A fast extraction technique for extracting polycyclic aromatic hydrocarbons (PAHs) from lichens samples used as biomonitors of air pollution: Dynamic sonication versus other methods

Investigation of Health Effects of Major Phenolic Compounds in Foods: Extraction Processes, Analytical Approaches and Applications

The escalating costs of healthcare services and a growing awareness of personal health responsibilities have led individuals to explore natural methods alongside conventional medicines for health improvement and disease prevention. The aging global population is experiencing increased health needs, notably related to conditions like diabetes, heart disease, and hypertension. Lifestyle-related diseases, poor dietary habits, and sedentary lifestyles underscore the importance of foods containing nutrients that can aid in preventing and managing these diseases. Phenolic compounds, a fundamental group of phytochemicals, are prominent in the chemical diversity of the natural world and are abundant in functional foods. Widely distributed in various plant parts, these compounds exhibit important functional and sensory properties, including color, taste, and aroma. Their diverse functionalities, particularly antioxidant activity, play a crucial role in mitigating cellular oxidative stress, potentially reducing damage associated with serious health issues such as cardiovascular disease, neurodegenerative disea23ses, and cancer. Phenolic compounds exist in different forms, some combined with glycosides, impacting their biological effects and absorption. Approximately 8000 polyphenols isolated from plants offer significant potential for natural medicines and nutritional supplements. Therefore, their extraction process and selective and sensitive food determination are very important. This review focuses on the extraction processes, analytical methods, and health effects of major phenolic compounds in foods. The examination encompasses a comprehensive analysis of analytical approaches and their applications in elucidating the presence and impact of these compounds on human health.

Lichen biomonitoring to assess spatial variability, potential sources and human health risks of polycyclic aromatic hydrocarbons (PAHs) and airborne metal concentrations in Manchester (UK)

Airborne metals and organic pollutants are linked to severe human health impacts, i.e. affecting the nervous system and being associated with cancer. Airborne metals and polycyclic aromatic hydrocarbons (PAHs) in urban environments are derived from diverse sources, including combustion and industrial and vehicular emissions, posing a threat to air quality and subsequently human health. A lichen biomonitoring approach was used to assess spatial variability of airborne metals and PAHs, identify potential pollution sources and assess human health risks across the City of Manchester (UK). Metal concentrations recorded in lichen samples were highest within the city centre area and along the major road network, and lichen PAH profiles were dominated by 4-ring PAHs (189.82 ng g-1 in Xanthoria parietina), with 5- and 6-ring PAHs also contributing to the overall PAH profile. Cluster analysis and pollution index factor (PIF) calculations for lichen-derived metal concentrations suggested deteriorated air quality being primarily linked to vehicular emissions. Comparably, PAH diagnostic ratios identified vehicular sources as a primary cause of PAH pollution across Manchester. However, local more complex sources (e.g. industrial emissions) were further identified. Human health risk assessment found a "moderate" risk for adults and children by airborne potential harmful element (PHEs) concentrations, whereas PAH exposure in Manchester is potentially linked to 1455 (ILCR = 1.45 × 10-3) cancer cases (in 1,000,000). Findings of this study indicate that an easy-to-use lichen biomonitoring approach can aid to identify hotspots of impaired air quality and potential human health impacts by airborne metals and PAHs across an urban environment, particularly at locations that are not continuously covered by (non-)automated air quality measurement programmes.

Biomonitoring of polycyclic aromatic hydrocarbons (PAHs) by Murraya paniculata (L.) Jack in South Kolkata, West Bengal, India: spatial and temporal variations

