Characterization Of Polycyclic Aromatic Hydrocarbons Research Articles

Adsorption Characteristics of Polycyclic Aromatic Hydrocarbons by Biomass-Activated Carbon in Flue Gas

Activated carbon (AC) injection is a well-proven end-of-pipe control technique for reducing polycyclic aromatic hydrocarbon (PAH) emission from flue gas. This paper introduces an effective and econ...

Genotoxicity and DNA damage signaling in response to complex mixtures of PAHs in biomass burning particulate matter from cashew nut roasting

Approximately 3 billion people world-wide are exposed to air pollution from biomass burning. Herein, particulate matter (PM) emitted from artisanal cashew nut roasting, an important economic activity worldwide, was investigated. This study focused on: i) chemical characterization of polycyclic aromatic hydrocarbons (PAHs) and oxygenated (oxy-) PAHs; ii) intracellular levels of reactive oxygen species (ROS); iii) genotoxic effects and time- and dose-dependent activation of DNA damage signaling, and iv) differential expression of genes involved in xenobiotic metabolism, inflammation, cell cycle arrest and DNA repair, using A549 lung cells. Among the PAHs, chrysene, benzo[a]pyrene (B[a]P), benzo[b]fluoranthene, and benz[a]anthracene showed the highest concentrations (7.8–10 ng/m3), while benzanthrone and 9,10-anthraquinone were the most abundant oxy-PAHs. Testing of PM extracts was based on B[a]P equivalent doses (B[a]Peq). IC50 values for viability were 5.7 and 3.0 nM B[a]Peq at 24 h and 48 h, respectively. At these low doses, we observed a time- and dose-dependent increase in intracellular levels of ROS, genotoxicity (DNA strand breaks) and DNA damage signaling (phosphorylation of the protein checkpoint kinase 1 – Chk1). In comparison, effects of B[a]P alone was observed at micromolar range. To our knowledge, no previous study has demonstrated an activation of pChk1, a biomarker used to estimate the carcinogenic potency of PAHs in vitro, in lung cells exposed to cashew nut roasting extracts. Sustained induction of expression of several important stress response mediators of xenobiotic metabolism (CYP1A1, CYP1B1), ROS and pro-inflammatory response (IL-8, TNF-α, IL-2, COX2), and DNA damage response (CDKN1A and DDB2) was also identified. In conclusion, our data show high potency of cashew nut roasting PM to induce cellular stress including genotoxicity, and more potently when compared to B[a]P alone. Our study provides new data that will help elucidate the toxic effects of low-levels of PAH mixtures from air PM generated by cashew nut roasting.

Size Distribution Characteristics and Inhalation Exposure of Particle-Bound PAHs in an Industrial City

Atmospheric particulate matter was collected during the heating period and the non-heating period of a typical steel industrial process in Northeast China to study the following:① the size-depended distribution and enrichment characteristics of polycyclic aromatic hydrocarbons (PAHs); ② the deposition concentrations of PAHs of different particle sizes in various organs of the human respiratory system; and 3 the risk from human respiratory exposure. The 14 priority PAHs in the samples were determined by high-performance liquid chromatography (HPLC), and respiratory exposure assessment was conducted by combining the atmospheric particle size fractionation sampling technique with an internal deposition model. The results showed that the PAH concentrations during the heating periods (743.9 ng·m-3) were higher than those during the non-heating periods (169.0 ng·m-3). Most PAH contributions (86.3%-89.9%) were related to fine particles with a diameter ≤ 2.06 μm; medium and low molecular weight PAHs showed two concentration peaks in 1.07-2.06 μm and 7.04-9.99 μm range, respectively. In contrast, high molecular weight PAHs showed a unimodal peak in 1.07-2.06 μm range. Four-ring PAHs accounted for 40% of the total PAHs concentrations. With respect to human exposure, 53.3% and 55.3% of the granular PAHs were deposited in the lungs during the heating and non-heating periods, respectively. The incremental lifetime cancer risk (R) of particulate PAHs in the population was calculated using the concentration in the human respiratory system and the total concentration associated with the particulate matter. The R values for adults ranged between 1.3×10-5 and 2.9×10-5 during the heating period, and between 3.1×10-6 and 6.0×10-6 during the non-heating period. The R values for children during the heating period ranged between 1.0×10-5 and 2.3×10-5, and between 2.4×10-6 and 4.8×10-6 during the non-heating period. The results indicated that particle size greatly affected the concentrations of particles deposited in the respiratory system and the level of carcinogenic risk. The combination of the grading sampling technique and the respiratory system settlement model can effectively avoid the over-evaluation of human respiratory exposure.

