry to determine the fine and coarse particulate concentrations of metallic elements (Ca, Fe, Mn, Pb, Cu, Zn and Cr). The concentration of PM2.5 and TSP showed a decreased trend for the daytime period. The fine particle concentrations were about two times as that of coarse particulate concentrations. The averaged fine particulate concentrations at daytime are higher than at night-time. Ca and Fe were mostly in the coarse particulate mode. The correlation coefficients were 0.63 and 0.69 for elements Ca and Fe in the coarse particle mode for day and night periods. Pb showed a similar distribution ratio with Mn for the fine to coarse particle ratios at both day and night period. Pb and Mn are highly correlated for the day (R = 0.78) and night period (R = 0.61) at particle size <2.5 microm. Cu and Zn were mainly in fine particles at both day and night period. Fe and Ca consist of the major parts of all the elements. Elemental Mn is the lowest among the rest of the heavy metals.     

Mass levels,crustal component and trace elements in PM10 in Palermo,Italy

Results concerning the levels and elemental compositions of daily PM₁₀ samples collected at four air quality monitoring sites in Palermo (Italy) are presented. The highest mean value of PM₁₀ concentrations (46 μg m⁻³, with a peak value of 158 μg m⁻³) was recorded at the Di Blasi urban station, and the lowest at Boccadifalco station (25 μg m⁻³), considered as a sub-urban background station. Seventeen elements (Al, As, Ba, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Pb, Sb, Sr, U, V, Zn) were measured by ICP-MS. Al and Fe showed the highest concentrations, indicating the significant contribution of soil and resuspended mineral particles to atmospheric PM₁₀. Ba, Cr, Cu, Mn, Mo, Ni, Pb, Sb, V and Zn had higher concentrations at the three urban sampling sites than at the sub-urban background station. Besides soil-derived particles, an R-mode cluster analysis revealed a group of elements, Mo, Cu, Cr, Sb and Zn, probably related to non-exhaust vehicle emission, and another group, consisting of Ba, As and Ni, which seemed to be associated both with exhaust emissions from road traffic, and other combustion processes such as incinerators or domestic heating plants. The results also suggest that Sb, or the association Sb–Cu–Mo, offers a way of tracing road traffic emissions.     

Active moss biomonitoring of small-scale spatial distribution of airborne major and trace elements in the Belgrade urban area

In urban environments, human exposure to air pollutants is expected to be significantly increased, especially near busy traffic streets, street canyons, tunnels, etc. where urban topography and microclimate may additionally cause poor air conditions giving rise to pollution hotspots. As a practical and cost-effective approach, active moss biomonitoring survey of some major and trace element air pollution was performed in the Belgrade street canyons and city tunnel in 2011 with the aim to evaluate possibility of using Sphagnum girgensohnii moss bags for investigation of the small-scale vertical and horizontal distribution patterns of the elements. In five street canyons, the moss bags were hung at heights of about 4, 8 and 16 m, during 10 weeks, and also, for the same time, the moss bags were exposed in the tunnel, in front of and out of it. After the exposure period, the concentrations of Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Sr, V and Zn in the moss were determined by inductively coupled plasma optical emission spectrometry. According to the results, in all street canyons, the vertical distribution patterns of the moss elements concentration (Al, Ba, Co, Cr, Cu, Ni, Pb, Sr, V and Zn) showed statistically significant decrease from the first to the third heights of bags exposure. In the tunnel experiment, from inner to out of the tunnel, for Al, Ba, Cd, Co, Cr, Cu, Fe, K and Zn, decreasing trend of concentrations was obtained. Significantly higher concentration of the elements was pronounced for the tunnel in comparison with the street canyons. The results indicate that the use of S. girgensohnii moss bags is a simple, sensitive and inexpensive way to monitor the small-scale inner city spatial distribution of airborne major and trace element content.     

