Polycyclic Aromatic Hydrocarbons In Aerosols Research Articles

Polycyclic Aromatic Hydrocarbons in the Atmosphere of the Southern Baikal Region (Russia): Sources and Relationship with Meteorological Conditions

This article presents the results of the long-term studies at two stations located in the city of Irkutsk and the Listvyanka settlement of the southern Baikal region (East Siberia) concerning the concentration of polycyclic aromatic hydrocarbons (PAHs) in atmospheric aerosol. The studies revealed the seasonal and interannual dynamics in the distribution of PAHs in aerosols from urban (source) and rural (receptor) areas. We carried out a comprehensive analysis of weather conditions such as wind direction, relative humidity, air temperature, and atmospheric pressure. The analysis determined high correlations between air temperature, atmospheric pressure, temperature inversions, and PAHs at the monitoring stations. The average annual concentrations of PAHs in the abnormally warm 2020 were three times lower than the average values obtained in the cold 2016. The toxic equivalent concentrations (BaPeq) increased from summer to winter with an increase in the contribution from benzo(a)pyrene, one of the most toxic and hazardous compounds of this class of organic substances. Four-, five- and six-ring PAHs mainly predominated in aerosol; the proportion of two- and three-ring PAHs increased from the warm season to the cold season. Diagnostic ratios of PAHs identified the main sources of air pollution by this class of compounds: combustion of coal, liquid fuel and firewood, vehicle emissions, and wildfires. The percentage of the transport of anthropogenic aerosol containing PAHs from industrial sources of the Southern Baikal region towards Lake Baikal was 65 to 71%.

Application of alternating trilinear decomposition-assisted multivariate curve resolution to gas chromatography-mass spectrometric data for the quantification of polycyclic aromatic hydrocarbons in aerosols.

For the first time, alternating trilinear decomposition-assisted multivariate curve resolution (ATLD-MCR) was applied to analyse complex gas chromatography–mass spectrometric (GC-MS) data with severe baseline drifts, serious co-elution peaks and slight retention time shifts for the simultaneous identification and quantification of polycyclic aromatic hydrocarbons (PAHs) in aerosols. It was also compared with the classic multivariate curve resolution-alternating least-squares (MCR-ALS) and the GC-MS-based external standard method. In validation samples, average recoveries of five PAHs were within the range from (96.2 ± 6.8)% to (106.5 ± 4.1)% for ATLD-MCR, near to the results of MCR-ALS ((98.0 ± 1.5)% to (106.7 ± 4.3)%). In aerosol samples, the concentrations of pyrene provided by ATLD-MCR were not significantly different from those of MCR-ALS. The other four PAHs including chrysene, benzo[a]anthracene, fluoranthene and benzo[b]fluoranthene were not detected by ATLD-MCR and the GC-MS-based external standard method. The results of figures of merit further demonstrated that ATLD-MCR achieved high sensitivities (8.9 × 104 to 1.7 × 106 mAU ml µg−1) and low limits of detection (0.003 to 0.087 µg ml−1), which were better than or similar to MCR-ALS, presenting a great choice to deal with complex GC-MS data for the simultaneous determination of targeted PAHs in aerosols.

Extremely high abundance of polycyclic aromatic hydrocarbons in aerosols from a typical coal-combustion rural site in China: Size distribution, source identification and cancer risk assessment

Air quality in China is tending to improve, especially in urban areas. Nevertheless, rural areas and underdeveloped cities in northern China are still suffering from severe air pollution in winter due to large usage of coal and unfavorable meteorological conditions. In this study, size-segregated aerosol samples were collected from a typical coal-combustion rural site in Linfen, China during an extreme air pollution episode in winter 2017. The polycyclic aromatic hydrocarbons (PAHs), n-alkanes, hopanes and steranes were identified to better understand the emission sources of the organic compounds and the health effects of the PAHs in the ambient air here. The PAHs showed a bimodal mode with the major peak in the Aitken mode (<0.4 μm) and the minor one in the size range of 0.7–2.1 μm. Daily PAHs level ranged from 0.5–1.6 μg m−3 (average: 1.1 ± 0.3 μg m−3) which was 1–2 orders of magnitude higher than other major cities in China. The plots of log (PAH/PM)-log(Dp) showed the slope near −1 for four-, five- and six-ring PAHs, indicating both the adsorption and absorption mechanisms controlled the size distribution. The deposition efficiency displayed a bimodal mode in alveolar region (AR), and the major peak was within the Aitken mode. The total deposition flux (DF) in AR region was 92.7 ng h−1, and the DF based lifetime cancer risk (LCR) was about 2.7 × 10−4 for adults and 2.0 × 10−4 for children which were 2 orders of magnitude higher than the acceptable level of 10−6 proposed by United States Environmental Protection Agency (US EPA). In summary, the residential coal combustion was the most important source of PAHs, especially they emitted a large amount of PAHs in Aitken mode which led to the terrible air quality and high level of health risk. Therefore, the environmental protection measures should be tightened in such rural areas of north China.

