One-year study of polycyclic aromatic compounds at an urban site in Grenoble (France): Seasonal variations, gas/particle partitioning and cancer risk estimation

Polycyclic aromatic hydrocarbon (PAHs) geographical distribution in China and their source, risk assessment analysis

In China, the huge amounts of energy consumption caused severe carcinogenic polycyclic aromatic hydrocarbon (PAHs) concentration in the soil and ambient air. This paper summarized that the references published in 2008-2018 and suggested that biomass, coal and vehicular emissions were categorized as major sources of PAHs in China. In 2016, the emitted PAHs in China due to the incomplete combustion of fuel was about 32720 tonnes, and the contribution of the emission sources was the sequence: biomass combustion > residential coal combustion > vehicle > coke production > refine oil > power plant > natural gas combustion. The total amount of PAHs emission in China at 2016 was significantly decreased due to the decrease of the proportion of crop resides burning (indoor and open burning). The geographical distribution of PAHs concentration demonstrated that PAHs concentration in the urban soil is 0.092-4.733 μg/g. At 2008-2012, the serious PAHs concentration in the urban soil occurred in the eastern China, which was shifted to western China after 2012. The concentration of particulate and gaseous PAHs in China is 1-151 ng/m3 and 1.08-217 ng/m3, respectively. The concentration of particle-bound PAHs in the southwest and eastern region are lower than that in north and central region of China. The incremental lifetime cancer risk (ILCR) analysis demonstrates that ILCR in the soil and ambient air in China is below the acceptable cancer risk level of 10-6 recommended by US Environmental Protection Agency (EPA), which mean that there is a low potential PAHs carcinogenic risk for the soil and ambient air in China.

Existence, removal and transformation of parent and nitrated polycyclic aromatic hydrocarbons in two biological wastewater treatment processes

Polycyclic aromatic hydrocarbons (PAHs) and nitrated polycyclic aromatic hydrocarbons (NPAHs) are pollutants commonly present in the environment. Some NPAHs are considered to have more severe toxic effects than their parent PAHs. The existence of 16 PAHs (678.5-3817.8 ng/L in wastewater, 499.9 ng/g-1239.6 ng/g in sludge) and 5 NPAHs (175.8-1392.4 ng/L in wastewater, 483.5 ng/g-2763.1 ng/g in sludge) was determined in a biological wastewater treatment plant (WWTP) in Qingdao, China. Anthracene and naphthalene were the predominant PAHs, and 2-nitrofluorene and 9-nitroanthracene were the predominant NPAHs. Petroleum, liquid fossil fuel combustion and exhaust emissions were the main sources of PAHs and NPAHs in this study. In both the sequencing batch reactor/moving-bed biofilm (SBR/MBBR) and the anaerobic-anoxic-aerobic (A²O) process, low-molecular-weight PAHs were mainly removed through volatilization and biodegradation/biotransformation. Meanwhile, the removal of high-molecular-weight PAHs and NPAHs depended on adsorption and sedimentation. The transformation from PAHs to NPAHs mainly occurred in the aqueous-phase, especially in summer and that was confirmed by mass flow and ratios variation. Overall, the removal capacity of the A²O process for PAHs and NPAHs was better than that of the SBR/MBBR process. Tertiary treatment processes had little effect or even a negative effect on the removal of PAHs and NPAHs.

A one-year record of particle-bound polycyclic aromatic hydrocarbons at an urban background site in Lisbon Metropolitan Area, Portugal

Polycyclic aromatic hydrocarbons (PAHs) are a class of organic chemicals that are widely distributed in the atmosphere and well known for their adverse health effects. This study aims to describe, for the first time, the levels, sources and associated health risks of particulate PAHs in an urban background atmosphere of Lisbon, the capital and largest city in Portugal. PM₁₀ aerosol samples were collected from early January to the end of December 2012 with a high-volume sampler and were later analyzed for 10 PAHs by high-performance liquid chromatography. The annual average of the sum of the concentrations of PAHs (ΣPAHs) was 1.64 ± 1.85 ng/m³. The dominant PAHs were pyrene, chrysene, benzo[b]fluoranthene, fluoranthene and benzo[g,h,i]perylene. Together these species accounted for approximately 70% of the ΣPAHs. A marked seasonal variation was observed for the investigated PAHs, with the highest values in winter and the lowest in spring and summer, reflecting the variation of emissions and meteorological conditions over time. The average concentration of benzo[a]pyrene was found to be 0.107 ± 0.152 ng/m³, not exceeding the target value of 1 ng/m³ established by European air quality legislation. Diagnostic ratios and principal component analysis were employed for the source apportionment of PAHs. Both tools indicated that vehicle exhaust was the main contributor to the atmospheric levels of PAHs in the study area.