Size-differentiated chemical characteristics of Asian paleo dust: records from aeolian deposition on Chinese Loess Plateau

The Chinese Loess Plateau (CLP) receives and potentially contributes to Asian dust storms that affect particulate matter (PM) concentrations, visibility, and climate. Loess on the CLP has experienced little weathering effect and is regarded as an ideal record to represent geochemical characteristics of Asian paleo dust. Samples were taken from 2-, 9-, and 15-m depths (representing deposition periods from approximately 12,000 to approximately 200,000 yr ago) in the Xi Feng loess profile on the CLP. The samples were resuspended and then sampled through total suspended particulates (TSP), PM10, PM2.5, and PM1 (PM with aerodynamic diameters < approximately 30, 10, 2.5, and 1 microm, respectively) inlets onto filters for mass, elemental, ionic, and carbon analyses using a Desert Research Institute resuspension chamber. The elements Si, Ca, Al, Fe, K, Mg, water-soluble Ca (Ca2+), organic carbon, and carbonate carbon are the major constituents (> 1%) in loess among the four PM fractions (i.e., TSP, PM10, PM2.5, and PM1). Much of Ca is water soluble and corresponds with measures of carbonate, indicating that most of the calcium is in the form of calcium carbonate rather than other calcium minerals. Most of the K is insoluble, indicating that loess can be separated from biomass burning contributions when K+ is measured. The loess has elemental abundances similar to those of the upper continental crust (UCC) for Mg, Fe, Ti, Mn, V, Cr, and Ni, but substantially different ratios for other elements such as Ca, Co, Cu, As, and Pb. These suggest that the use of UCC as a reference to represent pure or paleo Asian dust needs to be further evaluated. The aerosol samples from the source regions have similar ratios to loess for crustal elements, but substantially different ratios for species from anthropogenic sources (e.g., K, P, V, Cr, Cu, Zn, Ni, and Pb), indicating that the aerosol samples from the geological-source-dominated environment are not a "pure" soil product as compared with loess.     

Characteristics and impacts of trace elements in atmospheric deposition at a high-elevation site,southern China

To investigate the regional background trace element (TE) level in atmospheric deposition (dry and wet), TEs (Fe, Al, V, Cr, Mn, Ni, Cu, Zn, As, Se, Mo, Cd, Ba, and Pb) in 52 rainwater samples and 73 total suspended particles (TSP) samples collected in Mt. Lushan, Southern China, were analyzed using inductively coupled plasma-mass spectrometry (ICP-MS). The results showed that TEs in wet and dry deposition of the target area were significantly elevated compared within and outside China and the volume weight mean pH of rainwater was 4.43. The relative contributions of wet and dry depositions of TEs vary significantly among elements. The wet deposition fluxes of V, As, Cr, Se, Zn, and Cd exceeded considerably their dry deposition fluxes while dry deposition dominated the removal of pollution elements such as Mo, Cu, Ni, Mn, and Al. The summed dry deposition flux was four times higher than the summed wet deposition flux. Prediction results based on a simple accumulation model found that the content of seven toxic elements (Cr, Ni, Cu, Zn, As, Cd, and Pb) in soils could increase rapidly due to the impact of annual atmospheric deposition, and the increasing amounts of them reached 0.063, 0.012, 0.026, 0.459, 0.076, 0.004, and 0.145 mg kg^?1, respectively. In addition, the annual increasing rates ranged from 0.05% (Cr and Ni) to 2.08% (Cd). It was also predicted that atmospheric deposition induced the accumulation of Cr and Cd in surface soils. Cd was the critical element with the greatest potential ecological risk among all the elements in atmospheric deposition.     

Concentration and size distribution of ultrafine particles near a major highway

Motor vehicle emissions usually constitute the most significant source of ultrafine particles (diameter <0.1 microm) in an urban environment, yet little is known about the concentration and size distribution of ultrafine particles in the vicinity of major highways. In the present study, particle number concentration and size distribution in the size range from 6 to 220 nm were measured by a condensation particle counter (CPC) and a scanning mobility particle sizer (SMPS), respectively. Measurements were taken 30, 60, 90, 150, and 300 m downwind, and 300 m upwind, from Interstate 405 at the Los Angeles National Cemetery. At each sampling location, concentrations of CO, black carbon (BC), and particle mass were also measured by a Dasibi CO monitor, an aethalometer, and a DataRam, respectively. The range of average concentration of CO, BC, total particle number, and mass concentration at 30 m was 1.7-2.2 ppm, 3.4-10.0 microg/m3, 1.3-2.0 x 10(5)/cm3, and 30.2-64.6 microg/m3, respectively. For the conditions of these measurements, relative concentrations of CO, BC, and particle number tracked each other well as distance from the freeway increased. Particle number concentration (6-220 nm) decreased exponentially with downwind distance from the freeway. Data showed that both atmospheric dispersion and coagulation contributed to the rapid decrease in particle number concentration and change in particle size distribution with increasing distance from the freeway. Average traffic flow during the sampling periods was 13,900 vehicles/hr. Ninety-three percent of vehicles were gasoline-powered cars or light trucks. The measured number concentration tracked traffic flow well. Thirty meters downwind from the freeway, three distinct ultrafine modes were observed with geometric mean diameters of 13, 27, and 65 nm. The smallest mode, with a peak concentration of 1.6 x 10(5)/cm3, disappeared at distances greater than 90 m from the freeway. Ultrafine particle number concentration measured 300 m downwind from the freeway was indistinguishable from upwind background concentration. These data may be used to estimate exposure to ultrafine particles in the vicinity of major highways.     

