Atmospheric Concentrations Of Polycyclic Aromatic Hydrocarbons Research Articles

Variations of the atmospheric polycyclic aromatic hydrocarbon concentrations, sources, and health risk and the direct medical costs of lung cancer around the Bohai Sea against a background of pollution prevention and control in China

Abstract. The Bohai Sea (BS) region, an area of China that is severely polluted with atmospheric polycyclic aromatic hydrocarbons (PAHs), has received wide attention in recent decades. To characterize the variations of the concentrations and sources of PAHs from June 2014 to May 2019, 15 PAH congeners (Σ15PAHs) were measured in atmospheric samples (N = 228) collected at 12 sites around the BS, and the health risk and direct medical costs associated with lung cancer caused by exposure to PAHs were also estimated. The annual daily average concentration of Σ15PAHs was 56.78 ± 4.75 ng m−3, which was dominated by low molecular weight PAHs (LMW-PAHs) containing three rings (58.7 ± 7.8 %). During the 5-year sampling period, the atmospheric Σ15PAHs concentration reduced by 17.5 % for the whole BS region, with an especially large drop of 51.7 % observed in the tightly controlled area of Tianjin (TJ), which was mainly due to a decrease in the concentration of high molecular weight PAHs (HMW-PAHs) containing five or six rings. Generally, the concentration of Σ15PAHs was highest in winter and lowest in summer, which can mainly be attributed to the change in LMW-PAH concentration. Based on the positive matrix factorization (PMF) model, PAHs in the BS region were mainly ascribed to coal combustion and biomass burning. The PAH contributions of coal combustion and motor vehicles showed different trends for the BS region (PAHs from coal combustion rose by 7.2 % and PAHs from motor vehicles fell by 22.4 %) and for TJ (PAHs from coal combustion fell by 12.6 % and PAHs from motor vehicles rose by 6.9 %). The incidence of lung cancer (ILCR) caused by exposure to atmospheric PAHs decreased by 74.1 % and 91.6 % from 2014 to 2018 in the BS region and in TJ, respectively. This was mainly due to the decrease in the concentration of highly toxic HMW-PAHs and was reflected in USD 10.7 million of savings in direct medical costs of lung cancer caused by exposure to PAHs, which represent a decrease of 46.1 % compared to the corresponding costs before air pollution prevention and control was implemented around the BS. There was an even higher reduction in medical costs of 54.5 % in TJ. Hence, this study proves that implementing pollution prevention and control not only effectively reduced the concentration of pollutants and the risks caused by them, but it also significantly reduced the medical costs of diseases caused by the corresponding exposure.

Neural network for evaluation of the impact of the UK COVID-19 national lockdown on atmospheric concentrations of PAHs and PBDEs

The impact of measures to restrict population mobility during the COVID-19 pandemic on atmospheric concentrations of polycyclic aromatic hydrocarbons (PAH) and brominated flame retardants (BFRs) is poorly understood. This study analyses the effects of meteorological parameters and mobility restrictions during the COVID-19 pandemic on concentrations of PAH and BFRs at the University of Birmingham in the UK utilising a neural network (self-organising maps, SOM). Air sampling was performed using Polyurethane Foam (PUF) disk passive samplers between October 2019 and January 2021. Data on concentrations of PAH and BFRs were analysed using SOM and Spearman's rank correlation. Data on meteorological parameters (air temperature, wind, and relative humidity) and mobility restrictions during the pandemic were included in the analysis. Decabromodiphenyl ether (BDE-209) was the most abundant polybrominated diphenyl ether (PBDE) (23–91% Σ7PBDEs) but was detected at lower absolute concentrations (4.2–35.0 pg m−3) than in previous investigations in Birmingham. Air samples were clustered in five groups based on SOM analysis and the effects of meteorology and pandemic-related restrictions on population mobility could be visualised. Concentrations of most PAH decreased during the early stages of the pandemic when mobility was most restricted. SOM analysis also helped to identify the important influence of wind speed on contaminant concentrations, contributing to reduce the concentration of all analysed pollutants. In contrast, concentrations of most PBDEs remained similar or increased during the first COVID-19 lockdown which was attributed to their primarily indoor sources that were either unaffected or increased during lockdown.

