Concentrations Of Polycyclic Aromatic Compounds Research Articles

Characterization of cross-continental PM2.5: Insights into emissions and chemical composition

Atmospheric fine particulate matter (PM2.5) is a critical indicator of air quality, with substantial implications for human health. Understanding the emission sources and chemical composition of PM2.5 is crucial for mitigating possible adverse health effects. This study spans five diverse cities on three continents from north and south hemisphere: Stockholm (Sweden), Kyoto (Japan), Limeira, Ribeirão Preto, and Cáceres (Brazil). Our objective was to assess PM2.5 chemical composition and regional and long-range transport influences to identify the main sources of particulate air pollution at these cities during the winter/dry seasons. All studied cities but Kyoto exhibited PM2.5 levels above World Health Organization (WHO) guidelines, with the Brazilian cities experiencing the highest fine particle pollution levels, implying increased adverse health risks. We observed significant variations in concentrations of polycyclic aromatic compounds (PACs), monosaccharide anhydrides (MAs), and inorganic elements. Limeira exhibited the highest levels of total PACs (median level of 12.4 ng m−3), while Cáceres displayed high variability of PACs, most likely due to episodic regional wildfire events. MA concentrations were significantly higher in Limeira and Ribeirão Preto and together with elevated levels of retene and potassium (K) they suggested a substantial influence of biomass burning. Backward air mass trajectory analysis suggested widespread Amazon and Savanna wildfires along with local fires as main contributors for these sites. All source identification approaches highlighted differences among the cities, with Stockholm and Kyoto showing influence of sources related to traffic emissions, waste burning, and long-range transport, and Brazilian cities traffic, industrial, biogenic, and more evident biomass burning. This cross-continental study provides valuable insights into PM2.5 composition and emission sources, emphasizing the impact of different emissions on air quality. Our findings underscore the importance of local strategies to mitigate air pollution and protect public health, especially in regions where PM2.5 levels consistently exceed recommended guidelines.

Polycyclic aromatic compounds in a northern freshwater ecosystem: Patterns, sources, and the influences of environmental factors

Polycyclic aromatic compounds (PACs) - a large group of organic chemicals naturally present in petroleum deposits (i.e., petrogenic) or released into the environment by incomplete combustion of organic materials (i.e., pyrogenic) - represent a potential risk to the health of aquatic ecosystems. In high latitude freshwater ecosystems, concentrations of PACs may be increasing, yet there are limited studies in such systems to assess change and to understand threats. Using 10 years of contemporary data from passive samplers deployed across five regions (n = 43 sites) in the Mackenzie River Basin, we (i) describe baseline levels of PACs, (ii) assess spatiotemporal patterns, and (iii) evaluate the extent to which environmental factors (fire, snowmelt, and proximity to oil infrastructure) influence concentrations in this system. Measured concentrations were low, relative to those in more southern systems, with mixtures primarily being dominated by non-alkylated, low molecular weight compounds. Concentrations were spatially consistent, except for two sites near Norman Wells (an area of active oil extraction) with increased levels. Similarly, observed annual variation was minimal, with 2014 having generally higher levels of PACs. We did not detect effects of fire, snowmelt, or oil infrastructure on concentrations. Taken together, our findings suggest that PACs in the Mackenzie River are currently at low levels and are primarily petrogenic in origin. They further indicate that ongoing monitoring and testing of environmental drivers (especially at finer spatial scales) are needed to better predict how ecosystem change will influence PAC levels in the basin and in other northern systems.

Pollution Characteristics and Health Risks of Polycyclic Aromatic Compounds (PACs) in Soils of a Coking Plant.

Coke production is an important source of environmental polycyclic aromatic compounds (PACs), including parent polycyclic aromatic hydrocarbons (PAHs) and their derivatives. The focus near coking plants has primarily been on parent-PAH contamination, with less attention given to highly toxic derivatives. In this study, soil samples were collected from both within and outside of a coking plant. The concentrations of parent-PAHs and their derivatives, including methylated-PAHs, oxygenated-PAHs, and nitrated-PAHs, were examined. Spatial interpolation was employed to determine their spatial distribution patterns. Methods for identifying potential sources and conducting incremental lifetime cancer risk analysis were used. This could achieve a comprehensive understanding of the status of PAC pollution and the associated health risks caused by coke production. The concentrations of total PACs inside the plant ranged from 7.4 to 115.8 mg/kg, higher than those outside (in the range of 0.2 to 65.7 mg/kg). The spatial distribution of parent-PAH concentration and their derivatives consistently decreased with increasing distance from the plant. A significant positive correlation (p < 0.05) among parent-PAHs and their derivatives was observed, indicating relatively consistent sources. Based on diagnostic ratios, the potential emission sources of soil PACs could be attributed to coal combustion and vehicle emissions, while principal component analysis-multiple linear regression further indicated that primary emissions and secondary formation jointly influenced the PAC content, accounting for 60.4% and 39.6%, respectively. The exposure risk of soil PACs was dominated by 16 priority control PAHs; the non-priority PAHs' contribution to the exposure risk was only 6.4%.

