Average Polycyclic Aromatic Hydrocarbons Research Articles

Seasonal Trends of Atmospheric PAHs in Five Asian Megacities and Source Detection Using Suitable Biomarkers

The most prevalent pollutant, polycyclic aromatic hydrocarbons (PAHs) is now plenteously distributed in the global atmosphere. We recently quantified 36 polycyclic aromatic hydrocarbons (PAHs) associated with aerosols (particulate matter: PM) in five Asian cities: Tokyo (Japan), Beijing (China), Kolkata (India), Hanoi (Vietnam), and Kuala Lumpur (Malaysia). Average atmospheric PAH concentrations (Σ12 PAHs-ng m^(–3)) increased in the order of Kuala Lumpur (2.99) ≈ Tokyo (3.95) ＜ Hanoi (7.99) ＜＜ Kolkata (63.5) ＜＜ Beijing (142.8). The most abundant PAHs in PM samples in these cities were chrysene, benz[a]anthracene, benzofluoranthenes, benzo[a]pyrene, and benzo[e]pyrene. We used the PAH compositions, especially the relative abundances of alkylated PAHs, and hopanes to determine vehicle exhaust-derived PAHs, and levoglucosan as a tracer for biomass burning, especially from wood combustion. Vehicle exhaust contributed to atmospheric PAHs in all cities, indicated by higher ratios of (C_(30)17α)/total PAHs and MPAHs/PAHs than coal and wood combustion products. Coal combustion contributed also in winter aerosols in Beijing, indicated by higher abundance of β isomers i.e., 17β21β (H)-C30hopane (C_(30)17β) and 17β21β (H)-C_(29)hopane (C_(29)17β) signifying mass use of coal for heating. The ratio of levoglucosan/PAHs was high in Kuala Lumpur and Hanoi, suggesting greater inputs of PAHs from biomass burning there.

Phytoremediation of PAHs-contaminated Sludge in a Constructed Wetland

Wastewater sludge from metropolitan areas has become a source of polycyclic aromatic hydrocarbons (PAHs), and may result in pollution of soils and plants if applied to agricultural areas. It is important to stabilize wastewater sludge before its application to agricultural land. Constructed wetlands (CWs) have been widely applied for stabilization of sludge. In CWs, plants, especially reeds, promote degradation of pollutants in the rhizosphere and are the principal mechanisms for PAH-contaminated sludge phytoremediation. We studied PAH removal in sludge planted with Phragmites australis (common reeds) in onsite experiments over a 3-year period comprising 2 years of sludge application and 1 year of resting. The average PAH content in the feeder sludge was 5.7 mg kg–1 (DW), consisting of approximately 48% low-molecular-weight (2–3 ring) PAHs, 27% middle-molecular-weight (4 ring) PAHs and 25% high-molecular-weight (5–6 ring) PAHs. After 3 years, the average PAH content in stabilized sludge was 2.1 mg kg–1 (DW), which was lower than that of the feeder sludge. Overall, about 66% of low-molecular-weight PAHs (dominant type), 57% of middle-molecular-weight PAHs and 32% of high-molecular-weight PAHs were removed from the stabilized sludge. Additionally, there were spatial variations in PAHs in stabilized sludge, with PAHs being highest in the surface layer (12–14 cm) sludge, lower in the middle layer (6–8 cm) and lowest in the bottom layer (0–2 cm).

TBHQ and peanut skin inhibit accumulation of PAHs and oxygenated PAHs in peanuts during frying

The effects of tert-butylhydroquinone (TBHQ) and peanut skins on the concentrations of polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (OPAHs) in fried peanuts were investigated. Sixteen PAHs and five OPAHs were quantified using gas chromatography-mass spectrometry (GC-MS). Addition of TBHQ to the frying oil reduced the total PAH and total OPAH concentrations by up to 71.75% and 74.80%, respectively. After frying, average PAH and OPAH levels were respectively 22.63% and 79.22% lower in peanuts with skins versus those without skins. The concentration of benzo[a]anthracene (BaA) was significantly correlated with that of benzo[a]anthracene-7,12-dine (BaAQ) in the fried peanuts. These results may be helpful for production of good quality fried peanuts with a low PAH content, as well as providing guidance for reducing PAHs in other fried foods.