Combined effects of temperature and monsoon on seasonal variations of atmospheric polycyclic aromatic hydrocarbons in the coastal Shanghai, China

An intensive sampling program was conducted at two coastal sites of megacity Shanghai - the emerging town Lingang New Area (LGNA), and the petrochemical-industry zone Jinshan Area (JSA) from July 2016–June 2017, to study the occurrence, sources, environmental behavior and fate of atmospheric polycyclic aromatic hydrocarbons (PAHs). Results showed the median concentrations of total atmospheric PAHs were 18 ng m−3 and 12 ng m−3 in JSA and LGNA, respectively, which were lower than those recently detected in northern coastal China, and previously detected in urban/suburban Shanghai. There was strong/opposite temperature dependence for gaseous and particle-bound PAHs, indicating the importance of ongoing local and nearby volatilization; While the gas-particle partitions of individual PAH compound changed dramatically with seasons, with most easily adsorbed on particles during colder months. The potential source contribution function (PSCF) and concentration weight trajectory (CWT) model demonstrated the interactions of terrestrial and marine air mass regulated by the East Asian monsoon. Specifically, PAHs released by wintertime coal heating in northern China and summertime marine shipping in East China Sea, that transported through northwest and southeast monsoon, respectively, and aggravated the pollution of coastal Shanghai, especially for the background site in LGNA. The positive matrix factorization (PMF) source apportionment suggested the dominance of petrogenic sources for gaseous PAHs, coal and biomass combustion sources for particle-bound PAHs, and further demonstrated the seasonal variations of these potential sources. Atmospheric PAHs would deposit to the coastal waters, with gaseous absorption fluxes almost an order of magnitude higher than those of particle-bound deposition.

Polycyclic Aromatic Hydrocarbon (PAH) Residues in the Honeybee, Honey, and Pollen and Estimation of Atmospheric Concentrations in Bursa, Turkey

Polycyclic aromatic hydrocarbon (PAH) concentrations in urban and semi-urban areas were determined in the honeybee, honey and pollen in Bursa, Turkey. The total of 14 PAH (∑14PAH) concentrations measured in the honeybee in the urban and semi-urban areas were 267.65 ± 74.15 ng/g (mean ± standard deviation) and 109.11 ± 19.86 ng/g, respectively. Similarly, the ∑14PAH concentrations measured in honey were 650.24 ± 97.60 and 464.32 ± 57.92 ng/g, respectively, and measured in pollen were 304.32 ± 184.73 and 329.62 ± 154.24 ng/g, respectively. The PAH sources were determined using diagnostic ratios. According to the diagnostic ratios, it was concluded that the sources generally originated from the combustion of coal and biomass. In addition, the PAHs in both sampling areas showed a more dominant distribution in honey samples. The Pearson correlation coefficient method was applied to determine the relationships among the samples. According to the correlation results, there was a strong correlation between the honeybee and pollen samples in both sampling areas, while there were lower correlation results for the honey samples. Finally, atmospheric PAH concentrations were estimated using the leaf/air partition coefficients available in the literature with the help of pollen samples. According to the results obtained, it was determined that pollen samples can be used to estimate atmospheric PAH concentrations.

Clear Declining Behaviors and Causes in Atmospheric Polycyclic Aromatic Hydrocarbon Concentrations at the West End of Japan from 2017 to 2021

In order to determine recent behaviors in atmospheric polycyclic aromatic hydrocarbon (PAH) concentrations at the west end of Japan and to reveal the causes of these behaviors, atmospheric PAH concentrations were measured in suburban and forest sites of Nagasaki, Japan from 2017 to 2021. The results showed that the total concentration of PAHs decreased considerably by 60% and 57% in suburban and forest sites, respectively, over this period. When analyzed by season, the rate of decrease in winter was markedly high. Therefore, the decreasing behavior in PAH concentrations in Nagasaki in recent years was considered to be mainly due to less PAHs originating from cold continental regions such as northern China. In particular, the reduction in coal and biomass combustion for winter heating in households, the efforts to improve air quality, and the limitation of economic activities in response to COVID-19 were likely responsible for the decrease in atmospheric PAH concentrations. In addition, although the PAH concentrations decreased, there was no significant change in the breakdown of the number of benzene rings in the PAH or in the attributes of their sources.