Attempts have been made in the present study for ascertaining the concentrations of atmospheric polycyclic aromatic hydrocarbons (PAHs) using passive biosamplers in preference to conventional air sampling methods. Mechanical stirring, sonication, Soxhlet technique and microwave-assisted Soxhlet extraction (MASE) were employed to extract PAHs from an evergreen plant (Murraya paniculata) leaves (having long life-span) sampled from polluted places of South Kolkata, India, with dense population and heavy traffic. Effects of extraction methods and operational parameters (solvent and time) on the recovery levels of PAHs were also investigated. Purified extracts, acquired through adsorption chromatography, were subjected to GC-MS and HPLC-UV analyses for qualitative and quantitative assessment of PAHs. Spatio-temporal distribution of accumulated PAHs across the sampling sites was monitored over premonsoon, postmonsoon and winter supported by pollutant source characterization. The results displayed that the extraction yields of Soxhlet (272.07 ± 26.15 μg g-1) and MASE (280.17 ± 15.46 μg g-1) were the highest among the four techniques. Conditions of extraction with toluene for 6 h were found to be most favorable for PAHs. In spatio-temporal analysis, total concentrations of PAHs in the foliar samples varied from 200.98 ± 2.72 to 550.79 ± 10.11 μg g-1 dry weight, and the highest values being recorded in the samples of Exide More because of daylong inexorable traffic flow/crowding increasing the burden of ambient PAHs. Widespread changes in meteorology exerted influence on seasonal concentrations of PAHs in plant leaves, and extent of leaf contamination by PAHs was observed extreme in winter followed by postmonsoon and then, premonsoon. Foliar accretion of PAHs differed in the study sites with diverse sources of emission from motor vehicles, fossil fuel and biomass burning along with other human interferences.

Determination of polycyclic aromatic hydrocarbons extracted from lichens by gas chromatography–mass spectrometry

Lichens are well-known biomonitors for semi-volatile pollutants, due to their ability to absorb and retain different chemical compounds such as Polycyclic Aromatic Hydrocarbons (PAHs), directly linked to levels in the atmosphere. Based on that, this paper proposes an analytical method capable of quantifying 16 EPA-PAHs from lichens found in an intertropical zone, as a natural alternative to typical capture methods, with the aim of monitoring atmospheres polluted by toxic compounds. An analytical protocol, including sample pre-treatment, followed by ultrasound extraction, clean-up in a chromatographic column, concentration and quantification by Gas Chromatography-Mass Spectrometry (GC-MS) using Selective Ion Monitoring has been developed. Additionally, a set of guidelines on lichen collection and sample handling is given, in order to achieve representative samples.•

Limits of quantification (LOQ) and detection (LOD) varied from 2.0 to 16 µg/L and 1.0 to 5.0 µg/L, respectively. Calibration curves had correlation coefficients higher than 0.99 in all cases.

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Validation of the method for determining PAHs concentration associated to 30 lichen samples collected along two roads, with high and low traffic volumes was carried out.

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The method showed good performance according to the sources of PAHs, traffic patterns and gradient in roads.

A critical review on plant biomonitors for determination of polycyclic aromatic hydrocarbons (PAHs) in air through solvent extraction techniques

Polycyclic aromatic hydrocarbons (PAHs) are hydrocarbons having two or more fused aromatic rings, released from natural (like forest fires and volcanic eruption) as well as man-made sources (like burning of fossil fuel & wood, automobile emission). They are persistent priority pollutants and continue to last for a long time in the environment causing severe damage to human health owing to their genotoxicity, mutagenicity and carcinogenicity. The study of PAHs in environment has therefore aroused a global concern. PAHs adsorption to plant cell wall is facilitated by transpiration and plant root lipids which help PAHs transfer from roots to leaves and stalks, causing more accumulation of contaminants with the increase in lipid content. Hence, these bioaccumulators can be utilized as biomonitors for indirect assessment of ambient air pollution. Efficacy of specific plants, lichens and mosses as useful biomonitors of airborne PAHs pollution has been discussed in this review along with prevalent classical and modified extraction techniques coupled with proper analytical procedures in order to gain an insight into the assessment of atmospheric PAHs concentrations. Different modern and modified solvent extraction techniques along with conventional Soxhlet method are identified for extraction of PAHs from accumulative bioindicators and analytical methods are also developed for accurate determination of PAHs. Process parameters like choice of solvent, temperature, time of extraction, pressure and matrix characteristics are usually checked. An approach of biomonitoring of PAHs using plants, lichens and mosses has been discussed here as they usually trap the atmospheric PAHs and mineralize them.

