Concentrations Of Aromatic Hydrocarbons Research Articles

Atmospheric pah concentrations in a semi-urban site: temporal variation, risk assessment, source identification and estimation of levels in diverse environments.

This study evaluates atmospheric polycyclic aromatic hydrocarbon (PAH) concentrations in a semi-urban area, Görükle, Turkey, from June 2021 to February 2022. The average concentration of ∑16 PAHs was 24.85 ± 19.16 ng/m3, ranging from 6.70 to 59.11 ng/m3. Seasonal variations were observed, with winter concentrations approximately five times higher than those in summer, driven by increased residential heating emissions and adverse meteorological effects. The results were compared to literature values, revealing lower PAH levels than those found in other urban and industrial areas. Meteorological factors were statistically analyzed. PAH concentrations exhibited an inverse relationship with temperature and mixing height, while relative humidity showed a positive linear correlation. The study also estimated PAH concentrations in various environmental media using gas-particle partitioning and equilibrium models. The concentrations of PAHs in the particulate phase were minimal, suggesting that most PAHs were present in the gas phase. Additionally, the equilibrium concentrations of PAHs in soil, leaves, bark, and water were modeled, emphasizing the accumulation of heavier PAHs in these media yet 2- and 3-ring PAHs were predominant in the ambient air samples. Source apportionment and PCA studies identified vehicle emissions and combustion for heating purposes as the primary sources of pollution. However, air mass trajectory analysis indicated contributions from Kocaeli, an area with significant industrial activity. The cancer risk assessment yielded low risks for both adults and children.

Analysis of cytotoxicity and genotoxicity of diesel exhaust PM2.5 generated from diesel and dual natural gas-diesel engines.

Diesel exhaust particles (DEPs) are atmospheric pollutants associated with adverse health effects. In response to their impact, natural gas (NG) has emerged as a promising alternative fuel due to its cleaner combustion. Although the cytotoxicity and genotoxicity of DEPs from diesel or NG engines have been extensively studied, the impact of dual natural gas-diesel systems remains unexplored. This study evaluated the toxicity of DEPs (PM2.5) emitted by an engine in diesel mode and dual natural gas-diesel mode on cellular parameters such as viability, apoptosis, oxidative stress, and DNA damage. The results showed that diesel DEPs reduced cell viability by up to 31 %, compared to a 19.2 % reduction with dual-mode DEPs. Apoptosis induction was also higher with diesel DEPs, with a 7 % increase compared to the dual mode. While dual-mode DEPs increased the production of reactive oxygen species (ROS) without causing DNA damage, diesel DEPs generated high ROS levels and measurable DNA damage. These differences could be attributed to the physicochemical characteristics of each mode, as diesel DEPs contained higher concentrations of polycyclic aromatic hydrocarbons (PAHs). This study addresses a research gap by quantifying the health effects of emissions from dual-fuel engines and highlights the potential of these systems to reduce DEP-induced toxicity.

Transformation of polycyclic aromatic hydrocarbons during frying stinky tofu.

Reductions in polycyclic aromatic hydrocarbon (PAH) concentrations have been observed during frying. However, transformation mechanisms of PAHs remain unclear. We hypothesize that PAHs may be oxidized into oxygenated polycyclic aromatic hydrocarbons (OPAHs) and other derivatives during frying. First, the levels of 24 PAHs and 12 OPAHs during frying stinky tofu were evaluated. Among the OPAHs, 9,10-anthraquinone exhibited the greatest increase in frying oil, with an increase rate of 55%. The transformation of anthracene into 9,10-anthraquinone was further confirmed through stable isotope tracing. Targeted and untargeted mass spectrometry analyses suggested that anthrone, heavy PAHs, and alkyl derivatives were also produced from anthracene. Theoretical calculations revealed that radical addition was kinetically and thermodynamically more favourable than hydrogen abstraction in the initial reaction of anthracene. This study systematically elucidates, for the first time, the transformation mechanisms of anthracene in frying oil, paving the way for reducing health risks associated with PAHs.

Long-term effects of petroleum mulch on concentration, health, and ecological risks of polycyclic aromatic hydrocarbons in sand dune soils of Khuzestan province, Iran.