Seasonal Variability and Risk Assessment of Atmospheric Polycyclic Aromatic Hydrocarbons and Hydroxylated Polycyclic Aromatic Hydrocarbons in Kanazawa, Japan

Polycyclic aromatic hydrocarbons (PAHs) and hydroxylated PAHs (OH-PAHs) are ubiquitous atmospheric pollutants that are a concern because of their endocrine disrupting activities. In this study, seasonal air sampling was conducted in 2017 and 2018 in Kanazawa, Ishikawa Prefecture, Japan. The concentrations and seasonal variations of PAHs and OH-PAHs were analyzed, and health risks of individual congeners were evaluated based on their relative endocrine activity. The atmospheric concentrations of PAHs and OH-PAHs showed seasonal trends with higher concentrations in the winter (daily average ± standard deviation: 1.00 ± 0.26 ng/m3 for PAHs and 75.06 ± 23.38 pg/m3 for OH-PAHs) and lower concentrations in the summer (0.30 ± 0.09 ng/m3 for PAHs and 17.08 ± 4.83 pg/m3 for OH-PAHs). There were significant positive correlations between the concentrations of atmospheric PAHs and OH-PAHs. Additionally, the health risk from the endocrine disrupting potential of each OH-PAH was evaluated using relative estrogenic and antiestrogenic activities. OH-PAHs with four rings, such as OH-chrysenes and OH-benz[a]anthracene, had particularly high health risks. These results suggest that atmospheric OH-PAHs are a potential health risk for organisms and thus warrant further research.

Key Factors for Improving the Carcinogenic Risk Assessment of PAH Inhalation Exposure by Monte Carlo Simulation.

Monte Carlo simulation (MCS) is a computational technique widely used in exposure and risk assessment. However, the result of traditional health risk assessment based on the MCS method has always been questioned due to the uncertainty introduced in parameter estimation and the difficulty in result validation. Herein, data from a large-scale investigation of individual polycyclic aromatic hydrocarbon (PAH) exposure was used to explore the key factors for improving the MCS method. Research participants were selected using a statistical sampling method in a typical PAH polluted city. Atmospheric PAH concentrations from 25 sampling sites in the area were detected by GC-MS and exposure parameters of participants were collected by field measurement. The incremental lifetime cancer risk (ILCR) of participants was calculated based on the measured data and considered to be the actual carcinogenic risk of the population. Predicted risks were evaluated by traditional assessment method based on MCS and three improved models including concentration-adjusted, age-stratified, and correlated-parameter-adjusted Monte Carlo methods. The goodness of fit of the models was evaluated quantitatively by comparing with the actual risk. The results showed that the average risk derived by traditional and age-stratified Monte Carlo simulation was 2.6 times higher, and the standard deviation was 3.7 times higher than the actual values. In contrast, the predicted risks of concentration- and correlated-parameter-adjusted models were in good agreement with the actual ILCR. The results of the comparison suggested that accurate simulation of exposure concentration and adjustment of correlated parameters could greatly improve the MCS. The research also reveals that the social factors related to exposure and potential relationship between variables are important issues affecting risk assessment, which require full consideration in assessment and further study in future research.

Temporal Trend of Polycyclic Aromatic Hydrocarbons in Atmosphere Within 24 Hours After Snowfall

The atmosphere is a significant medium for the transportation and diffusion of volatile and semi-volatile pollutants. Furthermore, the atmosphere is the primary exposure route for pollutants to enter the human body. Therefore, the study of the environmental fate of pollutants in the atmosphere is essential. In this study, 16 polycyclic aromatic hydrocarbons (PAHs) were analyzed in snow samples and air samples within 24 hours after a snowfall, and the temporal trend of PAHs in the atmosphere was comprehensively studied. The results indicated that the detection rate of the 16 PAHs in snow was 100%, and the concentration of phenanthrene (538.3 ng·L-1) was the highest, followed by naphthalene (509.1 ng·L-1) and fluoranthene (429.9 ng·L-1), indicating that snowfall can remove PAHs from the atmosphere. After the snowfall, a falling-rising-falling temporal trend of the concentrations of PAHs in the atmosphere was observed. Higher concentrations appeared during rush hour, with the largest automobile exhaust emissions, while lower concentrations appeared during periods with the lowest human activity. The results indicated that the atmospheric concentrations of PAHs were predominantly influenced by human activities. Within 24 hours after snowfall, the ratio of PAHs between the gas phase and particle phase, which depends primarily on the physical and chemical properties of PAHs, had not changed substantially. The diagnostic ratios indicated that within 24 hours after snowfall, the PAHs in the atmosphere originated mostly from the emissions of solid fuel and liquid fuel combustion.

