Particulate PAHs Research Articles

Atmospheric concentrations, gaseous–particulate distribution, and carcinogenic potential of polycyclic aromatic hydrocarbons in Assiut, Egypt

The concentrations of 15 priority PAHs were determined in the atmospheric gaseous and particulate phases from nine sites across Assiut City, Egypt. While naphthalene, acenaphthene, and fluorene were the most abundant in the gaseous phase with average concentrations of 377, 184, and 181 ng/m(3), benzo[b]fluoranthene, chrysene, and benzo[g,h,i]perylene showed the highest levels in the particulate phase with average concentrations of 76, 6, and 52 ng/m(3). The average total atmospheric concentration of target PAHs (1,590 ng/m(3)) indicates that Assiut is one of the highest PAH-contaminated areas in the world. Statistical analysis revealed a significant difference between the levels of PAHs in the atmosphere of urban and suburban sites (P = 0.029 and 0.043 for gaseous and particulate phases, respectively). Investigation of diagnostic PAH concentration ratios revealed vehicular combustion and traffic exhaust emissions as the major sources of PAHs with a higher contribution of gasoline rather than diesel vehicles in the sampled areas. Benzo[a]pyrene has the highest contribution (average = 32, 4% for gaseous and particulate phases) to the total carcinogenic activity (TCA) of atmospheric PAHs. While particulate phase PAHs have higher contribution to the TCA, gaseous phase PAHs present at higher concentrations in the atmosphere are more capable of undergoing atmospheric reactions to form more toxic derivatives.

Levels and risks of particulate-bound PAHs in indoor air influenced by tobacco smoke: a field measurement

Considering tobacco smoke as one of the most health-relevant indoor sources, the aim of this work was to further understand its negative impacts on human health. The specific objectives of this work were to evaluate the levels of particulate-bound PAHs in smoking and non-smoking homes and to assess the risks associated with inhalation exposure to these compounds. The developed work concerned the application of the toxicity equivalency factors approach (including the estimation of the lifetime lung cancer risks, WHO) and the methodology established by USEPA (considering three different age categories) to 18 PAHs detected in inhalable (PM10) and fine (PM2.5) particles at two homes. The total concentrations of 18 PAHs (ΣPAHs) was 17.1 and 16.6 ng m(-3) in PM10 and PM2.5 at smoking home and 7.60 and 7.16 ng m(-3) in PM10 and PM2.5 at non-smoking one. Compounds with five and six rings composed the majority of the particulate PAHs content (i.e., 73 and 78 % of ΣPAHs at the smoking and non-smoking home, respectively). Target carcinogenic risks exceeded USEPA health-based guideline at smoking home for 2 different age categories. Estimated values of lifetime lung cancer risks largely exceeded (68-200 times) the health-based guideline levels at both homes thus demonstrating that long-term exposure to PAHs at the respective levels would eventually cause risk of developing cancer. The high determined values of cancer risks in the absence of smoking were probably caused by contribution of PAHs from outdoor sources.

Tracing typhoon effects on particulate transport in a submarine canyon using polycyclic aromatic hydrocarbons

The particles collected in a sediment trap in the Gaoping Submarine Canyon provided a high resolution PAH profile that traces typhoon (Kalmaegi) induced particle movement. Results provide further evidence that submarine canyons are an effective conduit for transporting terrestrial contaminants such as PAHs, particularly as typhoon-related hyperpycnal plumes at river mouths and ensuing turbidity currents in the submarine canyon. Observations here show that two typhoon-triggered turbidity currents passed the sediment trap. The beginnings of the two turbidity currents showed strong pyrogenic signatures suggesting coal and biomass burning sources. These turbidity currents carried enormous amounts of particulate PAHs (510kg in 12.5h), which accounted for 4.2% of the annual PAH flux from the Gaoping River. The PAH signature allowed the typhoon effect to be broken into five stages: (I) period before the typhoon effect (marine sources), (II) typhoon induced currents (resuspended sediments), (III) down-canyon flow (pyrogenic particles from northwestern shelf), (IV) river plume impact with two turbidity currents (arrival of terrestrial particles), and (V) end of typhoon discharge of anthropogenic PAHs to the canyon head.