Atmosphere–ocean exchange of heavy metals and polycyclic aromatic hydrocarbons in the Russian Arctic Ocean

Abstract. Heavy metals and polycyclic aromatic hydrocarbons (PAHs) can greatly influence biotic activities and organic sources in the ocean. However, fluxes of these compounds as well as their fate, transport, and net input to the Arctic Ocean have not been thoroughly assessed. During April–November of the 2016 “Russian High-Latitude Expedition”, 51 air (gases, aerosols, and wet deposition) and water samples were collected from the Russian Arctic within the Barents Sea, the Kara Sea, the Laptev Sea, and the East Siberian Sea. Here, we report on the Russian Arctic assessment of the occurrence of 35 PAHs and 9 metals (Pb, Cd, Cu, Co, Zn, Fe, Mn, Ni, and Hg) in dry and wet deposition as well as the atmosphere–ocean fluxes of 35 PAHs and Hg0. We observed that Hg was mainly in the gas phase and that Pb was most abundant in the gas phase compared with the aerosol and dissolved water phases. Mn, Fe, Pb, and Zn showed higher levels than the other metals in the three phases. The concentrations of PAHs in aerosols and the dissolved water phase were approximately 1 order of magnitude higher than those in the gas phase. The abundances of higher molecular weight PAHs were highest in the aerosols. Higher levels of both heavy metals and PAHs were observed in the Barents Sea, the Kara Sea, and the East Siberian Sea, which were close to areas with urban and industrial sites. Diagnostic ratios of phenanthrene/anthracene to fluoranthene/pyrene showed a pyrogenic source for the aerosols and gases, whereas the patterns for the dissolved water phase were indicative of both petrogenic and pyrogenic sources; pyrogenic sources were most prevalent in the Kara Sea and the Laptev Sea. These differences between air and seawater reflect the different sources of PAHs through atmospheric transport, which included anthropogenic sources for gases and aerosols and mixtures of anthropogenic and biogenic sources along the continent in the Russian Arctic. The average dry deposition of ∑9 metals and ∑35 PAHs was 1749 and 1108 ng m−2 d−1, respectively. The average wet deposition of ∑9 metals and ∑35 PAHs was 33.29 and 221.31 µg m−2 d−1, respectively. For the atmosphere–sea exchange, the monthly atmospheric input of ∑35 PAHs was estimated at 1040 t. The monthly atmospheric Hg input was approximately 530 t. These additional inputs of hazardous compounds may be disturbing the biochemical cycles in the Arctic Ocean.

The Role of Sources and Atmospheric Conditions in the Seasonal Variability of Particulate Phase PAHs at the Urban Site in Central Poland