Chemical (C, N, S, black carbon, soot and char) and stable carbon isotope composition of street dusts from a major West African metropolis: Implications for source apportionment and exposure

Street dust is a major source of pollution and exposure of residents of West Africa to toxic chemicals. There is however, limited knowledge about the chemical composition and sources of street dust in urban areas of sub-Saharan Africa. The total carbon (TC), nitrogen (TN), sulfur (TS) and the stable carbon isotope ratios (δ¹³C) contents of street dust sampled from 25 sites distributed across Kumasi (a metropolis in Ghana with a population of ca. 2 million) were determined. In addition, black carbon (BC) and their subunits (soot and char) in these samples were also determined. The concentrations of TC, TN and TS in the dusts were 5-71 mg g^-1, 0.3-4.3 mg g^-1 and 0.2-1.4 mg g^-1, respectively. The concentrations of TC, TN and TS were higher than at the background site of the metropolis by a factor of 5.1 (range: 1.7-12), 3.9 (1.1-13) and 2.8 (0.7-5), respectively. The BC, char and soot concentrations in these samples averaged 1.6 mg g^-1 (0.13-4.4), 1.2 mg g^-1 (0.08-3.7) and 0.36 mg g^-1 (0.05-1.5), respectively. The concentrations of BC, char and soot in the street dust were higher than in the background location by factors of 5 (range: 0.8-13), 6 (0.7-17) and 3 (0.5-12), respectively. The TC, TN, TS, BC, soot and char concentrations were positively correlated with each other and with polycyclic aromatic compounds (PAHs, oxygenated PAHs and azaarenes from a previous study), indicating their common origin and fate. The δ¹³C values ranged from -27 to -24 [‰], with more polluted sites being more depleted in ¹³C. Based on the chemical composition of the street dusts, the 25 sites could be clustered into four groups by hierarchical cluster analysis which reflect areas of varying anthropogenic influence and, accordingly, exposure to hazardous chemicals.

Fine particle-bound polycyclic aromatic hydrocarbons (PAHs) at an urban site of Wuhan, central China: Characteristics, potential sources and cancer risks apportionment

Levels, compositions, sources, and cancer risks of fine particle (PM_2.5)-bound PAHs were investigated at an urban site of Wuhan, Central China. Totally 115 PM_2.5 samples collected during four seasons from 2014 to 2015 were analyzed for 16 USEPA priority PAHs. The annual average of PM_2.5 and total PAHs were 106 ± 41.7 μg m^-3 and 25.1 ± 19.4 ng m^-3, respectively. The seasonal levels of PM_2.5 and PAHs varied in a similar trend, with the highest concentrations in winter and the lowest in summer. PM_2.5-bound PAHs under different pollution level was discussed and the highest average PAH levels were found at a moderate (115-150 μg m^-3) air quality level. Three sources including coal combustion and biomass burning, petrogenic source, and vehicle emissions were extracted and quantified by the positive matrix factorization (PMF) model, accounting for 22.7 ± 21.3%, 34.4 ± 29.0% and 42.9 ± 31.3% of the total PAHs, respectively. The potential source contribution function (PSCF) and the concentration-weighted trajectory (CWT) were combined to explore the geographic origins of PAHs. The spatial distributions of coal combustion and biomass burning, petrogenic source, and vehicle emissions were well correlated with medium molecular weight (MMW), low molecular weight (LMW) and high molecular weight (HMW) PAHs, respectively. Results of PSCF and CWT indicated that the long-distance transport form north of Wuhan as far as northern and eastern of China was higher than that from the southern China while the contribution of local areas was higher than those from the long-range transport. The overall lifetime lung cancer risk (LLCR) via inhalation exposure to PM_2.5-bound PAHs was estimated as 3.03 × 10^-4, with vehicle emissions contributed 57.1% (1.6 × 10^-4) to the total risk on average, followed by coal combustion and biomass burning (31.0%, 9.6 × 10^-5), and petrogenic source (11.9%, 3.6 × 10^-5).