Fingerprint of Carcinogenic Semi-Volatile Organic Compounds (SVOCs) during Bonfire Night

It is well known that increased incidences of lung, skin, and bladder cancers are associated with occupational exposure to PAHs. Animal studies show that certain PAHs also can affect the hematopoietic and immune systems and can produce reproductive, neurologic, and developmental effects. As a consequence, several studies have been attempted to investigate the fate of PAHs in atmospheric environment during the past decades. However, there is still a lack of information in regard to the atmospheric concentration of PAHs during the "Bon Fire Night". In this study, twenty-three polycyclic aromatic hydrocarbons and twenty-eight aliphatics were identified and quantified in the PM10 and vapour range in Birmingham (27th November 2001-19th January 2004). The measured concentrations of total particulate and vapour (P+V) PAHs were consistently higher at the BROS in both winter and summer. Arithmetic mean total (P+V) PAH concentrations were 51.04±47.62 ng m-3 and 22.30±19.18 ng m-3 at the Bristol Road Observatory Site (BROS) and Elms Road Observatory Site (EROS) respectively. In addition arithmetic mean total (P+V) B[a]P concentrations at the BROS were 0.47±0.39 ng m-3 which exceeded the EPAQS air quality standard of 0.25 ng m-3. On the other hand, the arithmetic mean total (P+V) aliphatics were 81.80±69.58 ng m-3 and 48.00±35.38 ng m-3 at the BROS and EROS in that order. The lowest average of CPI and Cmax measured at the BROS supports the idea of traffic emissions being a principle source of SVOCs in an urban atmosphere. The annual trend of PAHs was investigated by using an independent t-test and one- way independent ANOVA analysis. Generally, there is no evidence of a significant decline of heavier MW PAHs from the two data sets, with only Ac, Fl, Ph, An, 2-MePh, 1+9-MePh, Fluo and B[b+j+k]F showing a statistically significant decline (p<0.05). A further attempt for statistical analysis had been conducted by dividing the data set into three groups (i.e. 2000, 2001-2002 and 2003-2004). For lighter MW compounds a significant level of decline was observed by using one-way independent ANOVA analysis. Since the annual mean of O3 measured in Birmingham City Centre from 2001 to 2004 increased significantly (p<0.05), it may be possible to attribute the annul reduction of more volatile PAHs to the enhanced level of annual average O3. By contrast, the heavier MW PAHs measured at the BROS did not show any significant annual reduction, implying the difficulties of 5- and 6-ring PAHs to be subject to photochemical decomposition. The deviation of SVOCs profile measured at the EROS was visually confirmed during the "Bonfire Night" festival closest to the 6th November 2003. In this study, the atmospheric PAH concentrations were generally elevated on this day with concentrations of Fl, Ac, B[a]A, B[b+j+k]F, Ind and B[g,h,i]P being particularly high.

Temporal and Spatial Distribution of Particulate Carcinogens and Mutagens in Bangkok, Thailand

To investigate the level of genotoxicity over Bangkok atmosphere, PM10 samples were collected at the Klongchan Housing Authority (KHA), Nonsree High School (NHS), Watsing High School (WHS), Electricity Generating Authority of Thailand (EGAT), Chokchai 4 Police Station (CPS), Dindaeng Housing Authority (DHA) and Badindecha High School (BHS). For all monitoring stations, each sample covered a period of 24 hours taken at a normal weekday every month from January-December 2006 forming a database of 84 individual air samples (i.e. 12?7=84). Atmospheric concentrations of low molecular weight PAHs (i.e. phenanthrene, anthracene, pyrene and fluoranthene) were measured in PM10 at seven observatory sites operated by the pollution control department of Thailand (PCD). The mutagenicity of extracts of the samples was compared in Salmonella according to standard Ames test method. The dependence of the effects on sampling time and on sampling location was investigated with the aid of a calculation of mutagenic index (MI). This MI was used to estimate the increase in mutagenicity above background levels (i.e. negative control) at the seven monitoring sites in urban area of Bangkok due to anthropogenic emissions within that area. Applications of the AMES method showed that the average MI of PM10 collected at all sampling sites were 1.37±0.10 (TA98; +S9), 1.24±0.08 (TA98; -S9), 1.45±0.10 (TA100; +S9) and 1.30±0.09 (TA100; -S9) with relatively less variations. Analytical results reconfirm that the particulate PAH concentrations measured at PCD air quality monitoring stations are moderately low in comparison with previous results observed in other countries. In addition, the concept of incremental lifetime particulate matter exposure (ILPE) was employed to investigate the potential risks of exposure to particulate PAHs in Bangkok atmosphere.