Historic distribution of Polycyclic Aromatic Compounds (PAC) in a Skagerrak fjord, Swedish west coast as reflected in a high-resolution sediment record and compared to the Environmental Quality Standards (EQS)

We present the historic distribution of Polycyclic Aromatic Compounds (PAC) in a Skagerrak fjord, a relatively unexploited area, on the Swedish west coast. PACs encompass various compounds, including PAHs, alkyl-PAHs, nitro-PAHs, and oxy-PAHs. These compounds, have environmental implications due to their harmful properties. Using a high-resolution sediment record, PAC variations including standard PAHs, nitro-PAHs and oxy-PAHs were investigated over the last approximately 170 years, comparing them with other European records. The sediment record reveals a significant increase in PAC levels during the 1940s–1950s, followed by peaks in the 1960s and 1970s, and a subsequent decrease in the 1980s. These trends align with industrial growth and evolving stronger environmental regulations in the region. The highest recorded concentration of PACs (1950–1970) reached levels comparable to present-day polluted urban environments. The study also compared PAH levels with EQS values. Results indicated that PAH levels exceeded EQS standards, potentially posing risks to sediment-dwelling organisms.

Dissolved polycyclic aromatic compounds in Canada’s Athabasca River in relation to Oil Sands from 2013 through 2019

The Canada-Alberta Oil Sands Monitoring (OSM) Program began long-term surface water quality monitoring on the lower Athabasca River in 2012. Sampling of low level, bio-accumulative polycyclic aromatic compounds (PACs) targeted a suite of parent and alkylated compounds in the Athabasca River (AR) mainstem using semi-permeable membrane devices (SPMDs). Samples were collected along a gradient from upstream reference near Athabasca, Alberta, through exposure to the Athabasca oil sands deposit (AOSD), various tributary inflows, and mining activities within the OSMA, to downstream recovery near Wood Buffalo National Park (WBNP) and reference on the Slave River. The program adapted over the years, shifting in response to program review and environmental events. The AOSD chemical fingerprint was present in samples collected within the AOSD, through the oil sands mineable area (OSMA), downstream to recovery from 2013 to 2019. PACs were dominated by alkylated phenanthrenes/anthracenes (PAs) and dibenzothiophenes (Ds), with elevated levels of alkylated fluorenes (Fs), naphthalenes (Ns), fluoranthenes/pyrenes (FlPys) and benzo[a]anthracenes/chrysenes (BaACs), increasing in concentration from C1 < C2 < C3 < C4. Concentrations of these petrogenic PACs were at their highest within the OSMA and downstream of tributaries. The AOSD fingerprint was absent from sites located outside of the influence of the AOSD and downstream of the Peace-Athabasca Delta on the Slave River. PAC concentrations in the AR increased with mainstem discharge and loadings from tributaries, were moderated by the PAD, and diluted by the Peace River. This work bolsters the baseline PAC information previously reported for the Athabasca River and waters downstream, reporting 7 years of data, from all sites within the mainstem monitoring program, and exploring potential regional and hydrological drivers of these between sites and over time.