Tree bark as a biomonitor for assessing the atmospheric pollution and associated human inhalation exposure risks of polycyclic aromatic hydrocarbons in rural China

Inhalation exposure to atmospheric polycyclic aromatic hydrocarbons (PAHs) is posing a great threat to human health. Biomass combustion in rural areas contributes greatly to the total PAH emission in China. To conduct a comprehensive risk assessment of ambient PAHs in rural China, a nationwide air sampling campaign was carried out in this study. The 16 U.S. Environmental Protection Agency priority PAHs in tree bark, which was employed as a passive air sampler, were analyzed. The summation of the 16 PAHs ranged from 11.7 to 12,860 ng/m³ in the air of rural China. The national median benzo(a)pyrene equivalent (BaP_eq) concentration was 18.4 ng/m³, with the range from 0.334 to 2497 ng/m³. The total inhalation carcinogenic risks of individual PAHs, with the exception for naphthalene, were very low (<1 × 10^-6) at most of the sampling sites. The national median excess lifetime lung cancer risk associated with inhalation exposure to atmospheric PAHs was 20.3 × 10^-6, corresponding to a population attributable fraction (PAF) of 3.38‰. Our estimations using tree bark were comparable to those reported in other studies and the uncertainties of the variables in the dataset were within the acceptable levels, demonstrating that tree bark is feasible for assessing the atmospheric PAH pollution and associated health risks. We feel that the outputs from this study can assist decision-makers focusing on protecting human health against exposure to atmospheric PAHs in rural China.

Occurrence of the potent mutagens 2- nitrobenzanthrone and 3-nitrobenzanthrone in fine airborne particles

Polycyclic aromatic compounds (PACs) are known due to their mutagenic activity. Among them, 2-nitrobenzanthrone (2-NBA) and 3-nitrobenzanthrone (3-NBA) are considered as two of the most potent mutagens found in atmospheric particles. In the present study 2-NBA, 3-NBA and selected PAHs and Nitro-PAHs were determined in fine particle samples (PM 2.5) collected in a bus station and an outdoor site. The fuel used by buses was a diesel-biodiesel (96:4) blend and light-duty vehicles run with any ethanol-to-gasoline proportion. The concentrations of 2-NBA and 3-NBA were, on average, under 14.8 µg g⁻¹ and 4.39 µg g⁻¹, respectively. In order to access the main sources and formation routes of these compounds, we performed ternary correlations and multivariate statistical analyses. The main sources for the studied compounds in the bus station were diesel/biodiesel exhaust followed by floor resuspension. In the coastal site, vehicular emission, photochemical formation and wood combustion were the main sources for 2-NBA and 3-NBA as well as the other PACs. Incremental lifetime cancer risk (ILCR) were calculated for both places, which presented low values, showing low cancer risk incidence although the ILCR values for the bus station were around 2.5 times higher than the ILCR from the coastal site.

Characterization of Environmental Health Inequalities Due to Polyaromatic Hydrocarbon Exposure in France

Reducing environmental health inequalities has become a major focus of public health efforts in France, as evidenced by the French action plans for health and the environment. To evaluate environmental inequalities, routine monitoring networks provide a valuable source of data on environmental contamination, which can be used in integrated assessments, to identify overexposed populations and prioritize actions. However, available databases generally do not meet sufficient spatial representativeness to characterize population exposure, as they are usually not assembled for this specific purpose. The aim of this study was to develop geoprocessing procedures and statistical methods to build spatial environmental variables (water, air, soil, and food pollutant concentrations) at a fine resolution, and provide appropriate input for the exposure modelling. Those methods were designed to combine in situ monitoring data with correlated auxiliary information (for example, atmospheric emissions, population, and altitude), in order to better represent the variability of the environmental compartment quality. The MODUL’ERS multimedia exposure model developed by INERIS (French Institute for industrial Environment and Risks) was then used to assess the transfer of substances from the environment to humans, through inhalation and ingestion pathway characterization. We applied the methodology to a carcinogenic Polycyclic Aromatic Hydrocarbon substance, benzo[a]pyrene(B[a]P), to map spatialized exposure indicators, at the national scale. The largest environmental contribution corresponded to the ingestion pathway. Data processing algorithms and calculation of exposure will be integrated into the French coordinated integrated environment and health platform PLAINE (PLteforme intégrée d’Analyse des INégalités Environnementales) which has been developed to map and analyze environmental health inequalities.