Occurrence and risk characterization of polycyclic aromatic hydrocarbons of edible oils by the Margin of Exposure (MOE) approach

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic and genotoxic chemicals naturally derived from food during heat processing. Edible oil is one of the most frequently contaminated foods. Many researches were recently conducted to determine the contents of PAHs and to assess their risks, but there have been no studies characterising risks of PAHs by calculating Margin of Exposure (MOE) of total PAHs instead of toxic equivalency factors (TEFs) concept in Korea. To analyze the 4 PAHs including benz(a)anthracene (BaA), chrysene (CHR), benzo(b)fluoranthene (BbF), and benzo(a)pyrene (BaP) simultaneously, gas chromatography with mass spectrometry was optimized. Total 303 edible oils were investigated and contaminated by 4 PAHs at ND–12.91 ng g−1. The MOEs were estimated by PAHs contents, daily consumption, and were over 10,000. The risk of PAHs of edible oils in Korea was of low concern. Furthermore, the MOEs of the estimated equivalent BaP calculated by TEFs of other 3 PAHs were higher than those of mixed PAHs, which would be overestimated.

The Characteristics of Polycyclic Aromatic Hydrocarbons in Different Emission Source Areas in Shenyang, China.

Particulate matter (PM) was collected in three different areas, SY-1, SY-2, and SY-3, in Shenyang, China, during the warm and cold seasons from 2012 to 2014. SY-1 was located beside a thermal power plant, far from the central area. SY-2 was near a coal heating boiler on the main road, close to the central area. SY-3 was on the main road, without fixed emission sources. Nine PM-bound polycyclic aromatic hydrocarbons (PAHs) were analyzed. The results showed that the mean concentration of total PAHs was higher in the cold season (92.6–316 ng m−3) than in the warm season (18.4–32.2 ng m−3). Five- and six-ring PAHs occupied a large percentage at all sites in the warm season, and four-ring PAHs were the dominant components in the cold season. Several diagnostic PAH ratios indicated that the main sources of PAHs in Shenyang in the warm and cold seasons were not only coal burning but also vehicle emission. In this study, we suggest that a benzo[a]pyrene/benzo[ghi]perylene ratio ([BaP]/[BgPe]) of 0.6 was a useful indicator to speculate the relative significance of coal burning and vehicle exhaust. Although the Shenyang government has undertaken actions to address air pollution, the PM and PAH concentrations did not decrease significantly compared to those in our previous studies. The cancer risk calculated from the BaP equivalent total concentration at all three sites in the warm and cold seasons exceeded the acceptable limit established by the US EPA.

Vertical Distribution Characteristics of PAHs in Soils with Different Land Use Types During Rapid Urbanization