The 24-h records of polycyclic aromatic hydrocarbons (PAHs) concentrations in the particulate phase were obtained for the urban site (52.42°N, 16.88°E) in Poznan, one of the largest cities in central Poland, between January and December 2014. The main goal of this study was to identify major emission sources of PAHs congeners and factors controlling their seasonal variability. The most abundant in the particulate matter PAH compound was pyrene (mean concentration of 2.29 ± 4.68 ng m–3, maximum of 22.51 ng m–3), followed by benzo(a)pyrene, dibenz(ah)anthracene, benzo(k)fluoranthene, benzo(b)fluoranthene, phenanthrene, benzo(ghi)perylene, chrysene, benz(a)anthracene and fluoranthene. The results showed a sharp decrease in PAHs concentrations during summer measurements (photodecomposition, high precipitation frequency), and high levels of the quantified PAHs during cold study period (increase anthropogenic emission, low air temperature). During the cold season in 2014, predominant PAHs congeners were: pyrene (26.0%) and 5-ring PAH compounds such as benzo(a)pyrene (19.4%) > dibenz(ah)anthracene (13.7%) ≥ benzo(k)fluoranthene (13.3%) > benzo(b)fluoranthene (9.8%), mostly associated with mixed sources (i.e., combustion, wood burning, industrial emission, traffic emission), whereas during warm study period we observed a large contribution (> 20%) of pyrene, dibenz(ah)anthracene and benzo(a)pyrene in particulate matter. The summertime measurements showed that local emission from the traffic (i.e., diesel and gasoline exhausts) was the second important source of PAHs in aerosol. The coal combustion for residential heating and industrial usage were most pronounced PAHs sources during the entire study period. The multivariate statistical technique (Principal Component Analysis) combined with some diagnostic ratios were applied to provide detailed characteristics of sources and processes related to the polycyclic aromatic hydrocarbons in different seasons. The results from this study are in good agreement with most of the studies focused on seasonal variability of PAHs in the atmosphere.

Determination of Polycyclic Aromatic Hydrocarbons in F-15J, C-130H, and F-4EJ Aircraft Exhaust

There are occupational health concerns at Japan Air Self-Defense Force bases in regard to the exposure of military flightline personnel to carcinogens in aircraft emissions, such as polycyclic aromatic hydrocarbons (PAHs). To characterize the PAHs in military aircraft emissions from different types of engines, aerosol and gas samples were separately collected downwind from aircraft with a turboprop engine (C-130H), turbojet (F-4EJ), and turbofan (F-15J). The gas-phase PAHs were determined by gas chromatography coupled to mass spectrometry and the aerosol-phase PAHs were determined by high-performance liquid chromatography with fluorescence detection. The F-4EJ engine was a source of naphthalene vapor and aerosol PAHs, including carcinogens such as chrysene, benzo (b) fluoranthene, benzo (k) fluoranthene, benzo (a) pyrene, dibenzo (a,h) anthracene, benzo (ghi) perylene, and indeno (1,2,3-cd) pyrene. These heavier (five and six-ring) PAHs were also included in the emissions from the F-15J with its newer, high-temperature F-100 turbofan engine, but the concentrations were approximately one-tenth of those in the F-4EJ. In contrast to these fighter aircraft, the C-130H was found to be a significant aerosol source of the lighter, three-ring (phenanthrene and anthracene) and four-ring (fluoranthene and pyrene) PAHs, but not the heavier ones. These results demonstrate that various aircraft are sources of PAHs in the military flightline environment.

Inorganic and Organic Aerosols Downwind of California's Roseville Railyard

Inorganic and organic constituents of aerosols from a major railyard and repair facility were characterized to develop a profile of emissions from railyard activities. The railyard has very consistent downslope winds blowing laterally across the railyard for about 8 hours each night, so two sampling stations were used, one just upwind of the railyard and one downwind adjacent to the railyard fence line. Aerosol samples were collected by rotating drum impactors (DRUM and Lundgren) in up to 9 size modes for 5 weeks in summer and fall of 2005 in tandem with the Roseville Railyard Aerosol Monitoring Project (RRAMP), which measured, black carbon (BC) PM2, as well as NO and NO2. The DRUM aerosol samples were analyzed for mass, optical absorption, and elemental content in 3 h time resolution to allow separation of day and night. Organic analysis was conducted on another set of time integrated size-segregated samples taken by a Lundgren impactor during nighttime hours. The ratio between the downwind versus upwind sites at night was as high as 21.9 (NO, RRAMP) and 6.4 (optical absorption, DRUM) but many species had ratios greater than 2, demonstrating which aerosols arose from railyard activities. The main emissions from the railyard consisted of very fine (0.26 > D p > 0.09 μm) and ultrafine (<0.1 μm) aerosols associated with diesel exhaust such as mass, organic matter, transition metals, and sulfur, the latter 3.3% of the mass since locomotive diesel fuel still contained sulfur. There were also coarse soil aerosols contaminated with anthropogenic metals and petroleum-derived n-alkanes. The aerosol PAH (polycyclic aromatic hydrocarbons) profile showed higher proportions of the heavier PAHs, such as benzo[a]pyrene, compared to diesel truck exhaust on a per unit mass. These aerosols were mostly in the ultrafine (<0.1 μm) size mode, enhancing lung capture. These results and those of Roseville Railyard Aerosol Monitoring Project (RRAMP) largely confirm earlier California Air Resources Board's (ARB) model estimates of health impacts downwind of the railyard based on diesel exhaust, while adding data on very fine transition metals and contaminated soils, potentially important to human health.