An overview of research and development themes in the measurement and occurrences of polyaromatic hydrocarbons in dusts and particulates

Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds consisting of two or more fused aromatic rings and are probably one of the most studied groups of organic chemicals in environmental research. PAHs originate mainly from anthropogenic processes, particularly from incomplete combustion of organic fuels. PAHs are distributed widely in particulate matter. Due to widespread sources and persistent characteristics, PAHs disperse through atmospheric transport and exist almost everywhere. Human beings are exposed to PAH mixtures in gaseous or particulate phases in ambient air. Long-term exposure to high concentrations of PAHs is associated with adverse health problems. This review identifies the main research and development themes in the measurement and occurrences of PAHs in dusts and particulates using a new approach to carrying out a literature review where many peer-review publications have been produced. The review extracts the most important research themes from a literature search using a combination of text mining and a more detailed review of selected papers from within the identified themes.

Speciation of organic fractions does matter for aerosol source apportionment. Part 2: Intensive short-term campaign in the Paris area (France)

The present study aimed at performing PM₁₀ source apportionment, using positive matrix factorization (PMF), based on filter samples collected every 4h at a sub-urban station in the Paris region (France) during a PM pollution event in March 2015 (PM₁₀>50μgm^-3 for several consecutive days). The PMF model allowed to deconvolve 11 source factors. The use of specific primary and secondary organic molecular markers favoured the determination of common sources such as biomass burning and primary traffic emissions, as well as 2 specific biogenic SOA (marine+isoprene) and 3 anthropogenic SOA (nitro-PAHs+oxy-PAHs+phenolic compounds oxidation) factors. This study is probably the first one to report the use of methylnitrocatechol isomers as well as 1-nitropyrene to apportion secondary OA linked to biomass burning emissions and primary traffic emissions, respectively. Secondary organic carbon (SOC) fractions were found to account for 47% of the total OC. The use of organic molecular markers allowed the identification of 41% of the total SOC composed of anthropogenic SOA (namely, oxy-PAHs, nitro-PAHs and phenolic compounds oxidation, representing 15%, 9%, 11% of the total OC, respectively) and biogenic SOA (marine+isoprene) (6% in total). Results obtained also showed that 35% of the total SOC originated from anthropogenic sources and especially PAH SOA (oxy-PAHs+nitro-PAHs), accounting for 24% of the total SOC, highlighting its significant contribution in urban influenced environments. Anthropogenic SOA related to nitro-PAHs and phenolic compounds exhibited a clear diurnal pattern with high concentrations during the night indicating the prominent role of night-time chemistry but with different chemical processes involved.

Emission characteristics of polycyclic aromatic hydrocarbons from pyrolytic processing during dismantling of electronic wastes

Two typical types of electronic waste (E-waste) were selected to investigate the emission characteristics of polycyclic aromatic hydrocarbons (PAHs) during pyrolytic processing, including emission factor, compositional profile, size distribution and gas-particle partitioning. The mean emission factors (EFs) of total PAHs were measured to be 2.77 ± 1.41 μg/g and 23.65 ± 14.52 μg/g for printed wiring boards and plastic casings, respectively, lower than those for coal combustion and biomass burning. Low molecular weight species were predominant in exhaust fumes, with overwhelming amounts of naphthalene (NAP) and phenanthrene (PHE) in the gaseous phase and particulate phase, respectively. The particle-size distribution exhibited the largest enrichment of total PAHs in finer particles less than 2.1 μm. Similarly, the distributions of individual species were dominated by finer particles. Most freshly emitted PAHs were liable to exist in particulate phase relative to gaseous phase. Based on the benzo[a]pyrene equivalent carcinogenic power, PAHs in particulate phase may have much stronger toxicity compared with those present in gaseous phase. The gas-particle partitioning behaviors of freshly emitted PAHs from pyrolytic processing of E-wastes were mainly regulated by absorption rather than adsorption, and the gas-particle partitioning did not reach equilibrium.

