Toxic Equivalent Concentrations Research Articles

Spatial and temporal trends of polychlorinated naphthalenes in the Arctic atmosphere at Ny-Ålesund and London Island, Svalbard

Polychlorinated naphthalenes (PCNs) are ubiquitous atmospheric pollutants that can even be found in the most remote region of the Arctic. However, temporal trend analysis and reports on mono- to octa-CN in the Arctic air are still scarce. In the present study, 8 years of atmospheric monitoring data of PCNs on Svalbard was investigated using XAD-2 resin passive air samplers (PASs) from 2011–2019. The concentrations of ∑75 PCNs in the Arctic air ranged from 4.56 to 85.2 pg/m3, with a mean of 23.5 pg/m3. The mono-CNs and di-CNs were the dominant homologue groups accounting for 80 % of the total concentrations. The most abundant congeners were PCN-1, PCN-2, PCN-24/14, PCN-5/7, and PCN-3, respectively. A declining time trend of PCN concentration was observed from 2013 to 2019. The reduction in PCN concentrations is likely due to declining global emissions and banned production. However, no significant spatial difference was observed among the sampling sites. The total PCN toxic equivalency (TEQ) concentrations in the Arctic atmosphere ranged from 0.043 to 1.93 fg TEQ/m3 (mean 0.41 fg TEQ/m3). The fraction of combustion-related congeners to ∑PCNs (tri- to octa-CN) analysis results indicated that the sources of PCNs in the Arctic air were contributed mainly from reemissions of historical Halowax mixtures and combustion-related sources. To the best of our knowledge, this is the first research to report all 75 PCN congeners and homologue groups in Arctic air. Therefore, this study provides data on recent temporal trend analysis as well as all the 75 PCN congeners in the Arctic atmosphere.

PCDD/Fs in indoor environments of residential communities around a municipal solid waste incineration plant in East China: Occurrence, sources, and cancer risks

Prolonged exposure to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) can pose several adverse outcomes on human health. However, there is limited information on public health associated with indoor PCDD/F exposure in residential environments. Here, we examined PCDD/F concentrations in indoor air and indoor dust samples obtained from households near a municipal solid waste incineration (MSWI) plant. Our measurements revealed that the toxic equivalent (TEQ) concentrations of PCDD/Fs in indoor air ranged from 0.01 to 0.05 pg TEQ/m3, which were below intervention thresholds (0.6 pg TEQ/m3). Additionally, the TEQ concentrations of PCDD/Fs in indoor dust ranged from 0.30 to 11.56 ng TEQ/kg. Higher PCDD/F levels were found in household dust in the town of Taopu compared to those in the town of Changzheng. Principal component analysis (PCA) of PCDD/Fs suggested that waste incineration was the primary source of PCDD/Fs in indoor air, whereas PCDD/Fs in indoor dust came from multiple sources. The results of the health risk assessment showed the carcinogenic risk due to indoor PCDD/F exposure was higher for adults than for nursery children and primary school children. The carcinogenic risks of PCDD/Fs for age groups residing near the MSWI plant were all less than the risk threshold (10−5). Our findings will help to better understand the levels of PCDD/F exposure among urban populations living in residential communities around the MSWI plant and to formulate corresponding control measures to reduce probabilistic risk implications.

Health Risk Assessment of PAHs from Estuarine Sediments in the South of Italy

Increased concerns about the toxicities of Polycyclic Aromatic Hydrocarbons (PAHs), ubiquitous and persistent compounds, as well as the associated ecotoxicology issue in estuarine sediments, have drawn attention worldwide in the last few years. The levels of PAHs in the Sele, Sarno, and Volturno Rivers sediments were evaluated. Moreover, the cancerogenic risk resulting from dermal and ingestion exposure to PAHs was estimated using the incremental lifetime cancer risk (ILCR) assessment and the toxic equivalent concentration (TEQBaP). For Sele River, the results showed that the total PAH concentration ranged from 632.42 to 844.93 ng g-1 dw, with an average value of 738.68 ng g-1 dw. ∑PAHs were in the range of 5.2-678.6 ng g-1 dw and 434.8-872.1 ng g-1 dw for the Sarno and Volturno River sediments, respectively. The cancerogenic risk from the accidental ingestion of PAHs in estuarine sediments was low at all sampling sites. However, based on the ILCRdermal values obtained, the risk of cancer associated with exposure by dermal contact with the PAHs present in the sediments was moderate, with a mean ILCRdermal value of 2.77 × 10-6. This study revealed the pollution levels of PAHs across the South of Italy and provided a scientific basis for PAH pollution control and environmental protection.