Chemical Characterization and Source Identification of Polycyclic Aromatic Hydrocarbons in Aerosols Originating from Different Sources

To obtain the characteristic factors or signatures of particulate polycyclic aromatic hydrocarbons (PAHs) to help identify the sources of particulate PAHs in the atmosphere, different carbonaceous aerosols were generated by burning different fossil fuels and biomass under different conditions in the laboratory, and the chemical characteristics of 14 PAHs were studied in detail. The results showed that (1) carbonaceous aerosols derived from domestic burning of coal, diesel fuel, and gasoline have much higher concentrations of PAHs than those derived from domestic burning of biomass; (2) carbonaceous aerosols derived from domestic burning of diesel fuel/gasoline have similar PAH components as those derived from high-temperature combustion of diesel fuel/gasoline, although the former have much higher concentrations of PAHs than the latter, suggesting that the burning temperature obviously affects the emitting amount of particulate PAHs, but only slightly influences the PAHs components; and (3) the ratios of benzo[b]fluoranthene/acenaphthylene, benzo-[b]fluoranthene/fluorene, dibenzo[a,h]anthracene/acenaphthylene, dibenzo[a,h]anthracene/fluorine, and benzo[b]fluoranthene/benzo[k]fluoranthene in carbonaceous aerosols are sensitively dependent on their sources, indicating that these ratios are suitable for use as characteristic factors or signatures of particulate PAHs in the atmosphere.

Chemical and stable carbon isotopic characterization for PAHs in aerosol emitted from two indoor sources

Polycyclic aromatic hydrocarbons (PAHs) are with great environmental concerns due to their toxic, mutagenic, and carcinogenic properties. The harmful effects caused by PAHs emitted from indoor sources may be more direct and serious. In this study, PAHs in aerosol from two typical indoor sources, the cooking fume (CF) and environmental tobacco smoke (ETS) were collected by simulation emission in a chamber. Eighteen PAHs were analyzed by GC/MS and GC/C/IRMS. The chemical profiles of these two sources were described. Results indicated that Fluoranthene, Pyrene and Fluorene in CF, and Fluorene, Phenanthrene, Indeno(1,2,3-cd)pyrene and Benz(a)anthracene in ETS, relative quantity of which were variable in a smaller range, can be regarded as tracers of indoor PAHs sources. There are distinct differences among the ratios of Benz(a)anthracene/Chrysene, Benzo(e)pyrene/Benzo(a)pyrene and Indeno(1,2,3-cd)pyrene/Benzo(g,h,i)perylene between CF and EST. Distribution of δ 13C of individual PAHs in ETS samples ranged from −21.76‰ to −29.32‰, wider than that in CF samples (−22.94‰ to −28.39‰). The δ 13C of Phenanthrene, Benz(a)anthracene, Benzo(b)fluoranthene, Benzo(k)fluoranthene and Indeno(1,2,3-cd)pyrene between these two sources showed great differences. The 13C was enriched in low molecule weight compounds of CF samples and in high molecule weight compounds of ETS samples.

Modeling and prediction of photolysis half-lives of polycyclic aromatic hydrocarbons in aerosols by quantum chemical descriptors

Quantitative structure-property relationship (QSPR) modeling is a powerful approach for predicting environmental fate parameters of organic pollutants with their structure descriptors. This study reports QSPR models for photolysis half-lives of polycyclic aromatic hydrocarbons (PAHs) in aerosols. Quantum chemical descriptors computed with density functional theory at B3LYP/6-31G(d) level and partial least squares (PLS) analysis with optimizing procedure were used for generating QSPR models. The correlation coefficient of the optimal model was 0.993, and the fitting results showed this optimal model had high fitting precision and good predictability. The predicted photolysis half-lives by the optimal model are very close to those observed. The PLS assistant analysis indicated that PAHs with large electronic spatial extent tend to be photolyzed faster, while PAHs with high molecular total energy and small Mulliken atomic charges on the most negative carbon atom tend to be photolyzed slower in aerosols.