Quantitative ecological risk assessment of inhabitants exposed to polycyclic aromatic hydrocarbons in terrestrial soils of King George Island, Antarctica

This study aims to conduct a quantitative ecological risk assessment of human exposure to polycyclic aromatic hydrocarbons (PAHs) in terrestrial soils of King George Island, Antarctica. Generally, the average PAH concentrations detected in King George Terrestrial Soils (KGS) were appreciably lower than those of World Marine Sediments (WMS) and World Terrestrial Soils (WTS), highlighting the fact that Antarctica is one of the most pristine continents in the world. The total concentrations of twelve probably carcinogenic PAHs (ΣPAHs: a sum of Phe, An, Fluo, Pyr, B[a]A, Chry, B[b]F, B[k]F, B[a]P, Ind, D[a,h]A and B[g,h,i]P) were 3.21 ± 1.62 ng g−1, 5749 ± 4576 ng g−1, and 257,496 ± 291,268 ng g−1, for KGS, WMS and WTS, respectively. In spite of the fact that KGS has extremely low ΣPAHs in comparison with others, the percentage contribution of Phe is exceedingly high with the value of 50%. By assuming that incidental ingestion and dermal contact are two major exposure pathways responsible for the adverse human health effects, the cancer and non-cancer risks from environmental exposure to PAHs were carefully evaluated based on the “Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions” memorandum provided by US-EPA. The logarithms of cancer risk levels of PAH contents in KGS varied from −11.1 to −7.18 with an average of −7.96 ± 7.73, which is 1790 times and 80,176 times lower than that of WMS and WTS, respectively. All cancer risk levels of PAH concentrations observed in KGS are significantly (p < 0.001) lower than those of WMS and WTS. Despite the Comandante Ferraz Antarctic Station fire occurred in February 25th, 2012, both the cancer and non-cancer risks of environmental exposure to PAHs were found in “acceptable level”.

Removal of Polycyclic Aromatic Hydrocarbons by Extensive Green Roofs

In this study,four pilot-scale extensive green roof facilities with different substrate compositions were developed. In 8 rainfall events, concentrations of 16 kinds of polycyclic aromatic hydrocarbons (PAHs) in effluent of these facilities were investigated and compared with effluents of asphalt roofing, the blank control roof and rain water. Average PAHs concentrations in the effluent of these four facilities, asphalt roofing and blank control facilities were 145, 166, 151, 160, 900, 270 ng·L-1, respectively. The PAHs mass concentrations discharged by four simulation facilities were significantly lower than asphalt roofing and blank control roof. From the perspective of the mass loading control, all four simulation facilities could effectively control roof runoff PAHs load with an average load reduction rate of 71.76% compared with the blank control roof. Interception and adsorption by green roof substrates was the main removal way for PAHs. Facilities' PAHs removal efficiency could be improved by increasing the substrate thickness with the same substrate composition. Transforming traditional asphalt roofing into extensive green roof was an effective way to control PAHs emissions from roof runoff.

Composition and sources of polycyclic aromatic hydrocarbons in cryoconites of the Tibetan Plateau glaciers

Dark-colored cryoconite can absorb substantial solar radiation, reduce the surface albedo of glaciers, and thus greatly accelerate glacier melting. Organic matters in cryoconites such as polycyclic aromatic hydrocarbons (PAHs) are kind of the light absorbing compositions. In this study, 15 PAHs containing 3–7 rings were identified in 61 cryoconites samples collected from seven glaciers over the Tibetan Plateau (TP). The average concentration of total PAHs in cryoconites samples was in the range of 6.67–3906.66ngg−1 dry weight. The highest average total PAH concentration was found in the southeastern TP, followed by the northern TP. The central TP contained the lowest amount of PAHs. Moreover, correlation analysis showed that total organic carbon (TOC) and grain size were only a minor factor for the accumulation of PAHs in cryoconites of the TP. Factor analysis and diagnostic ratios indicated that the PAHs were produced mainly from the incomplete combustion of coal, fossil fuels and biomasses. The exhaust gas of locomotives also contributed to the accumulation of PAHs in the glaciers. The PAHs in these seven glaciers showed low toxic equivalent quantity (TEQ), and thus had low biological risk. Nevertheless, the pollution of PAHs in the southeastern TP needs to be addressed.