Characterization of Gaseous and Particulate Polycyclic Aromatic Hydrocarbons in Ambient Air of Delhi, India

Three seasonal sampling campaigns were undertaken at an urban site of Delhi for collection of PAHs in particulate and gas phase. Sampling was done by using modified Respirable Dust (PM ≤10μm) sampler attached with polyurethane foam (PUF) plugs and compared with conventional Respirable Dust (PM ≤10 μm) sampler. Total 16 EPA PAH (gaseous + particulate) were determined by Gas Chromatograph-Mass Spectrophotometer (GC-MS). The 3-ring PAH constitutes approximately 90% of the gaseous PAHs with phenanthrene, fluoranthene, acenapthylene, and acenaphthene being the most abundant gaseous PAHs. PAHs with 4- to 6- rings accounted for 92%, 87% and 78% in samples collected during winter, summer and monsoon season respectively. Gaseous PAHs, particulate PAHs and total PAHs were higher during winter as compared to summer and monsoon seasons. The contribution of particulate PAHs were 1.4, 2.1, and 2.5 times higher in winter, summer and monsoon, respectively than of gaseous PAHs. Indeno[123-cd]pyrene, benzo[ghi]perylene, dibenzo[ah]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene and chrysene were found to be the most abundant PAH compounds in the particulate PAHs during all the seasons. The result from application of diagnostic ratio suggests that the higher particulate PAHs emissions were predominantly associated with vehicular emissions along with emissions from biomass burning during winter season.

Impact of vehicular traffic emissions on particulate-bound PAHs: Levels and associated health risks

Considering vehicular transport as one of the most health‐relevant emission sources of urban air, and with aim to further understand its negative impact on human health, the objective of this work was to study its influence on levels of particulate‐bound PAHs and to evaluate associated health risks. The 16 PAHs considered by USEPA as priority pollutants, and dibenzo[a,l]pyrene associated with fine (PM2.5) and coarse (PM2.5–10) particles were determined. The samples were collected at one urban site, as well as at a reference place for comparison. The results showed that the air of the urban site was more seriously polluted than at the reference one, with total concentrations of 17 PAHs being 2240% and 640% higher for PM2.5 and PM2.5–10, respectively; vehicular traffic was the major emission source at the urban site. PAHs were predominantly associated with PM2.5 (83% to 94% of ΣPAHs at urban and reference site, respectively) with 5 rings PAHs being the most abundant groups of compounds at both sites. The risks associated with exposure to particulate PAHs were evaluated using the TEF approach. The estimated value of lifetime lung cancer risks exceeded the health‐based guideline levels, thus demonstrating that exposure to PM2.5‐bound PAHs at levels found at urban site might cause potential health risks. Furthermore, the results showed that evaluation of benzo[a]pyrene (regarded as a marker of the genotoxic and carcinogenic PAHs) alone would probably underestimate the carcinogenic potential of the studied PAH mixtures.

Traffic-Related Air Pollution and DNA Damage: A Longitudinal Study in Taiwanese Traffic Conductors

BackgroundThere is accumulating epidemiologic evidence that exposure to traffic-related air pollutants, including particulate matter (PM) and polyaromatic hydro carbons (PAHs), plays a role in etiology and prognosis of a large scale of illnesses, although the role of specific causal agents and underlying mechanisms for different health outcomes remains unknown.ObjectiveOur general objective was to assess the relations between personal exposure to traffic exhausts, in particular ambient PM2.5 and PAHs, and the occurrence of DNA strand breaks by applying personal monitoring of PM and biomarkers of exposure (urinary 1-hydroxypyrene-glucuronide, 1-OHPG) and effect (urinary 8-hydroxydeoxyguanosine, 8-OHdG and DNA strand breaks).MethodsWe recruited 91 traffic conductors and 53 indoor office workers between May 2009 and June 2011 in Taipei City, Taiwan. We used PM2.5 personal samplers to collect breathing-zone particulate PAHs samples. Spot urine and blood samples after work shift of 2 consecutive days were analyzed for 1-OHPG, 8-OHdG and DNA strand breaks, respectively. Statistical methods included linear regression and mixed models.ResultsUrinary 8-OHdG levels and the occurrence of DNA strand breaks in traffic conductors significantly exceeded those in indoor office workers in mixed models. Particulate PAHs levels showed a positive association with urinary 1-OHPG in the regression model (β = 0.056, p = 0.01). Urinary 1-OHPG levels were significantly associated with urinary 8-OHdG levels in the mixed model (β = 0.101, p = 0.023). Our results provide evidence that exposure to fine particulates causes DNA damage. Further, particulate PAHs could be biologically active constituents of PM2.5 with reference to the induction of oxidative DNA damages.