SOURCE IDENTIFICATION AND HEALTH RISK ASSESSMENTS OF POLYAROMATIC HYDROCARBONS (PAHS) IN MOLLUSC FROM IBENO, SOUTHEASTERN, NIGERIA

Polycyclic aromatic hydrocarbons (PAHs) are majorly a class of hazardous and persistent organic pollutants, consisting of fused benzene rings in linear, angular and cluster arrangements, which are derived mainly from incomplete combustion of organic materials and natural processes. By origin PAHs could be petrogenic, biogenic and pyrogenic. PAHs have been categorized as priority pollutants and probable human carcinogens. This study is undertaken to characterize the sources and levels of PAHs in clam (spisula solidissima), periwinkles (tympanotonus fuscatus) and snail (gastropoda) obtained from a local market in Ibeno, Nigeria. The samples were unshelled, air –dried, grinded and subjected to analyses for PAHs by Gas Chromatography – Mass Spectrometry. Tympanotonus fuscatus indicated the presesnce of fluorene (8.5 ± 0.21 ng/g), anthracene (33.90 ± 1.01 ng/g), phenanthrene (23.9 ± 1.12 ng/g), fluoranthene (27.9 ± 2.01 ng/g), pyrene (25.1 ±1.31 ng/g), benzo[a]anthracene (22.3±1.25 ng/g), chrysene (7.14 ± 0.56 ng/g. Gastropoda indicated the presesnce of fluorene (8.94 ± 0.42 ng/g), anthracene (31.18 ± 3.02 ng/g), phenanthrene (22.44 ± 1.95 ng/g), fluoranthene (27.58 ± 2.58 ng/g), pyrene (24.48 ±1.91 ng/g), benzo[a]anthracene (20.94±2.75 ng/g), chrysene (8.45 ± 0.39 ng/g). Spisula solidissima indicated the presesnce of fluorene (9.82 ± 0.75 ng/g) , anthracene (32.1 ± 4.01 ng/g), phenanthrene (22.98 ± 3.05 ng/g), fluoranthene (28.86 ± 5.03 ng/g), pyrene (25.3 ±2.53ng/g ), benzo[a]anthracene( 19.25±2.45 ng/g), chrysene (9.18 ± 1.03 ng/g). PAH molecular diagnostic ratios used for source identification were less than one, indicating pyrogenic source in the three food items. Toxic equivalent concentrations of PAHs (TEQ) were in the order, tympanotonus fuscatus ( 22.39 ng/g ) > gastropoda (21.35 ng/g) > spisula solidissima (19.68 ng/g), which were lower than the maximum permissible TEQ (33.0 ng/g) as a lethal level to raise a public health concern for the consumption of these food items in the study area.

Effects of COVID-19 Control Measures on the Concentration and Composition of PM2.5-Bound Polycyclic Aromatic Hydrocarbons in Shanghai