Concentrations and Sources of Atmospheric PM, Polycyclic Aromatic Hydrocarbons and Nitropolycyclic Aromatic Hydrocarbons in Kanazawa, Japan

PM2.5 (fine particles with diameters 2.5 micrometers and smaller) and PM>2.5 were separately collected in Kanazawa, Japan in every season, from the spring of 2017 to the winter of 2018, and nine polycyclic aromatic hydrocarbons (PAHs) and six nitropolycyclic aromatic hydrocarbons (NPAHs) were respectively determined using high-performance liquid chromatography (HPLC) with fluorescence and chemiluminescence detections. The atmospheric concentrations of both the PAHs and NPAHs showed seasonal changes (highest in the winter and lowest in the summer), which differed from the variations in the total suspended particulate matter (TSP) and PM2.5 amounts (which were highest in the spring). The contributions of major sources to the combustion-derived particulate (Pc) in the PM2.5 were calculated using the 1-nitropyrene-pyrene (NP) method, using pyrene and 1-nitropyrene as the representative markers of PAHs and NPAHs, respectively. The annual average concentration of Pc accounted for only 2.1% of PM2.5, but showed the same seasonal variation as PAHs. The sources of Pc were vehicles (31%) and coal heating facilities/industries (69%). A backward trajectory analysis showed that the vehicle-derived Pc was mainly from Kanazawa and its surroundings, and that coal heating facilities/industry-derived Pc was transported from city areas in central and northern China in the winter, and during the Asian dust event in the spring. These results show that large amounts of PAHs were transported over a long range from China during the winter. Even in the spring, after the coal heating season was over in China, PAHs were still transported to Japan after Asian dust storms passed through Chinese city areas. By contrast, the main contributors of NPAHs were vehicles in Kanazawa and its surroundings. The recent Pc concentrations were much lower than those in 1999. This decrease was mostly attributed to the decrease in the contribution of vehicle emissions. Thus, the changes in the atmospheric concentrations of Pc, PAHs and NPAHs in Kanazawa were strongly affected not only by the local emissions but also by long-range transport from China.

A WRF-CMAQ modeling of atmospheric PAH cycling and health risks in the heavy petrochemical industrialized Lanzhou valley, Northwest China

Polycyclic aromatic hydrocarbons (PAHs) are omnipresent air pollutants with mutagenic and carcinogenic characteristics. Lanzhou city in Northwest China, where the first photochemical smog incident occurred in China, is located in an area characterized by mountain-valley topography. The city has been known as a heavy and petrochemical industry base and heavily contaminated by PAHs. There are large knowledge gaps in the understanding of atmospheric environmental fate of PAHs in Lanzhou city due to sparse observation data. We performed extensive numerical investigations of PAHs for August (summertime) and December (wintertime) of 2014 in Lanzhou city, using the Community Multiscale Air Quality (CMAQ) model, aiming to fill knowledge gaps in the spatial-temporal distribution and health consequences across the city. Strong seasonality in the atmospheric concentrations of PAHs was found, with high concentrations in winter and low concentrations in summer. The modeling results show high days in which daily air concentrations of BaP exceeding the level Ⅱ of Chinese National Standard (CNS) (2.5 ng/m3) in several August days in industrial suburb and urban area. In December, 77% and 80% of simulated BaP daily air concentrations were well above this national standard in the two areas. The modeled NAP and PHE in the atmosphere were predominantly in gas phase, whereas BaP was mainly in particulate phase. It was also found that the dry deposition dominated total PAHs deposition in Lanzhou. The incremental lifetime cancer risk (ILCR) ranged from 4.0 × 10−6 to 16.0 × 10−6, which were higher than the satisfactory risk level of 1.0 × 10−6, suggesting that local residents in Lanzhou city have a potential carcinogenic risk through exposure to ambient BaP. Especially, children had a higher exposure risk than adults. We suggest that the different actions in different regions of the city should be taken by the local government and those industries with high PAH emission, so as to reduce PAH contamination and risk.