Seasonal characteristics of the gaseous and particulate PAHs at a roadside station in Seoul, Korea

Gaseous and particulate PAHs were measured at a roadside station in Seoul, Republic of Korea and 16 PAH compounds were analyzed in order to investigate the seasonal variation of the roadside PAHs concentrations, evaluate the toxicity from the PAHs, and identify the contribution of vehicular emissions. Evident seasonal variation was observed both in the gaseous and particulate PAH concentrations though the degree of the variation was lower than the non-road urban area and background measurements. From the toxicity analysis, it was revealed that the toxic PAH compounds were mostly associated with particulates with the highest toxicity in winter. The considerable toxicity of the roadside PAHs indirectly implies that the toxicities of PAHs in tunnel could be a level of significant concern in Seoul. The distributions of individual PAH compounds in the gas and particle phases were more variable at the roadside station than the tunnel, since the roadside measurements are more susceptible to variable sources although the major source is vehicular emission. From the analysis of PAH profiles, the toxicity analysis, and the source evaluation using the diagnostic ratios, it was suggested that the PAH concentrations in spring might be particularly influenced by the transport of PAHs produced by biomass burning from China and/or North Korea.

Quantification and seasonal pattern of atmospheric reaction products of gas phase PAHs in PM2.5

Six unique OH-reaction products of naphthalene and phenanthrene were detected and quantified in ambient PM2.5 collected in Seoul, Korea between 2006 and 2007. The range of annual average concentrations of six reaction products, 2-formylcinnamaldehyde, phthalic acid, phthalide, dibenzopyranone, 9-fluorenone, and 1,2-naphthalic anhydride extended from 2.45 to 49.9 ng m−3 and all of these values were higher than the average concentration of single particulate PAH compounds in Seoul, Korea. The seasonal pattern of six reaction products generally showed higher concentrations in winter months than in summer months. This indicates that the formation of these compounds by atmospheric photochemical reactions is significant both in winter and summer and that enhanced primary sources and higher particle to gas partitioning activity due to lower ambient temperature may contribute to the high concentrations of these compounds in the winter months in Seoul, Korea. The high correlation of the formation of 2-formylcinnamladehyde and dibenzopyranone with the estimated SOC concentration, suggests that the formation of SOA from gas phase PAH reactions in the real atmospheres is significant. Also, we suggest that (E)-2-formylcinnamaldehyde and dibenzopyranone could be used as unique indicators for the atmospheric oxidative reactions of naphthalene and phenanthrene, respectively.

Particle Associated Polycyclic Aromatic Hydrocarbons (PAHS) in Urban Air of Agra

Total Suspended Particulate Matter (TSPM) samples were collected at Nunhai Agra from April to September 2006. The concentrations of 16 PAHs in aerosols were quantified. The dominated predominant PAHs in TSPM include high molecular weight (HMW) congeners BghiP, DbA, IP and BaP. Nap and Acy were not detected in any of the samples. The sum of 14 priority PAHs ranged from 150 to 480 ng m−3 with a mean value of 269 ± 121 ng m−3. The Results indicated that PAH concentrations at Nunhai were higher than in other industrial sites, but are comparable to those measured in several urban Chinese cities, however, and less than the industrial locations of China. Higher HMW PAH concentration were attributable to higher rates of emissions as well as or greater scavenging and adsorption of vapor phase PAH on available TSPM. Potential sources of PAHs in aerosols were identified using the diagnostic ratios between PAHs. Vehicular emissions were the main contributors of particulate-associated PAHs, with minor contribution from stationary combustion sources may also contribute to the particulate PAHs. PAHs in aerosols were predominantly from gasoline and diesel engines.