A complex mixture of polycyclic aromatic compounds causes embryotoxic, behavioral, and molecular effects in zebrafish larvae (Danio rerio), and in vitro bioassays

Polycyclic aromatic compounds (PACs) are prevalent in the environment, typically found in complex mixtures and high concentrations. Our understanding of the effects of PACs, excluding the 16 priority polycyclic aromatic hydrocarbons (16 PAHs), remains limited. Zebrafish embryos and in vitro bioassays were utilized to investigate the embryotoxic, behavioral, and molecular effects of a soil sample from a former gasworks site in Sweden. Additionally, targeted chemical analysis was conducted to analyze 87 PACs in the soil, fish, water, and plate material. CALUX® assays were used to assess the activation of aryl hydrocarbon and estrogen receptors, as well as the inhibition of the androgen receptor. Larval behavior was measured by analyzing activity during light and darkness and in response to mechanical stimulation. Furthermore, qPCR analyses were performed on a subset of 36 genes associated with specific adverse outcomes, and the total lipid content in the larvae was measured. Exposure to the sample resulted in embryotoxic effects (LC50 = 0.480 mg dry matter soil/mL water). The mixture also induced hyperactivity in darkness and hypoactivity in light and in response to the mechanical stimulus. qPCR analysis revealed differential regulation of 15 genes, including downregulation of opn1sw1 (eye pigmentation) and upregulation of fpgs (heart failure). The sample caused significant responses in three bioassays (ERα-, DR-, and PAH-CALUX), and the exposed larvae exhibited elevated lipid levels. Chemical analysis identified benzo[a]pyrene as the predominant compound in the soil and approximately half of the total PAC concentration was attributed to the 16 PAHs. This study highlights the value of combining in vitro and in vivo methods with chemical analysis to assess toxic mechanisms at specific targets and to elucidate the possible interactions between various pathways in an organism. It also enhances our understanding of the risks associated with environmental mixtures of PACs and their distribution during toxicity testing.

Fatty-acid based assessment of benthic food-web responses to multiple stressors in a large river system

Rivers are often exposed to multiple stressors, such as nutrients and contaminants, whose impacts on the river food webs may not be distinguished by sole assessment of biological community structures. We examined the benthic algal assemblages and the fatty acids (FA) of benthic macroinvertebrates in the lower Athabasca River in Canada, aiming to assess the changes in algal support and nutritional quality of the benthic food web in response to cumulative exposure to natural bitumen, municipal sewage discharge (hereafter, “sewage”), and oil sands mining (“mining”). Data show that the decline in water quality (increases in nutrient concentrations and total suspended solids) was associated with decreases in benthic diatom abundance, and was driven mainly by sewage-induced nutrient enrichment. Responses in nutritional quality of benthic macroinvertebrates, indicated by their polyunsaturated FA (PUFA) concentrations, were taxon- and stressor-specific. Nutritional quality of the larval dragonfly predator, Ophiogomphus, decreased nonlinearly with decreasing benthic diatom abundance and was lowest at the sewage-affected sites, although exposure to natural bitumen also resulted in reduced Ophiogomphus PUFA concentrations. In contrast, the PUFA concentrations of mayfly grazers/collector-gatherers were not affected by natural bitumen exposure, and were higher at the sewage and sewage+mining sites. The PUFA concentrations of the shredder Pteronarcys larvae did not change with cumulative exposure to the stressors. Sediment metal and polycyclic aromatic compound concentrations were not associated with the macroinvertebrate FA changes. Overall, we provide evidence that sewage induced reduction in trophic support by PUFA-rich diatoms, and was the predominant driver of the observed changes in FA composition and nutritional quality of the benthic macroinvertebrates. Fatty-acid metrics are useful to untangle effects of concurrent stressors, but the assessment outcomes depend on the functional feeding guilds used. A food-web perspective using multiple trophic levels and feeding guilds supports a more holistic assessment of the stressor impacts.

Variation in Polycyclic Aromatic Compound (PAC) Concentrations in a Norway Spruce Stand Close to a Major Traffic Route—Influence of Distance and Season

Air concentrations of polycyclic aromatic compounds (PACs) were measured in a Norway spruce (Picea abies) stand at four different distances from a major traffic route near Gothenburg, Sweden, during summer and winter 2019, using passive samplers. In total, the concentrations of 32 polycyclic aromatic hydrocarbons (PAHs) and six dibenzothiophenes (DBTs) and NO2 were analysed. PAC air concentrations were on average 2.5 times higher during the winter compared to the summer. All investigated PAH categories and compounds as well as dibenzothiophene declined linearly with the logarithmic distance from the traffic route. This indicates that the length of pollutant pathways through vegetation is a valid proxy to assess health risks of traffic-related PAC pollutants. Concentrations of heavier PAHs declined faster (concentration at site furthest away from the road was 6% and 33% of concentration at site closest to road, for summer and winter respectively) with increasing distance from traffic compared to lighter PAHs (63% and 68% for summer and winter respectively). As a result, the mix of PAHs changed with the depth into the forest stand (i.e. distance from the road) with potential effects on the toxicity as well as on diagnostic ratios used for source attribution. This is likely caused by different deposition rates among the PAH compounds to the vegetation surfaces, although the exact mechanism needs to be further investigated. This study provides new information that can improve air quality risk assessment and limit the exposure of the population to toxic air pollutants such as PACs.