Aerosols near by a coal fired thermal power plant: Chemical composition and toxic evaluation

Industrial processes discharge fine particulates containing organic as well as inorganic compounds into the atmosphere which are known to induce damage to cell and DNA, both in vitro and in vivo. Source and area specific studies with respect to the chemical composition, size and shape of the particles, and toxicity evaluations are very much limited. This study aims to investigate the trace elements associated with the aerosol particles distributed near to a coal burning thermal power plant and to evaluate their toxicity through Comet assay. PM₁₀ (particles determined by mass passing an inlet with a 50% cut-off efficiency having a 10-μm aerodynamic diameter) samples were collected using respirable dust samplers. Twelve elements (Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, Se, Hg, and As) were analyzed using ICP-AES. Comet assay was done with the extracts of aerosols in phosphate buffered saline (PBS). Results show that Fe and Zn were found to be the predominant elements along with traces of other analyzed elements. Spherical shaped ultrafine particles of <1 μm aerodynamic diameter were detected through scanning electron microscope. PM₁₀ particles near to the coal burning power plant produced comets indicating their potential to induce DNA damage. DNA damage property is found to be depending upon the chemical characteristics of the components associated with the particles besides the physical properties such as size and shape.     

Chemical characterization and source identification/apportionment of fine and coarse air particles in Thessaloniki,Greece

The distribution of air particulate mass and selected particle components (trace elements and polycyclic aromatic hydrocarbons (PAHs)) in the fine and the coarse size fractions was investigated at a traffic-impacted urban site in Thessaloniki, Greece. 76±6% on average of the total ambient aerosol mass was distributed in the fine size fraction. Fine-sized trace elemental fractions ranged between 51% for Fe and 95% for Zn, while those of PAHs were between 95% and 99%. A significant seasonal effect was observed for the size distribution of aerosol mass, with a shift to larger fine fractions in winter. Similar seasonal trend was exhibited by PAHs, whereas larger fine fractions in summer were shown by trace elements. The compositional signatures of fine and coarse particle fractions were compared to that of local paved-road dust. A strong correlation was found between coarse particles and road dust suggesting strong contribution of resuspended road dust to the coarse particles. A multivariate receptor model (multiple regression on absolute principal component scores) was applied on separate fine and coarse aerosol data for source identification and apportionment. Results demonstrated that the largest contribution to fine-sized aerosol is traffic (38%) followed by road dust (28%), while road dust clearly dominated the coarse size fraction (57%).     

Aeolian flux of metals in Taiwan in the past 2600 years

To identify anthropogenic sources of pollution, it is useful to compare recent and historical data, yet unfortunately such data are lacking in Taiwan. Thus, we studied the sediments deposited in the remote anoxic, subalpine Great Ghost Lake over a time span of 2600 yrs. Not only could a baseline be established, but also natural variations could be identified. Aeolian Asian dust particles seem to have played a significant role in the flux of 26 elements (Al, As, Ba, Br, Ca, Cd, Ce, Cl, Cr, Cs, Cu, Fe, Ga, K, Mg, Mn, Na, Ni, Pb, Rb, Si, Sr, Ti, V, Zn and Zr) in Great Ghost Lake. The fluxes have generally been higher during dry periods, especially since 1350 AD. On the other hand, local pollution from lead seems to have gained importance since 1945 AD. Recent aeolian fluxes were also calculated based on sediment data, and those results agree with direct measurements obtained in the region.     

