Gaseous Polycyclic Aromatic Hydrocarbons Research Articles

The assessment of organic contaminants at a paint manufacturing site: implications for health risks and source identification

The daily variation of organic contaminants, both gaseous and associated with suspended particulate matter, was investigated within the National Company of Paintings estate in Lakhdaria, Algeria, spanning the period 2014-2015. The research emphasizes the chemical characterization of suspended particulate matter, analyzing a range of organic compounds, including n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and highly polar organics (HPOC), such as phthalate esters and heterocyclic compounds. Vapours of PAHs and polychlorobiphenyls (PCBs) were also analyzed. Low molecular weight compounds were primarily associated with the gas phase (2-ring PAHs, approximately 95%; 3-ring PAHs, around 70%), while high molecular weight congeners were mainly associated with the particle phase (6-ring PAHs, 55%). The concentrations of PCBs (ranging from 0.6 to 42 ng m-3) were higher than those reported in other cities in Algeria and Europe. The source reconciliation of organic contaminants through principal component analysis (PCA) demonstrated that the primary sources were petroleum combustion, industrial manufacturing, tobacco smoking, and vehicular traffic. The significance of tobacco smoke was further confirmed by the analysis of PAHs diagnostic ratios. The variations in diagnostic ratio rates between gaseous and particulate PAHs were attributed to distinct contributions from sources such as industrial processes. Health risks for workers exposed to PAHs and PCBs in PM10 were quantitatively assessed in terms of Benzo[a]pyrene equivalent concentration (BaPeq) and incremental lifetime cancer risk (ILCR). ILCR presents novel findings, showcasing heightened risks among workers exposed to specific PAHs within production areas, whereas that related to PCBs suggested a high potential health risk for laboratory workers.

Seasonal and Emission Characteristics of PAHs in the Ambient Air of Industrial Complexes

Particulate and gaseous polycyclic aromatic hydrocarbon (PAHs) samples (n = 108) were measured every six days from January to December 2022 at a representative point in the Korean Banwol National Industrial Complex. The measurement results revealed that the concentration of particulate Σ18 PAHs was 7.92 ± 4.04 ng/Sm3 in winter, 1.83 ± 1.99 ng/Sm3 in spring, 1.43 ± 0.95 ng/Sm3 in summer, and 2.58 ± 2.14 ng/Sm3 in autumn. The concentration of gaseous Σ18 PAHs was 3.32 ± 3.72 ng/Sm3 in winter, 6.34 ± 5.95 ng/Sm3 in spring, 8.33 ± 8.13 ng/Sm3 in summer, and 3.88 ± 1.71 ng/Sm3 in autumn. The results of the correlation analysis showed that particulate PAHs have positive relationships with PM10 and PM2.5 and negative relationships with temperature and O3. The diagnostic ratio and PAHs component slope showed that the emission source characteristics of the Banwol National Industrial Complex were dominated by biomass coal combustion over four seasons; however, the influence of petroleum combustion (automobile emissions) was not negligible. As for coal combustion, bituminous coal was the most influential, and lignite was relevant in summer and autumn.

Impact of Atmospheric Conditions and Source Identification of Gaseous Polycyclic Aromatic Hydrocarbons (PAHs) during a Smoke Haze Period in Upper Southeast Asia.

Gaseous polycyclic aromatic hydrocarbons were measured in northern Thailand. No previous studies have provided data on gaseous PAHs until now, so this study determined the gaseous PAHs during two sampling periods for comparison, and then they were used to assess the correlation with meteorological conditions, other pollutants, and their sources. The total concentrations of 8-PAHs (i.e., NAP, ACY, ACE, FLU, PHE, ANT, FLA, and PYR) were 125 ± 22 ng m-3 and 111 ± 21 ng m-3, with NAP being the most pronounced at 67 ± 18 ng m-3 and 56 ± 17 ng m-3, for morning and afternoon, respectively. High temperatures increase the concentrations of four-ring PAHs, whereas humidity and pressure increase the concentrations of two- and three-ring PAHs. Moreover, gaseous PAHs were estimated to contain more toxic derivatives such as nitro-PAH, which ranged from 0.02 ng m-3 (8-Nitrofluoranthene) to 10.46 ng m-3 (1-Nitronaphthalene). Therefore, they could be one of the causes of local people's health problems that have not been reported previously. Strong correlations of gaseous PAHs with ozone indicated that photochemical oxidation influenced four-ring PAHs. According to the Pearson correlation, diagnostic ratios, and principal component analysis, mixed sources including coal combustion, biomass burning, and vehicle emissions were the main sources of these pollutants.