Worldwide distribution of polyclyclic aromatic hydrocarbons in urban road dust

Polycyclic aromatic hydrocarbons (PAHs) are considered as one of the most important groups of organic environmental contaminants due to their toxicity, persistence and ubiquity. PAHs have been monitored in urban road dust at various locations worldwide in about last three decades. Resuspension of road dust containing PAHs is an important route of human exposure to PAHs. This paper collates the available information on reported concentrations of PAHs in urban road dust at various worldwide locations classified as industrial, residential, traffic, city and commercial and other areas, reported sources of PAHs and related interpretations. The available information has been reviewed and documented country-wise. Variation in PAHs concentrations over various worldwide locations have been scrutinized, and interestingly, most of the reported average PAHs concentrations were found to be distributed within a very narrow range of values, implying only little variation in average PAH concentrations in spite of great distances between locations, climatic variation and differences in anthropogenic activities.

Mapping PAH sizes in NGC 7023 with SOFIA

NGC 7023 is a well-studied reflection nebula, which shows strong emission from polycyclic aromatic hydrocarbon (PAH) molecules in the form of aromatic infrared bands (AIBs). The spectral variations of the AIBs in this region are connected to the chemical evolution of the PAH molecules which, in turn, depends on the local physical conditions. We use the capabilities of SOFIA to observe a 3.2' x 3.4' region of NGC 7023 at wavelengths that we observe with high spatial resolution (2.7") at 3.3 and 11.2 um. We compare the SOFIA images with existing images of the PAH emission at 8.0 um (Spitzer), emission from evaporating very small grains (eVSG) extracted from Spitzer-IRS spectral cubes, the ERE (HST and CFHT), and H_2 (2.12 um). We create maps of the 11.2/3.3 um ratio to probe the morphology of the PAH size distribution and the 8.0/11.2 um ratio to probe the PAH ionization. We make use of an emission model and of vibrational spectra from the NASA Ames PAHdb to translate the 11.2/3.3 um ratio to PAH sizes. The 11.2/3.3 um map shows the smallest PAH concentrate on the PDR surface (H_2 and extended red emission) in the NW and South PDR. We estimated that PAHs in the NW PDR bear, on average, a number of carbon atoms (N_c) of ~70 in the PDR cavity and ~50 at the PDR surface. In the entire nebula, the results reveal a factor of 2 variation in the size of the PAH. We relate these size variations to several models for the evolution of the PAH families when they traverse from the molecular cloud to the PDR. The PAH size map enables us to follow the photochemical evolution of PAHs in NGC 7023. Small PAHs result from the photo-evaporation of VSGs as they reach the PDR surface. Inside the PDR cavity, the PAH abundance drops as the smallest PAH are broken down. The average PAH size increases in the cavity where only the largest species survive or are converted into C_60 by photochemical processing.

Airborne Petcoke Dust is a Major Source of Polycyclic Aromatic Hydrocarbons in the Athabasca Oil Sands Region.