Temporal change of the accumulation of persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) in lichens in Switzerland between 1995 and 2014

The aim of this study was to assess the temporal change of atmospheric deposition patterns of persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) in Switzerland between 1995 and 2014 by a passive biomonitoring with lichens. Lichen tissues sampled at 16 representative sites in the same season of 1995 and 2014 were analyzed for a total of 94 individual and 27 sum parameters of POPs and PAHs by means of gas chromatography-mass spectrometry (GC/MS). The comparative analyses showed a decrease of 40 to 80% (medians) for most of the POPs and PAHs concentration in lichens at all site categories. Reduction in tissue concentration of the polychlorinated dibenzo-p-dioxins/furans (PCDD/PCDFs), such as the highly toxic 2,3,7,8-TetraCDD and the TEQ according to WHO (2005) were 66% and 73%, respectively. For the dioxin- and non-dioxin-like PCBs, a decrease of 67% and 58% was found. The average decrease of 30 organochlorine pesticides and insecticides (OCPs) was 65%, with a 94% decrease for lindane. For the 27 PAHs and for benzo(a)pyrene, an average decrease of 58% and 59% was found. Polybrominated diphenyl ethers (PBDE) showed reduced concentrations in lichens at rural and agglomeration sites, but an increase of contamination was observed at industrial and road traffic sites. The direct comparison of changes of POPs and PAHs concentrations in lichens and of emissions between 1995 and 2014 revealed consistent results. The results of this study highlight for the first time in biota the positive effect of emission regulation of POPs in Switzerland.

Comparison of extraction techniques for polycyclic aromatic hydrocarbons from lichen biomonitors

Lichens are useful biomonitors for atmospheric polycyclic aromatic hydrocarbons (PAHs). Different sample preparation techniques were explored in this regard, including ultrasound-assisted solvent extraction, microwave-assisted extraction, Soxhlet, and the quick, easy, cheap, effective, rugged, and safe (QuEChERS) technique. It was found that a QuEChERS technique using hexane:acetone (1:1, v/v), never reported before for application to lichens, provided the best recoveries of internal standards, the highest total peak area for all PAHs of interest, and %RSDs comparable with the other preparation techniques tested. The optimized sample preparation technique was found to be a comparatively fast method (45 min), with good recoveries (96%), using less solvents and minimal energy consumption. Strong matrix effects were found: both strong enhancement (for the lighter PAHs) and strong suppression (for the heavier PAHs). The use of matrix-matched standards is thus imperative for the accurate determination of PAH concentrations in the lichen samples. Graphical abstract "Note: This data is mandatory. Please provide."

Characterization of atmospheric emission sources in lichen from metal and organic contaminant patterns

Lichen samples from contrasted environments, influenced by various anthropic activities, were investigated focusing on the contaminant signatures according to the atmospheric exposure typologies. Most of the contaminant concentrations measured in the 27 lichen samples, collected around the industrial harbor of Fos-sur-Mer (France), were moderate in rural and urban environments, and reached extreme levels in industrial areas and neighboring cities (Al up to 6567 mg kg^-1, Fe 42,398 mg kg^-1, or ΣPAH 1417 μg kg^-1 for example). At the same time, a strong heterogeneity was noticed in industrial samples while urban and rural ones were relatively homogeneous. Several metals could be associated to steel industry (Fe, Mn, Cd), road traffic, and agriculture (Sb, Cu, Sn), or to a distinct chemical installation (Mo). As well, PCDFs dominated in industrial samples while PCDDs prevailed in urban areas. The particularities observed supported the purpose of this work and discriminated the contributions of various atmospheric pollution emission sources in lichen samples. A statistical approach based on principal component analysis (PCA) was applied and resolved these potential singularities into specific component factors. Even if a certain degree of mixing of the factors is pointed out, relevant relationships were observed with several atmospheric emission sources. By this methodology, the contribution of industrial emissions to the atmospheric metal, PAH, PCB, and PCDD/F levels was roughly estimated to be 60.2%, before biomass burning (10.2%) and road traffic (3.8%). These results demonstrate that lichen biomonitoring offers an encouraging perspective of spatially resolved source apportionment studies.

QuEChERS extraction for multi-residue analysis of PCBs, PAHs, PBDEs and PCDD/Fs in biological samples