Firefighters' personal exposure to gaseous PAHs during controlled forest fires: A case study with estimation of respiratory health risks and in vitro toxicity

Firefighters are daily exposed to adverse health-hazardous pollutants. Polycyclic aromatic hydrocarbons (PAHs), well known endocrine disruptors with carcinogenic, mutagenic, and teratogenic properties, are among the most relevant pollutants. The characterization of firefighters' occupational exposure to airborne PAHs remains limited; information is scarce for European firefighters. Also, the in vitro assessment of firefighters' respiratory health risks is inexistent. To reply to these scientific gaps, this work characterizes the levels of gaseous PAH in firefighters' personal air during regular working activities at controlled forest fires and at fire stations (control group). Breathable levels were 2.2–26.7 times higher during fire events than in the control group (2.63–32.63 μg/m3versus 1.22 μg/m3, p < 0.001); the available occupational guidelines (100 and 200 μg/m3 defined by the US National Institute for Occupational Safety and Health and the North American Occupational Safety and Health Administration, respectively) were not exceeded. Concentrations of (possible/probable) carcinogenic PAHs were 1.9–15.3 times superior during firefighting (p < 0.001). Increased values of total benzo(a)pyrene equivalents (p = 0.101), dose rates (p < 0.001), and carcinogenic risks (p = 0.063) were estimated in firefighters during controlled fires comparatively with the control group. Firefighters' breathable gaseous phase collected during fire events contributed to induce a significant viability decrease (<70 %; p < 0.05) in A549 and Calu-3 cell lines. The principal component analysis (PCA) allowed the differentiation between firefighters participating in controlled fire events from the control group. PCA analysis demonstrated the potential of PAHs to distinguish different sources of firefighters´ occupational exposure and of combining estimated health risk parameters with in vitro toxicities determined with human-breathable air collected during real-life scenarios. Overall, the participation in controlled fire events contributes to the respiratory health burden of firefighting forces. However, more studies are needed to corroborate these preliminary findings, explore the respiratory toxicological mechanisms, and support the implementation of preventive actions and mitigation strategies to pursue firefighters' health.

Estimation of gaseous polycyclic aromatic hydrocarbons (PAHs) and characteristics of atmospheric PAHs at a traffic site in Kanazawa, Japan

Size-fractionated particulate matter (PM2.5 and PM>2.5) was collected at a traffic site in Kanazawa, Japan in a seasonal sampling work in 2020. Nine polycyclic aromatic hydrocarbons (4- to 6-ring PAHs) were determined in fine and coarse particles. The gas/particle partitioning coefficients (Kp) of the PAHs were calculated from the supercooled liquid vapour pressure and octanol-air partitioning coefficient based on the relationships obtained in previous traffic pollution-related studies. Gaseous PAHs were estimated by Kp and the concentrations of PM and particulate PAHs. The concentrations of total PAHs were 32.5, 320.1 and 5646.2 pg/m3 in the PM>2.5, PM2.5 and gas phases, respectively. Significant seasonal trends in PAHs were observed (particle phase: lowest in summer, gas phase: lowest in spring, particle and gas phase: lowest in spring). Compared to 2019, the total PAH concentrations (in particles) decreased in 2020, especially in spring and summer, which might be due to reduced traffic trips during the COVID-19 outbreak. The incremental lifetime cancer risk (ILCR) calculated from the toxic equivalent concentrations relative to benzo[a]pyrene (BaPeq) was lower than the acceptable limit issued by the US Environmental Protection Agency, indicating a low cancer risk in long-term exposure to current PAH levels. It is notable that gaseous PAHs considerably contributed to BaPeq and ILCR (over 50%), which highlighted the significance of gaseous PAH monitoring for public health protection. This low-cost estimation method for gaseous PAHs can be expected to reliably and conveniently obtain PAH concentrations as a surrogate for traditional sampling in the future work.

