Particle-associated Polycyclic Aromatic Hydrocarbons Research Articles

Oxidation 1-methyl naphthalene based on the synergy of environmentally persistent free radicals (EPFRs) and PAHs in particulate matter (PM) surface

Studies of the environmental fate through the interactions of particle-associated polycyclic aromatic hydrocarbons (PAHs) with environmentally persistent free radicals (EPFRs) are presented. The formation of PAHs and EPFRs typically occurs side by side during combustion-processes. The laboratory simulation studies of the model PAH molecule 1-Methylnaphthalene (1-MN) interaction with model EPFRs indicate a transformational synergy between these two pollutants due to mutual and matrix interactions. EPFRs, thorough its redox cycle result in the oxidation of PAHs into oxy-/hydroxy-PAHs. EPFRs have been shown before to produce OH radical during its redox cycle in aqueous media and this study has shown that produced OH radical can transform other PM constituents resulting in alteration of PM chemistry.In model PM, EPFRs driven oxidation process of 1-MN produced 1,4-naphthoquinone, 1-naphthaldehyde, 4-hydroxy-4-methylnaphthalen-1-one, and various isomers of (hydroxymethyl) naphthalene. Differences were observed in oxidation product yields, depending on whether EPFRs and PAHs were cohabiting the same PM or present on separate PM. This effect is attributed to the OH radical concentration gradient as a factor in the oxidation process, further strengthening the hypothesis of EPFRs’ role in the PAH oxidation process.This finding is revealing new environmental role of EPFRs in a natural degradation process of PAHs. Additionally, it points to implications of such PM surface chemistry in the changing mobility of PAHs into an aqueous medium, thus increasing their bioavailability.

Development of Phase and Seasonally Dependent Land-Use Regression Models to Predict Atmospheric PAH Levels.

Polycyclic aromatic hydrocarbons (PAHs) are an important class of pollutants in China. The land use regression (LUR) model has been used to predict the selected PAH concentrations and screen the key influencing factors. However, most previous studies have focused on particle-associated PAHs, and research on gaseous PAHs was limited. This study measured representative PAHs in both gaseous phases and particle-associated during the windy, non-heating and heating seasons from 25 sampling sites in different areas of Taiyuan City. We established separate prediction models of 15 PAHs. Acenaphthene (Ace), Fluorene (Flo), and benzo [g,h,i] perylene (BghiP) were selected to analyze the relationship between PAH concentration and influencing factors. The stability and accuracy of the LUR models were quantitatively evaluated using leave-one-out cross-validation. We found that Ace and Flo models show good performance in the gaseous phase (Ace: adj. R2 = 0.14-0.82; Flo: adj. R2 = 0.21-0.85), and the model performance of BghiP is better in the particle phase (adj. R2 = 0.20-0.42). Additionally, better model performance was observed in the heating season (adj R2 = 0.68-0.83) than in the non-heating (adj R2 = 0.23-0.76) and windy seasons (adj R2 = 0.37-0.59). Those gaseous PAHs were highly affected by traffic emissions, elevation, and latitude, whereas BghiP was affected by point sources. This study reveals the strong seasonal and phase dependence of PAH concentrations. Building separate LUR models in different phases and seasons improves the prediction accuracy of PAHs.

The Aryl Hydrocarbon Receptor in Asthma: Friend or Foe?

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that has emerged as an important player in asthma control. AhR is responsive to environmental molecules and endogenous or dietary metabolites and regulates innate and adaptive immune responses. Binding of this receptor by different ligands has led to seemingly opposite responses in different asthma models. In this review, we present two sides of the same coin, with the beneficial and deleterious roles of AhR evaluated using known endogenous or exogenous ligands, deficient mice or antagonists. On one hand, AhR has an anti-inflammatory role since its activation in dendritic cells blocks the generation of pro-inflammatory T cells or shifts macrophages toward an anti-inflammatory M2 phenotype. On the other hand, AhR activation by particle-associated polycyclic aromatic hydrocarbons from the environment is pro-inflammatory, inducing mucus hypersecretion, airway remodelling, dysregulation of antigen presenting cells and exacerbates asthma features. Data concerning the role of AhR in cells from asthmatic patients are also reviewed, since AhR could represent a potential target for therapeutic immunomodulation.

