Polycyclic aromatic hydrocarbons (PAHs) in gas, PM2.5, and frost samples in a severely polluted rural site of the North China Plain: Distribution, source, and risk assessment

Recycling process of decoration and demolition waste is a neglected source for emerging concerns in particulate phase: PAHs as an example

Decoration and demolition waste (DDW) has been widely studied because of its annual surge in output, complex composition, and high utilization potential. DDW recycling is a key element of circular economy, with the potential for emerging pollutants in the particulate phase. Thus, this study selected polycyclic aromatic hydrocarbons (PAHs) as the representative and investigated their emission characteristics and occupational risk in the particulate phase, including 2.5-μm (PM2.5), inhalable (PM10), total suspended particles (TSP), and dust samples of different sizes (75-100 μm, 50-75 μm, and < 50 μm), from dust collectors during DDW recycling. Acenaphthylene (Acy), chrysene (Chr), benz[a]anthracene (BaA), fluoranthene (Fla), pyrene (Pyr), phenanthrene (Phe) were detected in all samples. PM2.5 and dust in 75-100 μm own the highest total occupation risk of 1.51 × 10-13 and 2.07 × 10-15, respectively. Chr and BaA had the control priority with the converted toxicity of 162.82 ng/g and 233.35 ng/g. Moreover, nontarget screening was applied to mining out isophorone, benzophenone, and other carcinogenic micropollutants in the PM2.5, PM10, TSP, and dust samples. Global PAHs from DDW recycling production can reach 193.44 ± 241.80 kg/a under reasonable estimation. This study provides strong evidence that DDW recycling is a neglected source of concern in the particulate phase.

Nontargeted Screening Nitrogen-Containing Organic Compounds in Frost and Wet Deposition in Rural Northeast China

Nitrogen-containing organic compounds (NOCs) in frost serve as a critical pathway for atmospheric nitrogen deposition, significantly impacting the biogeochemical cycles of nitrogen. However, the molecular characteristics of NOCs in frost and their deposition fluxes are scarcely studied. In this work, frost samples, collected in rural Northeast China in the winter of 2023, were analyzed using nontargeted ultrahigh performance liquid chromatography-orbitrap mass spectrometry (UHPLC-Orbitrap MS) to reveal their content in nitrogen-containing organic compounds (NOCs) and explore their wet deposition fluxes. The average number of assigned molecular formulas were lager on hazy days compared to nonhazy days for both water-soluble (WSOM) and water-insoluble organic matter (WISOM) in frost (3114 vs. 1934 for WSOM and 3042 vs. 2224 for WISOM in electrospray ionization (ESI-); 6921 vs. 5954 for WSOM and 6629 vs. 5547 in ESI+). Specifically, the number proportions of CHON were 35.6-49.9% (724-1517) and 47-51.1% (2686-3388) in the ESI- and ESI+ modes, respectively. Nitrophenol (C6H5NO3) and methyl nitrophenol (C7H7NO4) were the most abundant NOCs, with wet deposition fluxes (at maximum average concentrations) of 22.2 and 21.2 μg m-2·h-1, respectively. On hazy days, the deposition fluxes of nitrophenol compounds reached up to 1.73 times that of nonhazy days, indicating significant ambient nitrogen deposition during the haze episode. This deposition flux positively correlated with PM2.5 concentration, implying the important role of atmospheric particulates in influencing NOC deposition through frost. These findings highlight the susceptibility of frost to capturing NOCs from the atmosphere, potentially impacting nitrogen cycling in ecosystems.

Unintended side effect of the coal-to-gas policy in North China Plain: Migration of the sources and health risks of ambient PAHs