The Preliminary Study on the Association Between PAHs and Air Pollutants and Microbiota Diversity.

The purpose of this study was to investigate the association among polycyclic aromatic hydrocarbons (PAHs) exposure and air pollutants and the diversity of microbiota. Daily average concentrations of six common air pollutants were obtained from China National Environmental Monitoring Centre. The PAHs exposure levels were evaluated by external and internal exposure detection methods, including monitoring atmospheric PAHs and urinary hydroxyl-polycyclic aromatic hydrocarbon (OH-PAH) metabolite levels. We analyzed the diversity of environmental and commensal bacterial communities with 16S rRNA gene sequencing and performed functional enrichment with Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Correlation analysis and logistic regression modeling were conducted to evaluate the relationship of PAHs levels with air pollutants and microbial diversity. Correlation analysis found that the concentrations of atmospheric PAHs were significantly positively correlated with those of PM10, NO2, and SO2. There also was a positive correlation between the abundance of the genus Micrococcus (Actinobacteria) and high molecular weight PAHs, and Bacillus, such as genera and low molecular weight PAHs in the atmosphere. Logistic regression showed that the level of urinary 1-OHPyrene was associated with childhood asthma after sex and age adjustment. The level of urinary 1-OHPyrene was significantly positively correlated with that of PM2.5 and PM10. In addition, the level of 1-OHPyrene was positively correlated with oral Prevotella-7 abundance. Functional enrichment analysis demonstrated that PAHs exposure may disturb signaling pathways by the imbalance of commensal microbiota, such as purine metabolism, pyrimidine metabolites, lipid metabolism, and one carbon pool by folate, which may contribute to public health issues. Our results confirmed that atmospheric PAHs and urinary 1-OHPyrene were correlated with part of six common air pollutants and indicated that PAHs pollution may alter both environmental and commensal microbiota communities associated with health-related problems. The potential health and environmental impacts of PAHs should be further explored.

Distribution, seasonal trends, and lung cancer risk of atmospheric polycyclic aromatic hydrocarbons in North China: A three-year case study in Dalian city.

Atmospheric monitoring data of polycyclic aromatic hydrocarbons (PAHs) over a three-year period were collected from an urban site in Dalian, northeast China. The status of PAHs in the atmosphere in Dalian were evaluated by assessing concentration levels, congener profiles, seasonal trends, primary source, inhalation exposure and the risk of developing lung cancer risk. Average concentrations were recorded for 53 PAHs (95±40ng/m3), 16 EPA priority PAHs (68±33ng/m3), 26 alkylated PAHs (17±7.6ng/m3) and 4 high-molecular-weight (302Da) PAHs (1.3±1.3ng/m3). Atmospheric PAH concentrations in winter were almost twice as high as those recorded in the summer, possibly due to enhanced local emissions and long-range transport of atmospheric PAHs during the winter. PAH congeners were dominated by phenatherene, fluoranthene, pyrene and fluorene, accounting for 46.0% of total ∑53PAH concentrations. Ship/vehicle emission and mixed combustion were identified as the main sources of PAHs using diagnostic PAH concentration ratios and principal component analysis-multiple linear regression. Benzo(a)pyrene toxicity equivalent concentration had an average content of 32±37 ng/m-3 over the sampling period, with dibenzo(a,h)anthracene (50.7%) and dibenzo(a,l)pyrene (26.4%) being the largest contributors. The risk of developing lung cancer due to inhalation exposure to outdoor PAHs was calculated at 12.0‰ using the overall population attributable fraction (PAF). Our results estimate that, due to PAH exposure in Dalian, the average excess lung cancer risk during a person's lifetime is 35.7 cancer cases per one million inhabitants.