Chemical Speciation and Source Assignment of Particulate (PM10) Phase Molecular Markers in Mumbai

Particulate matter (PM10) has emerged as the single most important pollutant across Indian cities, as its levels exceed the regulated standards at most places. PM10 was collected and analyzed at seven sites representing different land use patterns in Mumbai during 2007–08 for organic carbon (OC) and elemental carbon (EC). OC was further speciated for organic markers, which are useful for identifying sources. Average PAH concentration ranged from 47.84 ± 14.07 to 247.70 ± 163.19 ng/m3. n-alkanes concentration varied from 157.20 ± 35.28 to 759.13 ± 451.65 ng/m3. Hopanes and steranes showed the highest concentrations of 94.14 ± 28.66 and 32.64 ± 11.79 ng/m3 and lowest concentrations of 7.81 ± 2.00 ng/m3 and 2.83 ± 0.73 ng/m3, respectively. The values for levoglucosan varied from 0.69 ± 0.46 to 3.23 ± 2.07 µg/m3. The percentage contribution of the sum of the concentrations of these compounds to the total organic carbon varied from 1.7–5.1%. The sources contributing to particulate PAHs were identified using diagnostic ratios. Indicators like the Carbon Preference Index (CPI), Cmax and Plant Wax Number (%WNA) were used to identify the relative contributions to n-alkanes from anthropogenic and biogenic emissions. The source apportionment results and also the concentration trends for these molecular markers indicate that anthropogenic sources, especially vehicular exhaust, wood combustion and coal combustion, are mainly responsible for the organic fraction of particulate matter in Mumbai city. The sources identified qualitatively in this work can help in selecting the appropriate source profiles for estimating the quantitative contribution of these sources.

A multidisciplinary approach to characterise exposure risk and toxicological effects of PM10 and PM2.5 samples in urban environments

Urban aerosol samples collected in Barcelona between 2008 and 2009 were toxicologically characterised by means of two complementary methodologies allowing evaluation of their Reactive Oxidative Stress (ROS)-generating capacity: the plasmid scission assay (PSA) and the dichlorodihydrofluorescin assay (DCFH). The PSA determined the PM dose able to damage 50% of a plasmid DNA molecule (TD50 values), an indication of the ability of the sample to exert potential oxidative stress, most likely by formation of ·OH. This toxicity indicator did not show dependency on different air mass origins (African dust, Atlantic advection), indicating that local pollutant sources within or near the city are most likely to be mainly responsible for PM health effect variations. The average TD50 values show PM2.5–0.1 samples to be more toxic than the PM10–2.5 fraction, with doses similar to those reported in previous studies in polluted urban areas. In addition, the samples were also evaluated using the oxidant-sensitive probe DCFH confirming the positive association between the amount of DNA damage and the generation of reactive oxidant species capable of inducing DNA strand break. Results provided by the PSA were compared with those from two other different methodologies to evaluate human health risk: (1) the toxicity of particulate PAHs expressed as the calculated toxicity equivalent of benzo[a]pyrene (BaPteq) after application of the EPA toxicity factors, and (2) the cancer risk assessment of the different PM sources detected in Barcelona with the receptor model Positive Matrix Factorisation (PMF) and the computer programme Multilinear Engine 2 (ME-2) using the organic and inorganic chemical compositions of particles. No positive associations were found between PSA and the toxicity of PAHs, probably due to the inefficiency of water in extracting organic compounds. On the other hand, the sum of cancer risk estimates calculated for each of the selected days for the PSA was found to correlate with TD50 values in the fine fraction, with fuel oil combustion and industrial emissions therefore being most implicated in negative health effects. Further studies are necessary to determine whether toxicity is related to PM chemical composition and sources, or rather to its size distribution.

Characterization of polycyclic aromatic hydrocarbon emissions in the particulate phase from burning incenses with various atomic hydrogen/carbon ratios

Polycyclic aromatic hydrocarbons in the particulate phase generated from burning various incense was investigated by a gas chromatography/mass spectrometry. Among the used incenses, the atomic H/C ratio ranged from 0.51 to 1.69, yielding the emission factor ranges for total particulate mass and PAHs of 4.19–82.16mg/g and 1.20–9.50μg/g, respectively. The atomic H/C ratio of the incense was the key factor affecting particulate mass and the PAHs emission factors. Both the maximum emission factor and the slowest burning rate appear at the H/C ratio of 1.57. The concentrations of the four-ring PAHs predominated and the major species among the 16 PAHs were fluoranthene, phenanthrene, pyrene, and chrysene for most incense types. The benzo[a]pyrene, benzo[a]anthracene, benzo[b]fluoranthene, and dibenzo[a,h]anthracene accounted for 87.08–93.47% of the total toxic equivalency emission factor.