Seasonal and annual changes in PAH concentrations in a remote site in the Pacific Ocean

This paper reports the long term observation of particle-associated polycyclic aromatic hydrocarbons (PAHs) at Cape Hedo Atmosphere and Aerosol Monitoring Station, a remote site in the Western Pacific Ocean, from 2008 to 2015. This is the first long-term study that evaluated the contribution of long-range transport of PAHs in East Asia. No obvious trend (P > 0.05) was found in a particular season over the years. However, there are seasonal variations of PAH concentrations with higher in spring and winter. The higher PAH are attributed to air masses from the area including part of China. Source apportionment using three different approaches, i.e., PAH compositional pattern analysis, PAH diagnostic ratio analysis and positive matrix factorization modeling, showed the combined high contribution of biomass burning (18%, 14%) and coal combustion (33%, 24%) in spring and winter. In addition, the contribution of ship emissions (35%) was relatively high in spring, whereas that of vehicle emissions (36%) was relatively high in winter. The contribution of coal combustion to PAH has decreased throughout the years, likely due to changes in energy structure in China. The contribution of biomass burning to PAH has showed no trend, being stable, and that of vehicular emissions has increased.

Particle-associated polycyclic aromatic hydrocarbons in a representative urban location (indoor-outdoor) from South Europe: Assessment of potential sources and cancer risk to humans.

PM10 -bound polycyclic aromatic hydrocarbons (PAHs) levels were monitored at urban locations (outdoor/indoor) within the city of Madrid between May 2017 and April 2018. Fourteen PAH congeners were measured, potential emission sources were identified as were potential carcinogenic risks. The ΣPAHs averaged 0.577 and 0.186ng/m3 in outdoor and indoor air, with a high linear correlation per individual mean PAH and month. The largest contributors to the ΣPAHs were the high-molecular-weight PAHs. Principal component analysis-multiple linear regression results showed that emissions from diesel and vehicular processes explained 27% and 23% of the total variance of outdoor and indoor air, while combustion processes accounted for 30% and 25% in ambient and indoor air, respectively. During the cold season, biomass burning plus coal and wood combustion were additional sources of outdoor emissions. The heavy-, medium- and light-molecular-weight PAH originating from outdoor sources accounted for 72%, 80%, and ~60% of the indoor levels of the three respective PAH groups. Average BaP concentration was 0.029 and 0.016ng/m3 in outdoor and indoor air, respectively. Estimated BaPeq concentration averaged 0.072, 0.035, and 0.027ng/m3 for outdoor, indoor, and indoor-generated individual PAH concentrations, respectively. The estimated carcinogenic risk falls within the range of acceptable risk targeted by the US-EPA.

Airborne and Dermal Exposure to Polycyclic Aromatic Hydrocarbons, Volatile Organic Compounds, and Particles among Firefighters and Police Investigators.

The main aim of this study was to assess dermal exposure to polycyclic aromatic hydrocarbons (PAHs) and airway exposure to PAHs, volatile organic compounds (VOCs; benzene and 1,3-butadiene), and particles among firefighters (FFs) and police forensic investigators (PFIs) in Sweden. Active (pump with a filter and sorbent tube) and passive (polyurethane foam -cyl and perkin elmer carbopack-tube) personal air sampling and dermal tape stripping (wrist and collar bone) were performed on seven FF team leaders during training fires and nine PFIs investigating the aftermath of live fire events. In addition, passive personal air sampling was performed on eight FF team leaders during live emergency fires. PAHs and VOCs were analysed using high-resolution gas chromatography low-resolution mass spectrometry. The mass concentration of total dust (particles) was determined using standard gravimetric methods. The air samples showed that the exposure to PAHs, benzene, 1,3-butadiene, and particles was below Swedish occupational exposure limits (OELs). Naphthalene was the predominant PAH in all air samples. Benzene and 1,3-butadiene were more abundant in live emergency fires, which caused higher exposures than the other studied situations. Both gaseous- and particle-associated PAHs were present on skin. The wrists seemed to be less well protected than the collarbone area. FFs and PFIs are exposed to several hazardous compounds during their work. Air exposures varied considerably between working scenarios. The observed exposures were substantially higher than urban background levels but well below Swedish OELs. The measured dermal PAH exposures were comparable to previously reported doses for US FFs but lower than the exposures reported for Swedish chimney sweeps.