To study the vertical distribution characteristics of polycyclic aromatic hydrocarbons (PAHs) in the soils from different land use types during urbanization, three land use types (urban land, cultivated land, and woodland) were selected in the eastern part of Shenyang, where urbanization is occurring rapidly. In each case, five soil samples were obtained from different depths (0-1 m). Change in the concentrations of PAHs, vertical migration factors, and the distribution and sources of PAHs were analyzed in the vertical soil profiles. Total concentrations of PAHs in the different soil type were ordered as follows:city 1 (513.19-12689.04 μg·kg-1); dry field (36.18-7196.10 μg·kg-1); paddy field (70.92-747.53 μg·kg-1); city 2 (19.39-636.47 μg·kg-1); and woodland (4.79-349.24 μg·kg-1). PAHs were mainly trapped in shallow soils in urban and forest land, but can migrate deeper into the soil profile in cultivated land. High-ring PAHs were abundant at depths of 0-30 cm, while low-ring PAHs were abundant deeper in the soil profiles. SOM had a significant effect on the vertical distribution of PAHs, and the physical and chemical properties of PAHs had a significant influence on their migration ability. However, combustion sources from industrial activities and transportation in the region are still considered the main sources of PAHs despite the fact that some low-ring PAHs derive from petroleum product inputs.

Characterization of polycyclic aromatic hydrocarbons and their phenanthroperylene quinone precursors in fossil crinoids using liquid chromatography–atmospheric pressure photoionization mass spectrometry

The distribution and origin of diagenetic products of polycyclic quinone pigments in fossil crinoids was investigated using high-performance liquid chromatography–diode array detection–atmospheric pressure photoionization mass spectrometry (HPLC–DAD–APPI-MS). A number of characteristic higher-molecular-weight polycyclic aromatic hydrocarbons (PAHs) were identified in toluene extracts of diverse crinoid samples, with 1,2,3,4,5,6-hexahydrophenanthro[1,10,9,8-opqra]perylene as the main compound. Moreover, phenanthro[1,10,9,8-opqra]perylene-7,14-dione (PPQ) and further derivatives were detected for the first time in the fossil record, representing intermediates between hydroxylated phenanthroperylene quinone pigments such as fringelite F and phenanthroperylene PAHs. The widespread presence of PPQ, its derivatives and related PAHs in fossil crinoids which contain phenanthroperylene quinone pigments confirms the diagenetic formation of specific PAHs by reductive degradation of quinone pigments.

Emission Characteristics of Polycyclic Aromatic Hydrocarbons and Nitro-Polycyclic Aromatic Hydrocarbons from Open Burning of Rice Straw in the North of Vietnam.

This research investigated the distribution and contribution of polycyclic aromatic hydrocarbons (PAHs) and nitro-polycyclic aromatic hydrocarbons (NPAHs) bound to particulate matter (PM) emitted from open burning of rice straw (RS) into the atmosphere in the north of Vietnam. The experiments were conducted to collect PM2.5 and total suspended particulates (TSP) prior to and during burning in the period of 2016–2018 in suburban areas of Hanoi. Nine PAHs and 18 NPAHs were determined using the HPLC-FL system. The results showed that the proportion of RS burning seasonally affects the variation of PAHs emission in atmospheric environment. The levels of nine PAHs from RS burning were 254.4 ± 87.8 µg g−1 for PM2.5 and 209.7 ± 89.5 µg g−1 for TSP. We observed the fact that, although fluoranthene (Flu) was the most abundant PAH among detected PAHs both in PM2.5 and TSP, the enrichment of Flu in TSP from burning smoke was higher than that in PM2.5 while the contribution of benzo[a]pyrene (BaP) and indeno[1,2,3- cd]pyrene (IDP) in PM2.5 from burning smoke were much higher than those in TSP. This research found that 1-nitropyrene (1-NP) and 6-nitrochrysene (6-NC) emit from RS burning with the same range with those from wood burning. The 2-nitrofluorene (2-NF) and 2-nitropyrene (2-NP) released from RS burning as the secondary NPAHs. This research provides a comprehensive contribution characterization of PAHs and NPAHs in PM with different size emitted from traditional local rice straw burning in the north of Vietnam. The results help to clarify the environmental behavior of toxic organic compounds from RS burning in Southeast Asia.