Gas–particle concentration and characterization of sources of PAHs in the atmosphere of a suburban area in Athens, Greece

Atmospheric polycyclic aromatic hydrocarbons (PAH) were determined in two places in a suburban area of Athens greater area (AGA) during June and November 2003. Fourteen PAHs were quantified in the collected samples. The total concentration in the gas phase ranged between 6.89 and 124 ng m −3, while in the particulate phase between 0.44 and 13.2 ng m −3. Maximum concentrations of the total PAHs (gas and particulate phase) were observed during the cold period with an average of 40.7 ng m −3. PAHs were correlated with NO, NO 2 and O 3, wind speed, wind direction and temperature. Positive correlation was observed between PAHs and NO, NO 2, while negative correlation was detected between PAHs and O 3. The most abundant members were phenanthrene, anthracene, fluorene, fluoranthene and pyrene. Potential sources of PAHs in aerosols were investigated using molecular diagnostic ratios, which reflect sources such as diesel and gasoline engines, although other sources such as coal combustion and liquefied petroleum gas also contributed.

Characteristics and sources of polycyclic aromatic hydrocarbons and fatty acids in PM 2.5 aerosols in dust season in China

The concentrations and distributions of 10 polycyclic aromatic hydrocarbons (PAHs) and seven fatty acids (FAs) in PM 2.5 collected in dust season in six sites located in the source regions and on the pathway of the two dust storm episodes over China in 2004 were observed. The average concentrations of the total PAHs in Beijing were ∼10 times higher than those measured in 1980s, indicating that the PAH pollution has been much aggravated due to the rapid development and the motorization in the past 20 years. In non-dust storm days, the highest PAH was found at Yulin (YL) in the dust source region, as there are three large coal mines located around YL. The characteristic ratios of the individual PAH at the six sites indicated that coal combustion and traffic emission were the major contributors to PAHs in urban areas. The high abundances of oleic acid and linoleic acid in the aerosols suggested that cooking emission was the main source of FAs in urban areas. In dust storm episodes, the total concentrations of PAHs and FAs decreased sharply after the dust storm, while the ratios of PAH/PM 2.5 and FAs/PM 2.5 increased, demonstrating that the organic pollutants were cleared out through deposition or transport of the dust particles after dust episodes passed. The ratio of PAH(4)/PAH(5,6) was developed to be a tracer to deduce the sources of PAHs in the aerosols based on the different environmental behavior of PAH(4) and PAH(5,6) during the long-range transport. The higher ratios of PAH(4)/PAH(5,6) in BNU-DE2 suggested that the PAHs in the dust aerosols in the urban area in the dust storm episode were from the long-range transport, whereas the lower ratios in YL-DE2 and DL-DE2, which were similar to the ratios in non-dust days, implied that the local emission contributed greatly to the organic pollutants in the aerosols in the dust source regions. The ratio of FAs, C 18:1/C 18:0, could also be used to trace the sources of the organic pollutants in the dust storm episode.

Separation of PAHs in aerosol by thin layer chromatography for compound-specific stable carbon isotope analysis

A method using a thin layer chromatography (TLC) for compound-specific stable carbon isotope analysis of polycyclic aromatic hydrocarbons (PAHs) with four to seven rings was developed in this study. Five aerosol samples were used as test samples. Two stationary phases and eight developing systems were tested. The results indicated: (1) silica gel is superior to aluminum oxide and the silica gel precoated plate developed with hexane:chloroform (45:5, v/v) can give the best separation effect; (2) individual PAHs associated with aerosols can be effectively separated from unresolved complex mixture (UCM) by this procedure. The carbon isotope composition of PAHs can be measured with a standard deviation (S.D.) < 0.5‰, n = 4. No significant isotopic fractionation was observed during the TLC procedure. And this technique can be used as a potential tool for source identification of PAHs in the aerosols.