Development of an Online Instrument for Continuous Gaseous PAH Quantification: Laboratory Evaluation and Comparison with The Offline Reference UHPLC-Fluorescence Method

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants formed during incomplete combustion or pyrolysis of organic material. The reliable quantification of PAH in airborne samples is still difficult, costly, and time-consuming due to the use of offline techniques, including long sampling on filters/adsorbents, laboratory extraction, purification, and concentration steps before analysis. To tackle these drawbacks, this work focused on the development of a fully automatic gas chromatograph (GC) equipped with a flame ionization detector (FID) and a sample preconcentration unit (PC) for gas sampling. This instrument was validated under laboratory-controlled conditions in the range 0–10 ng for 18 PAH. The chromatographic separation was rather satisfactory except for two PAH pairs, which were quantified together. For all compounds, the peak areas increased perfectly with the gaseous PAH concentration (R2 &gt; 0.98), without any significant memory effect between two consecutive analyses. Considering a gaseous sample volume of 1 L, the extrapolated limits of detections (LOD) were in the range 19.9–62.6 ng/m3, depending on the PAH. Its analytical performances were then compared to those of the offline reference UHPLC-fluorescence method, widely used for airborne PAH monitoring. This was also compared with the very few portable or continuously operating instruments.

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.

Effectively removing gaseous polycyclic aromatic hydrocarbons (PAHs) by willow catkins: Do you still dislike the catkins floating?

The floating catkins generated by willow and poplar trees have been criticized for spreading germ and causing fire for decades. It has been found that catkins are with a hollow tubular structure, which made us wonder if the floating catkins can adsorb atmospheric pollutions. Thus, we conducted a project in Harbin, China to investigate whether and how willow catkins could adsorb atmospheric polycyclic aromatic hydrocarbons (PAHs). The results suggest that both the catkins floating in the air and on the ground preferred to adsorb gaseous PAHs rather than particulate PAHs. Moreover, 3- and 4-ring PAHs were the dominating compositions adsorbed by catkins, which significantly increased with exposure time. The gas/catkins partition (KCG) was defined, which explained why 3-ring PAHs are more easily adsorbed by catkins than by airborne particles when their subcooled liquid vapor pressure is high (log PL > −1.73). The removal loading of atmospheric PAHs by catkins were estimated as 1.03 kg/year in the center city of Harbin, which may well explain the phenomenon that levels of gaseous and total (particle + gas) PAHs are relatively low in the months with catkins floating reported in peer-reviewed papers.

Gaseous polycyclic aromatic hydrocarbons over the South China Sea: Implications for atmospheric transport under monsoon influences

The seasonal monsoon variations have significant impact on the atmospheric transport of semi-volatile organic pollutants over the South China Sea (SCS). We analyzed polycyclic aromatic hydrocarbons (PAHs) over the basin and island areas (Yongxing Island and Yongshu Island) in 2017. Gaseous PAHs (0.17–1.4 ng m−3) showed spatio-temporal distinctions in their composition and sources among the basin and island areas. Mixed combustion sources of PAHs were identified over the SCS, including a petroleum source near the island areas. The transport routes of PAHs were inferred by the air mass back trajectories and potential source contribution factor analysis, identifying strong biomass burning signals from the Indochina Peninsula and other Southeast Asian countries. Emissions from approximately 90 % of the combustion sources were transported to basin areas by monsoons, whereas the island areas were dominated by local emissions. This study emphasizes the main potential terrestrial source of PAHs over the SCS under monsoon influences.

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.

Physicochemical characteristics of polycyclic aromatic hydrocarbons in condensable particulate matter from coal-fired power plants: A laboratory simulation

The objective of this study was to examine the physicochemical characteristics of polycyclic aromatic hydrocarbons (PAHs) in condensable particulate matter (CPM) during fast condensation (within several seconds). The concentration of PAHs increased as the condensation temperature decreased, indicating that the conversion of gaseous PAHs to CPM would be enhanced at low temperatures. PAH concentrations increased in relation to the number of rings in the fragment, with the high-ring (4-,5- and 6-ring) PAHs accounting for 89.70–92.30% and 99.78–99.80% of the total concentration and total toxic equivalent of PAHs. In addition, particulate-phase PAHs (0.1–1.0 μm), developed through the synergistic effect of PAHs and fine particles, were difficult to collect by fast condensation. Inorganic fine particles could be formed when ammonia-rich conditions prevail, reducing PAH condensation further. Furthermore, CPM was morphologically and chemically characterized. During the experiment, fine and well-aggregated CPMs were detected on the membrane, and the diameter of CPMs was further enhanced by the addition of 16 PAHs. Most of the C element was collected in the rinse fluid, thus indicating that PAHs in CPM were collected through condensation. Based on these findings, basic guidelines can be provided for the control of PAHs in flue gas from coal-fired power plants.