In order to explore the effects of COVID-19 control measures on the concentration and composition of PM2.5-bound polycyclic aromatic hydrocarbons (PAHs), and to better understand the sources of PM2.5-bound PAHs, PM2.5, samples were collected at two sites in urban and suburban areas of Shanghai before the lockdown, during the lockdown, after the lockdown in 2020, and during the same periods in 2019. The mass concentrations of 21 individual PAHs were determined via GC-MS analysis. While the COVID-19 control measures significantly reduced the absolute concentration of PM2.5-bound PAHs, they had no significant effect on their relative abundances, indicating that the significantly reduced traffic emission may not originally be the major source of PAHs in Shanghai. The differences in the composition of PM2.5-bound PAHs at three different lockdown-related periods may be caused by the gas-particle distribution of semi-volatile PAHs. The similarity in the composition of PM2.5-bound PAHs in different functional areas and different periods brings more uncertainties to the identification of PAH sources using the diagnostic ratios. During the lockdown period, the toxic equivalent concentration of PM2.5-bound PAHs in Shanghai was estimated to decrease by about 1/4, which still exhibits substantial carcinogenic risk upon exposure via inhalation.

Distribution, sources, and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in Kaokaowusu river sediments near a coal industrial zone.

This study systematically analyzed the contents, compositions, and sources of polycyclic aromatic hydrocarbons (PAHs) in river sediments near an important energy and chemical base in northwest China. In addition, their possible adverse effects on the ecology and human health were assessed. The PAH concentrations in this study area ranged from 2641.28 to 16783.72 (ng/gdw). PAHs of medium molecular weight (3-ring and 4-ring) showed the largest proportion, followed by PAHs of higher molecular weight (5-ring and 6-ring). The results of molecular diagnostic ratios and principal component analysis revealed that PAHs in the region have complex sources, with incomplete combustion of local fossil fuels and traffic exhaust factors being the main sources. The total toxic equivalent concentration of PAHs varied from 10.05 to 760.26ng/g, and according to the sediment quality guidelines, PAHs have high potential ecological risk in the lower reaches of the river. The mean effect range-median quotient for the region was 0.46, and the combined ecological risk was at moderate to high levels (21% probability of toxicity). The lifetime carcinogenic risks for adults and children exposed to PAHs were 2.95 × 10-3 and 1.87 × 10-2, respectively, which are much higher than the limit of 10-4, indicating moderate to high potential cancer risks. Therefore, the local government should consider taking some environmental remediation measures. This study can provide theoretical support for pollution prevention measures and ecological restoration strategies for rivers in resource-rich areas.

Levels, sources, and risk assessment of PAHs residues in soil and plants in urban parks of Northwest China

Polycyclic aromatic hydrocarbons (PAHs) will be ingested by people through different ways to threaten their health during play, so the environmental quality of the park directly affects the health of tourists and residents. Using eight typical parks in Urumqi in Northwest China as the study area, we used GC–MS to detect the PAHs content in the park surface soil and 10 common plants in the park in different seasons. The results showed that the content of PAHs in park soil in the summer was 5–6 times that in the winter, and the monomer PAHs in some park soil sampling points were higher than the soil pollution risk screening value. And the contamination level at these sampling sites was also higher compared to other sampling sites. In summer, the plants with high PAHs content in leaves are short herbs, while in winter, they are tall arbors. The PAHs of the park soil are mainly composed of high-cyclic aromatic hydrocarbons, and are mainly of traffic origin. The proportion of low-ring aromatic hydrocarbons in the winter was significantly higher than that in the summer. The source of PAHs in plants in summer is similar to that in soil, but the source of PAHs in plants in winter is more complex. The toxicity equivalent concentration method values of soil PAHs in South Park, Zhiwu Park, Shihua Park and Toutunhe Park were higher than that in other parks. The lifetime carcinogenic risk (ILCRs) values of some sampling points in these four parks in the summer were relatively high. The average ILCRs of adults and children in all parks reached a low-risk level in summer. The carcinogenic risk in children is much higher than that of adults.