Speciation of organic fraction does matter for source apportionment. Part 1: A one-year campaign in Grenoble (France)

PM₁₀ source apportionment was performed by positive matrix factorization (PMF) using specific primary and secondary organic molecular markers on samples collected over a one year period (2013) at an urban station in Grenoble (France). The results provided a 9-factor optimum solution, including sources rarely apportioned in the literature, such as two types of primary biogenic organic aerosols (fungal spores and plant debris), as well as specific biogenic and anthropogenic secondary organic aerosols (SOA). These sources were identified thanks to the use of key organic markers, namely, polyols, odd number higher alkanes, and several SOA markers related to the oxidation of isoprene, α-pinene, toluene and polycyclic aromatic hydrocarbons (PAHs). Primary and secondary biogenic contributions together accounted for at least 68% of the total organic carbon (OC) in the summer, while anthropogenic primary and secondary sources represented at least 71% of OC during wintertime. A very significant contribution of anthropogenic SOA was estimated in the winter during an intense PM pollution event (PM₁₀>50μgm^-3 for several days; 18% of PM₁₀ and 42% of OC). Specific meteorological conditions with a stagnation of pollutants over 10days and possibly Fenton-like chemistry and self-amplification cycle of SOA formation could explain such high anthropogenic SOA concentrations during this period. Finally, PMF outputs were also used to investigate the origins of humic-like substances (HuLiS), which represented 16% of OC on an annual average basis. The results indicated that HuLiS were mainly associated with biomass burning (22%), secondary inorganic (22%), mineral dust (15%) and biogenic SOA (14%) factors. This study is probably the first to state that HuLiS are significantly associated with mineral dust.

Seasonal variation, phase distribution, and source identification of atmospheric polycyclic aromatic hydrocarbons at a semi-rural site in Ulsan, South Korea

Polycyclic aromatic hydrocarbons (PAHs) in gaseous and particulate phases (n = 188) were collected in Ulsan, South Korea, over a period of one year (June 2013‒May 2014) to understand the seasonal variation and phase distribution of PAHs as well as to identify the seasonal PAH emission sources. The target compounds were the 16 US-EPA priority PAHs, with the exception of naphthalene, acenaphthylene, and acenaphthene. Winter and spring had the highest and lowest PAH concentrations, respectively. The mean of the Σ₁₃ PAHs in the gaseous phase (4.11 ng/m³) was higher than that in the particulate phase (2.55 ng/m³). Fractions of the gaseous or 3- and 4-ring PAHs (i.e., Flu, Phe, and Ant) were high in summer, and those of the particulate or 5- and 6-ring PAHs (i.e., BkF, BaP, Ind, DahA, and BghiP) increased in winter. Gas/particle partitioning models also demonstrated the increased contributions of the particulate PAHs in spring and winter. Source identification of PAHs was undertaken using diagnostic ratios, principal component analysis, and positive matrix factorization. The results indicated that pyrogenic sources (e.g., coal combustion) were dominant in winter. Other types of pyrogenic (e.g., industrial fuel combustion) and petrogenic sources were the main PAH sources in summer and autumn. The influence of both sources, especially in summer, might be due to seasonal winds transporting PAHs from the industrial areas. Two types of pyrogenic sources, diesel and coal combustion, were identified as the main PAH sources in spring. This study clearly demonstrates a source-receptor relation of PAHs at a semi-rural site in a heavily industrialized city.