Seasonal Variation and Health Risk Assessment of Polycyclic Aromatic Hydrocarbons in Miaoli City, Taiwan

The ambient PAHs levels in the downtown area of a traditional small city were analyzed for winter and summer seasons. A total of 16 PAHs in gaseous and particulate phase were quantified. The average gaseous PAHs were 2,189 ± 1,194 and 623.8 ± 545.1 ng/m(3) in winter and summer seasons, respectively. For the PAHs in particulate phase, they were 40.32 ± 12.15 and 11.99 ± 5.63 ng/m(3) in winter and summer seasons, respectively. These values were comparable to those reported for large cities or even higher. The estimated BaPeq was 12.32 ± 6.34 ng/m(3). As low-molecular-weight PAHs primarily existed in gaseous phase, high-molecular-weight PAHs in particulate phase became a significant fraction of total particulate phase PAHs. Particulate phase PAHs was significantly inversely associated with the ambient temperature for each individual PAHs species. However, this relationship did not exist for high-molecular-weight PAHs in gaseous phase. The results indicated the photo-degradation of high-molecular-weight PAHs should warrant a further thoughtfully investigation.

Physicochemical characterization of fine particles from small-scale wood combustion

Abstract Emissions from small-scale wood combustion appliances are of special interest since fine particles have been consistently associated with adverse health effects. It has been reported that the physicochemical characteristics of the emitted particles affect also their toxic properties but the mechanisms behind these phenomena and the causative role of particles from wood combustion sources are still mostly unknown. Combustion situations vary significantly in small-scale appliances, especially in batch combustion. Combustion behaviour is affected by fuel properties, appliance type and operational practice. Particle samples were collected from six appliances representing different combustion situations in small-scale combustion. These appliances were five wood log fuelled stoves, including one stove equipped with modern combustion technology, three different conventional combustion appliances and one sauna stove. In addition, a modern small-scale pellet boiler represented advanced continuous combustion technology. The aim of the study was to analyze gas composition and fine particle properties over different combustion situations. Fine particle (PM 1 ) emissions and their chemical constituents emerging from different combustion situations were compared and this physicochemical data was combined with the toxicological data on cellular responses induced by the same particles (see Tapanainen et al., 2011 ). There were significant differences in the particle emissions from different combustion situations. Overall, the efficient combustion in the pellet boiler produced the smallest emissions whereas inefficient batch combustion in a sauna stove created the largest emissions. Improved batch combustion with air-staging produced about 2.5-fold PM 1 emissions compared to the modern pellet boiler (50.7 mg MJ −1 and 19.7 mg MJ −1 , respectively), but the difference in the total particulate PAH content was 750-fold (90 μg MJ −1 and 0.12 μg MJ −1 , respectively). Improved batch combustion and conventional batch combustion showed almost the same PM 1 emissions (51.6 mg MJ −1 ), but a 10-fold difference in total particulate PAH emissions (910 μg MJ −1 ). These results highlight that same PM 1 emissions can be associated with very different chemical compositions, potentially leading to different toxic properties of the particles. Thus, changing from an old, less efficient, combustion appliance to a modern appliance can have a greater impact on toxic properties than the emitted PM 1 mass might indicate.

Particle-bound polycyclic aromatic hydrocarbons in an urban, industrial and rural area in the western Mediterranean