Characterization of polycyclic aromatic hydrocarbons in urban-rural integration area soil, North China: Spatial distribution, sources and potential human health risk assessment

The promotion of urbanization has accelerated the development of small manufacturing workshops and brought serious environmental problems. In this study, spatial distribution, sources and potential health risk for polycyclic aromatic hydrocarbons (PAHs) in urban-rural integration area soil in North China (800 km2) were discussed. The average total concentration of 16 PAHs was 225 μg kg−1, and range from 25 to 15155 μg kg−1 (n = 250). According to the European soil quality standards, more than 70% of the samples don't reach the pollution level, while around the small workshop concentration area and non-ferrous metal smelter were more contaminated than other area. The spatial distribution of soil PAHs concentration shows that low molecular weight, medium molecular weight and high molecular weight is very similar to the distribution of total PAHs, indicating that is likely to be caused by point source pollution. The sources of PAHs were identified by positive matrix factorization. The main six sources in the region are coal and biomass combustion, creosote, coke tar, vehicle and oil, which is consistent with the local energy consumption structure. Finally, a deterministic assessment of the cancer risk showed that the range for children was 5.94 × 10−8 to 2.53 × 10−5, and adults it ranged from 2.11 × 10−8 to 9.01 × 10−6. There is not a carcinogenic risk value greater than 10−4 in the entire region, but potential carcinogenic risks persisted in some areas. We conclude that PAHs pollution of soil in the area is an issue that deserves urgent attention for the relevant departments.

Characterization of polycyclic aromatic hydrocarbon (PAHs) source profiles in urban PM2.5 fugitive dust: A large-scale study for 20 Chinese cites

Polycyclic aromatic hydrocarbons (PAHs) in road dust (RD) and construction dust (CD) in PM2.5 were quantified in the samples collected in 20 Chinese cities. The PAHs profiles in urban PM2.5 fugitive dusts were determined and their potential health risks were evaluated. Seven geographical regions in China were identified as northwest China (NWC), the North China Plain (NCP), northeast China (NEC), central China (CC), south China (SC), southwest China (SWC), and east China (EC). The overall average concentrations of total quantified PAHs (ΣPAHs) were 23.2 ± 18.9 and 22.8 ± 29.6 μg·g−1 in RD and CD of PM2.5, indicating that severe PAHs pollution to urban fugitive dusts in China. The differences of ΣPAHs between RD and CD were minor in northern and central regions of China but much larger in southern and east regions. The ƩPAHs for RD displayed a pattern of “high in northern and low in southern”, and characterized by large abundance of high molecular weights (HMWs) PAHs, indicating that vehicle emission was the predominant pollution origin. Additionally, higher diagnostic ratios of fluoranthene/(fluoranthene + pyrene) in NCP, CC, and SWC suggest critical contributions of biomass burning and coal combustion for RD in these areas. In comparison, gasoline combustion was the major pollution source for CD PAHs in NWC, NCP, NEC, and CC, whereas industrial emissions such as cement production and iron smelting had strong impacts in the heavy industrial regions. The total benzo[a]pyrene (BaP) carcinogenic potency concentrations (BaPTEQ) for RD and CD both showed the lowest in SC (0.05 and 0.07, respectively) and the highest in NCP (10.99 and 7.67, respectively). The highest and lowest incremental life cancer risks (ILCR) were found in NCP and SC, coinciding with the spatial distributions of ambient PAHs levels. The total CD-related cancer risks for adults and children (~10−4) suggest high potential health risks in NCP, SWC, and NWC, whereas the evaluated values in EC and SC indicate virtual safety (≤10−6).