Biomass burning particles in the Brazilian Amazon region: Mutagenic effects of nitro and oxy-PAHs and assessment of health risks

Emissions from burning of biomass in the Amazon region have adverse effects on the environment and human health. Herein, particulate matter (PM) emitted from biomass burning in the Amazon region during two different periods, namely intense and moderate, was investigated. This study focused on: i) organic characterization of nitro- and oxy-polycyclic aromatic hydrocarbons (PAHs); ii) assessment of the excess lifetime cancer risk (LCR); and iii) assessment of the in vitro mutagenic effects of extractable organic matter (EOM). Further, we compared the sensitivity of two mutagenicity tests: Salmonella/microsome test and cytokinesis-block micronucleus (CBMN) with human lung cells. Among the nitro-PAHs, 2-nitrofluoranthene, 7-nitrobenz[a]anthracene, 1-nitropyrene, and 3-nitrofluoranthene showed the highest concentrations, while among oxy-PAHs, 2-metylanthraquinone, benz[a]anthracene-7,12-dione, and 9,10-anthraquinone were the most abundant. The LCR calculated for nitro-PAH exposure during intense biomass burning period showed a major contribution of 6-nitrochrysene to human carcinogenic risk. The EOM from intense period was more mutagenic than that from moderate period for both TA98 and YG1041 Salmonella strains. The number of revertants for YG1041 was 5-50% higher than that for TA98, and the most intense responses were obtained in the absence of metabolic activation, suggesting that nitroaromatic compounds with direct-acting frameshift mutagenic activity are contributing to the DNA damage. Treatment of cells with non-cytotoxic doses of EOM resulted in an increase in micronuclei frequencies. The minimal effective dose showed that Salmonella/microsome test was considerably more sensitive in comparison with CBMN mainly for the intense burning period samples. This was the first study to assess the mutagenicity of EOM associated with PM collected in the Amazon region using Salmonella/microsome test. The presence of compounds with mutagenic effects, particularly nitro- and oxy-PAHs, and LCR values in the range of 10^-5 indicate that the population is potentially exposed to an increased risk of DNA damage, mutation, and cancer.

Review on characteristics of PAHs in atmosphere, anthropogenic sources and control technologies

Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds composed of multiple aromatic rings. PAHs are ubiquitous atmospheric pollutants which are well-recognized as carcinogenic, teratogenic and genotoxic compounds. PAHs are released from incomplete combustion or pyrolysis of materials containing carbon and hydrogen, such as coal, oil, wood and petroleum products. Understanding the characteristics of PAHs in atmosphere, source profiles and technologies available for controlling PAHs emission is essential to reduce the impacts of PAHs. This paper offers an overview on concentration and distribution of atmospheric PAHs, emission factors and distribution of PAHs in different sources, and available control technologies. Characteristics of atmospheric PAHs vary with meteorological conditions and emission sources, while characteristics of PAHs emission depend on burned material and combustion condition. Combination of some technologies may be necessary for effective removal of both low-ring and high-ring PAHs.

Aerosol Health Effects from Molecular to Global Scales

Poor air quality is globally the largest environmental health risk. Epidemiological studies have uncovered clear relationships of gaseous pollutants and particulate matter (PM) with adverse health outcomes, including mortality by cardiovascular and respiratory diseases. Studies of health impacts by aerosols are highly multidisciplinary with a broad range of scales in space and time. We assess recent advances and future challenges regarding aerosol effects on health from molecular to global scales through epidemiological studies, field measurements, health-related properties of PM, and multiphase interactions of oxidants and PM upon respiratory deposition. Global modeling combined with epidemiological exposure-response functions indicates that ambient air pollution causes more than four million premature deaths per year. Epidemiological studies usually refer to PM mass concentrations, but some health effects may relate to specific constituents such as bioaerosols, polycyclic aromatic compounds, and transition metals. Various analytical techniques and cellular and molecular assays are applied to assess the redox activity of PM and the formation of reactive oxygen species. Multiphase chemical interactions of lung antioxidants with atmospheric pollutants are crucial to the mechanistic and molecular understanding of oxidative stress upon respiratory deposition. The role of distinct PM components in health impacts and mortality needs to be clarified by integrated research on various spatiotemporal scales for better evaluation and mitigation of aerosol effects on public health in the Anthropocene.