Material transport between the atmosphere and sediment of the Lake Balaton

A monitoring system was developed to gain information on the present level of pollutants in the Lake Balaton, Hungary. Determination of 13 polycyclic aromatic hydrocarbons (PAHs) and inorganic pollutants (mostly toxic metals) in aerosol, precipitation and sediment samples was carried out. The aim of collecting aerosol and precipitate samples in the same site at the same period was to determine the distribution of elements in two depositions. For the fractionation by particle size, aerosols were sampled by a cascade impactor. A simple three-stage sequential leaching procedure was applied to establish the distribution of metals among environmentally mobile, bound to carbonates and oxides, and environmentally immobile, (bound to silicates) fractions in aerosols. Sediment samples were collected from 17 different sites inside of the lake and 10 sites at harbors at 30–70 cm in depth. Core samples were cut to 10-cm pieces, dried at room temperature, and finally passed through a 63-μm sieve. Total concentrations of elements were determined by atomic absorption spectrometry (AAS) after an acidic digestion. The concentrations of PAHs were determined by HPLC method with fluorescence detection. In aerosol samples collected from September 6, 2002 to January 26, 2003, concentration of Cd was <0.1 μg/m 3, and the majority of Cd has been found in the mobile fraction. Cadmium was associated to particles between 0.25 and 2 μm indicating the anthropogenic origin. Similar distribution of Pb was obtained in all seasons, and the highest concentration of Pb was found as 8.6 ng/m 3 in particle size of 0.7 and 1.4 μm. Results of total concentration of elements of bottom sediments of the Lake Balaton and harbors were compared to Interim Sediment Quality Guideline (ISQG) values and the Probable Effect Level (PEL) values. Data showed that the average concentrations of elements were usually less than those of ISQGs and other background data for soils and geochemical values. The sediment is not polluted and its disposal is feasible. There is no direct correlation between the concentration of elements deposited onto the surface of the lake from dry and wet deposition and the upper part of the sediment. So, from the budget of the deposition, the concentration of elements in the upper layer of the sediment cannot be predicted. Seasonal changes of the concentration of PAHs in aerosol was observed, samples collected at winter contained the highest values. In December–January 2002/2003, the wet deposition was found as 64 μg/m 2 period. Among the individual compounds, the wet deposition rate of phenantrane, fluoranthene and pyrene was dominant, while for dry deposition, these compounds were fluoranthene and pyrene. The concentrations of ∑PAHs found for all sites and depth of sediment samples ranged from 11 to 1734 μg/kg dry weight with an average of 132 μg/kg. These values represent a quite low pollution level compared to other sediment with anthropogenic influence. Based on the results, it can be definitely confirmed that the chemical quality of the water and sediment of the Lake Balaton is satisfactory.

Particle-associated polycyclic aromatic hydrocarbons in urban air of Hong Kong

Abstract PM2.5 and PM10 samples were collected at two sampling sites in Hong Kong in wintertime from November 2000 to March 2001 and in summertime from June to August 2001. The concentrations of 16 selected polycyclic aromatic hydrocarbons (PAHs) in aerosols were quantified. Spatial and seasonal variations of PAHs were characterized. The dominated PAHs in PM2.5 and PM10 included benzo[b]fluoranthene, pyrene, fluoranthene, indeno[1,2,3-cd]pyrene and chrysene, accounting for 50–82% of total PAHs. The sum of 16 PAHs in PM2.5 at roadside ranged from 3 to 330 ng/m3, and in PM10 between 5 and 297 ng/m3, whereas at a residential/industrial/commercial site, the total PAHs in PM2.5 was from 0.5 to 122 ng/m3, and 2–269 ng/m3 in PM10. Results indicated that most of the PAHs were in the PM2.5 fraction. Spatial variations were predominantly due to the difference of source strength. For both PM2.5 and PM10, the total PAHs at PU site was higher than that at KT site. The average concentrations of individual PAHs in aerosols at PU site were also higher than that at KT site. Higher winter PAHs concentrations and lower summer concentrations were observed at the two sites. Higher winter PAHs concentrations were mainly caused by local emission sources superimposed by highly polluted air masses from Mainland China. The lower summer PAHs concentrations were likely due to easier dispersion of air pollutants, washout effects and to a lesser extent, photo-degradation and higher percentage in the air in vapor phase. Potential sources of PAHs in aerosols were identified using the diagnostic ratios between PAHs and PCA analysis. At PU site, vehicular emissions were the main contributors of particle-associated PAHs, and stationary combustion sources may also contribute to the particulate PAHs. On the contrary, at the KT site, PAHs in aerosols were predominantly from gasoline and diesel engines.