Effect of northern boreal forest fires on PAH fluctuations across the arctic

Polycyclic aromatic hydrocarbons (PAHs) are formed by the incomplete combustion of fossil fuels and forest or biomass burning. PAHs undergo long-range atmospheric transport, as evidenced by in situ observations across the Arctic. However, monitored atmospheric concentrations of PAHs indicate that ambient PAH levels in the Arctic do not follow the declining trend of worldwide anthropogenic PAH emissions since the 2000s, suggesting missing sources of PAHs in the Arctic or other places across the Northern Hemisphere. To trace origins and causes for the increasing trend of PAHs in the Arctic, the present study reconstructed PAH emissions from forest fires in the northern boreal forest derived by combining forest carbon stocks and MODIS burned area. We examined the statistical relationships of forest biomass, MODIS burned area, emission factors, and combustion efficiency with different PAH congeners. These relationships were then employed to construct PAH emission inventories from forest biomass burning. We show that for some PAH congeners, for example, benzo[a]pyrene (BaP)—the forest-fire-induced air emissions are almost one order of magnitude higher than previous emission inventories in the Arctic. A global-scale atmospheric chemistry model, GEOS-Chem, was used to simulate air concentrations of BaP, a representative PAH congener primarily emitted from biomass burning, and to quantify the response of BaP to wildfires in the northern boreal forest. The results showed that BaP emissions from wildfires across the northern boreal forest region played a significant role in the contamination and interannual fluctuations of BaP in Arctic air. A source-tagging technique was applied in tracking the origins of BaP pollution from different northern boreal forest regions. We also show that the response of BaP pollution at different Arctic monitoring sites depends on the intensity of human activities.

Age dependence accumulation of organochlorine pesticides and PAHs in needles with different forest types, southeast Tibetan Plateau.

In this study, organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) in needle leaves with different ages were measured in three prevalent coniferous forests including spruce, fir and pinus in southeast Tibetan Plateau (TP) to investigate accumulation behavior of persistent organic pollutants (POPs) during entire growth cycle of needles. The accumulation concentration of POPs was higher in pinus and fir needles than in spruce needles. Concentrations for most of OCPs significantly increased with needle ages, especially dichlorodiphenyltrichloroethane (DDT) and its metabolites showed more remarkable increasing trend than hexachlorocyclohexane isomers (HCHs) and hexachlorobenzene (HCB) in the three tree species. However, age dependence accumulation of PAHs was not observed in most cases, possibly due to its easier degradation property and the influence by dramatic change of ambient atmospheric concentration of PAHs. The lipid normalized concentrations in needles exhibited similar accumulation pattern with that of dry weight basis. The controlling factors for concentration variation in needles were identified using multiple linear regression. The suitability of these needle species acting as potential passive sampler for atmospheric POPs was evaluated. The different-age needles could reflect atmospheric OCP concentrations in the past long-term trend. Findings of this study provide guidance in use of needle as passive samples for the background monitoring of the atmospheric contamination at remote and poorly accessible locations such as the TP.

Characteristics of Polycyclic Aromatic Hydrocarbons (PAHs) and Common Air Pollutants at Wajima, a Remote Background Site in Japan.

Background: Background sites are mainly affected by long-range-transported air pollutants, resulting in potential adverse effects on local atmospheric environments. A 4–5 year observational study was conducted to illustrate the air pollution profile at the Kanazawa University Wajima air monitoring station (KUWAMS), an ideal remote background site in Japan. Methods: Nine polycyclic aromatic hydrocarbons (PAHs) in the particulate phase and various air pollutants were continuously monitored for 4–5 years. Diagnostic ratios of PAHs and back-trajectory analysis were applied to trace the possible sources of the air pollutants collected at the sampling site. Results: The atmospheric concentration of PAHs in the atmosphere at the site decreased from 2014 to 2019, benefit from the predominant air pollution control policy in China and Japan. Common air pollutants including sulfur dioxide (SO2), nitrogen oxides (NOx), ozone, methane (CH4), and non-methane hydrocarbon (NMHC) were detected in low concentrations from 2016 to 2019, while ozone (O3) and particulate matter (PM2.5, PM with a diameter less than 2.5 μm) were present in high levels that exceeded the Japanese standards. Most air pollutants peaked in spring and showed evident diurnal variations in spring and summer. Conclusions: This is the first study to clarify the atmospheric behaviors of multiple air pollutants at a background site in Japan. Significant external air pollutant impact and unneglectable air pollution were demonstrated at KUWAMS, indicating the importance of studying atmospheric pollution at remote sites.