Complex polycyclic aromatic compound mixtures in PM2.5 in a Chinese megacity: Spatio-temporal variations, toxicity, and source apportionment

Polycyclic aromatic compounds (PACs) are important toxic organic components in fine particulate matter (PM2.5), whereas the links between PM2.5 toxicity and associated PACs in ambient air are poorly understood. This study investigated the spatial–temporal variations of PACs in PM2.5 collected from 11 sampling sites across a Chinese megacity and characterized the reactive oxygen species (ROS) generation and cytotoxicity induced by organic extracts of PM2.5 based on cellular assays. The extra trees regression model based on machine learning and ridge regression were used to identify the key toxicants among complex PAC mixtures. The total concentrations of these PACs varied from 2.12 to 71.7 ng/m3 across the study city, and polycyclic aromatic hydrocarbons (PAHs) are the main PACs. The spatial variations of the toxicological indicators generally resembled those of the PAC concentrations, and the PM2.5 related to waste treatment facilities exhibited the strongest toxic potencies. The ROS generation was highly correlated with high molecular weight PAHs (MW302 PAHs), followed by PAHs with MW<302 amu and oxygenated PAHs, but not with nitrated PAHs and the plastics additives. The cell mortality showed weak correlations with these organic constituents. The associations between the biological endpoints and these PM2.5-bound contaminants were further confirmed by exposure to authentic chemicals. Four primary sources of PACs were identified, among which coal and biomass combustion sources (30.2% of the total PACs) and industrial sources (31.0%) were predominant. PACs emitted from industrial sources were highly associated with ROS generation in this city. Our findings highlight the potent ROS-generating potential of MW302 PAHs and the importance of industrial sources contributing to PM2.5 toxicity in this megacity, raising public concerns and further administration.

Emissions of PAHs, Nitro-PAHs and Quinones (Oxy-PAHs) Associated to PM1.0 and PM2.5 Emitted by a Diesel Engine Fueled with Diesel-Biodiesel-Ethanol Blends

Emissions of PAH, nitro-PAHs, and oxy-PAHs from a diesel engine fueled with diesel-biodiesel-ethanol blends need to be controlled and reduced, as they are unregulated emissions harmful to the environment and human health. The objective of this work was to investigate the effect of ethanol concentration on diesel engine emissions when fueled with diesel–biodiesel–ethanol blends. Ethanol was added with biodiesel–diesel blends. Diesel B7 and two ternary blends, B7E3 and B7E10, with 3% and 10% ethanol, were tested and studied in a diesel engine to determine engine performance characteristics and particulate matter emissions and to quantify polycyclic aromatic compounds (PACs) associated with PM1.0 and PM2.5. Under the same engine conditions, 18 PAHs, 27 nitro-PAHs, and 6 quinones (oxy-PAHs) were determined by GC–MS in real samples obtained from the engine. The mean concentrations of PACs found in the B7, B7E3, and B7E10 blends for PM1.0 ranged from 0.1 µg m−3 (coronene) to 118.1 µg m−3 (2-nitrofluorene). The concentrations for PM2.5 ranged from 0.1 µg m−3 (acenaphthylene) to 99.7 µg m−3 (2-nitrofluorene). Potent mutagens benzanthrone (BA) and 3-nitrobenzanthrone (3-NBA) were found at concentrations ranging from 0.10 µg m−3 to 1.9 µg m−3 and 0.3 µg m−3 to 1.6 µg m−3, respectively. Low molecular weight (LMW) PAHs were mainly PACs bounded to the PM1.0 and PM2.5 particles emitted by B7E10. Flow properties were improved by adding 3% and 10% ethanol to biodiesel. B7E3 and B7E10 blends presented low fuel consumption and a reduction in the emission factor (EF) by the engine. B7E10 blending showed a smaller total concentration of ∑PAH (26.8 µg m−3), ∑nitro-PAH (85.4 µg m−3), and ∑oxy-PAH (6.0 µg m−3) associated with PM2.5 particles compared PM1.0.