Particle-bound PAHs were measured at three sites in southeastern Spain (an urban background location, a suburban-industrial site in the vicinity of two cement plants and a rural area) in order to investigate the influence of the type of location on PAH concentrations. A clear influence of cement production on particulate PAH levels could not be established since for the urban background and suburban-industrial sites the average concentrations of total PAHs in the PM2.5 fraction were very similar (1.085 and 1.151 ng m(-3), respectively), with benzo[b+k]fluoranthene and chrysene as the predominant compounds. Diagnostic ratios, used to identify PAH emission sources, pointed to traffic as the main source of particulate PAH at both locations. As expected, PAH levels at the rural site were significantly lower (0.408 ng m(-3) in the PM10 fraction) due to increasing distance from the emission sources. PAH seasonal variations at the urban background and suburban-industrial sites were the same as reported in many previous studies. Average winter to summer ratios for total PAHs were 4.4 and 4.9 for the urban background and industrial sites, in that order. This seasonal cycle could be partially explained by the higher temperature and solar radiation during summer enhancing PAH evaporation from the particulate phase and PAH photochemical degradation, respectively. The study of PAH distribution between the fine and coarse fraction at the urban site revealed that on average around 80% of total PAHs were associated with fine particles.

Distribution and Numerical Prediction of Polycyclic Aromatic Hydrocarbons (PAHs) on Atmospheric Particles in Jinan, China

16 EPA-priority PAHs on ambient airborne particles with different diameters were measured at 7 urban sites in Jinan during heating and non-heating periods to characterize their distribution and pollution levels. The concentrations of 16 particulate PAHs were between 7.56 and 800 ng•m−3 with an average of 308 ng•m−3. PAHs on atmospheric particles were dominated by 4- to 6-ring components and exhibited pronounced spatial distribution, temporal variation and size distribution. The emission strength and meteorological conditions were the most important factors affecting these trends. Furthermore, a numerical prediction model was proposed to forecast and prevent PAHs air pollution in Jinan. The coincidence between predicted and measured concentrations of PAHs demonstrated the good capability of this prediction model system.

A new analytical methodology for a fast evaluation of semi-volatile polycyclic aromatic hydrocarbons in the vapor phase downstream of a diesel engine particulate filter

A new sampling method was developed to collect vapor-phase polycyclic aromatic compounds (PAHs) downstream of a diesel engine equipped with a diesel particulate filter (DPF). This configuration allowed us to collect separately the particulate phase, which was trapped inside the DPF, and the vapor phase, which was sampled downstream of the DPF. PAHs, which were not predominantly absorbed into the poor organic fraction of the diesel soot, but were rather physically sorbed on high energetic adsorption sites, should be extracted using very drastic extraction conditions Microwave-assisted extraction using solvent mixtures composed of pyridine and diethylamine were used to desorb particulate PAHs, and the total PAH amounts corresponded to a very low value, i.e., 8μgg−1 or 0.24μgkm−1, with a predominance of low weight PAHs. For collection of the vapor phase, gas bubbling in an aqueous medium was preferred to conventional methods, e.g., trapping on solid sorbents, for several reasons: aqueous trapping allowed us to use a solid phase enrichment process (SPE) that permitted PAH sampling at the sub-picogram levels. Consequently, low volume sampling was possible even if the sampling duration was very short (20min). Additionally, the amount of time saved for the analysis was considerable when coupling SPE to the analytical system (liquid chromatography with fluorimetric detection). Solvent consumption for the overall sampling and analytical processes was also drastically reduced. Experiments on a diesel engine showed that vapor phase samples collected downstream of the DPF contained all of the 15 target priority PAHs, even the heaviest ones. The total vapor-phase PAH amount was 6.88μgNm−3 or 10.02μgkm−1, which showed that the gaseous fraction contains more PAHs than the particulate fraction. Partitioning coefficients (Kp) were estimated showing the predominance in the vapor phase of all the PAHs. However, the DPF technology effects a considerable decrease in the total PAH emission when compared to non-equipped diesel vehicles.

Resuspension of particulate matter and PAHs from street dust

Winter street sanding activities in northern countries are often associated with elevated pollution by particulate matter. There are indications that street dust may act as a source of particle-bound PAHs. However, very few studies have addressed the resuspension potential of PAHs from street dust. The purpose of this study was to quantitatively assess emissions of particulate matter and PAHs from street dust by laboratory-scale simulation of particle resuspension. Increases in air velocity caused proportional increases in air-borne PM2.5, PM10 and PMtotal concentrations, while the concentrations of PAHs associated with resuspended particles did not show clear statistically significant dependence on air velocity. A substantial difference in particle and PAH resuspension was observed between dust from the city center street and dust from the connecting street. The data obtained in the present study indicate that street dust may be a significant source not only of PMs but also of particle-bound PAHs in ambient air.