Characteristics of polycyclic aromatic hydrocarbons (PAHs) in soil horizon from high-altitude mountains in Northeastern China

Previous studies have reported that soils from high altitude mountains act as primary reservoirs of polycyclic aromatic hydrocarbons (PAHs). This study aims to investigate the spatial distribution and illuminate the behaviors of PAHs in soil profiles from Mt. Wangtiane in Northeastern China. Soil samples were collected by different soil genetic horizon rather than by depths at 10 sites, with altitudes from 1000 m to 2022 m. Results showed significantly (p < 0.05) higher concentrations of total PAHs (16 PAHs) in O-horizons (371 ± 32 to 2224 ± 207 ng g−1) than those in A- and B-horizons (362 ± 30 to 666 ± 58 ng−1 and 289 ± 23 to 571 ± 50 ng g−1, respectively). An increasing trend of PAH concentrations with altitude was observed from elevation ca. 1000 m to ca. 1800 m, but no correlation between PAH concentrations and altitude along transect was found. Total organic carbon (TOC) was strongly correlated (p < 0.05) with PAH concentrations in O-horizons but showed no relation with those in A- and B-horizons. Low molecular weight (LMW) PAHs were dominated in each soil horizon, and decreased percentage of high molecular weight (HMW) PAHs with depths in soils profiles was observed. Principle component analysis (PCA) separated O-horizons and A-/B-horizons based on PAH compositions, again suggesting different PAH compositions among soil horizons. These results reflect various processes of PAHs, including deposition, vertical motion, degradation and photolysis. This study suggests it is better to investigate characteristics of PAHs in soils by horizon rather than by depths.

Gas–particle partition and spatial characteristics of polycyclic aromatic hydrocarbons in ambient air of a prototype coking plant

This study investigated the gas–particle partition and spatial characteristics of polycyclic aromatic hydrocarbons (PAHs) in the ambient air of a prototype coking plant. High-volume samplers with glass fiber filters (GFFs) and polyurethane foams (PUFs) were used to collect PAHs in both gaseous and particulate phases. The EPA's 16 priority-controlled PAHs were measured using gas chromatography equipped with a mass-selective detector (GC-MS). The total PAH concentrations ranged from 1.32 μg m−3 to 9.41 μg m−3, with an average of 4.20 μg m−3. PAH abundance at the various sites of the coking plant was determined to be in the following order: coke side > machine side > leeward site; the lowest values were at the reference site and factory boundary. The medium-molecular-weight PAHs had the highest fraction at the coke side, whereas the low-molecular-weight PAHs were predominant at other sampling sites. Considerable amount of chrysene was detected at the coke side, fluorene at the machine side, acenaphthene at the leeward site (240 m downwind of the coke oven), and naphthalene at the other three sites. The gaseous fractions of PAHs at the six sampling sites ranged from 46.3% to 85.8% of the total PAHs in the gas–particle systems; and gaseous PAHs were predominant in the ambient air of the coking plant—except for the coke side, where the PAHs were dominantly partitioned to the particles. In addition, the particulate benzo(a)pyrene equivalence (BaPeq) fraction was high in the coking plant air. The slope (mr) values ranged from −0.59 to −0.39 in the plant, indicating that the absorption mechanism, rather than the adsorption mechanism, dominated the gas–particle partitioning. The intercept (br) values carry the information on the gaseous–particulate phase distribution of semivolatile organic compounds when the mr values are similar. The organic matter fraction in particles, particulate phase fraction of PAHs, and toxicity of particulate matter were found to increase with an increase in br values at similar mr values. The predominant mechanism was absorption for dibenz(a,h)anthracene, benzo(ghi)perylene, and indeno(1,2,3-cd)pyrene, but adsorption for benzo(b)fluoranthene, benzo(a)pyrene, and benzo(k)fluoranthene at the coke and machine sides. By contrast, for most high-molecular-weight PAHs, absorption into the organic matter was the predominant mechanism at other sites. The gas–particle partitioning mechanism of individual PAHs was closely related to the distance from the coke oven, rather than the orientation to the oven. These results may be of great importance in understanding the pollutant process and atmospheric transport of PAHs and may provide guidance to decision makers regarding air pollution control.

Sources and Characteristics of Polycyclic Aromatic Hydrocarbons in Ambient Total Suspended Particles in Ulaanbaatar City, Mongolia.