Distribution pattern of polycyclic aromatic compounds in coal gangue from coal city—East China

Coal gangue is a by-product of coal, the output of which is as high as 30% of raw coal, whereas only 30% of it is recycled. The leftover remains in the environment from gangue backfilling areas and overlap with residential, agricultural, and industrial areas. Coal gangue accumulated in the environment is easily weathered and oxidized and becomes a source of various pollutants. In this paper, 30 coal gangue samples (fresh and weathered coal gangues) were collected from three mine areas in Huaibei, Anhui province, China. Gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) was used to qualitatively and quantitatively analyze thirty polycyclic aromatic compounds (PACs), including 16 polycyclic aromatic hydrocarbons (16PAHs), preferentially controlled by the United States Environmental Protection Agency (US EPA), and the corresponding alkylated polycyclic aromatic hydrocarbons (a-PAHs). The results showed that PACs existed objectively in coal gangue, and the content of a-PAHs was higher than that of 16PAHs (average values for 16PAHs ranged from 77.8 to 581ng/g; average values for a-PAHs ranged from 97.4 to 3179ng/g). Moreover, coal types not only affected the content and type of PACs but also affected the distribution pattern of a-PAHs at different substitution sites. With the increase of gangue weathering degree, the composition of a-PAHs kept changing; the low ring a-PAHs were more easily diffused to the environment, and the high ring a-PAHs remained enriched in the weathered coal gangue. The correlation analysis showed that the correlation between fluoranthene (FLU) and alkylated fluoranthene (a-FLU) was as high as 94%, and the calculated ratios were not more than 1.5. The basic conclusion is that not only 16PAHs and a-PAHs objectively existed in the coal gangue, but also the characteristic compound belonging to the pollution source of coal gangue oxidation have been discovered. The results of the study provide a new perspective for the analysis of existing pollution sources.

Contamination characteristics of polycyclic aromatic compounds from coal sources in typical coal mining areas in Huaibei area, China

The Huaibei area is rich in coal resources and serves as the main energy production base in East China. However, serious environmental consequences are associated with coal mining and utilization. With increasing reports on distribution and risks by polycyclic aromatic compounds (PACs), the potential pollution of coal sources must be addressed. Here, the PAC concentrations in the topsoil, coal, and coal gangue of a typical coal mining area in Huaibei were evaluated. The mean ΣPACs in topsoil, coal, and coal gangue were 1528.3, 274,815.8, and 10,908.3 μg·kg−1, respectively. Alkyl polycyclic aromatic hydrocarbons (aPAHs) were identified as primary contributors to PACs, and the concentrations of oxygenated PAHs (oPAHs) were significantly higher in coal and coal gangue than in topsoil. PAC pollution was mainly concentrated in the coal mine area and near the coal gangue landfill road. Not only sixteen high priority pollutant PAHs (16PAHs), but PAH derivatives also contributed to the organic pollution from coal sources. Principal components analysis, multiple linear regression, characteristic ratios, and positive matrix factor analysis were used to trace PAC sources. The characteristic ratios for organic pollution from coal and gangue particles involving 16PAHs, aPAHs, and oPAHs were proposed. Further, the high–ring 16PAH ratio was also found suitable for coal mining areas. The Monte–Carlo risk assessment showed that coal particles were highly carcinogenic, and despite the low carcinogenicity of coal gangue and topsoil, they might also serve as potential carcinogens. This study aimed to disseminate knowledge on PACs from coal and coal gangue, provide a useful background for efficient resource utilization of coal gangue, and a reference for tracing PAC sources in coal mine environment media.

Polycyclic aromatic compound and trace metal element residues in Mytilus mussels at marine wildlife hotspots on the Pacific coast of Canada