Oil sands mining has been linked to increasing atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) in the Athabasca oil sands region (AOSR), but known sources cannot explain the quantity of PAHs in environmental samples. PAHs were measured in living Sphagnum moss (24 sites, n = 68), in sectioned peat cores (4 sites, n = 161), and snow (7 sites, n = 19) from ombrotrophic bogs in the AOSR. Prospective source samples were also analyzed, including petroleum coke (petcoke, from both delayed and fluid coking), fine tailings, oil sands ore, and naturally exposed bitumen. Average PAH concentrations in near-field moss (199 ng/g, n = 11) were significantly higher (p = 0.035) than in far-field moss (118 ng/g, n = 13), and increasing temporal trends were detected in three peat cores collected closest to industrial activity. A chemical mass-balance model estimated that delayed petcoke was the major source of PAHs to living moss, and among three peat core the contribution to PAHs from delayed petcoke increased over time, accounting for 45-95% of PAHs in contemporary layers. Petcoke was also estimated to be a major source of vanadium, nickel, and molybdenum. Scanning electron microscopy with energy-dispersive X-ray spectroscopy confirmed large petcoke particles (>10 μm) in snow at near-field sites. Petcoke dust has not previously been considered in environmental impact assessments of oil sands upgrading, and improved dust control from growing stockpiles may mitigate future risks.

Identification of concentrations and sources of PM2.5-bound PAHs in North China during haze episodes in 2013

An analysis of 12 polycyclic aromatic hydrocarbons (PAHs) in PM2.5 (particulate matter with a diameter smaller than 2.5 microns) samples collected at Yucheng, Shandong, in June 2013 was conducted to determine the concentrations, composition, sources, and associated cancer risk. The results revealed that the average PAH concentration was higher during haze episodes (28.28 ± 8.35 ng m−3) when compared to non-haze episodes (23.68 ± 4.17 ng m−3), and diagnostic ratio and principal component analyses indicate that the predominant sources of PAHs were from fossil fuel and coal combustion, likely from vehicle emissions and industrial sources and biomass burning. Coal combustion and biomass burning contributed significantly more during haze episodes, whereas liquid fossil fuel combustion (e.g. petroleum) was the dominant contributor during the non-haze periods. In addition, back-trajectory calculations revealed that the long-distance transport of air masses from regions with industrial pollution and biomass burning contributed significantly to the concentrations of PAHs in the region. The concentration of high molecular weight PAHs (HMW-PAHs) increased from 62.3 % under non-haze conditions to 67.9 % during the haze periods. The benzo[a]pyrene-equivalent carcinogenic potency value during haze episodes was higher (7.09 ng m−3) than that during non-haze (5.64 ng m−3) periods and adults over 30 years old in the Shandong province are at an increased risk of cancer from PAHs.

Analysis of Polycyclic Aromatic Hydrocarbon, Toxic Equivalency Factor and Related Carcinogenic Potencies in Roadside Soil within a Developing City of Northern India

Preliminary analysis was performed to assess contamination levels in roadside soils, distribution behavior and human exposure with Polycyclic Aromatic Hydrocarbons (PAHs) during summer, winter, rainy, and autumn during 2013 in one of the developing cities of northern India. The concentration of PAHs was measured at ten different locations (at 1, 2, and 3 m) from roadside soil. Recovery range was 30% and 80% with lower value corresponding to the lower molecular weight PAHs compound. Identification and quantification of PAHs was done by GC-FID. Average PAHs concentration (city average) was found to be 16.53, 4.04, 17.49, and 7.82 μg g−1, during summer, winter, autumn, and the rainy seasons, respectively. Average concentration of low and high carcinogenic PAHs during summer, winter, autumn, and rainy was 5.1 and 31.29, 2.1 and 6.4, 4.74 and 35.08, 3.97 and 12.77μg g−1, respectively. The average ratio of low and high carcinogenic PAHs was found to be 1:6, 1:3, 1:7.6, and 1:3.21 during summer, winter, autumn, and the rainy seasons at most intercepts. Dib(ah)A and B(a)P were the two individual PAHs found in highest concentration during summer, winter, and the rainy seasons, whereas B(a)P and IP were individual PAHs found in highest concentration during autumn. It was also analyzed that high carcinogenic PAHs concentration was quite higher (around 85%) in comparison to low carcinogenic PAHs (around 15%) at most intercepts. This article also deals with the behavior of PAHs at places of average/high population and traffic density intercepts. Five-ringed PAHs were in highest concentration at all intercepts and seasons. Two-tailed T test was applied for authenticity of the data and results. Toxic equivalency factor of B(a)P and Dib(ah)A was maximum as compared to other PAHs.