The purpose of this study was to identify pollution sources by characterizing polycyclic aromatic hydrocarbons from total suspended particles in Ulaanbaatar City. Fifteen polycyclic aromatic hydrocarbons were measured in total suspended particle samples collected from different sites, such as the urban center, industrial district and ger (Mongolian traditional house) areas, and residential areas both in heating (January, March), and non-heating (September) periods in 2017. Polycyclic aromatic hydrocarbon concentration ranged between 131 and 773 ng·m−3 in winter, 22.2 and 530.6 ng·m−3 in spring, and between 1.4 and 54.6 ng·m−3 in autumn. Concentrations of specific polycyclic aromatic hydrocarbons such as phenanthrene were higher in the ger area in winter and spring seasons, and the pyrene concentration was dominant in late summer in the residential area. Polycyclic aromatic hydrocarbons concentrations in the ger area were particularly higher than the other sites, especially in winter. Polycyclic aromatic hydrocarbon ratios indicated that vehicle emissions were likely the main source at the city center in the winter time. Mixed contributions from biomass, coal, and petroleum combustion were responsible for the particulate polycyclic aromatic hydrocarbon pollution at other sampling sites during the whole observation period. The lifetime inhalation cancer risk values in the ger area due to winter pollution were estimated to be 1.2 × 10−5 and 2.1 × 10−5 for child and adult exposures, respectively, which significantly exceed Environmental Protection Agency guidelines.

Impacts of photochemical ageing on the half-lives and diagnostic ratio of polycyclic aromatic hydrocarbons intrinsic to PM2.5 collected from 'real-world' like combustion events of wood and rice straw burning.

The present experimental study describes the characteristics of polycyclic aromatic hydrocarbons (PAHs) emitted with PM2.5 particles during wood and rice straw burning as well as impacts of photochemical ageing on the half lives of particulate PAHs and their diagnostic ratio values. The photochemical degradation kinetics experiments were carried out by exposing the PM2.5 to light and synthetic air flow. Pseudo first order rate constants were calculated based on PAH loss as a function of exposure time. Relatively quick degradation of lighter PAHs (3-rings) [(0.2-0.5)h-1] than heavier PAHs (4-6 rings) [(0.0005-0.03)h-1] indicates substantial impact of PAH-substrate interaction through π-π stacking with the carbonaceous substrates. Moreover, our results showed distinct PAH diagnostic ratios (DR) for wood and rice straw burnings which, however, change with time due to photochemical degradation. The later may add uncertainties in the applications of DR values for source apportionment. Furthermore, considerably large half lives (100-3000 h) of the carcinogenic PAHs as estimated under ambient solar radiation may cause poor and adverse air quality in long range and therefore demands immediate regulations against uncontrolled biomass burning.

Health risk assessment and source apportionment of polycyclic aromatic hydrocarbons associated with PM10 and road deposited dust in Ahvaz metropolis of Iran.

The objective of this study was to compare the characteristics of polycyclic aromatic hydrocarbons (PAHs) in PM10 and road dust samples, as well as to identify and quantify the contributions of each source profile using the positive matrix factorization (PMF) receptor model. Health risk assessment was carried out using toxic equivalency factors and incremental lifetime cancer risk (ILCR), which quantitatively estimate the exposure risk for age-specific groups. PM10 samples were collected on PTFE filters in the metropolitan area of Ahvaz. Road dust samples were also collected from all over the urban areas with different land uses. Total PAH concentrations in PM10 and road dust samples were 0.5-25.5ng/m3 and 49.3-16,645µg/kg, respectively. Pyrene was the highest PAH in the PM10 profile, whereas fluoranthene became the highest PAH in the road dust. Abundance of benzo[ghi]perylene at PM10 and road dust samples suggested a source indicator for traffic emissions. The results demonstrate that in 36.5% of samples, PM10 concentrations exceed the maximum concentration level recommended by EPA. A multiple linear regression model was used to estimate the influence of meteorological parameters (temperature, wind speed, and relative humidity) on buildup of PAHs. All of PAH species show higher concentrations during the cold and typical days rather than the dust event days and warm periods. PMF analysis showed that vehicular emissions (50.6%) and industrial activities (especially steel industries) (30.4%) were first two sources of PAHs bounded with PM10, followed by diesel emissions (11.6%) and air-soil exchange (7.4%). For road dust samples, three common sources were also identified: vehicular traffic (48%), industrial activities (42.3%), and petrogenic sources (9.7%), in line with that of diagnostic molecular ratios results. According to the results of health risk assessment model, the ILCR of exposure to PAHs associated with PM10 and road-deposited dust was higher than the guidelines of USEPA, indicating high carcinogenic risk.