Metals in particle-size fractions of the soils of five European cities

Soils from Aveiro, Glasgow, Ljubljana, Sevilla and Torino have been investigated in view of their potential for translocation of potentially toxic elements (PTE) to the atmosphere. Soils were partitioned into five size fractions and Cr, Cu, Ni, Pb and Zn were measured in the fractions and the whole soil. All PTE concentrated in the <10 microm fraction. Cr and Ni concentrated also in the coarse fraction, indicating a lithogenic contribution. An accumulation factor (AF) was calculated for the <2 and <10 microm fraction. The AF values indicate that the accumulation in the finer fractions is higher where the overall contamination is lower. AF for Cr and Ni are particularly low in Glasgow and Torino. An inverse relationship was found between the AF of some metals and the percentage of <10 microm particles that could be of use in risk assessment or remediation practices.     

Size distribution of airborne particulate matter and associated heavy metals in the roadside environment

The size distributions of airborne particulate matter (PM) and associated heavy metals Pb, Cd, Ni, Cr, V, Mn, Cu and Fe in different inhalable fractions (< 0.8 microm, 0.8-1.3 microm, 1.3-2.7 microm, 2.7-6.7 microm and > 6.7 microm) were determined at a traffic-orientated urban site in the city of Thessaloniki, northern Greece. The airborne PM displayed a bimodal distribution with most of the mass (52%) contained in the submicron size range (< 0.8 microm) and an additional minor mode (20%) in the coarse size fraction (> 6.7 microm). Characteristic size distributions of heavy metals allowed identification of three main behavioral types: (a) metals whose mass was resided mainly within the accumulation mode (Pb,Cd), (b) those which were distributed between fine, intermediate and coarse modes (Ni,Cu,Mn), and (c) those which were mainly found within particles larger than 2.7 microm in diameter (Fe). The mean mass median aerodynamic diameter (MMAD) of PM was found at 0.85+/-0.71 microm, while the mean MMADs of heavy metals followed the order Pb (0.96 +/- 0.71 microm) < Cd (1.14 +/- 0.82 microm) < V (1.38 +/- 0.63 microm) < Ni (1.45 +/- 0.88 microm) < Cu (2.04 +/- 0.77 microm) < Mn (2.61 +/- 1.23 microm) < Cr (2.91 +/- 1.40 microm) < Fe (3.82 +/- 0.88 microm). The measured distributions are believed to result from a combination of processes including local anthropogenic and natural sources, such as traffic, industrial emissions and resuspension of road dust.     

Fine,ultrafine and nanoparticle trace element compositions near a major freeway with a high heavy-duty diesel fraction

Trace elements and metals in the ultrafine (<0.18 μm) and accumulation (0.18–2.5 μm) particulate matter (PM) modes were measured during the winter season, next to a busy Southern California freeway with significant (∼20%) diesel traffic. Both ambient and concentrated size-segregated impactor samples were taken in order to collect enough mass for chemical analysis. Data at this location were compared to a site located 1 mile downwind of the freeway, which was reflective of urban background. The most abundant trace elements in the accumulation mode detected by inductively coupled plasma mass spectroscopy (ICPMS) were S (138 ng m⁻³), Na (129 ng m⁻³), and Fe (89 ng m⁻³) while S (35 ng m⁻³) and Fe (35 ng m⁻³) were the most abundant in the ultrafine mode. The concentrations of several trace elements, including Mg, Al, and Zn, and in particular Ca, Cu, and Pb, did not uniformly increase with size within fine PM, an indication that various roadway sources exist for these elements. Calculation of crustal enrichment factors for the two sites indicates that the freeway traffic contributed to enriched levels of ultrafine Cu, Ba, P and Fe and possibly Ca. The results of this study show that trace elements constitute a small fraction of PM mass in the nanoparticle size range, but these can and should be characterized due to their likely importance to human health.     

Changes in elemental composition and mass of atmospheric aerosol pollution between 1996 and 2002 in a Central European city

Median atmospheric concentrations of Pb, Br, S, As, Se, and particulate matter (PM) decreased, and median concentrations of Sb, Cu, Zn, Fe, Ca, Cr and Ba increased in urban aerosol in downtown Budapest between 1996 and 2002. The changes in Pb and Br concentrations were unambiguously attributed to the phasing out of leaded gasoline. The increments were mainly related to and explained by non-exhaust vehicular emissions. The mechanical wear of asbestos-free brake linings of road vehicles contributed to the concentration of Cu and Sb on average by 69% and 66%, respectively in the PM10 size fraction. Tire rubber abrasion was a major source for atmospheric Zn; on average, non-crustal sources accounted for 67% of Zn in the PM10 size fraction. Contribution of the tire wear component to the PM10 mass was estimated to be 6% at most, while its contribution to organic aerosol was of the order of 15%.