In this study, a fast and rugged method is presented for the analysis of PCBs, PAHs, PBDEs and PCDD/Fs in biological tissues using a simple Quick, Easy, Cheap, Efficient, Rugged and Safe (QuEChERS) extraction and a clean-up by Gel Permeation Chromatography (GPC) and silica Solid Phase Extraction (SPE). Development was performed on blue mussels (Mytilus edulis) and Atlantic salmon (Salmo salar) for evaluation of two ranges of lipid and water content of biological tissues. Statistical validation was performed with Atlantic salmon samples. Forty-five PAHs were analyzed including the priority list of the US EPA and the European Union with 41 PCBs, 24 PBDEs and 17 PCDD/Fs. Instrumental analyses were performed on Gas Chromatography - High Resolution Mass Spectrometry (GC-HRMS). Accuracy was evaluated for PCBs and PCDD/Fs with a certified reference material furnished by the National Research Council Canada (NRCC) and also compared with results obtained by the conventional Soxhlet extraction. Statistical validation showed recoveries for PCBs, PAHs, PBDEs and PCDD/Fs close to 100% with average Relative Standard Deviation (RSD) lower than 10% and internal standard recoveries in the range of 70% with average RSD ranging from 5-15%. Average calculated Method Detection Limits (MDLs) were lower than 0.05μg/Kg for PCBs, 0.2μg/Kg for PAHs and PBDEs and 1ng/Kg for PCDD/Fs. The method is a faster and cheaper alternative to the time-consuming conventional method that has been used in most environmental laboratories.

Guidelines for biomonitoring persistent organic pollutants (POPs), using lichens and aquatic mosses--a review

During the last decades, awareness regarding persistent organic pollutants (POPs), such dioxins and furans (PCDD/Fs) and polycyclic aromatic hydrocarbons (PAHs), has become a cutting-edge topic, due to their toxicity, bioaccumulation and persistency in the environment. Monitoring of PCDD/Fs and PAHs in air and water has proven to be insufficient to capture deposition and effects of these compounds in the biota. To overcome this limitation, environmental biomonitoring using lichens and aquatic mosses, have aroused as promising tools. The main aim of this work is to provide a review of: i) factors that influence the interception and accumulation of POPs by lichens; ii) how lichens and aquatic bryophytes can be used to track different pollution sources and; iii) how can these biomonitors contribute to environmental health studies. This review will allow designing a set of guidelines to be followed when using biomonitors to assess environmental POP pollution.

A step towards the use of biomonitors as estimators of atmospheric PAHs for regulatory purposes

One of the main drawbacks of using lichens to monitor atmospheric PAHs has been reported as the inexistence of studies aiming to translate PAH values in lichens into the atmospheric equivalents ones, in order to use this information for regulatory purposes. In this work, PAH concentrations in lichens were compared with PAH concentrations measured in a conventional active sampler in an outdoor environment for a 9-month span. Significant positive correlations between HMW-PAHs, Σ16 EPA-PAHs, and BaP equivalent concentrations in lichens and those in air (TSP) were found. Concentrations of Σ16 EPA-PAHs in lichens and air showed a seasonal variation, with highest values during winter and lowest values during summer. Meteorological variables - temperature, atmospheric pressure, relative humidity, and wind speed - showed to significantly influence PAH concentrations in both lichens and air. Based on the significant linear correlations, equations for translating PAH concentrations measured in lichens into equivalent ones for air were proposed for the first time, allowing a broader use of lichens' information regarding PAHs in monitoring schemes and decision-making.

Techniques for analysis of plant phenolic compounds

Phenolic compounds are well-known phytochemicals found in all plants. They consist of simple phenols, benzoic and cinnamic acid, coumarins, tannins, lignins, lignans and flavonoids. Substantial developments in research focused on the extraction, identification and quantification of phenolic compounds as medicinal and/or dietary molecules have occurred over the last 25 years. Organic solvent extraction is the main method used to extract phenolics. Chemical procedures are used to detect the presence of total phenolics, while spectrophotometric and chromatographic techniques are utilized to identify and quantify individual phenolic compounds. This review addresses the application of different methodologies utilized in the analysis of phenolic compounds in plant-based products, including recent technical developments in the quantification of phenolics.

Use of bioindicators to evaluate air quality and genotoxic compounds in an urban environment in Southern Brazil

Biological indicators are widely used to monitor genotic compounds and air quality in urban environments. Parmotrema tinctorum and Teloschistes exilis have been used to verify the presence of pollutants and analyze morphophysiological alterations in the thallus of species caused by their action. Species were exposed for seven months, in an urban area, in southern Brazil. Mutagenicity and cytotoxicity of PM10 organic extracts were assessed in the Salmonella/microsome assay at two stations. High concentrations of S, Pb, Cr, Zn and Hg were registered in the last period of exposure and more significant morphophysiological damages were verified in the lichens. Generally a higher mutagenic activity is observed in organic extracts of airborne particulate matter during the first months and in the third period of exposure of lichens. In addition, nitro compounds was detected through nitro-sensitive strains. Lichens and mutagenic biomarkers enabled the evaluation of air quality and the presence of environmentally-aggressive compounds.