Multi-Endpoint Toxicity Tests and Effect-Targeting Risk Assessment of Surface Water and Pollution Sources in a Typical Rural Area in the Yellow River Basin, China

Multi-endpoint toxicity tests were used to evaluate the acute toxicity, estrogenic activity, neurotoxicity, genotoxicity, and ecological risks of surface water and sewage from possible pollution sources in rural areas of the Yellow River (China). Toxicity testing results showed that the luminescence inhibition rates of acute toxicity ranged from not detected (ND) to 38%, the 17β-estradiol equivalent (E2-EQ) values of estrogenic activity ranged from 4.8 to 131.0 ng·L−1, neurotoxicity was not detected, and the protein effect level index (PELI) values of genotoxicity ranged from 1 to 6.06. Neither acute toxicity nor genotoxicity were detected in the tributaries of the Yellow River (River 2) flowing through the investigated rural area. The distribution of high estrogenic activity sites was relatively scattered, but mainly located in the tributaries of River 2. Industrial, domestic, and livestock and poultry breeding sewage were all possible sources of toxicity, and the contribution of livestock and poultry to environmental estrogens in the surface water was significant. Furthermore, the potential effect-targeting risks of toxic substances in the surface water for aquatic organisms were assessed using the risk quotient method, by considering the toxic equivalent concentration. The results indicated that the risk of estrogenic activity was the main ecological risk in the surface water of this rural area. Except for the reservoir site, the other sampling sites showed a moderate to high estrogenic activity risk, especially in the tributaries of River 2.

Health Risks Associated with Polycyclic Aromatic Hydrocarbons (PAHs) in Dustfall Collected from Universities in Wuhan, China

Atmospheric dustfall samples from the libraries and dormitories of 14 universities in Wuhan, China, were collected and analyzed for 16 priority polycyclic aromatic hydrocarbons (PAHs). The results showed that the levels of Σ16PAHs in the dustfall from libraries varied from 2.45 to 13.4 μg·g−1, with an average value of 5.06 μg·g−1, while that of dormitories ranged from 2.61 to 10.6 μg·g−1, with an average of 5.19 μg·g−1. The compositions of PAHs in library and dormitory dustfall were similar, and they were dominated by high molecular weight PAHs (HMW-PAHs) (including fluoranthene, benzo(b)fluoranthene, and chrysene), which accounted for 79.2% of the total PAHs. Spatially, the higher levels of PAHs contamination were mainly distributed in areas with high population density and heavy traffic, which suggests that anthropogenic activities made an important contribution to the PAHs emissions. The diagnostic ratios and principal component analyses (PCA) indicated that combustion-related anthropogenic sources, such as petroleum, coal, and biomass combustion, as well as vehicular traffic emission, were the main sources of PAHs bound to dustfall. The toxic equivalent concentrations (BaPeq) of dustfall-bound PAHs ranged from 271 to 2510 μg·kg−1. According to the health risk assessment results, dermal contact was the predominant exposure pathway, followed by ingestion and inhalation. The incremental lifetime cancer risks (ILCRs) of exposure to PAHs in dustfall was 1.230 × 10−6−1.140 × 10−5, which indicates that there are low potential carcinogenic risks in the universities.

An unexpected synergistic toxicity caused by competitive bioconcentration of perfluoroalkyl acid mixtures to Daphnia magna: Further promoted by elevated temperature

The mixed pollution of the global water environment by perfluoroalkyl acids (PFAAs) and their ecological risks have aroused widespread concern. However, the relationship between the combined toxicity of PFAA mixtures and their accumulation in aquatic organisms is not well understood in the context of global warming. Here, we study the bioconcentration and combined toxicity of three PFAA mixtures (PFOA, PFDA, PFDoA) to Daphnia magna (D. magna) under different exposure concentrations and temperatures. The results show that although competitive bioconcentration exists, the combined toxicity of the PFAA mixtures to D. magna is synergistic. These contradictory phenomena occur because although the longer-chain PFDoA inhibits the bioconcentration of the shorter-chain PFOA and PFDA, the bioconcentration of PFDoA itself is promoted, and PFDoA is more toxic to D. magna than PFOA and PFDA. The toxic equivalent concentration for the PFAA mixture is 1.38–1.67 times higher than that obtained from simple addition for the three PFAAs when exposed separately. Moreover, elevated temperature promotes not only the bioconcentration of each PFAA and the competition of bioconcentration between shorter-chain and longer-chain PAFF, but also the synergistic toxicity of PFAA mixtures to D. magna. This study suggests that the effect of the interactions among different PFAAs on their bioconcentration and toxicity under different water environmental conditions, such as temperature, should be considered for ecological risk assessment of PFAA mixtures.