Characterization of polycyclic aromatic hydrocarbons (PAHs) in small craft harbour (SCH) sediments in Nova Scotia, Canada

Polycyclic aromatic hydrocarbons (PAHs) have been widely studied in sediments due to their ubiquity and persistence in aquatic environments and potential for impairment to biota. Small craft harbour (SCH) sediments in Nova Scotia (NS), Canada, have yet to be studied comprehensively. SCHs are essential to the fishing industry, which is important for the Canadian economy. This spatiotemporal characterization study evaluated thirty-one SCHs across NS between 2001 and 2017 by analyzing sediment reports (secondary data). Sediment PAH concentrations varied widely across all SCHs. Few SCHs exhibited sediment PAH concentrations likely to impair biota based on comparison to sediment quality guidelines. Sediments in the Gulf region of NS were least impacted by PAHs, while the Southwest region was most impacted. Distribution of individual PAHs in sediments follows global trends, with high molecular weight PAHs dominating samples.

Characteristics of polycyclic aromatic hydrocarbons components in fine particle during heavy polluting phase of each season in urban Beijing

Beijing experienced a period of severe atmospheric particulate pollution from 2015 to 2016. In order to acquire the characteristics of polycyclic aromatic hydrocarbons (PAHs) under heavy polluting status, one year sampling campaign was carried out. We selected PM2.5 samples which had the highest concentrations or suffered serious haze-fog weathers in each month. Through the analysis of data from heavily polluting phase, the mean concentrations of PM2.5 and PAHs in winter (369.63 μg m−3 and 223.60 ng m−3) were obviously higher than that in other seasons. The concentration of Σ16PAHs ranged from 3.22 to 297.01 ng m−3, with a mean value of 77.48 ng m−3. In winter, 4-ring PAH congeners (52.33%) contributed the most in PM2.5, followed by 5-rings (27.05%), 6-rings (11.55%) and 2∼3-rings (9.06%). Summertime measurements showed the highest decline in PAHs concentrations for 3∼5-ring congeners. The diagnostic ratios and PCA analysis manifest that vehicle and combustion emission were major sources and totally occupied 88.57% under heavy polluting stage. Moreover, exponential relationship between LWM/HWM (light/high weight molecule-PAHs) and combustion-derived PAHs, as well as linear relationship between BghiP and ∑PAHs verified that the pollution sources mentioned above affected local atmosphere environment as major sources. The highest total BaP equivalent concentration suggested that toxicity potency under heavy polluting phase was mainly attributed to 5-ring PAHs. Through analysis of carcinogenic-PAHs, potency risk to adults was significantly higher than that to children. BaP, BbF and DahA, which belong to 5-ring congeners, contributed the highest potency carcinogenic risk. BbF in winter, BaP in spring and winter may cause potential risk to local residents.

Determination and risk characterization of polycyclic aromatic hydrocarbons of tea by using the Margin of Exposure (MOE) approach.