Polycyclic aromatic hydrocarbons in Fildes Peninsula, maritime Antarctica: Effects of human disturbance

This study provides the first data on the distribution, sources, and transport dynamics of polycyclic aromatic hydrocarbons (PAHs) in Fildes Peninsula, Antarctica via summertime analyses of lakes, seawater, snow, and air in 2013. Relatively high PAH levels and similar composition profiles (dominance of two- and three-ring PAHs) in the investigated marine and terrestrial environmental matrices were found, indicating substantial primary emissions of petrogenic PAHs. This result was corroborated by nonequilibrium partitioning of atmospheric PAHs caused by release of anthropically-derived lighter PAHs and air mass movement trajectories mainly originated from the Antarctic marginal seas. Notable geographical disparities of PAH pollution in the various types of samples consistently suggested impacts of station-related activities, rather than long-range atmospheric transport, on PAHs in Fildes Peninsula. The lack for temperature dependence for gas-phase concentrations and various molecular diagnostic ratios of atmospheric PAHs demonstrated that the impact of local anthropogenic inputs on air PAH variability supersedes the re-emission effect. The derived air–water and air–snow exchanges of PAHs in this remote region indicated a disequilibrium state, partially associated with intense local emissions of PAHs. PAH outgassing from, and absorption into, lake and marine waters were both observed, probably due to differences in anthropogenic influences among sites, while the net deposition of gaseous PAHs into snow prevailed. The results of this study shed lights on the major importance of native anthropogenic sources in the footprint and fate of PAHs in the Fildes Peninsula, which merits further monitoring.

Gas-PM2.5 partitioning, health risks, and sources of atmospheric PAHs in a northern China city: Impact of domestic heating

The diurnal variation, gas-particle partitioning, health risks, and sources of polycyclic aromatic hydrocarbons (PAHs) were investigated in a northern basin city of China in winter, 2020. The mean concentrations of particulate and gaseous PAHs were 87.90 ng m−3 and 69.65 ng m−3, respectively, and their concentrations were considerably enhanced during the domestic heating period. The relationship between the gas-particle partitioning coefficient of PAHs (KP) and subcooled liquid vapor pressure of PAHs (PL0) indicated organic absorption as the mechanism for this partitioning. However, the dual sorption model confirmed adsorption onto elemental carbon (EC). The health risks indicated by several equivalent parameters showed an important health effect of PAHs, especially of particulate PAHs bound onto PM2.5 during the heating period. Environmentally persistent free radicals (EPFRs) were also studied as an auxiliary parameter to evaluate the health impact of PAHs. According to the diagnostic ratios of PAHs and PMF model results, petroleum volatilization and coal combustion were the dominant sources of particulate PAHs during the non-heating and heating periods, respectively. The source apportionment results can help efficiently control PAHs and their health risks.

Analysis of gaseous polycyclic aromatic hydrocarbon emissions from cooking devices in selected rural and urban kitchens in Bomet and Narok counties of Kenya.

Traditional combustion devices and fuels such as charcoal, wood and biomass, are widely utilised in rural and urban households in Africa. Incomplete combustion can generate air pollutants which are of human toxicological importance, including polycyclic aromatic hydrocarbons (PAHs). In this study, portable multi-channel polydimethylsiloxane rubber traps were used to sample gas phase emissions from cooking devices used in urban and rural households in Bomet and Narok counties of Kenya. A wide range of total PAH concentrations was found in samples collected (0.82 - 173.69 µg/m3), which could be attributed to the differences in fuel type, combustion device, climate, and nature of households. Wood combustion using the 3-stone device had the highest average total PAH concentration of ~71 µg/m3. Narok had higher indoor total gas phase PAH concentrations averaging 35.88 µg/m3 in urban and 70.84 µg/m3 in rural households, compared to Bomet county (2.91 µg/m3 in urban and 9.09 µg/m3 in rural households). Ambient total gas phase PAH concentrations were more similar (Narok: 1.26 - 6.28 µg/m3 and Bomet: 2.44 - 6.30 µg/m3). Although the 3-stone device and burning of wood accounted for higher PAH emissions, the charcoal burning jiko stove produced the highest toxic equivalence quotient. Monitoring of PAHs emitted by these cooking devices and fuels is critical to public health and sustainable pollution mitigation.

Polycyclic Aromatic Hydrocarbons in the Marine Atmosphere from the Western Pacific to the Southern Ocean: Spatial Variability, Gas/Particle Partitioning, and Source Apportionment.