MONITORING OF PERSISTENT ORGANIC POLLUTANTS (POPs) IN AEROSOLS USING HPLC

ABSTRACT Isocratic reversed phase high performance liquid chromatography (HPLC) with ultra violet (UV) detection was optimized for separation and quantification of polycyclic aromatic hydrocarbons (PAHs). Acetonitrile-water mixture (70 : 30 v/v) was used as mobile phase at a flow rate of 1.5 mL per minute. The volume of the sample loop was 0.1 mL. The UV detection was carried out at 254 nm. A method for the simultaneous determination of PAHs in aerosols is described. The recoveries of the compounds are in the range of 89–99% for the extraction. The detection limits typically are at the low to sub-ng/m3. Concentrations of PAHs in aerosol samples collected at five different locations in Mumbai, India were measured. In addition to PAHs in ambient aerosols, concentrations of PAHs in indoor aerosol samples, where kerosene is used as cooking fuel, were also measured.

Occurrence and determination of organic pollutants in aerosol, precipitation, and sediment samples collected at Lake Balaton

The results of the determination of different organic pollutants [organic acids, polycyclic aromatic hydrocarbons (PAHs), n-alkanes, volatile hydrocarbons] in aerosols, precipitation, atmosphere, and sediment samples collected at Lake Balaton are presented. Different chromatographic methods were used: capillary zone electrophoresis (CZE) for organic acids, GC–MS for n-alkanes, solid-phase extraction (SPE) and HPLC for PAHs and thermal desorption–GC for BTEX (benzene, toluene, ethylbenzene, m- and p-xylene) compounds. For the determination of the size distribution of organic compounds aerosol was collected by an 8-stage Berner-type low-pressure impactor. Low-molecular mass organic acids were extracted in water in an ultrasonic bath and analysed by CZE. n-Alkanes were extracted by n-hexane, cleaned up on a silica cartridge and analysed by GC–MS. For analysis of PAHs in aerosols, samples were extracted in dichloromethane and acetone, cleaned on a Sep-Pak C 1 8 cartridge and analysed by HPLC–fluorescence detection. Enrichment of PAHs of the precipitation samples was accomplished by SPE on a C 1 8 cartridge. PAHs were eluted with dichloromethane and analysed by HPLC–fluorescence detection. The detection limit was <1 ng l −1 for several PAHs. Well dried and sieved (500-μm sieve) sediment samples were extracted with dichloromethane and acetone. The extracts were cleaned and analysed by HPLC–fluorescence detection. Fourteen PAHs were determined and fluoranthene was found to have the highest concentration at 24 μg kg −1. BTEX compounds were collected by diffusive sampling on Carbopack adsorbent. Samples were analysed by a GC–thermal desorber method and one magnitude higher concentration of volatile compounds was found among the different locations.

Compound specific isotope analysis of fatty acids and polycyclic aromatic hydrocarbons in aerosols: implications for biomass burning