Tea is one of the most frequently consumed drinks due to its favourite taste and the health benefit. Tea is produced by several processes and drying is very important step to develop the flavour and destroys the enzymes in tea. However, during drying tea, polycyclic aromatic hydrocarbons some of which are carcinogen and genotoxin are naturally produced. The risk of PAHs by drinking tea was characterized by determining contents of 4 PAHs in tea. 4 PAHs including Benz(a)anthracene (BaA), Chrysene (CHR), Benzo(b)fluoranthene (BbF) and Benzo(a)pyrene (BaP) were investigated by GC-MS in total 468 tea products, which were contaminated up to 4.63ngg-1. Mate tea was the most highly contaminated by BaA, CHR, BbF and BaP and followed by Solomon's seal and Chrysanthemum. The Margin of Exposures calculated by the concentration of BaA, CHR, BbF and BaP and consumption amount of tea were higher than 10,000, and the risk of PAHs in tea were low concern to public health.

Sources and contamination characteristics of PAHs in environmental media in a karst underground river system (southern China)

The aim of this study was to determine the sources and contamination characteristics of polycyclic aromatic hydrocarbons (PAHs) in various environmental media in a karst underground river system. For this purpose, air, underground river water, sediment, and soil samples were collected from a typical underground river in southern China in the dry and wet seasons of 2013–2014, and the compositional spectra, distribution, and ratio characteristics of 16 PAHs were determined for comparative analysis. The results show that three 2–3-ring PAHs (naphthalene, phenanthrene, and fluoranthene) mainly occur in air and underground river water. In sediments and soils, 4–6-ring PAHs are the main components. The PAH concentrations in the air in the wet season are clearly greater than those in the dry season, while it is the opposite in the underground water. Seasonal differences in the concentration of PAHs in the sediments and soils are minor. The concentrations of PAHs in the environmental media overall showed variation in the following order: upstream < midstream < downstream, and this is related to pollutant discharge, adsorption, etc. The main source of PAHs in the upstream area is the combustion of grass, wood, and coal, while it is petroleum in the midstream area, and combustion of grass, wood, coal, and petroleum near the outlet of the underground river. It is necessary to change the energy structure in the study area, improve the efficiency of environmental protection facilities, reduce the emission in vehicle exhaust, and control pollution by PAHs at their sources.

Characterization of polycyclic aromatic hydrocarbons (PAHs) in vegetables near industrial areas of Shanghai, China: Sources, exposure, and cancer risk

Dietary consumption of contaminated vegetables may contribute to polycyclic aromatic hydrocarbon (PAH) exposure in humans; however, this exposure pathway has not been examined thoroughly. This study aims to characterize the concentrations of PAHs in six types of vegetables grown near industrial facilities in Shanghai, China. We analyzed 16 individual PAHs on the US EPA priority list, and the total concentration in vegetables ranged from 65.7 to 458.0 ng g−1 in the following order: leafy vegetables (romaine lettuce, Chinese cabbage and Shanghai green cabbage) > stem vegetables (lettuce) > seed and pod vegetables (broad bean) > rhizome vegetables (daikon). Vegetable species, wind direction, and local anthropogenic emissions were determinants of PAH concentrations in the edible part of the vegetable. Using isomer ratios and principal component analysis, PAHs in the vegetables were determined to be mainly from coal and wood combustion. The sources of PAHs in the six types of vegetables varied. Daily ingestion of PAHs due to dietary consumption of these vegetables ranged from 0.71 to 14.06 ng d−1 kg−1, with contributions from Chinese cabbage > broad bean > romaine > Shanghai green cabbage > lettuce > daikon. The daily intake doses adjusted by body weight in children were higher than those in teenagers and adults. Moreover, in adults, higher concentrations of PAHs were found in females than in males. For individuals of different age and gender, the incremental lifetime cancer risks (ILCRs) from consuming these six vegetables ranged from 4.47 × 10−7 to 6.39 × 10−5. Most were higher than the acceptable risk level of 1 × 10−6. Our findings demonstrate that planting vegetables near industrial facilities may pose potential cancer risks to those who consume the vegetables.