Ongoing coal-to-gas (CTG) largely cut down both coal consumption and associated PM2.5. However, a knowledge gap still existed in CTG impacts on the other energy and organic pollutant emissions. Coupling on-site investigation with statistical yearbooks, we provided a more realistic energy evolutions before (BCTG), during (DCTG), and after (ACTG) the CTG for Hebei Province. Together, we examined the impacts of CTG derived energy conversion on PM2.5-bound PAHs at urban (UA)/suburban rural (SRA)/remote rural (RRA) sites in winter 2022. As expected, the consumptions of coal and natural gas (NG) far decreased and increased from BCTG to ACTG, respectively. Accidentally, biomass usage rose by 60.7%, and rural CTG acted as a main driver. Specially, SRA's NG-shortage and coal-stove demolition should be the main inducements, and RRA's coal-sale ban was another trigger in the early stage of CTG. ∑18PAHs and ∑8TPAHs stand for the sum of 18 PAHs and 8 toxic PAHs, respectively. ∑18PAHs (ng/m3) presented as SRA (81.8) > RRA (46.4) > UA (19.4). Biomass burning (BB) and NG combustion (NGC) contributed most to∑18PAHs of 31.0% and 23.1% at SRA, resulting in the highest ∑18PAHs, ∑18PAHs/PM2.5, and ∑8TPAHs/PM2.5, and incremental lifetime cancer risk values. Also, NGC has become the second largest contributor at UA. Variations in both diagnostic ratios and source-depend isomers further proved the prominence of NGC related PAHs at UA vs. SRA. Notably, RRA was least affected by the CTG, coal combustion (CC, 40.4%) and BB (32.6%) still occupied the top positions. In short, CTG gave rise to an upsurge in biomass usage, and the incremental PAHs emissions from BB vs. NGC. This study underlined that the priorities should be given to rural NG guarantee and subsidy retention, and biomass prohibition for further air quality improvement.

The Constituent-Dependent Translocation Mechanism for PM2.5 to Travel through the Olfactory Pathway

The neurotoxic risk of PM2.5 is of worldwide concern, but the pathways through which PM2.5 gets to the central nervous system are still under debate. The olfactory pathway provides a promising shortcut to the brain, which bypasses the blood-brain barrier for PM2.5. However, direct evidence is lacking, and the translocation mechanism is still unclear. This study used the primary murine olfactory sensory neurons (OSNs) as an in vitro model to explore the translocation mechanism of PM2.5 in the olfactory system. We found that PM2.5 can be internalized into the OSNs via vesicle transportation. This process responds only to the water-insoluble compositions of PM2.5 (WIS-PM2.5) and cannot be affected by the water-soluble compositions of PM2.5 (WS-PM2.5). PM2.5 can further disrupt the integrity of the barrier constituted by the OSNs, and WS-PM2.5 plays a heightened role in inducing the damages. Our results suggested that both cellular and paracellular pathways are possibly involved in the translocation of PM2.5 in the olfactory system. More advanced microscopy techniques need to be developed to explore the whole translocation process in the olfactory-brain pathway in both in vitro and in vivo models.

Characteristics, source apportionment and health risks of indoor and outdoor fine particle-bound polycyclic aromatic hydrocarbons in Jinan, North China

To investigate the pollution characteristics of polycyclic aromatic hydrocarbons (PAHs) indoors and outdoors and their influencing factors, PM2.5 samples were systematically collected from both environments in Jinan during the summer and autumn seasons. During the observation period, the concentration of ∑ 19PAHs was 18.57 ± 10.50 ng/m3 indoors and 23.79 ± 16.13 ng/m3 outdoors. Most PAHs exhibited indoor-to-outdoor (I/O) ratios less than 1, indicating that indoor PAHs were primarily derived from the infiltration of outdoor sources. Correlation analysis underscored the significant influence of temperature on both outdoor concentrations and I/O ratios of PAHs. By utilizing diagnostic ratios and principal component analysis (PCA), vehicle emissions were identified as the predominant source of outdoor PAHs. Our study found that the toxic equivalents of benzo[a]pyrene (TEQBaP) values exceeded the European Commission's standard of 1 ng/m3, with indoor values at 2.78 ng/m3 and outdoor values at 3.57 ng/m3. Moreover, the total incremental lifetime cancer risk (ILCRTotal) associated with exposure to PM2.5-bound PAHs surpassed the acceptable level of 10E-6, indicating potential adverse health effects. These results underscore the urgent necessity for more stringent regulatory measures to reduce PAH emissions. Additionally, our findings provide valuable insights into how environmental factors shape the relationship between indoor and outdoor PAHs.