A method for assessing carcinogenic risk of air fine particle-associated polycyclic aromatic hydrocarbons by considering bioaccessibility in lung fluids

This study was conducted to evaluate the inhalation carcinogenic risk of PAHs in biochar fine particles using total concentration-based assessment approach and bioaccessibility-based assessment approach. Only limit PAHs in particles can be released in simulated lung fluids, leading to a low bioaccessibility (only ranging from 0.34% to 1.48% for biochar fine particles and from 3.21% to 44.2% for PM2.5), which would significantly affect health risk assessment. Therefore, bioaccessibility should always be favored over more traditional evaluations based on total concentration, while evaluating inhalation health risks of biochar-bound PAHs. To prove the broad applicability of bioaccessibility-based assessment approaches, we also compared health risk of actual atmospheric particles (PM2.5 collected from Nanjing, China) using total concentration-based approaches and bioaccessibility-based approaches.•Proposed bioaccessibility-based approaches for assessing biochar risk are more accurate than traditional total concentration-based approaches;•Proposed bioaccessibility-based approaches can be applied to health risk assessment of actual air particles;•A more practical method was proposed to evaluate the bioaccessibility of PAHs in biochar fine particles or other specific component of atmospheric particle matters: using wet sieving method to prepare fine particles, using volatile organic solvent-drying method to load 14C-PAHs on fine particles, and using desorption experiments to determine bioaccessibility of PAHs.

A preliminary study on the role of suspended particulate matter in the bioavailability of oil-derived polycyclic aromatic hydrocarbons to oysters

Suspended particulate matter (SPM) refers to fine-grained materials that are suspended in water columns. By providing a surface for the adsorption of non-polar organic compounds, SPM is a carrier for persistent and toxic contaminants. A wide range of organic pollutants, including polycyclic aromatic hydrocarbons (PAHs), can be adsorbed onto SPM. The formation of particle-associated PAHs can sequentially increase the potential for exposure to and bioaccumulation by organisms. Until recently, most oil exposure studies were performed using freely dissolved and dispersed forms, and therefore the role of SPM in influencing the bioavailability and bioaccumulation of PAHs has not been considered. This study found that SPM influences the bioavailability of petrogenic PAHs in the water column and their potential for accumulation in oysters. SPM significantly enhanced the water column entrainment of petrogenic PAHs, thus increasing the potentials for uptake by exposed organisms. PAHs in the water column was highest from mechanically dispersed oil (MDO; 2.27 μg/mL) ≥ oil-SPM aggregate (OSA; 1.96 μg/mL) > water accommodated fraction (WAF; 0.19 μg/mL) but the percentage of PAHs accumulated in oysters were highest from WAF (18.3%) > MDO (14.2%) > OSA (9.62%). Despite the high water column available PAHs, oysters exposed to SPM-associated oil accumulated PAHs at half the accumulation efficiency compared with those exposed to PAHs without SPM.

Role of fluoranthene and pyrene associated with suspended particles in their bioaccumulation by zebrafish (Danio rerio)