The spatial variability of polycyclic aromatic hydrocarbons (PAHs) in the marine atmosphere contributes to the understanding of the global sources, fate, and impact of this contaminant. Few studies conducted to measure PAHs in the oceanic atmosphere have covered a large scale, especially in the Southern Ocean. In this study, high-volume air samples were taken along a cross-section from China to Antarctica and analyzed for gaseous and particulate PAHs. The data revealed the spatial distribution, gas-particle partitioning, and source contributions of PAHs in the Pacific, Indian, and Southern Oceans. The median concentration (gaseous + particulate) of ∑24PAHs was 3900 pg/m3 in the Pacific Ocean, 2000 pg/m3 in the Indian Ocean, and 1200 pg/m3 in the Southern Ocean. A clear latitudinal gradient was observed for airborne PAHs from the western Pacific to the Southern Ocean. Back trajectories (BTs) analysis showed that air masses predominantly originated from populated land had significantly higher concentrations of PAHs than those from the oceans or Antarctic continents/islands. The air mass origins and temperature have significant influences on the gas-particle partitioning of PAHs. Source analysis by positive matrix factorization (PMF) showed that the highest contribution to PAHs was from coal combustion emissions (52%), followed by engine combustion emissions (27%) and wood combustion emissions (21%). A higher contribution of PAHs from wood combustion was found in the eastern coastal region of Australia. In contrast, engine combustion emissions primarily influenced the sites in Southeast Asia.

Occurrence, Distribution and Risk Assessment of PAHs in Road Dust Sediment in Daejeon Metropolitan City, South Korea

In this study, the occurrence and distribution of polycyclic aromatic hydrocarbons (PAHs) in road dust sediment(RDS) deposited from main traffic roads as well as residential and industrial areas were examined with a total of 144 samples in seasons. Based on the results, the concentrations of PAHs were found to be higher in winter and ranged between 0.15 and 1.94 mg/kg with an average of 0.65 mg/kg. The results indicate that pyrene, fluoranthene, phenanthrene, and benzo(ghi)perylene were commonly found in RDS, likely originated from vehicle exhaust emissions and fuel combustion by the diagnostic ratio study. Non-cancer risk from PAHs for humans exposed to RSD was found to be low (HI 1.2E-05). The estimated excess cancer risks by PAHs in RDS was also much less than the regulatory guideline for cancer risk (1×10-6). Thus, current concentrations of PAHs in RDS are expected to be pose no threat to humans under the assumed exposure scenarios with applied exposure factors. However, more extensive and long-term sample analysis for gaseous and particulate PAHs is still warranted to determine potential risks to humans and the fate in the environment, since their concentration and distribution can be influenced by micro-metrological conditions, traffic volumes, or road clean-up conditions.

Comprehensive characterization of polycyclic aromatic hydrocarbon emissions from heavy-duty diesel vehicles utilizing GC × GC-ToF-MS

Comprehensive characterization of diesel vehicle emitted polycyclic aromatic hydrocarbon (PAH) emissions is yet to achieve due to the limitation of analytical methods. Therefore, we herein developed a two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-ToF-MS) method and quantified the total PAHs from diesel vehicles based on their characteristic fragments and mass spectral patterns. Overall, the emission factors (EFs) of total PAHs (gas + particle) are observed to range from 4.1 ± 2.5 mg km−1 to 51.4 ± 22.2 mg km−1 under cold-start and hot-start conditions for one China IV and two China VI heavy-duty diesel vehicles (HDDVs), of which the un-speciated PAHs account for more than 97%. Gaseous PAHs (g-PAHs) are dominated by three-ring PAHs, whereas particulate PAHs (p-PAHs) are dominated by two-ring PAHs. The total PAHs partition significantly into the gas phase for whole fleets and cycles, except that five-ring PAHs partition almost completely into the particle phase. The aftertreatment technologies (e.g., diesel particulate filter, DPF) significantly reduce the total PAH emissions by 49.8 ± 33.2%. The minimum toxic equivalency factors (TEFs) are deployed to estimate the toxicity of the total PAHs. Much higher toxicity is obtained than those in previous studies, indicating that the PAH toxicity of diesel vehicle emissions might be largely underestimated.