A cost effective, sensitive, and environmentally friendly sample preparation method for determination of polycyclic aromatic hydrocarbons in solid samples

A simple, cost effective, and yet sensitive sample preparation technique was investigated for determining Polycyclic Aromatic Hydrocarbons (PAHs) in solid samples. The method comprises ultrasonic extraction, Stir Bar Sorptive Extraction (SBSE), and thermal desorption-gas chromatography-mass spectrometry to increase analytical capacity in laboratories. This method required no clean-up, satisfied PAHs recovery, and significantly advances cost performance over conventional extraction methods, such as Soxhlet and Microwave Assisted Extraction (MAE). This study evaluated three operational parameters for ultrasonic extraction: solvent composition, extraction time, and sample load. A standard material, SRM 1649 a (urban dust), was used as the solid sample matrix, and 12 priority PAHs on the US Environmental Protection Agency (US EPA) list were analyzed. Combination of non-polar and polar solvents ameliorated extraction efficiency. Acetone/hexane mixtures of 2:3 and 1:1 (v/v) gave the most satisfactory results: recoveries ranged from 63.3% to 122%. Single composition solvents (methanol, hexane, and dichloromethane) showed fewer recoveries. Comparing 20 min with 60 min sonication, longer sonication diminished extraction efficiencies in general. Furthermore, sample load became a critical factor in certain solvent systems, particularly MeOH. MAE was also compared to the ultrasonic extraction, and results determined that the 20-min ultrasonic extraction using acetone/hexane (2:3, v/v) was as potent as MAE. The SBSE method using 20 mL of 30% alcohol-fortified solution rendered a limit of detection ranging from 1.7 to 32 ng L(-1) and a limit of quantitation ranging from 5.8 to 110 ng L(-1) for the 16 US EPA PAHs.

An overview of sample preparation and extraction of synthetic pyrethroids from water, sediment and soil

The latest developments in sample preparation and extraction of synthetic pyrethroids from environmental matrices viz., water, sediment and soil were reviewed. Though the synthetic pyrethroids were launched in 1970s, to the best of authors' knowledge there was no review on this subject until date. The present status and recent advances made during the last 10 years in sample preparation including conservation and extraction techniques used in determination of synthetic pyrethroids in water, sediment and soil were discussed. Pre- and post-extraction treatments, sample stability during extraction and its influence upon the whole process of analytical determination were covered. Relative merits and demerits including the green aspects of extraction were evaluated. The current trends and future prospects were also addressed.

Lichens as an integrating tool for monitoring PAH atmospheric deposition: a comparison with soil, air and pine needles

The aim of this study was to validate lichens as biomonitors of PAH atmospheric deposition; for that, an inter-comparison between the PAH profile and concentrations intercepted in lichens with those of air, soil and pine needles was performed. The study was conducted in a petro-industrial area and the results showed that PAH profiles in lichens were similar to those of the air and pine needles, but completely different from those of soils. Lichens accumulated higher PAH concentrations when compared to the other environmental compartments and its concentrations were significantly and linearly correlated with concentrations of PAHs in soil; we showed that a translation of the lichen PAHs concentrations into regulatory standards is possible, fulfilling one of the most important requirements of using lichens as biomonitors. With lichens we were then able to characterize the air PAHs profile of urban, petro-industrial and background areas.

Spatial modeling of PAHs in lichens for fingerprinting of multisource atmospheric pollution

PAHs are toxic compounds emitted by several anthropogenic sources, which have a great impact on human health. We show, for the first time, how spatial models based on PAHs intercepted by lichens can be used for fingerprinting multisource atmospheric pollution in a regional area. Urban-industrial areas showed the highest atmospheric deposition of PAHs followed by urban > industrial > agricultural > forest Multivariate analysis of lichen data showed, for the first time, a clear distinction between various sources of PAHs in the same area: urban are dominated by 4-ring PAHs, forest by 3-ring PAHs, and industrial by 5- and 6-ring PAHs or by 2-ring PAHs (petrogenic or pyrogenic, respectively). Heavy metals were also used for supporting the fingerprinting of PAH sources, reinforcing the industrial origin of 5- and 6-ring PAHs and revealing their particular nature. The spatial structure of the models for different PAHs seems to be dependent on the following factors: size and hydrophilic character of different PAHs, type of emission sources (point or nonpoint), and dispersion associated with particulates of different sizes. Based on the long-term integration of PAHs in lichens, these spatial models will significantly improve our knowledge on the impact of PAH chronic-exposure to humans and ecosystems.