Hydrophobic organic compounds (HOCs) tend to be associated with suspended particles in surface aquatic systems, however, the bioavailability of HOCs on suspended particles to fish is not well understood. In this study, a passive dosing device was used to control the freely dissolved concentrations (Cfree) of polycyclic aromatic hydrocarbons (PAHs) including fluoranthene and pyrene, and the influence of particle-associated PAHs on their bioaccumulation by zebrafish was investigated. The results showed that, when the Cfree of PAHs were kept constant, the presence of suspended particles did not significantly affect the steady state of PAH bioaccumulation in zebrafish tissues excluding head and digestive tracts, suggesting that the bioaccumulation steady state was controlled by the freely dissolved concentrations of PAHs. However, suspended particles promoted the uptake and elimination rate constants of PAHs in zebrafish body excluding head and digestive tracts. The uptake rate constants with 0.5 g/L suspended particles were approximately twice of those without suspended particles, and the body burden in zebrafish increased by 16.4% − 109.3% for pyrene and 21.8% − 490.4% for fluoranthene during the first 8-d exposure. This was due to the reasons that suspended particles could be ingested, and part of PAHs associated with them could be desorbed in digestive tract and absorbed by the zebfrafish, leading to the enhancement of uptake rates of PAHs in zebfrafish. The findings obtained from this study indicate that PAHs on suspended particles are partly bioavailable to zebrafish and particle ingestion is an important route in PAH bioaccumulation. Therefore, it is important to consider the bioavailability of HOCs on suspended particles to improve ecological risk assessment.

Validation of Miniaturized Particulate-Matter Real-Time Samplers for Characterizing Personal Polycyclic Aromatic Hydrocarbon Exposure.

This study validates the analysis of polycyclic aromatic hydrocarbons (PAHs) in microgram levels of particulate matter (PM) collected on filters by two low-flow rate, real-time monitors, microPEM™ and microAeth®. Particle-associated PAHs were analyzed by a coupling of a gas chromatograph to a sensitive, atmospheric-pressure laser ionization-mass spectrometer. Air particulate samples were collected over the course of one or two days in the living room of a fourth-floor apartment in New York City. Three types of samplers, the two aforementioned personal samplers and a high-flow rate pump (4 liters per minute), were operated side by side, and three samples of each type were collected during each sampling period. Intrasampler agreement as measured by relative standard deviation (RSD) was within 1% to 18%. After background subtraction, total PAH measured by all three sampler types had good agreement (R=0.99). This ability to accurately characterize personal PAH exposure in archived filters collected by these real-time samplers could provide additional important PAH exposure information that can benefit many environmental health studies using these monitors.

Particle-Associated Polycyclic Aromatic Hydrocarbons (PAHs) in the Atmosphere of Hefei, China: Levels, Characterizations and Health Risks.

Airborne PM2.5 and PM10 samples were collected in summertime (August 2015) and wintertime (December 2015-January 2016) in an industrial complex area in Hefei, China. The average concentrations of PM2.5 and PM10 (90.5 and 114.5μg/m3, respectively) were higher than the regulated levels of China National Ambient Air Quality Standard (grade I) and the WHO Ambient (outdoor) Air Quality and Health Guideline Value. Seasonal variations in PM2.5/PM10 indicated that the secondary sources of particulate matters, formed by gas-to-particle conversion, were enhanced in summer due to longer time of solar radiation and higher temperature. The total concentrations of PM2.5- and PM10-associated PAHs were 5.89 and 17.70ng/m3 in summer as well as 63.41 and 78.26ng/m3 in winter, respectively. Both PM2.5- and PM10-associated PAHs were dominated by 4- to 6-ring PAHs, suggesting that the fossil fuel combustion and vehicle emissions were the primary sources of PAHs in atmospheric particulate matters in Hefei. The total concentration of PAHs had a slightly higher correlation coefficient with PM2.5 (R=0.499, P<0.05) than PM10 (R=0.431, P>0.05), indicating the higher association tendency of PAHs with PM2.5. The coefficient of divergence analysis showed that the compositions of PAH were quite different between summer and winter. Total BaP equivalent concentration (BaP-TEQ) for particulate-bound PAHs in winter (58.87ng/m3) was higher than that in summer (5.53ng/m3). In addition, particulate-bound PAHs in winter had an inhalation cancer risk (ICR) value of 2.8×10-3, which was higher than the safe range (10-4-10-6).