Environmental consequences of petroleum mulch application are crucial in regions prone to wind erosion and desertification. This study aimed to assess the long-term effects of petroleum mulching on soil polycyclic aromatic hydrocarbon (PAH) concentrations and the associated human and ecological risk indices. These indices include incremental lifetime cancer risk (ILCR), hazard index (HI), toxic equivalent concentration (TEQBaP), toxic unit (TU), and risk quotient (RQ) in soil samples from Khuzestan province, Iran. Soil samples were collected from two depths: surface soil (0-10cm) and deep soil (10-50cm) across four regions with varying durations of petroleum mulch application: less than 5years (T5), 5-20years (T20), 20-30years (T30), and 30-40years (T40), and a control sample without mulching. Gas chromatography-mass spectrometry (GC-MS) was used to analyze the concentrations of 19 PAHs and 23 groups of alkylated PAHs (alkyl PAHs) in the soil. Petroleum mulching significantly impacted heavily contaminated soil samples (T5 and T20) with PAH levels ranging from 2.03 to 2.08mgkg-1. Older samples (T30 and T40) showed lower contamination levels (0.29 and 0.41mgkg-1), primarily due to thealkylated compounds. ILCR, HI, TEQBaP, TU, and RQ indices were highest in T5 and T20 surface samples, indicating high risk in T5 surface soil from RQ and moderate risk inthe others, despite low cancer and non-carcinogenic risks. Although the risk from thecompounds, particularly alkyl PAHs, has decreased over time, they could still adversely affect the ecosystem, emphasizing the use of environmentally friendly alternative mulches in such areas.

Concentration of total petroleum and total aromatic hydrocarbons in tar balls collected from the Red Sea coast of Yemen

The Red Sea is one of the main traffic routes of oil tankers, resulting in environmental damage and marine resource pollution due to the spillage. Quantitative analysis of tar ball was used to detect the concentrations of total petroleum hydrocarbons (TPHs) and total aromatic hydrocarbons (TAHs). In this study, six stations across the Red Sea coast of Yemen were selected according to their suitability and accessibility. An ultraviolet fluorescence technique was used to analyze the TPHs and TAHs after being extracted by an ultrasound-assisted solvent extraction procedure. The concentrations of TPHs ranged from 175.67 ± 11.20 mg/g to 708.55 ± 6.57 mg/g, and for TAHs were from 16.06 ± 1.89 mg/g to 48.25 ± 1.76 mg/g. The highest values of TPHs and TAHs were noticed in Ras Isa-II station, which reflected a continued oil spill from the Safir oil loading terminal. The study revealed significant environmental and health risks to marine organisms and humans.

Application of EU Geographical Indications for the Protection of Smoked Dry-Cured Ham-Impact on Quality Parameters.

This study compares Dalmatinski pršut, an EU Protected Geographical Indication (PGI)-labelled smoked dry-cured ham from the Dalmatia region in Croatia, with non-PGI hams from the same area, focusing on the impact of PGI certification on the product quality. The investigation is prompted by the increasing presence of dry-cured hams lacking the PGI label on the market, aspiring to compete with esteemed high-value PGI products. Samples of 28 smoked dry-cured hams (12 PGI and 16 non-PGI) were analysed for chemical properties, fatty acid composition, volatile compounds, PAH content and sensory characteristics. The results showed that PGI and non-PGI hams differ in their chemical and physical properties, with non-PGI hams having a lower water content and a higher salt content, which was also confirmed by the saltier taste in the sensory evaluation. PGI hams had a lower b* colour value, and, while the differences in texture were minimal, non-PGI hams had slightly more monounsaturated fatty acids. The aroma analysis revealed that PGI hams contained more aldehydes and alcohols, while non-PGI hams had a higher content of phenolic compounds and aromatic hydrocarbons, probably due to differences in smoking practices. PAH levels, however, were within the EU limits, indicating controlled smoking of both type of hams. Overall, these results show that the quality of smoked dry-cured ham can be distinguished by the PGI designation. The study illustrates how the traditional production methods prescribed by the PGI production protocols shape the sensory and chemical profiles of Dalmatinski pršut, with the PGI certification playing a crucial role in maintaining product quality and certifying its typicality, to distinguish it from non-PGI products.

Emissions and Chemistry of Volatile Organic Compounds in the Los Angeles Basin in Summer 2022

AbstractThe ozone air quality standard is regularly surpassed in the Los Angeles air basin, and efforts to mitigate ozone production have targeted emissions of precursor volatile organic compounds (VOCs), especially from mobile sources. In order to assess how VOC concentrations, emissions, and chemistry have changed over the past decade, VOCs were measured in this study using a Vocus‐2R proton‐transfer reaction time‐of‐flight mass spectrometer in Pasadena, California, downwind of Los Angeles, in summer 2022. Relative to 2010, ambient concentrations of aromatic hydrocarbons have declined at a similar rate as carbon monoxide, suggesting reduced overall emissions from mobile sources. However, the ambient concentrations of oxygenated VOCs have remained similar or increased, suggesting a greater relative importance of oxidation products and other emission sources, such as volatile chemical products whose emissions are largely unregulated. Relative to 2010, the range of measured VOCs was expanded, including higher aromatics and additional volatile chemical products, allowing a better understanding of a wider range of emission sources. Emission ratios relative to carbon monoxide were estimated and compared with 2010 emission ratios. Average measured ozone concentrations were generally comparable between 2022 and 2010; however, at the same temperature, daytime ozone concentrations were lower in 2022 than 2010. Faster photochemistry was observed in 2022, with average hydroxyl radical exposure being ∼68% higher during midday (statistically significant at 95% confidence), although this difference reduces to ∼35% when comparing observations at ambient temperatures of 25–30°C only. Future trends in temperature are important in predicting ozone production.