Spatial and temporal trends in polychlorinated naphthalenes in sediment from Ulsan and Onsan Bays of Korea: Potential sources and ecotoxicological concerns.

Few studies have been conducted on spatial and temporal trends in polychlorinated naphthalenes (PCNs) in coastal environments. Here, we describe 18 PCN congeners found in surface and dated sediment samples collected from highly industrialized bays of Korea. Measurable levels of PCN congeners were detected in all sediment samples, suggesting concurrent and historical contamination. The highest PCN concentrations were observed in sediment from rivers, streams, and the inner portions of the bays, which are surrounded by industrial complexes and commercial harbors. CNs 73, 66/67, and 52 were dominant in surface and dated sediment samples. Congener patterns and diagnostic ratios revealed that PCN contamination is originated from combustion processes and the use of polychlorinated biphenyl (PCB) technical mixtures. PCN concentrations in dated sediment increased from the 1980s to the mid-2000s and then decreased to 2015. Although the toxic equivalent (TEQ) levels of PCNs in our study did not exceed sediment quality guidelines proposed by international authorities, the cumulative risks from the TEQ concentrations of polychlorinated dibenzo-p-dioxins, furans, PCBs, and PCNs can be expected for benthic organisms.

Polycyclic Aromatic Hydrocarbons (PAHs) in the Dissolved Phase, Particulate Matter, and Sediment of the Sele River, Southern Italy: A Focus on Distribution, Risk Assessment, and Sources.

The Sele River, located in the Campania Region (southern Italy), is one of the most important rivers and the second in the region by average water volume, behind the Volturno River. To understand the distribution and sources of polycyclic aromatic hydrocarbons (PAHs) in the Sele River, water sediment samples were collected from areas around the Sele plain at 10 sites in four seasons. In addition, the ecosystem health risk and the seasonal and spatial distribution of PAHs in samples of water and sediment were assessed. Contaminant discharges of PAHs into the sea were calculated at about 1807.9 kg/year. The concentration ranges of 16 PAHs in surface water (DP), suspended particulate matter (SPM), and sediment were 10.1–567.23 ng/L, 121.23–654.36 ng/L, and 331.75–871.96 ng/g, respectively. Isomeric ratio and principal component analyses indicated that the PAH concentrations in the water and sediment near the Sele River were influenced by industrial wastewater and vehicle emissions. The fugacity fraction approach was applied to determine the trends for the water-sediment exchange of 16 priority PAHs; the results indicated that fluxes, for the most part, were from the water into the sediment. The toxic equivalent concentration (TEQ) of carcinogenic PAHs ranged from 137.3 to 292.6 ngTEQ g−1, suggesting that the Sele River basin presents a definite carcinogenic risk.

Particulate PCDD/F size distribution and potential deposition in respiratory system from a hazardous waste thermal treatment process

The particulate polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) of various sizes produced from the waste incinerators might have different toxicities, deposition characteristics, and potential health effects in the respiratory system, and their total toxicity equivalent (TEQ) concentration has been strictly regulated in recent years. There is a knowledge gap on the effects of air pollution control devices on particle size distributions (PSDs) of PCDD/Fs and their TEQ deposition. A hazardous waste thermal treatment plant equipped with an advanced scrubber, a cyclone demister, and activated carbon adsorption coupled with a baghouse filtration was investigated in this study. An 8-stage impactor was used to collect the particle distribution of PM10 and bounded PCDD/Fs from the gas stream at four sampling points located before and after each control unit. A “TEQDE” index is defined for the toxicity deposition of PM10-PCDD/F in the respiratory system. The advanced scrubbers significantly reduced the PM10-PCDD/F levels, especially for those with sizes ≥0.6 and ≤ 0.4 μm. Additionally, the cyclone also showed a better performance than the general dry gas treatment but had an efficiency drop with 1.5–4 μm particles. The PM10-PCDD/F loads in the final adsorption-filtration unit were eased and effectively removed the PM10-PCDD/Fs to sizes ≤0.5 or≥1.5 μm. The total TEQDE was 0.00052 ng WHO-TEQ Nm−3 and had a peak level of 0.000157 ng WHO-TEQ Nm−3 at 1.2 μm. PSDs were more sensitive to the PSDs of PM mass at high PM levels but strongly correlated with the PSDs of “PM10-PCDD/Fs/PM10” at low PM10 loads. Consequently, the advanced control system could effectively remove the PM10-PCDD/Fs and might extend the adsorption-filtration lifetime. However, the PM10-PCDD/Fs ≤ 0.4 μm had a higher TEQ deposition rate and should be further considered in emissions and ambient air quality evaluations.