Correlation between Polycyclic Aromatic Hydrocarbon Concentration and Particulate Matter during the Removal Process of a Low-Low Temperature Electrostatic Precipitator

To check the relation between polycyclic aromatic hydrocarbons (PAHs) and particulate matter (PM), this study chose a low-low temperature electrostatic precipitator (LLT-ESP) in an ultra-low-emission coal-fired power plant to study the mechanism at two operation conditions. Sixteen U.S Environmental Protection Agency PAHs in filterable and condensable PM were analyzed. The removal efficiency of the LLT-ESP for filterable PM2.5 was 98.8% and 98.4% at two different stages. The removal efficiency of the LLT-ESP for condensable PM was 77.1% at high temperature and 89.6% at low temperature. The boiler load markedly affected the emission of filterable PM, condensable PM, and particle-associated PAHs. The PAHs’ concentration distribution was related to the PM concentration distribution. The mass concentration of total PAHs and the proportion of 5-ring and 6-ring PAHs in filterable PM2.5 increased significantly when the flue gas passed through the LLT-ESP. The 3- and 4-ring PAHs accounted for the main part of con...

Influence of urbanization on air quality based on the occurrence of particle-associated polycyclic aromatic hydrocarbons in a tropical semiarid area (Fortaleza-CE, Brazil)

This study reports the first measurements of polycyclic aromatic hydrocarbons (PAHs) in particulate matter in the metropolitan area of Fortaleza-CE, Brazil. We studied the influence of urban topography on the occurrence of PAHs and the depositional flux (F PAHs) and characterized the emission sources and health risks of PAHs. Of the 16 PAHs evaluated, only 10 PAHs with more than 4 aromatic rings were found. The total PAH concentration (ΣPAHs) ranged from 1.73 to 2.83 ng m−3. The F PAHs value ranged from 0.008 to 0.0182 μg m−2 day−1. These fluxes are comparable to the values obtained at sites with developing urbanization or sites that use heating; however, they are smaller than the values obtained at industrial and large metropolis sites. An examination of the influence of urban topography revealed that the building density considerably increased the particulate matter concentration; however, urban vegetation had the opposite effect. Light-duty vehicles were the most important emission source of PAHs in the metropolitan area of Fortaleza. However, industrial activities (e.g., asphalt and steel production), combustion (e.g., coal and wood), and paved roads had a modest contribution. The health risk from PAHs in Fortaleza is higher at sites with a higher traffic flow, and the level of this health risk is similar to the risk level in other developing cities.

Dry and wet deposition of polycyclic aromatic hydrocarbons and comparison with typical media in urban system of Shanghai, China

Polycyclic aromatic hydrocarbons (PAHs) were studied in dry and wet deposition samples collected at urban and suburban sites of Shanghai, China from April 2014 to April 2015. Average wet deposition fluxes of PAHs were higher than dry deposition (62.6 ± 41.5 vs. 26.9 ± 14.4 μg/m2/day). However, dry deposition removed more PAHs than wet deposition (69% vs. 31%) due to much shorter durations of wet deposition. The highest dry and wet deposition fluxes were in fall and winter, respectively. The highest amount of dry deposition was in fall and the highest of wet deposition was in summer. The contribution of wet deposition to total deposited PAHs in Shanghai, East China was higher than that in northern China and lower than that in southern China. The difference can be explained by both precipitation amount and removal efficiency (washout ratio). Average dry deposition velocity and washout ratio of particle-associated PAHs were 5.2 cm/s and 5.8 × 104, respectively. Four sources of deposited PAHs were unraveled by positive matrix factorization (PMF) model: traffic, coal combustion, coking and volatilization, contributing 28.7%, 24.6%, 23.7% and 23.0%, respectively. More contribution of traffic and less coal combustion and volatilization were found at urban than at suburban site. As the connection between aerosol and surface soil, deposition had a different PAH composition from those in the two sides, containing more low MW PAHs. That arose the concern that dry deposition velocity and particle washout ratio could be overestimated if coarse particulate matter was excluded from the calculation. Although deposition has been considered as the predominant pathway of PAHs to urban surface system, the PAH composition in street dust differed drastically from that in deposition. This indicated that other sources (e.g. traffic) in urban system could have a greater contribution to PAHs than it had been identified in deposition samples.