Assessing the effects of fluoxetine on Physa acuta (Gastropoda, Pulmonata) and Chironomus riparius (Insecta, Diptera) using a two-species water-sediment test

Fluoxetine has been tested in a two-species water-sediment system, which allowed a two-generation study with Chironomus riparius and a partial life-cycle with the freshwater snail Physa acuta to be performed at the same time. The design considered the continuous application of fluoxetine to overlaying water for nominal concentrations of 31.25, 62.5, 125 and 250 microg/L. A fifth treatment (87.5 microg/L) level consisted of pulse applications once a week. Measures of water and sediment concentrations were determined once a week and at the end of experiment (day 44), respectively. The fate study demonstrated that water dissipation can be explained by partitioning of fluoxetine to sediment. At the end of experiment, the percentage of detected fluoxetine was up to 10-fold higher in sediment than in overlaying water. The employed two-species test allowed distinguishing, in the same exposure conditions, effects due to waterborne exposure together ingestion at the sediment surface (freshwater grazing snail P. acuta) and exposure by burrowing activities (sediment-dwelling insect larvae C. riparius). The effect assessment showed a stimulation of P. acuta reproduction at lower concentrations (31.25 and 62.5 microg/L), while the opposite effect was observed at the highest treatment (250 microg/L). Additional studies should be conducted to establish if the statistically significant differences observed in F0 sex ratio at the 62.5 microg/L and F1 adult emergence at 31.25 microg/L of C. riparius have a toxicological significance. This study showed that fluoxetine can affect reproduction of freshwater molluscs. The results of the present study may contribute to knowledge on ecotoxicology of pharmaceuticals, about which little data is available. The possible consequences and implications for targeting the environmental risk assessment of fluoxetine are discussed.

Sample handling strategies for the determination of persistent trace organic contaminants from biota samples

Even after emergence of most advanced instrumental techniques for the final separation, detection, identification and determination of analytes, sample handling continues to play a basic role in environmental analysis of complex matrices. In fact, sample preparation steps are often the bottleneck for combined time and efficiency in many overall analytical procedures. Thus, it is not surprising that, in the last two decades, a lot of effort has been devoted to the development of faster, safer, and more environment friendly techniques for sample extraction and extract clean up, prior to actual instrumental analysis. This article focuses on the state of the art in sample preparation of environmental solid biological samples dedicated to persistent organic pollutants (POPs) analysis. Extraction techniques such as Soxhlet extraction, sonication-assisted extraction, supercritical fluid extraction (SFE), microwave-assisted extraction (MAE), pressurised liquid extraction (PLE) and matrix solid-phase dispersion (MSPD) are reviewed and their most recent applications to the determination of POPs in biota samples are provided. Additionally, classical as well as promising novel extraction/clean-up techniques such as solid phase microextraction (SPME) are also summarized. Finally, emerging trends in sample preparation able to integrate analytes extraction and their adequate clean-up are presented.

Use of lichens as pollution biomonitors in remote areas: comparison of PAhs extracted from lichens and atmospheric particles sampled in and around the Somport tunnel (Pyrenees)

Lichens of the species Parmelia sulcata were collected from sites on both sides of the Somport tunnel (which links France and Spain) and atmospheric particles were collected by air samplers installed within and on either side of the tunnel. Polycyclic aromatic hydrocarbons (PAHs) in the lichen and particle samples were then extracted, identified, quantified, and compared to evaluate the potential utility of lichens as pollution biomonitors in remote areas. The origin of the PAHs was also assessed using the Phe/Ant, Flu/Pyr, Ant/Ant+Phe, Flu/Flu+Pyr, and BaA/BaA+Chr concentration ratios. The total concentration of 16 priority PAHs ranged from 6.79 to 23.3 microg/g in particles outside the tunnel, from 18.3 to 265.2 microg/g in particles inside the tunnel, and from 0.91 to 1.92 microg/g in the lichen samples. The PAH ratios found in the lichens and particulate matter indicate that they were of pyrogenic origin and that road traffic was a major contributor. Results from the lichen samples suggest that they may be excellent biomonitors of pollution in remote areas.