Underground emissions and miners’ personal exposure to diesel and renewable diesel exhaust in a Swedish iron ore mine

PurposeUnderground diesel exhaust exposure is an occupational health risk. It is not known how recent intensified emission legislation and use of renewable fuels have reduced or altered occupational exposures. We characterized these effects on multipollutant personal exposure to diesel exhaust and underground ambient air concentrations in an underground iron ore mine.MethodsFull-shift personal sampling (12 workers) of elemental carbon (EC), nitrogen dioxide (NO2), polycyclic aromatic hydrocarbons (PAHs), and equivalent black carbon (eBC) was performed. The study used and validated eBC as an online proxy for occupational exposure to EC. Ambient air sampling of these pollutants and particle number size distribution and concentration were performed in the vicinity of the workers. Urine samples (27 workers) were collected after 8 h exposure and analyzed for PAH metabolites and effect biomarkers (8-oxodG for DNA oxidative damage, 4-HNE-MA for lipid peroxidation, 3-HPMA for acrolein).ResultsThe personal exposures (geometric mean; GM) of the participating miners were 7 µg EC m−3 and 153 µg NO2 m−3, which are below the EU occupational exposure limits. However, exposures up to 94 µg EC m−3 and 1200 µg NO2 m−3 were observed. There was a tendency that the operators of vehicles complying with sharpened emission legislation had lower exposure of EC. eBC and NO2 correlated with EC, R = 0.94 and R = 0.66, respectively. No correlation was found between EC and the sum of 16 priority PAHs (GM 1790 ng m−3). Ratios between personal exposures and ambient concentrations were similar and close to 1 for EC and NO2, but significantly higher for PAHs. Semi-volatile PAHs may not be effectively reduced by the aftertreatment systems, and ambient area sampling did not predict the personal airborne PAHs exposure well, neither did the slightly elevated concentration of urinary PAH metabolites correlate with airborne PAH exposure.ConclusionMiners’ exposures to EC and NO2 were lower than those in older studies indicating the effect of sharpened emission legislation and new technologies. Using modern vehicles with diesel particulate filter (DPF) may have contributed to the lower ambient underground PM concentration and exposures. The semi-volatile behavior of the PAHs might have led to inefficient removal in the engines aftertreatment systems and delayed removal by the workplace ventilation system due to partitioning to indoor surfaces. The results indicate that secondary emissions can be an important source of gaseous PAH exposure in the mine.

Research on Adsorption and Desorption Performance of Gas-Phase Naphthalene on Hydrophobic Modified FDU-15

Naphthalene (NAP) is a typical gaseous polycyclic aromatic hydrocarbons (PAHs) pollutant that displays toxicological effects on biosystems. Ordered mesoporous carbon has relatively adequate adsorption capacity; however, the attached hydrophilic functional groups were proven to affect the adsorption performance in the presence of moisture. In this paper, trimethylchlorosilane (TMCS) is used to carry out the hydrophobic modification of ordered mesoporous carbon FDU-15, and the adsorption and desorption properties of FDU-15 were studied. Furthermore, the adsorption isotherms of naphthalene on FDU-15 and modified FDU-15 were fitted by L-F equation, and the kinetic parameters of desorption of naphthalene on modified FDU-15 were analyzed based on the method of temperature programming desorption (TPD). The results showed that the micropore volume and specific surface area of FDU-15 were significantly increased after hydrophobically modified by TMCS, and the polar functional groups of the hydrophobically modified FDU-15 were significantly reduced. Furthermore, the adsorption of naphthalene by FDU-15 before and after modification conformed to the L-F equation (R2 &gt; 99%), and the adsorption of naphthalene by modified FDU-5 at low concentration was significantly improved due to the increase of micropores. Based on desorption kinetic performance study of modified FDU-15, it can be seen that the adsorption kinetic characteristics of naphthalene on the modified FDU-15 conform to the mechanical function of the JMA equation. When the mass ratio of TMCs to FDU-15 is 1:10 in the modification process, the pore structure and surface hydrophobicity of the modified FDU-15 reach an excellent balance. At this time, the adsorbent had the optimum desorption performance under experimental conditions, and the desorption activation energy was decreased from 60.98 kJ/mol of FDU-15 to 50.28 kJ/mol.

Gaseous Polycyclic Aromatic Hydrocarbons (PAHs) Over the South China Sea (SCS): Implications on Atmospheric Transport with Monsoon Influence

Gaseous Polycyclic Aromatic Hydrocarbons (PAHs) Over the South China Sea (SCS): Implications on Atmospheric Transport with Monsoon Influence