Atmospheric concentrations of polycyclic aromatic hydrocarbons (PAHs) in an urban traffic site in Erzurum, Turkey

This study presents daily and seasonal variations of PAH concentrations in Erzurum atmosphere in summer season of 2008 and in winter seasons of 2008 and 2009. Sampling location at Erzurum urban center was selected to represent the effects of traffic (University junction). 18 PAH compounds were analyzed by GC–MS. Average total PAH concentration (gas + particulate) of 18 PAH compounds were measured during 2008 winter (431 ngm−3) and summer (103 ngm−3) seasons at the University junction. Daily and seasonal variations of PAH compounds were investigated and compared with other urban centers in the literature. Multiple linear regression and artificial neural network (ANN) models were constructed to determine the impacts of meteorological parameters on measured individual PAH concentrations. Results of the multiple linear regression and ANN models indicated that wind speed, wind direction and intensity of total solar radiation were the most significant factors for the measured concentrations of PAH compounds.

Monitoring of polycyclic aromatic hydrocarbons on agricultural lands surrounding Tehran oil refinery.

Soil samples at two depths were collected and analyzed to determine the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs), organic carbon, and soil pH. The Σ16PAHs were 0.13 to 3.92mgkg(-1) at depth 1 and 0.21 to 50.32mgkg(-1)at depth 2. The averages of the PAH compounds indicate that the area is contaminated with oil, and this pollution was greater at depth 2. Interpolation maps showed that the southern region, especially at depth 2, has been contaminated more by anthropogenic activity. The diagnostic ratios indicate several sources of pollution of the agricultural soil. A comparison of average PAHs and standard values revealed that higher molecular weight compounds in the topsoil (InP and BghiP) and subsoil (BaA, BkF, BaP, DBA, and BghiP) exceed standard values for farmland. The pH interpolation map for both depths showed that most of the area has alkaline soil from long-term irrigation with untreated urban wastewater.

Subway construction activity influence on polycyclic aromatic hydrocarbons in fine particles: Comparison with a background mountainous site

Intensive construction activities worsened the surrounding atmospheric environment in China. Eighteen polycyclic aromatic hydrocarbons (PAHs) in fine particles (PM2.5) were collected at a subway construction site (SC) of Nanjing and compared with a regional background mountainous site (BM) to examine the influence of anthropogenic activities on concentrations, sources and health risks of PAHs. Average PAH concentrations at SC were higher than BM at a factor of about 5.9. All PAH species at SC were higher than BM, with the SC/BM ratios ranging from 1.3 (NaP) to 10.3 (BaP). PAH profiles differed for the two sites. The SC site had higher mass fractions of PAHs from coal combustion and vehicle emission, while the BM site held higher mass percentages of PAHs from long-range transported wood combustion and industrial activities. Lower temperature at BM may lead to the higher mass percentages of low ring PAHs. Coal combustion, traffic emissions and biomass burning were the common sources for PAHs at both SC and BM. Construction workers were exposed to higher BaPeq concentrations, nearly ten times of the background site and their lifetime cancer risk reached to 0.6 per 1,000,000 exposed worker, owing to the influence of coal combustion, vehicle emission and industrial activities at the surroundings of SC.

PAH Measurements in Air in the Athabasca Oil Sands Region.

Polycyclic aromatic hydrocarbon (PAH) measurements were conducted by Wood Buffalo Environmental Association (WBEA) at four community ambient Air quality Monitoring Stations (AMS) in the Athabasca Oil Sands Region (AOSR) in Northeastern Alberta, Canada. The 2012 and 2013 mean concentrations of a subset of the 22 PAH species were 9.5, 8.4, 8.8, and 32 ng m(-3) at AMS 1 (Fort McKay), AMS 6 (residential Fort McMurray), AMS 7 (downtown Fort McMurray), and AMS 14 (Anzac), respectively. The average PAH concentrations in Fort McKay and Fort McMurray were in the range of rural and semirural areas, but peak values reflect an industrial emission influence. At these stations, PAHs were generally associated with NO, NO2, PM2.5, and SO2, indicating the emissions were from the combustion sources such as industrial stacks, vehicles, residential heating, and forest fires, whereas the PAH concentrations at AMS 14 (∼35 km south of Fort McMurray) were more characteristic of urban areas with a unique pattern: eight of the lower molecular weight PAHs exhibited strong seasonality with higher levels during the warmer months. Enthalpies calculated from Clausius-Clapeyron plots for these eight PAHs suggest that atmospheric emissions were dominated by temperature-dependent processes such as volatilization at warm temperatures. These findings point to the potential importance of localized water-air and/or surface-air transfer on observed PAH concentrations in air.