Atmospheric Polycyclic Aromatic Hydrocarbons (PAHs) at Two Sites, in Bursa, Turkey: Determination of Concentrations, Gas-Particle Partitioning, Sources, and Health Risk.

This study investigated the concentration of polycyclic aromatic hydrocarbons (PAHs) using particle and gas-phase air samples collected in the Ovaakca and Cumalikizik region of Bursa, between May and September 2017. The concentration of Σ16PAH measured in the gas phase, for Ovaakca and Cumalikizik, were 5.32 ± 1.98 and 4.91 ± 3.41ngm-3, respectively; and for the particle phase, 0.81 ± 0.56 and 1.84 ± 1.82ngm-3, respectively. The coefficient of gas-particle partitioning was related to the excessive cooled vapor pressure. The determined slope values were - 0.319 (Ovaakca) and - 0.505 (Cumalikizik), which showed the strong effect of organic carbon absorption and the distance to the equilibrium. These experimental values were compared with the results obtained using the octanol/air and Dual partition models, and Dual partition model showed more accurate values than the octanol/air model. The relations between temperature and concentration in the gas phase of PAHs were evaluated using the Clausius-Clapeyron equation. The results indicated the influence of long-range transport of the atmospheric concentrations of PAHs at the regions. Diagnostic ratio analysis showed that biomass burning, coal combustion, and vehicular emissions contributed greatly to the atmospheric PAHs in the regions. In principal component analysis analysis, wood-burning was found to be the predominant parameter in addition to PAH sources determined with diagnostic ratios. In this study, the lifetime risk of lung cancer was calculated according to the mean and max BaP-TEQ values. When calculated according to the average values, while both regions were acceptable risk levels (Ovaakca: 2.6 × 10-6 and Cumalikizik: 8.6 × 10-6), at low-risk level was determined according to max BaP-TEQ values only in the Cumalikizik region (1.93 × 10-5).

Spatiotemporal distribution and dynamic modeling of atmospheric gaseous polycyclic aromatic hydrocarbons in a rapidly urbanizing city: Nanjing, China.

Multiple studies have evaluated the concentration and lung cancer risk of polycyclic aromatic hydrocarbons (PAHs). However, the monitoring and dynamic modeling of PAHs with a high resolution were relatively insufficient. We investigated the spatiotemporal distribution of gaseous PAH concentrations using passive air samplers with high sampling density in an industrial city of Nanjing, China (January and October 2015) and found that the gaseous PAH concentrations in western Nanjing were higher than those in eastern Nanjing, mainly because of emission source distribution and wind action. There were notable seasonal changes in PAH concentrations: winter > autumn > spring > summer. We developed an atmospheric PAH dynamic model with a high resolution of 1km2 based on the advection-diffusion equation and coupled with an emissions inventory and atmospheric transportation processes. Acenaphthene was selected as a proxy for gaseous PAHs. The modeled acenaphthene concentrations were similar to the concentrations measured. Moreover, we used the model to identify the impact of meteorological factors on gaseous PAHs via scenario analysis and found that a narrow-range temperature change and even heavy rainfall may not significantly affect atmospheric gaseous PAH concentrations, whereas the wind played an important part in transferring PAHs and changing their geographic distribution.

Volatilization and oxidative artifacts of PM bound PAHs collected at low volume sampling (1): Laboratory and field evaluation