The Pacific coast of Canada has a rich marine fauna and a growing human population with increasing potential for pollution releases, but there is currently little overlap between marine wildlife hotspots and ongoing biomonitoring efforts for less bioaccumulative contaminants such as polycyclic aromatic compounds (PAC) and trace metals (metals). We surveyed PACs and metals at marine bird breeding colonies in coastal British Columbia in 2018 by analyzing chemical residues in the soft tissue of bivalve Mytilus sp. mussels collected from stations (n = 3) at seven sites. The concentration of sum PACs (∑43PAC) and high molecular weight (HMW) PACs were highest at the Second Narrows colony in Vancouver Harbour, a highly urbanized and industrialized port within the Salish Sea. For conservation areas, two Salish Sea and three Pacific Ocean coast colonies, PACs were generally lower. However, ∑43PAC, ∑HMWPAC, and several HMW congeners at the remote site of Triangle Island, a Marine National Wildlife Area, were not significantly different from Second Narrows. The dominant PAC sources at all sites are likely pyrogenic rather than petrogenic, as suggested by PAC profiles, proportion of parent PACs, and source-indicator congeners. For metals, site differences were found for seven out of eight priority metals, but principal component analysis indicated that site differences, such as high mercury and cadmium at offshore sites, are likely related to environmental and biological variables including salinity, condition index, water temperature, and shell length. Our survey across a broad coastal region shows that PAC and metal biomonitoring programs with mussels should include wildlife hotspots where the exposure of protected vertebrate species to pollutants with low bioaccumulation potential would be less obvious, and shows that collection of data on key covariates (e.g. lipid content, salinity) will be critical to tracking long-term trends and detecting pollution release events.

Alkylated Polycyclic Aromatic Hydrocarbons Are the Largest Contributor to Polycyclic Aromatic Compound Concentrations in the Topsoil of Huaibei Coalfield, China.

Alkyl polycyclic aromatic hydrocarbons (APAHs) are more toxic and persistent than their parent compounds. Here, the concentrations, composition profiles, and spatial distribution of polycyclic aromatic compounds (PACs) in 127 topsoil samples from Huaibei coalfield were analyzed. The PAC concentrations in different functional areas were significantly different: mining area > industrial area > residential area > agricultural area. APAHs were the major contributors to PACs, accounting for 71–83% of total PACs. Alkylnaphthalenes and alkylphenanthrenes were the primary APAH components, accounting for 83–87% of APAHs. Principal component analysis showed that petrogenic source, coal and biomass combustion, and vehicle emissions were the primary sources of PACs. By comparing the fingerprint information of soil, coal, and coal gangue, it was hypothesized that the petrogenic source of PAC pollution in typical mining areas and surrounding areas are coal particle scattering and coal gangue weathering. Some coal mining and industrial areas potentially pose risks to children, whereas others do not. There are limited evaluation criteria for alkyl PAHs; hence, the estimated risk is likely lower than the actual risk. In addition to the conventional 16 PAHs, it is critical to consider a broader range of PACs, especially APAHs.

Bioaccumulation and toxicokinetics of polycyclic aromatic compounds and metals in giant floater mussels (Pyganodon grandis) exposed to a simulated diluted bitumen spill

Oil spills constitute a major risk to the environment and the bioaccumulation potential of the derived oil constituents will influence their impact on aquatic biota. Here we determined the bioaccumulation potential and toxicokinetic parameters of polycyclic aromatic compounds (PACs) and various selected metals in the giant floater mussels (Pyganodon grandis) following experimental oil spills in a freshwater lake. Specifically, these mussels were exposed ex situ for 25 days to water contaminated with naturally weathered diluted bitumen (dilbit), a form of oil commonly transported through pipelines. We detected greater concentrations of total PAC in mussels (∑PAC44) exposed to dilbit-contaminated water (25.92–27.79 μg g−1 lipid, n = 9, at day 25 of the uptake phase) compared to mussels from a control with no exposure to dilbit (average of 2.62 ± 1.95 μg g−1 lipid; ±SD, n = 17). This study demonstrates the importance of including alkylated PACs when assessing the impacts of an oil spill as the concentration of alkylated PACs in mussel tissue were an order of magnitude higher than their parent counterparts. However, metal accumulation in dilbit-exposed mussels did not exceed the unexposed controls, suggesting no excess metal accumulation by mussels from a 25-day dilbit exposure. From first-order one-compartment models, mean uptake rate constants (0.78–18.11 L g−1 day−1, n = 29) and bioconcentration factors (log values from 4.02 to 5.92 L kg−1, n = 87) for the 29 individual PACs that accumulated in mussels demonstrated that some alkylated PACs had greater bioaccumulation potential compared to their parent PAC counterpart but for the most part, alkylated and parent PACs had comparable BCF values. Results from this study also demonstrated that giant floater mussels could be used to biomonitor PAC contamination following oil spills as PACs accumulated in mussel tissue and some were still detectable following the 16-day depuration phase. This study provides the largest, most comprehensive set of toxicokinetic and bioaccumulation parameters for PACs and their alkylated counterparts (44 analytes) in freshwater mussels obtained to date.