Polycyclic aromatic hydrocarbons emissions from biomass-fueled boilers in China

Biomass serves as a sustainable energy source; however, the environmental risks associated with polycyclic aromatic hydrocarbons (PAHs) emitted from industrial biomass-fueled boilers are not well understood. This study analyzed 16 priority PAHs in both particulate and gaseous phases from 13 representative real-world industrial biomass-fueled boilers. Flue gas samples were collected from the stacks and analyzed using advanced techniques. Total PAHs concentrations ranged from 1.36 to 8870 μg m-3 (9 % O2 v/v), with benzo[a]pyrene emissions from certain boilers exceeding the allowable emissions standards for the coking chemical and petroleum refining industries in China. PAHs were predominantly found in the gaseous phase, with both gas and particle phases exhibiting similar toxicity. The average emission factor (EFmass) was 9.23 mg kg-1, while the toxicity-equivalent emission factors (EFCEQ, EFMEQ, and EFTEQ) were 1.96 × 10-2, 1.39 × 10-2 and 7.61 × 10-4 mg kg-1, respectively. It is estimated that annual PAH emissions from 2020 to 2050 will significantly decrease if biomass is used as industrial fuel in boilers (0.61 to 1.32 Gg y-1) instead of being openly burned in the field (3.39 to 7.21 Gg y-1). Overall, this study provides a comprehensive evaluation of PAH emissions from industrial biomass combustion, offering valuable data for future research and policy-making.

Exploring source-specific ecological risks of PAHs near oil platforms in the Yellow River Estuary, Bohai Sea

The Yellow River Estuary (YRE) is one of highly remarkable regions profoundly impacted by human activities, with numerous oil platforms dispersed throughout. In this area, offshore oil exploitation may pose significant ecological risks. To comprehensively evaluate the quantitative impacts of oil field exploitation on the marine coastal ecosystem, this study investigated the occurrence, sources, and ecological risks associated with 16 polycyclic aromatic hydrocarbons (PAHs) in seawater and sediment near oil platforms in the YRE. We found that 1) The concentrations of PAHs decreased from the surface seawater to sediments; 2) The ecological risk level of PAHs in seawater exceeded that in sediments; 3) terrestrial sources (combustion), rather than offshore oil drilling activities, significantly influenced regional ecological risks through processes of atmospheric deposition and surface runoff. These findings provide essential data for future estuarine research efforts while supporting mitigation measures aimed at addressing marine environmental pollution related to oil production activities.

Exposure to polycyclic aromatic hydrocarbons (PAHs) from domestic heating and cooking combustion of different fuel types for elders in rural China

Solid fuel combustion emitted abundant pollutants, especially polycyclic aromatic hydrocarbons (PAHs) which had significant minus impact on human health in rural China. PAHs in PM2.5 emitted from different fuels combustion and hydroxylated metabolites of PAHs (OH-PAHs) in urine samples of different fuel users were detected in this study. The indoor PAHs were higher than that in outdoors for solid fuel use households, and the concentration of PAHs in the indoor of liquefied petroleum gas (LPG) use household was not much lower than solid fuel use households. Biogas-use household produced the lowest PAHs, which significantly reduced 64-82% compared with those emitted by solid fuel combustion. The different combustion conditions influenced the gaseous PAHs in indoors between two sampling sites. The gas/particle partition indicated that PAHs tended to occur in the particle phase with increased molecular weight, and the absorption was the main mechanism. The relative higher contribution of high molecular weight PAHs (HMW-PAHs) in solid fuel use households than in clean fuel use households, induced more health risks of PAHs. The concentration of Σ10OH-PAHs in the urine samples for elders of different fuel-use households displayed the trend of coal (83.27 ng/mL) > wood (79.32 ng/mL) > LPG (51.61 ng/mL) > biogas (28.96 ng/mL), and OH-NaPs was the predominant metabolites, which accounted for more than 90% of the total concentration. The carcinogenic risk of PAHs based on internal exposure was greater than or close to 10-4, with serious carcinogenic risks. This was different with the incremental lifetime cancer risk based on the atmospheric concentrations. The exposure of PAHs from solid fuel combustion for human being especially for the elders in this region should be concerned, and more data should be done for the internal exposure of PAHs.