Quantifying the equilibrium partitioning of substituted polycyclic aromatic hydrocarbons in aerosols and clouds using COSMOtherm

Functional groups attached to polycyclic aromatic hydrocarbons (PAHs) can significantly modify the environmental fate of the parent compound. Equilibrium partition coefficients, which are essential for describing the environmental phase distribution of a compound, are largely unavailable for substituted PAHs (SPAHs). Here, COSMOtherm, a software based on quantum-chemical calculations is used to estimate the atmospherically relevant partition coefficients between the gas phase, the aqueous bulk phase, the water surface and the water insoluble organic matter phase, as well as the salting-out coefficients, for naphthalene, anthracene, phenanthrene, benz(a)anthracene, benzo(a)pyrene and dibenz(a,h)anthracene and 62 of their substituted counterparts. They serve as input parameters for the calculation of equilibrium phase distribution of these compounds in aerosols and clouds. Our results, which were compared with available experimental data, show that the effect of salts, the adsorption to the water surface and the dissolution in a bulk aqueous phase can be safely neglected when estimating the gas-particle partitioning of SPAHs in aerosols. However, for small PAHs with more than one polar functional group the aqueous phase can be the dominant reservoir in a cloud.

Nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) in the environment - A review

Nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) are derivatives of PAHs with at least one nitro-functional group (-NO₂) on the aromatic ring. The toxic effects of several nitro-PAHs are more pronounced than those of PAHs. Some nitro-PAHs are classified as possible or probable human carcinogens by the International Agency for Research on Cancer. Nitro-PAHs are released into the environment from combustion of carbonaceous materials (e.g. fossil fuels, biomass, waste) and post-emission transformation of PAHs. Most studies on nitro-PAHs are about air (gas-phase and particulate matter), therefore less is known about the occurrence, concentrations, transport and fate of nitro-PAHs in soils, aquatic environment and biota. Studies on partition and exchange of nitro-PAHs between adjacent environmental compartments are also sparse. The concentrations of nitro-PAHs cannot easily be predicted from the intensity of anthropogenic activity or easily related to those of PAHs. This is because anthropogenic source strengths of nitro-PAHs are different from those of PAHs, and also nitro-PAHs have additional sources (formed by photochemical conversion of PAHs). The fate and transport of nitro-PAHs could be considerably different from their related PAHs because of their higher molecular weights and considerably different sorption mechanisms. Hence, specific knowledge on nitro-PAHs is required. Regulations on nitro-PAHs are also lacking. We present an extensive review of published literature on the sources, formation, physico-chemical properties, methods of determination, occurrence, concentration, transport, fate, (eco)toxicological and adverse health effects of nitro-PAHs. We also make suggestions and recommendations about data needs, and future research directions on nitro-PAHs. It is expected that this review will stimulate scientific discussion and provide the basis for further research and regulations on nitro-PAHs.

Evaluation of a Conceptual Model for Gas-Particle Partitioning of Polycyclic Aromatic Hydrocarbons Using Polyparameter Linear Free Energy Relationships

A model for gas-particle partitioning of polycyclic aromatic hydrocarbons (PAHs) was evaluated using polyparameter linear free energy relationships (ppLFERs) following a multiphase aerosol scenario. The model differentiates between various organic (i.e., liquid water-soluble (WS)/organic soluble (OS) organic matter (OM), and solid/semisolid organic polymers) and inorganic phases of the particulate matter (PM). Dimethyl sulfoxide and polyurethane were assigned as surrogates to simulate absorption into the above-mentioned organic phases, respectively, whereas soot, ammonium sulfate, and ammonium chloride simulated adsorption processes onto PM. The model was tested for gas and PM samples collected from urban and nonurban sites in Europe and the Mediterranean, and the output was compared with those calculated using single-parameter linear free energy relationship (spLFER) models, namely Junge-Pankow, Finizio, and Dachs-Eisenreich. The ppLFER model on average predicted 96 ± 3% of the observed partitioning constants for semivolatile PAHs, fluoranthene, and pyrene, within 1 order of magnitude accuracy with root-mean-square errors (RMSE) of 0.35-0.59 across the sites. This was a substantial improvement compared to Finizio and Dachs-Eisenreich models (37 ± 17 and 46 ± 18% and RMSE of 1.03-1.40 and 0.94-1.36, respectively). The Junge-Pankow model performed better among spLFERs but at the same time showed an overall tendency for overestimating the partitioning constants. The ppLFER model demonstrated the best overall performance without indicating a substantial intersite variability. The ppLFER analysis with the parametrization applied in this study suggests that the absorption into WSOSOM could dominate the overall partitioning process, while adsorption onto salts could be neglected.