Fatty acids and polycyclic aromatic hydrocarbons (PAH) have been investigated as potential tracer species for the products of biomass burning. Fatty acids extracted from unburned sugar cane plants and from particulate aerosols collected during laboratory burns of sugar cane under smoldering and flaming conditions have been chemically and isotopically characterized by gas chromatography-mass spectrometry (GCMS) and gas chromatography-isotope ratio mass spectrometry (GCIRMS), respectively. Fatty acids and PAH produced during the burning of a sugar cane field in South Africa were similarly characterized. The fatty acids identified in the aerosols collected above the fire were saturated even-chain species ranging from C12 to C22. The carbon isotopic signatures of the fatty acids ranged between −19.9‰ and −23.6‰, and were more depleted in 13C than the bulk sugar cane plant (−12.9‰) and the total lipid extract (−17.9‰). The isotopic signatures of the individual fatty acids were conserved during the smoldering laboratory burn. However, the fatty acids collected during the flaming burn showed a depletion of 1‰ to 6‰ relative to the fatty acids extracted from the unburned plant. This observed depletion was even greater for the fatty acids obtained from the sugar cane field burn. Low levels of various PAH were identified in aerosols from the laboratory burns. Phenanthrene, fluoranthene and pyrene obtained from the field burn aerosols were isotopically depleted relative to the bulk lipid material, with carbon isotopic signatures ranging from −22.9‰ to −25.4‰. The alterations in the isotopic compositions of fatty acids that occur during combustion provide variables by which burn-derived compounds can be distinguished from those produced from aeolian transport of detrital vegetative matter. The combination of fatty acid isotopic data and PAH data may allow a better understanding of the relative contributions of biogenic and anthropogenic source materials to aerosols.

Selective determination of substituted PAH in aerosols using liquid CO2‐extraction, HPLC prefractionation on chemically activated silica, and HRGC combined with negative ion mass spectrometry

AbstractA method is described which allows the determination of different substituted polycyclic aromatic hydrocarbons (PAH) such as NO2‐PAH, carbazoles, keto‐PAH, and aza‐arenes in aerosol samples. Liquid CO2‐extraction is used to minimize the loss of reactive compounds. High performance liquid chromatography on chemically activated silica is employed to prefractionate the samples into subfractions with a minimum of overlap between different PAH compound classes. Both electron capture detection and negative ion chemical ionization combined with capillary gas chromatography are used for identification and quantification. The latter method also allows distinction between isomers with different toxic properties when N2O/CH4 reaction gas mixtures are used. Selectivity for tetrachlorodibenzo‐p‐dioxins as against pesticides and polychlorinated biphenyls can be improved by this technique. The applicability of the method is critically discussed and different examples are given.

Toxicological implications of the organic fraction of aerosols: a chemist's view

In the first part of this review, the analytical methodology used to determine the particle size distributions of organic pollutants in particulate matter is described. Several problems affecting the precision of this procedure are discussed: the calibration of commercial Hi-Vol cascade impactors, physical and chemical sampling artifacts, recovery of organics from particles, and analytical methods for quantitation. In combination with the ICRP model for the retention of particles in the human respiratory tract, deposited concentrations of organic pollutants can be calculated, which are of great toxicological significance. The application of this model to the polydisperse aerosol fractions collected by cascade impaction was validated using particle size distributions from the literature, which have been measured in very small particle size intervals. Results for suburban and rural aerosol samples are briefly discussed. Reliable estimates of the average daily intake (ADI) of organic pollutants by respiration will require the experimental determination of the absorption efficiency. As a first approximation for organic pollutants, the ADI can be set at 4 C ng, where C is the total concentration of the compound in the aerosol. The second part of this review is concerned with the chemical reactivity of organic aerosol constituents in the atmosphere as well as on sampling substrates. The use of the Ames Salmonella microbiological assay has shown significant direct mutagenic activity of the frameshift type in aerosol extracts from different sources, which cannot be attributed to known carcinogenic polycyclic aromatic hydrocarbons (PAH). Thus, it was realized that aerosol particles might contain secondary pollutants as the result of gas-particle interactions in emission stacks, plumes or during atmospheric transport. Laboratory experiments were performed to evaluate the chemical reactivity of PAH towards several gaseous pollutants (SO 2, NO 2, O 3) under simulated atmospheric conditions both on filter substrates and on PAH-enriched aerosol samples. The results were most encouraging: the carcinogen benzo[ a]pyrene, for example, could be degraded rapidly by ozone to a series of polar compounds; the direct mutagenicity of the reaction mixture was found to be caused by the presence of a benzo[ a]pyrene-epoxide, in small amounts. However, it is expected that the efficiency of chemical transformation of PAH in aerosols will largely depend on several factors: particle size and specific surface area will affect the conversion of PAH in a heterogeneous system; the close interaction between aerosol matrix and the adsorbed organics can induce a different chemical behaviour of PAH from that observed in model systems.