The Use of Reverse Osmosis in the Removal of PAHs from Municipal Landfill Leachate

Polycyclic aromatic hydrocarbons (PAHs) are relatively well-known organic pollutants and due to their carcinogenic and mutagenic properties their presence in the environment still attracts a lot of attention.According to literature reports and own research, PAHs presence in wastewaters is common. It was confirmed that PAHs are the components of municipal landfill leachate. Membrane techniques are one of the most interesting ways of removing PAHs from leachate.The purpose of this article is to monitor PAHs concentration changes during the membrane (reverse osmosis - RO) leachate treatment processes. In the first stage of testing leachates were filtrated on the sand bed (pre-filtration). After the pre-filtration they were directed to the membrane module for the main filtration.Sixteen PAHs listed by EPA were analyzed. The results with information on PAHs concentration in leachate samples were presented using HPLC with fluorescence detection (FLD). The changes in PAHs concentration were determined in leachate samples before and after pre-filtration as well as after RO. The decrease of PAHs concentration in the samples was observed after these processes. The total concentration of 16 PAHs in raw municipal landfill leachates amounted to 23.64–26.95 μg/L. The research confirmed the high efficiency in removal of PAHs while using a reverse osmosis (59–72%). Including the pre-filtration, the overall level of removed PAHs reached 81–86%. The average PAHs concentration after pre-filtration and RO was in the 4.46–4.99 μg/L range. The municipal landfill leachate with a high concentration of PAHs should be cleaned before it is discharged into the environment.

Long term observations of PM2.5-associated PAHs: Comparisons between normal and episode days

The pollution characteristic of fine particular matter (PM2.5) and associated polycyclic aromatic hydrocarbons (PAHs) are currently drawing a great deal of interest because of their influence on environment and health. In this study, PM2.5 was collected from 2011 to 2013 (n = 188) in a suburban area of Zhengzhou, China. 16-PAHs were analyzed to determine the concentration, seasonal variation and potential sources during normal days and episode events. The total mass of 16 PAHs and PM2.5 were in the range of 7–961 ng m−3 and 55–697 μg m−3, with a 3-year average of 174 ng m−3 and 194 μg m−3 respectively. Winter is most polluted for both PM2.5 and PAHs. Average PAH and PM2.5 concentrations during three episode events are 454 ng m−3 and 453 μg m−3, respectively, much higher than values during normal days (299 ng m−3 and 180 μg m−3, respectively). Ratios of Σ16PAH/PM2.5 varied with seasons and concentrations of PM2.5, but showed a negative correlation with PM2.5 concentrations during episode events. The dominant components of PAHs are Benzo[b]fluoranthene, Chrysene, Fluoranthene, and Benzo[k]fluoranthene, Benz[a]anthracene, Pyrene, Indeno(1,2,3-cd)pyrene and their total concentrations vary from 27 to 342 ng m−3, accounting for 58–82% (average = 73%) of 16 PAHs. The Benzo[a]pyrene (Bap) concentration obtained was 9.4 ng m−3 (3-year average), exceeding nearly one order of magnitude of ambient air BaP standard (annual average: 1.0 ng m−3) in China. Diagnose ratios and Positive Matrix Factorization results show that coal combustion, vehicles, coking plant, and biomass burning are main sources for PAHs in this area. The high concentrations of PM2.5 and PAHs, especially during episode events, reflected a potential health problem for nearby public and the necessity of air pollution control for both stationary and mobile sources.