Identification and seasonal variation of specific particulate bound (halogenated) polycyclic aromatic hydrocarbons in air from different metal industrial parks in Northwest China

During the process of industrial heating, a large amount of polycyclic aromatic hydrocarbons (PAHs) and their halogenated compounds (Cl/Br-PAHs) can be formed. However, there is still limited understanding of the chemicals from different metal smelting industrial parks. This study evaluated the seasonal variations, composition profiles, and source allocations of the atmospheric particulate-bound PAHs and Cl/Br-PAHs in different metal industrial parks in a typical industrial city in northwest China. The results showed that the main PAHs produced by metal smelting were low molecular weight isomers, and the concentrations of Cl-PAHs were lower compared to Br-PAHs. The main Br-PAHs were 1-Br-Pyr and 4-Br-Pyr, while 9-Cl-Fle, 1-Cl-Pyr, and 6-Cl-BaP were the dominated Cl-PAH isomers. No significant difference was found in the concentrations among the sites, whereas the levels of the target chemicals were higher during cold months compared to warm months. The main source of PAHs was coal combustion and gasoline vehicle emission during metal smelting, and that of Cl/Br-PAHs was also industrial coal burning. In addition to the primary source, the secondary chlorination of parent PAHs was also a significant source of Cl-PAHs in the production of high purity aluminum. This study suggests that Cl-PAHs and Br-PAHs may behave differently in the atmosphere.

The key characteristics of cardiotoxicity for the pervasive pollutant phenanthrene

The key characteristic (KCs) framework has been used previously to assess the carcinogenicity and cardiotoxicity of various chemical and pharmacological agents. Here, the 12 KCs of cardiotoxicity are used to evaluate the previously reported cardiotoxicity of phenanthrene (Phe), a tricyclic polycyclic aromatic hydrocarbon (PAH), and major component of fossil fuel-derived air pollution. Phe is a semi-volatile pollutant existing in both the gas phase and particle phase through adsorption onto or into particulate matter (PM). Phe can translocate across the airways and gastrointestinal tract into the systemic circulation, enabling body-wide effects. Our evaluation based on a comprehensive literature review, indicates Phe exhibits 11 of the 12 KCs for cardiotoxicity. These include adverse effects on cardiac electromechanical performance, the vasculature and endothelium, immunomodulation and oxidative stress, and neuronal and endocrine control. Environmental agents that have similarly damaging effects on the cardiovascular system are heavily regulated and monitored, yet globally there is no air quality regulation specific for PAHs like Phe. Environmental monitoring of Phe is not the international standard with benzo[a]pyrene being frequently used as a proxy despite the two PAH species exhibiting significant differences in sources, concentration variations and toxic effects. The evidence summarised in this evaluation highlights the need to move away from proxied PAH measurements and develop a monitoring network capable of measuring Phe concentration. It also stresses the need to raise awareness amongst the medical community of the potential cardiovascular impact of PAH exposure. This will allow the production of mitigation strategies and possibly the development of new policies for the protection of the societal groups most vulnerable to cardiovascular disease.

Characteristics and health risk assessment of indoor and outdoor PM2.5 in a rural village, in Northeast of China: impact of coal and biomass burning

Fine particulate matter (PM2.5) has health effects that may depend on its sources and chemical composition. In this study, characteristics of PM2.5 chemical composition and health risk assessment from Songyuan, China, were investigated during day and night in indoor and outdoor from February 4 to 19, 2021. Relative high concentrations of PM2.5 were obtained in indoor environment than outdoor, with 503.95 ± 209.62 μg/m3 during the day and 357.52 ± 232.81 μg/m3 at night for the indoor environment. Relatively high total carbon, organic carbons, elemental carbons, polycyclic aromatic hydrocarbons (PAHs), and oxygenated polycyclic aromatic hydrocarbons (OPAHs) were obtained in indoor environment. However, the average concentrations of PAHs were higher during night (73.57 ± 43.09 ng/m3) in indoor and OPAHs during day (6.027 ± 2.960 ng/m3) in outdoor. They had different I/O distributions of these compounds during day and night. Indeno(1,2,3-cd) pyrene was the dominant PAHs, and benzanthrone was the dominant OPAHs; this is different with the previous studies. The high indoor/outdoor ratios showed the indoor coal and biomass burning greatly affect the indoor pollutants. Average ILCR health risk assessment for PAHs was all higher than 10-6 for different age gender, suggesting there has potential cancer risk existed for populations living in the rural coal and biomass burning area Songyuan, China.