Determination of Particle-Associated PAH Derivatives (ClPAHs, NPAHs, OPAHs) in Ambient Air and Automobile Exhaust by Gas Chromatography/Mass Spectrometry with Negative Chemical Ionization

ABSTRACTThe concentrations of functionalized polycyclic aromatic hydrocarbons (PAHs), i.e., oxygenated PAHs (OPAHs), nitrated PAHs (NPAHs), and chlorinated PAHs (ClPAHs), in soluble organic fractions of automobile exhaust particles (NIST SRM 1975 and NIES CRM No.8) and airborne particles (NIST SRM1648a and PM2.5 collected at Kyoto, Japan) were simultaneously determined using gas chromatography–mass spectrometry with negative chemical ionization (GC–NCI–MS). The concentrations of PAH derivatives in standard reference materials determined by GC–NCI–MS were in good agreement with the certified and literature values. Ten OPAHs, 12 NPAHs, and 12 ClPAHs were detected in ambient PM2.5 collected in Kyoto, Japan by the proposed analytical method.

Determination of semi-volatile and particle-associated polycyclic aromatic hydrocarbons in Stockholm air with emphasis on the highly carcinogenic dibenzopyrene isomers

The concentrations of polycyclic aromatic hydrocarbons (PAHs) have been determined in the gaseous phase and in various particulate matter (PM) size fractions at different locations in and outside of Stockholm, Sweden, representative of street level, urban and rural background. The focus has been on the seldom determined but highly carcinogenic dibenzopyrene isomers (DBPs) dibenzo[a,l]pyrene, dibenzo[a,e]pyrene, dibenzo[a,i]pyrene and dibenzo[a,h]pyrene. PAHs with 3 rings were found to be mainly associated with the vapor phase (>90%) whereas PAHs with 5–6 rings were mostly associated with particulate matter (>92%) and the 4-ringed PAHs partitioned between the two phases. PAH abundance was determined to be in the order street level > urban background > rural background with the PM10 street level 2010 mean of benzo[a]pyrene (B[a]P) reaching 0.24 ng/m3, well below the EU annual limit value of 1 ng/m3. In addition, higher PAH concentrations were found in the sub-micron particle fraction (PM1) as compared to the super-micron fraction (PM1-10) with the abundance in PM1 varying between 57 and 86% of the total PAHs.The B[a]P equivalent concentrations derived for DB[a,l]P and total DBPs exceeded 1–2 and 2–4 times, respectively, that of B[a]P at the four sampling sites; therefore underestimation of the cancer risk posed by PAHs in air could be made if the DBPs were not considered in risk assessment using the toxic equivalency approach, whilst the high correlation (p < 0.001) found in the relative concentrations supports the use of B[a]P as a marker substance for assessment of the carcinogenic risk associated to PAHs. However, the big difference in concentration ratios of B[a]P and the DBPs between the present study and some literature data calls for further research to evaluate the temporal and spatial invariance of the B[a]P/DBP ratios.

Atmospheric polycyclic aromatic hydrocarbons (PAHs) of southern Taiwan in relation to monsoons.

The concentrations and gas-particle partitioning of atmospheric polycyclic aromatic hydrocarbons (PAHs) were intensively measured in the Hengchun Peninsula of southern Taiwan. The concentrations of total PAH (Σ38PAH), including gas and particle phases, ranged from 0.85 to 4.40ngm(-3). No significant differences in the PAH levels and patterns were found between the samples taken at day and at night. The gas phase PAH concentrations were constant year-round, but the highest levels of particle-associated PAHs were found during the northeast monsoon season. Long-range transport and rainfall scavenging mechanisms contributed to the elevated levels in aerosols andΣ38PAH concentrations. Results from principal component analysis (PCA) indicated that the major sources of PAHs in this study were vehicular emissions. The back trajectories demonstrated that air mass movement driven by the monsoon system was the main influence on atmospheric PAH profiles and concentrations in the rural region of southern Taiwan. Gas-particle partition coefficients (K p ) of PAHs were well-correlated with sub-cooled liquid vapor pressures (P (o) L ) and demonstrated significant seasonal variation between the northeast (NE) and the southwest (SW) monsoon seasons. This study sheds light on the role of Asian monsoons regarding the atmospheric transport of PAHs.