Laboratory and field studies were carried out to assess the effects of oxidative degradation and volatilization on PM10 bound polycyclic aromatic hydrocarbons (PAHs), collected at low volume condition according to the EU sampling reference method EN12341:2014 (flow rate 2.3 m3 h−1), on 47 mm quartz filters. For the laboratory experiments, pairs of twin samples were collected in field and, after treatments favoring decomposition or/and volatilization of PAHs on one sample, the PAH amount was compared with that of the corresponding untreated sample. Ozone exposure caused a general PAHs decay with more marked effects on benzo [a]pyrene, perylene and benz [a]anthracene; these compounds showed, similarly to benzo [ghi]perylene, correlations between ozone dose and losses. Treatments with zero air exhibited losses due to volatilization even for 5-ring PAHs up to benzo [a]pyrene, whereas a linear dependence was observed between filter PAH load and losses for benzo [a]anthracene, chrysene and benzofluoranthenes. Concentrations on samples collected simultaneously over 48, 24, 12 and 6 h were compared. Results confirmed a lack of temporal auto-consistency in the PAHs sampling methodology here adopted. In particular higher atmospheric PAH concentrations were ascertained on samples constituted by cumulative filters exposed over shorter sampling times. When 24–h and 2 × 12-h samples were compared, comparable losses were evaluated in the hot and cold seasons. This finding shows that, although in summer meteorology conditions favor sampling artifacts, the effectiveness of these phenomena continue in the winter, probably due to the larger amount of PAH available on the sampling filter (total PAHs ∼ 10 vs 0.5 ng m−3).

Long term trends in atmospheric concentrations of polycyclic aromatic hydrocarbons and nitropolycyclic aromatic hydrocarbons: A study of Japanese cities from 1997 to 2014.

Total suspended particulate matter (TSP) was collected during the summer and winter in five Japanese cities spanning Hokkaido to Kyushu (Sapporo, Kanazawa, Tokyo, Sagamihara and Kitakyushu) from 1997 to 2014. Nine polycyclic aromatic hydrocarbons (PAHs) with four to six rings, including pyrene (Pyr) and benzo[a]pyrene (BaP), were identified using high-performance liquid chromatography (HPLC) with fluorescence detection. Two nitropolycyclic aromatic hydrocarbons (NPAHs), 1-nitropyrene (1-NP) and 6-nitrobenzo[a]pyrene (6-NBaP), were identified by HPLC with chemiluminescence detection. A comparison of PAH and NPAH concentrations and [NPAH]/[PAH] ratios such as [1-NP]/[Pyr] and [6-NBaP]/[BaP] revealed the following characteristics in the five cities: (1) In Sapporo, Kanazawa, Tokyo and Sagamihara, the concentrations of PAHs and NPAHs were high at the beginning of the sampling period and then steadily decreased, with NPAHs decreasing faster than PAHs. The large initial [1-NP]/[Pyr] ratios suggest that the major contributor was automobiles but subsequent decreases in this ratio suggest decreased automobile contributions. (2) By contrast, PAH concentrations in Kitakyushu did not decrease during the sampling period, though concentrations of NPAHs decreased. The consistently smaller [1-NP]/[Pyr] ratio and larger [6-NBaP]/[BaP] ratio in Kitakyushu suggests that the major contributor of PAHs was not automobiles but iron manufacturing which uses a large amount of coal. The sudden increase in atmospheric PAH concentrations in the winter of 2014 may also be due to iron manufacturing.

Seasonal variations and sources of atmospheric polycyclic aromatic hydrocarbons and organochlorine compounds in a high-altitude city: Evidence from four-year observations.

Lijiang is a high-altitude city located on the eastern fringe of the Tibetan Plateau, with complex seasonal atmospheric circulations (i.e. westerly wind, Indian Monsoon, and East Asia Monsoon). Very few previous studies have focused on seasonal variations and sources of organic pollutants in Lijiang. In this study, a four-year air campaign from June 2009 to July 2013 was conducted to investigate the temporal trends and the sources of polycyclic aromatic hydrocarbons (PAHs) and organochlorine compounds [including organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs)]. The atmospheric PAH concentrations in winter are 2-3 times of those in summer, probably because of the combined result of enhanced local emission and long-range atmospheric transport (LRAT) during winter. Traffic pollution was the primary local source of PAHs, while biomass burning is the dominant LRAT source. OCPs and PCBs also mainly underwent LRAT to reach Lijiang. The peak concentrations of most of OCPs occurred in pre-monsoon season and winter, which were carried by air masses from Myanmar and India through westerly winds. As compared with other sites of the Tibetan Plateau, without the direct barrier of the Himalaya, Lijiang is easily contaminated by the incursion of polluted air masses.