Polyaromatic hydrocarbon thin film layers on glass, dust, and polyurethane foam surfaces

An investigation was conducted into the dynamic behavior of two polyaromatic hydrocarbon (PAH) semi-volatile organic compound (SVOC) naphthalene (NAP) and benzo [ghi]perylene (BghiP) in air and on various surfaces including glass, dust, and polyurethane foam (PUF) to understand their interaction with different media. A confocal fluorescence microscope and an infrared microscope were employed to detect and monitor the concentration-, time-, and temperature-dependent changes of the aromatic NAP and BghiP species on the surfaces. Infrared two-dimensional mapping of the vibrational characteristic peaks was used to track the two PAHs on the surfaces. Gas chromatography-mass spectrometry (GC-MS) was employed to measure the gaseous concentrations. The sorption of NAP and BghiP on the surfaces was estimated using Arizona desert sand fine (ISO 12103-1 A2) dust and organic contaminant household (SRM 2585) dust. The surface-to-air partition coefficients of NAP and BghiP were estimated on the different surfaces of glass, dust, and PUF. Molecular dynamic simulations were performed on dust surfaces based on the Hatcher model to understand the behavior of NAP and BghiP on dust surfaces. The Weschler-Nazaroff model was introduced to predictPAH film accumulation on the surfaces, providing a better understanding of PAH interaction with different environmental media. These findings could contribute to developing effective strategies to mitigate the adverse impact of PAHs on the environment and human health.

Biochar loaded with cobalt ferrate activated persulfate to degrade naphthalene

Considering the simple preparation of biochar and the excellent activation performance of cobalt ferrate material, a biochar supported cobalt ferrate composite was synthesized by a solvothermal method. The material was used to activate persulfate (PS) to degrade naphthalene (NAP) in water. The structure and morphology characterization showed that the composite (CoFe₂O₄-BC) was successfully prepared. Under the conditions of 0.25 g L^-1 CoFe₂O₄-BC and 1 mM PS, 90.6% NAP (the initial concentration was 0.1 mM) was degraded after 30 minutes. The degradation kinetics of NAP followed the pseudo-first-order kinetic model with a rate constant of 0.0645 min^-1. With the increase of the dosage of activator and PS, the removal rate of NAP could be increased to 99.5%. The coexistence of anions and humic acids inhibited the removal of NAP. The acid environment promoted the removal of NAP while the alkaline environment inhibited it. After four cycles of CoFe₂O₄-BC material, the removal rate of NAP decreased from 90.6% to 79.4%. The removal of TOC was about 45% after each cycle. After the first cycle, the concentration of leached cobalt ion and leached iron ion was about 310 μg L^-1 and 30 μg L^-1 respectively. The free radical quenching experiments showed that SO₄ ^-˙ and OH˙ were the main causes of NAP removal, and the possible degradation path of NAP was elucidated by DFT calculation.

Compositional and seasonal differences of gas and particle phase polycyclic aromatic hydrocarbons (PAHs) over the southern Baltic Sea coast

In this study, 16 USEPA-prioritized PAHs in gas- and particle-phase (PAH_g+p), associated chemical and meteorological parameters, and backward trajectory simulations were explored in a coastal city in Poland, between April 2019 and May 2020. This study reports several important aspects of PAH_g+p, i.e. variation, composition, distribution profiles, impact of weather conditions, and correlation analysis between target PAH compounds and influencing inorganic gaseous pollutants. Specifically, higher and more variable concentrations of total PAH_g+p (mean ± SD, ng m^-3) were observed during winter (36.38 ± 24.19) compared to autumn (22.3 ± 17.44), summer (21.52 ± 13.30) and spring (19.90 ± 13.13). A distribution profile of parent PAH_g+p was as follows: 3-ring > 4-ring > 2-ring > 5-ring > 6-ring, although their relative contribution to the total PAHs showed statistically significant differences between seasons (p < 0.05). Precipitation-driven loss of ΣPAH_g+p was lower in the warm period than in the cold one, reflecting higher PAH concentrations in winter. A seasonal model-based analysis of incremental lifetime cancer risk showed a higher potential cancer risk for children than those for adult females and males. The adverse health impacts associated with PAH exposure via inhalation route indicate the need for implementation of pollution-control policies in this region.