Measurements and source apportionment of particle-associated polycyclic aromatic hydrocarbons in ambient air in Riyadh, Saudi Arabia

Ambient air samples were obtained in Riyadh, the capital and largest city of Saudi Arabia, during two measurement campaigns spanning September 2011 to September 2012. Sixteen particle-phase polycyclic aromatic hydrocarbons (PAH) were quantified in 167 samples. Pyrene and fluoranthene were the most abundant PAH, with average of 3.37 ± 14.01 ng m−3 and 8.00 ± 44.09 ng m−3, respectively. A dominant contribution from low molecular weight (LMW) PAH (MW < 228) suggested a large influence of industrial emissions on PAH concentrations. Monte Carlo source apportionment using diagnostic ratios showed that 80 ± 10% of the average LMW PAH concentrations were contributed by petroleum vapor emissions, while 53 ± 19% of high molecular weight (HMW) PAH were from solid fuel combustion emissions. The positive matrix factorization model estimated that oil combustion emissions dominated total PAH concentrations, accounting for on average 96%, likely due to widespread use of oil fuels in energy production (power plants and industries). Our results demonstrate the significant influence of petroleum product production and consumption on particulate-phase PAH concentrations in Riyadh, but also point to the importance of traffic and solid fuel burning, including coke burning and seasonal biomass burning, especially as they contribute to the ambient levels of HMW PAH.

Suspended particle-associated PAHs in the open eastern Mediterranean Sea: Occurrence, sources and processes affecting their distribution patterns

In this study, we report spatial and vertical profiles of suspended particle-associated polycyclic aromatic hydrocarbons (PAHs) collected from nine stations across the open eastern Mediterranean Sea (Ionian and northwestern Levantine Seas — EMS) corresponding to various water column depths (1008–4087m). Concentrations of total determined PAHs (sum of 16 compounds) ranged between 90.6 and 918pgL−1 comparable to those reported for unpolluted open/deep-sea settings. Values recorded for particles in mesopelagic and bathypelagic waters were fairly comparable to those measured in surface particulate matter, implying that deep EMS waters constitute a pollutant depository. The occurrence of the studied PAHs is attributed to a mixed contribution from both fossil and pyrolytic compounds, while results are indicative of chronic petrogenic pollution in the study area, with a prominent fossil PAHs signal in deep waters. The residence time of suspended particle-associated PAHs in the water column (considering only particle settling) was estimated at approximately 30y, while their spatial and vertical distribution patterns exhibited distinct characteristics amongst the studied sites with their overall occurrence and fate being controlled by both biogeochemical processes and water mass circulation patterns.

Personal Exposure of Children to Particle-Associated Polycyclic Aromatic Hydrocarbons in Tianjin, China

Polycyclic aromatic hydrocarbons (PAHs) associated with fine particles are harmful to human health, particularly to children, who are most vulnerable. To evaluate the respiratory exposure of children to particle-associated PAHs properly, personal air sampling near breathing zone of 36 schoolchildren were conducted in Tianjin, China. Sixteen priority PAHs designated by the United States Environmental Protection Agency were measured using GC-MS. The average concentrations of personal exposure to ∑16PAH were 27.31 ± 3.91 ng/m3 in summer and 58.18 ± 24.68 ng/m3 in winter. Moreover, PAH profiles were studied and the results showed NAP, BbF, and IPY were the most abundant PAHs. Five rings PAH species made up the largest proportion, accounting for 25.7% in summer and 32.6% in winter. Diagnostic ratios and principal component analysis indicated combustion activities were the major source for children exposure to particle-associated PAHs in this study. According to the risk assessment results, the inhalation exposure risk for children were higher than the acceptable risk level of 10–6, indicating the health issues of children should be paid more attention. On the basis of sensitivity analysis results, further research should be done to improve the inhalation cancer slope factor of BaP and the concentration distribution of PAHs in order to improve the accuracy of the health risk assessment.