Toxicity evaluation of polycyclic aromatic hydrocarbons (PAHs) in soils of coal chemical industry areas, North China.

Objectives of this study were to investigate the concentrations, distributions, toxicities, and risk assessment of 16 polycyclic aromatic hydrocarbons in surface soils surrounding a coal chemical industrial zone in the southeast of Shanxi province, China. A total of 52 topsoil samples were collected from different land-use areas: cereal agriculture, roadsides, and parkland. Results show that the total PAHs (∑16PAHs) ranged from 3.87 × 103 to 116 × 103µg kg-1 and that the total carcinogenicity PAHs (∑BPAHs) ranged from 3.11 × 103 to 94.2 × 103µg kg-1, with the highest concentration of ∑16PAHs noted in the RS samples, followed by PS and AS. The entire risk quotient of all PAH maximum permissible concentrations (RQ∑PAHMPCi) was greater than 1.0, and the minimum concentration entire risk quotient (RQ∑PAHNCi) of 84.3% of all samples was higher than 800. The value of the total toxicity equivalent concentration of PAH (PAHBapeq) for areas surrounding the coal chemical industrial zone was higher than the value of the standard level, and the incremental lifetime cancer risk (ILCR) far exceeds the U.S. EPA's risk standard. The toxic properties of PAHs indicated that the soils in the survey areas have a high risk to human health and the environment.

Bioaccumulation and Biomagnification of Polychlorinated Biphenyls and Dichlorodiphenyltrichloroethane in Biota from Qilianyu Island, South China Sea.

Six biota species were collected from Qilianyu Island, South China Sea to determine the bioaccumulation and biomagnification of polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane and its metabolites (DDTs). Concentrations of ΣPCBs and ΣDDTs in biota from Qilianyu Island ranged from 6.88 to 519.1 ng/g lipid weight (lw) and 7.0 to 19,413 ng/g lw, respectively. Significant differences for PCBs and DDTs concentrations were found among the six biota species from Qilianyu Island. The levels of PCBs and DDTs in intermediate egret were significantly higher than the other five biota species, which can be attributed to their different feeding and living habits. Significantly negative relationships between concentrations of PCBs and DDTs and δ13C values in the six biota species confirmed that dietary source is an important factor to determine the levels of PCBs and DDTs in biota species. ΣPCBs, ΣDDTs, PCB 28/31, PCB 52, and p,p′-DDE were biomagnified in the biota species from Qilianyu Island, and native species are suitable for studying the biomagnification of the contaminants. The toxic equivalent concentrations in birds from Qilianyu Island were significantly and positively correlated with PCBs concentrations, indicating that high concentrations of non- and mono-ortho-PCB congeners may induce adverse effects on bird species.