Contamination characteristics of alkyl polycyclic aromatic hydrocarbons in dust and topsoil collected from Huaibei Coalfield, China.

Alkyl polycyclic aromatic hydrocarbons (APAHs) are more toxic and persistent than their parent compounds. In this study, the concentrations of polycyclic aromatic compounds (PACs) in dust, topsoil and coal gangue from Huaibei Coal mine, China were analyzed by gas chromatography-mass spectrometry, confirming APAHs were the dominant pollutants. The mean concentrations of APAHs were substantially higher than those of 16 PAHs in both dust and topsoil. The mean concentration of APAHs in dust was 9197µgkg-1, accounting for 80% of the total mean concentration of PACs. The mean concentration of APAHs in topsoil was 2835µgkg-1, accounting for 77% of the mean concentration of PACs. Alkyl naphthalenes and alkyl phenanthrenes were the primary pollutants in APAHs. Their mean concentrations in dust and topsoil were 7782µgkg-1 and 2333µgkg-1, respectively. This accounted for 85% and 82% of the concentration of APAHs, respectively. Additionally, low-molecular-weight APAHs dominated the PACs of the coal mine, exhibiting petrogenic characteristics; distribution of C1-C4 NAP and C1-C4 PHE exhibited "bell shape" pattern indicated as petrogenic source. Source identification indicated that the PACs were mainly derived from petrogenic sources and vehicle emissions, followed by biomass and coal burning. Fingerprinting information of dust and topsoil were consistent with coal gangue, indicating that PACs are most likely derived from coal gangue. Coalfields comparable to our study area are widely distributed in China. Therefore, investigating PAC pollution derived from coal gangue warrants further attention.

Combustion of crude oil during in-situ burning can introduce polycyclic aromatic compounds (PACs) into small-scale freshwater systems

In-situ burning (ISB) is the controlled combustion of an oil slick to remove large quantities of spilled oil from the aquatic environment. Prior to employing ISB as a remediation technique, an oil slick must often be corralled by physical or chemical means to achieve a sufficient thickness (typically >1 mm) for ignition. While ISB is an effective means to remove oil mass, less is known about the potential for ISB to mobilize polycyclic aromatic compounds (PACs) into the aquatic environment. The PACs are primary contaminants of concern in crude oil due to their environmental persistence and toxicity. We examined the potential for ISB to mobilize PACs into underlying waters in a series of small-scale burns conducted across a gradient of oil slick thicknesses (0–7 mm). Concentrations of PACs in underlying waters were evaluated and compared to reference conditions using an equivalent gradient of oil slick thicknesses that were not ignited. At thinner slick thicknesses (i.e. 0 – 4 mm) ISB enhanced the mobilization of total PACs, likely a result of heat transfer to underlying waters; this effect increased as slick thickness increased. Among thicker slicks (i.e. 4 – 7 mm), pyrogenic PACs became more prevalent and greater concentrations of 4-ring PACs were detected in underlying waters. The potential for PAC mobilization needs to be considered in scenarios where ISB may be the only viable oil spill remediation option (e.g. wetlands, marshes, or where oil is entrained) and in shallow systems susceptible to temperature changes.

Extensive chemical and bioassay analysis of polycyclic aromatic compounds in a creosote-contaminated superfund soil following steam enhanced extraction

Polycyclic aromatic compounds (PACs) are organic compounds commonly found in contaminated soil. Previous studies have shown the removal of polycyclic aromatic hydrocarbons (PAHs) in creosote-contaminated soils during steam enhanced extraction (SEE). However, less is known about the removal of alkyl-PAHs and heterocyclic compounds, such as azaarenes, and oxygen- and sulfur-heterocyclic PACs (OPACs and PASHs, respectively). Further, the impact of SEE on the freely dissolved concentration of PACs in soil as well as the soil bioactivity pre- and post-SEE have yet to be addressed. To fulfil these research gaps, chemical and bioanalytical analysis of a creosote-contaminated soil, collected from a U.S. Superfund site, pre- and post-SEE were performed. The decrease of 64 PACs (5–100%) and increase in the concentrations of nine oxygenated-PAHs (OPAHs) (150%) during SEE, some of which are known to be toxic and can potentially contaminate ground water, were observed. The freely dissolved concentrations of PACs in soil were assessed using polyoxymethylene (POM) strips and the concentrations of 66 PACs decreased post-SEE (1–100%). Three in vitro reporter gene bioassays (DR-CALUX®, ERα-CALUX® and anti-AR CALUX®) were used to measure soil bioactivities pre- and post-SEE and all reporter gene bioassays measured soil bioactivity decreases post-SEE. Mass defect suspect screening tentatively identified 27 unique isomers of azaarenes and OPAC in the soil. As a remediation technique, SEE was found to remove alkyl-PAHs and heterocyclic PACs, reduce the concentrations of freely dissolved PACs, and decrease soil bioactivities.