Concentrations, gas-particle partitioning, and seasonal variations of polycyclic aromatic hydrocarbons at four sites in Turkey.

Ambient air polycyclic aromatic hydrocarbon (PAH) samples were collected at traffic, residential, coastal, and semiurban sites in Bursa, Turkey, between June 2008 and June 2009. For the traffic, residential, coastal, and semiurban sites, the average gas phase total PAH (∑12PAH) concentrations were 113 ± 131, 142 ± 204, 53 ± 73, and 19 ± 34 ng/m(3), respectively, whereas the average particle phase total PAH concentrations were 28 ± 36, 56 ± 85, 24 ± 40, and 11 ± 23 ng/m(3), respectively. Phenanthrene and fluoranthene had the highest concentrations of all of the sampling sites in the gas phase. The PAH concentrations in the heating period were 5-7 times greater than the nonheating period concentrations. Principal component analysis (PCA) was used to investigate the relationship between the levels of PAHs determined in ambient samples and their possible sources. The PCA model shows that coal combustion and vehicle emissions affected PAH emissions. Moreover, the molecular diagnostic ratios indicated that coal-burning and traffic emissions were the dominant PAH sources. The multiple linear regression analysis indicated that the meteorological parameters also affected the ambient PAH concentrations. The sampling site characteristics, meteorological conditions, dispersion, and local sources all affected the concentration levels.

Polycyclic Aromatic Hydrocarbons in the Snowpack and Surface Water in Blackwood Canyon, Lake Tahoe, CA, as Related to Snowmobile Activity

Snowpack in alpine environments may contain appreciable levels of regional pollution acquired through natural processes of wet and dry deposition, as well as from immediate sources such as snowmobile engine exhaust. Understanding the fate and transport of pollutants in alpine environments is a crucial step towards managing emission sources in alpine terrain to mitigate their impacts on natural resources. This study presents detailed chemical analysis for 94 species of polycyclic aromatic hydrocarbons (PAH) in 55 samples of snow and surface water collected in Blackwood Canyon, a tributary to the west shore of Lake Tahoe that is a popular winter recreation area for snowmobile riders. Analyses included toxic and persistent PAH, emitted as products of incomplete combustion and useful for identifying fossil fuel combustion emissions in the environment. Average background snow PAH concentrations were used to estimate background PAH surface loading (μg.m−2). Loadings in excess of the estimated background are mapped and compared with observations of snowmobile activity to determine effects of snowmobile emissions on snow water quality. Loading of heavy PAH, those having three or more aromatic rings, in snow was found to be significantly greater than background loading (α = 5%) where snowmobile tracks cover more than 50% of the snow surface. Loadings were 8–20 times greater than background levels where snowmobile traffic was most concentrated over snow covered roads. PAH were also measured in snow melt and surface water samples in Blackwood Canyon for comparison with snow samples. Flux of PAH (g.day−1) from Blackwood Creek into Lake Tahoe was calculated and compared to estimates of background flux, increasing from 74 g.day−1 to 480 g.day−1 over an 8-day period during spring run-off.

Determination of Polycyclic Aromatic Hydrocarbon (PAH) Content and Risk Assessment From Edible Oils in Korea

Polycyclic aromatic hydrocarbons (PAH) content and a risk assessment from consumption of Korean edible oils were investigated. Liquid–liquid extraction and gas chromatography–mass spectroscopy were used to measure eight PAH in edible oils commonly consumed in Korea. The total average PAH concentration was 0.548 μg/kg from edible oils and the content of the 8 PAH was lower than 2 μg/kg, which is the maximum tolerable limit reported by the commission regulation. The contents of the eight PAH were converted to exposure assessment and risk characterization values. Dietary exposure to PAH from edible oils was 0.025 ng-TEQBaP/kg/d, and margin of exposure (MOE) was 4 × 106, which represents negligible concern. Although PAH were detected from edible oils in Korea, their contribution to human exposure to PAH is considered not significant.