Ecological risk assessment of priority PAHs pollutants in crude oil contaminated soil and its impacts on soil biological properties

Polycyclic aromatic hydrocarbons (PAHs) are one of the major toxic constituents of crude oil and therefore, an understanding on PAHs associated risks and their relationship with soil biological parameters are necessary for adopting effective risk-based and site specific remediation strategies in the contaminated soil. Here, risks evaluation of eight detected PAHs in terms of toxic equivalent concentration (TEQC), benzo(a)pyrene equivalent (BaPeq), contamination factor (CF), pollution load index (PLI), hazard quotient (HQ), hazard index (HI), toxic unit for individual PAHs (TU) and PAHs mixture (TUm) have been evaluated. Besides, the effect of PAHs contamination on soil biological properties has also been investigated and correlated with PAHs concentrations. The TEQc of eight PAHs was recorded in the range of 0.06–5.0 mg kg−1 soil, whereas the BaPeq value was 25.3 mg kg−1 soil which exceed the permissible limit. Similarly, CF (85.5–1668.2), PLI (322.8), HQ (311.7–8340.9), HI (26,443.8), TU (227.9–3821.6) and TUm(7916.2) also exceed the permissible values for non-toxic conditions indicating carcinogenic risk for humans. Besides, activities of soil dehydrogenase, urease, alkaline-phosphatase, catalase, amylase and cellulase were decreased by 1.5–2.3 folds in the contaminated soil than control. The results of Pearson’s correlation matrix also established negative impact of PAHs on the soil's biological properties.

Halogenated polycyclic aromatic hydrocarbons and their parent compounds in ready-to-eat seafood rich in salt: Method validation, profiles, correlation, and exposure risks

The coexistence of polycyclic aromatic hydrocarbons (PAHs) and halogenated PAHs (XPAHs) in fresh seafood poses a threat to food safety and attracts much attention recently, while ready-to-eat seafood is more susceptible to XPAHs contamination through the secondary formation of XPAHs during processing. Little has been known about PAHs and XPAHs in ready-to-eat seafood so far. In this study, a modified QuEChERS combined with GC-MS/MS method for the determination of PAHs and XPAHs in ready-to-eat seafood was developed and validated. Forty-two analytes including PAHs, chlorinated and brominated PAHs (Cl/BrPAHs) were investigated in 32 ready-to-eat seafood including shredded squid and cod fillet. Concentrations of PAHs/XPAHs in shredded squid (mean value at 68.32/4.99 μg/kg) were generally higher than those in cod fillet (mean value at 61.81/0.54 μg/kg). The concentration of ClPAHs showed a significant correlation with that of PAHs (r = 0.576, p < 0.05) and Cl− (r = 0.709, p < 0.01), which indicated that ClPAHs were mainly derived from the reaction of their parent PAHs and Cl−. Cl/BrAnt were predominant components of XPAHs. The concentration of XAnts showed a significant correlation with Ant. Meanwhile, the high ratio of 9,10-Cl2Ant/9-ClAnt showed a newly formed source instead of aged pollution, and therefore enhanced the potential of secondary formation source of XPAHs instead of direct pollution. The toxic equivalent quotient concentrations of XPAHs (mean value at 1.17 μg/kg) were even higher than that of PAHs (mean value at 0.48 μg/kg) in shredded squid. The maximum allowable consumption rate of ready-to-eat seafood was estimated based on the HQ and ILCR model. The results suggested a potential carcinogenic risk for seafood snack lovers (intake rate >27.2 g/d) via dietary intake of ready-to-eat seafood.

Characterization, source apportionment, and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in urban soils from 23 cities in China.

Concentrations, composition profiles, sources, and health risks of 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) in urban soils from 23 cities across China based on metadata collected from previous studies between 2005 and 2021 were investigated. ΣPAH concentrations in urban soils from 23 cities across China ranged from 0.1231 to 17.2000mg/kg (mean = 2.7171 ± 3.8276mg/kg). Overall PAH contamination in urban soils across China was moderate compared to that in global cities. Based on energy consumption and climate conditions, the spatial distributions of mean ΣPAH concentrations in Northeast China were highest, followed by those in North China, West China, East China, and South China. Individual PAH composition profiles decreased in the order: 4-ring PAHs (41.36%) > 5-ring PAHs (21.77%) > 3-ring PAHs (18.53%) > 6-ring PAHs (14.00%) > 2-ring PAHs (2.27%). Diagnostic ratios and positive matrix factorization (PMF) revealed that PAHs in urban soils were mainly derived from fossil fuel combustion (from coal, natural gas, and biomass), especially in North, Northeast, and East China, with smaller contributions from petrogenic sources. Health risk assessment results suggest that although there are potential cancer risks from PAHs, risks were acceptable. Toxic equivalent concentration (TEQ) and the corresponding oral cancer slope factor (CFS0) contributed most to the uncertainty of total risks. This study will help develop strategies to reduce PAH risk management in urban soils in China.