Characteristics of particle-bound polycyclic aromatic hydrocarbons (PAHs) in indoor PM2.5 of households in the Southwest part of Ulaanbaatar capital, Mongolia

Air pollution, including PM2.5 concentration in Ulaanbaatar (capital of Mongolia) is a serious matter of concern. As the majority of households use coal in large areas of the city, indoor air quality is also posing a serious risk to human health. This study investigated the concentration of polycyclic aromatic compounds (PAHs) in indoor particulate matter (PM2.5) in 10 non-smoker households. Sampling was conducted in winter of 2018, between 27 January and 09 February. Concentrations of PM2.5 in the indoor air of households ranged between 62.8 and 324.8 µg m−3. Total concentration of PAHs also varied in a relatively wide range, between 46.2 and 175.7 ng m−3. Five-ring PAHs represented a considerably high fraction of total PAHs between 25 and 53%, benzo[b]fluoranthene (BbF) and benzo[a]pyrene (BaP) were the two predominant compounds within five-ring PAHs. Significant correlation was found between indoor and outdoor particulate matter levels in wintertime. Considering individual characteristic PAHs, heavier PAHs homologues (4- to 5-ring and 6-ring PAHs) were detected in all households, which suggested the influence of coal combustion and traffic exhaust. Health risk of children attributed to PAHs inhalation was assessed by taking into account the lifetime-average daily dose (LADD) and corresponding lifetime cancer risk. Lifetime average daily dose for children in only one household were slightly higher than health-based guideline level (1.0 × 10−5), defined by WHO, whereas LADD for adults and children of other households were within acceptable limit. The cancer risks from the exposure of children to air pollutants in all households except HH-3 were found high. In the Vibrio fischeri bioluminescence inhibition assay, according to the toxic unit (TU) values of indoor PM2.5 from ten households, all samples were classified as toxic.

Alkylated Polycyclic Aromatic Compounds in Road Runoff Are an Environmental Risk and Should Be Included in Future Investigations.

Polycyclic aromatic compounds (PACs) and metals are important contaminants in road runoff. Vital mitigation measures against aquatic contamination from road runoff include the use of sedimentation ponds. However, it has been demonstrated that ecosystems in sedimentation ponds might be affected by road runoff. Sediments from six natural ponds and 27 sedimentation ponds were investigated to determine the environmental risk of contaminants. The amount of traffic on the respective roads associated with the sedimentation ponds was correlated with the environmental concentrations. Quantification included seven metals, the 16 US Environmental Protection Agency polycyclic aromatic hydrocarbons, alkylated PACs, dibenzothiophene, benzo[e]pyrene, and perylene. The environmental risk was assessed according to the European Union Water Framework Directive guidelines. Sedimentation ponds had a higher level of contaminants than natural ponds, and environmental risks were dominated by the concentration of PACs. Alkylated PACs contributed to the environmental risk posed by PACs and should be included in future monitoring. Only Cu and Zn were measured at concentrations above the environmental quality standards (EQSs), while 13 PACs exceeded the EQS. Sediment concentrations of Cu, Zn, and most PACs correlated significantly with the amount of traffic. The sources of PACs were determined by source apportionment ratios between PACs. Alkylation and pyrogenic indices showed that sources in natural ponds were of mostly pyrogenic origin, whereas in sedimentation ponds they were predominantly petrogenic. Asphalt was the probable main source of PACs. A hierarchical clustering technique was used to investigate both the environmental risks and the pattern of PACs in the ponds and revealed that a few sedimentation ponds were not protecting the environment as intended because the upper sediment layers had not been regularly dredged. Environ Toxicol Chem 2022;41:1838–1850. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.