Occurrence of polycyclic aromatic compounds and interdomain microbial communities in oilfield soils

Soil polycyclic aromatic compound (PAC) pollution as a result of petroleum exploitation has caused serious environmental problems. The unclear assembly and functional patterns of microorganisms in oilfield soils limits the understanding of microbial mechanisms for PAC elimination and health risk reduction. This study investigated the polycyclic aromatic hydrocarbons (PAHs) and substituted PAHs (SPAHs) occurrence, and their impact on the bacteria-archaea-fungi community diversity, co-occurrence network and functionality in the soil of an abandoned oilfield. The results showed that the PAC content in the oilfield ranged from 3429.03 μg kg−1 to 6070.89 μg kg−1, and risk assessment results suggested a potential cancer risk to children and adults. High molecular weight PAHs (98.9%) and SPAHs (1.0%) contributed to 99.9% of the toxic equivalent concentration. For microbial analysis, the abundantly detected degraders and unigenes indicated the microbial potential to mitigate pollutants and reduce health risks. Microbial abundance and diversity were found to be negatively correlated with health risk. The co-occurrence network analysis revealed nonrandom assembly patterns of the interdomain microbial communities, and species in the network exhibited strong positive connections (59%). The network demonstrated strong ecological linkages and was divided into five smaller coherent modules, in which the functional microbes were mainly involved in organic substance and mineral component degradation, biological electron transfer and nutrient cycle processes. The keystone species for maintaining microbial ecological functions included Marinobacter of bacteria and Neocosmospora of fungi. Additionally, benzo [g,h,i]pyrene, dibenz [a,h]anthracene, indeno [1,2,3-cd]perylene and total phosphorus were the key environmental factors driving the assembly and functional patterns of microbial communities under pollution stress. This work improves the knowledge of the functional pattern and environmental adaptation mechanisms of interdomain microbes, and provides valuable guidance for the further bioremediation of PAC-contaminated soils in oilfields.

Polycyclic Aromatic Hydrocarbons in the Atmosphere of the Southern Baikal Region (Russia): Sources and Relationship with Meteorological Conditions

This article presents the results of the long-term studies at two stations located in the city of Irkutsk and the Listvyanka settlement of the southern Baikal region (East Siberia) concerning the concentration of polycyclic aromatic hydrocarbons (PAHs) in atmospheric aerosol. The studies revealed the seasonal and interannual dynamics in the distribution of PAHs in aerosols from urban (source) and rural (receptor) areas. We carried out a comprehensive analysis of weather conditions such as wind direction, relative humidity, air temperature, and atmospheric pressure. The analysis determined high correlations between air temperature, atmospheric pressure, temperature inversions, and PAHs at the monitoring stations. The average annual concentrations of PAHs in the abnormally warm 2020 were three times lower than the average values obtained in the cold 2016. The toxic equivalent concentrations (BaPeq) increased from summer to winter with an increase in the contribution from benzo(a)pyrene, one of the most toxic and hazardous compounds of this class of organic substances. Four-, five- and six-ring PAHs mainly predominated in aerosol; the proportion of two- and three-ring PAHs increased from the warm season to the cold season. Diagnostic ratios of PAHs identified the main sources of air pollution by this class of compounds: combustion of coal, liquid fuel and firewood, vehicle emissions, and wildfires. The percentage of the transport of anthropogenic aerosol containing PAHs from industrial sources of the Southern Baikal region towards Lake Baikal was 65 to 71%.