Influence of Smoking and Paprika Spice on the Content of Polycyclic Aromatic Hydrocarbons (PAHs) in the Traditional Spanish Smoked Sausage 'Botillo del Bierzo'.

The content of polycyclic aromatic hydrocarbons (PAHs) in a traditional Spanish smoked sausage known as 'Botillo del Bierzo' was analysed. The determination and quantification of PAH4 (the sum of benzo[a]pyrene, benz[a]anthracene, benzo[b]-fluoranthene and chrysene) in the smoked sausage were performed using GC-MS. The results showed that smoking 'Botillo del Bierzo' for 24 h contributes very little to the increase in PAH levels in the product, with no significant differences (p < 0.05). The paprika used in the production of botillo also contributes to PAH content, depending on the paprika's production process (smoked, low-smoked, mixed paprika (smoked + unsmoked or low-smoked + unsmoked), and unsmoked), with significant differences among them (p < 0.05). Using paprika with a lower PAH content (unsmoked or mixed) enables the production of 'Botillo del Bierzo', in accordance with Protected Geographical Indication specifications, with a lower PAH content while maintaining the organoleptic characteristics provided by the paprika. The contamination levels detected in 'Botillo del Bierzo' do not pose a risk to consumer health, as the benzo[a]pyrene and PAH4 values are well below the regulatory limits of 5 μg/kg and 30 μg/kg, respectively.

Influence of smoking method and anatomical location on the content of polycyclic aromatic hydrocarbons in Turopolje ham

In order to support a more sustainable breeding of the local Turopolje pig, the breed needs to be valorised through high added-value meat products, such as dry-cured and smoked Turopolje ham. To date, there are very few data on the quality and safety of Turopolje ham, including information on the content and distribution of potential contaminants such as polycyclic aromatic hydrocarbons (PAHs) from smoke. Hence, the aim of this study was to investigate the influence of smoking method (traditional or industrial) and anatomical site (M. biceps femoris - BF or M. semimembranosus - SM) on the content of PAHs in Turopolje ham. All hams (n=15) were produced the same way, differing only in smoking procedures; a traditional way above the firebox (group TRAD, n=5) or in the smoking chamber (group IND A - standard smoking, n=5 or B – 50 % reduced smoking, n=5). PAHs content (μg/kg) was determined and quantified by high-performance liquid chromatography with fluorescence detection (HPLC-FLD). Two-way analysis of variance was performed (GLM procedure of SAS) with fixed effects of smoking (S), muscle (M) and their interaction (SxM). Of the PAHs investigated, 14 compounds were detected. The results showed that TRAD hams had higher levels of anthracene (Ant), chrysene (Chr), benzo[b]fluoranthene (BbFA), benzo[a]pyrene (BaP), and the sum of benz[a]anthracene (BaA), Chr, BbFA and BaP (PAH 4) than hams from both A and B IND groups. TRAD hams had also higher content of acenaphthene (Acp), phenanthrene (Phen), pyrene (Py), BaA, and total PAHs than IND B hams. Compared to BF, SM muscle had higher content of several PAHs i.e. naphthalene (Nap), fluorine (Flu), Acp, Phen, Ant, fluoranthene (Flt), Py, BaA, benzo[k]fluoranthene (BkFA), benzo[ghi]perylene (BghiP), and also higher total PAH content. However, a significant SxM interaction was observed for Phen and Ant content which were higher only in SM muscle of TRAD hams. In conclusion, this study shows a marked influence of smoking method and anatomical site on the PAHs content in Turopolje hams, mainly in the form of lower BaP and the sum of PAH4 content in all chamber smoked hams compared to traditionally smoked hams and higher levels of light PAHs, some heavy PAHs and total PAH content in the more exposed SM compared to the inner BF muscle. Reduced smoking in IND hams did not affect BaP and the sum of PAH4 content, but reduced the content of some individual and total PAHs content. All IND hams and TRAD hams were below the maximum permitted level for BaP. However, two out of five hams from the TRAD group exceeded the limit for the sum of PAH4 (30 μg/kg) set by EU legislation for traditionally smoked meat products, indicating the need for stricter control of the traditional smoking process.

Physicochemistry and comparative metagenomics of a tropical estuary persistently inundated with anthropogenic pollutants.

The physicochemistry, metabolic properties, and microbial community structure of a tropical estuary persistently inundated with anthropogenic pollutants were elucidated using diverse analytical tools and a shotgun metagenomics approach. The physicochemistry of the Awoye estuary surface water (AEW) and sediment (AES) revealed higher values in the sediment for most of the parameters analyzed, while aside from copper and zinc, the concentrations of the detected heavy metals (Cd, Cr, Pb, Fe, As, Ni, Hg, Mn, Se) in the water and sediment were higher than the acceptable thresholds. Hydrocarbon content analysis revealed increasingly high concentrations of high molecular weight polycyclic aromatic hydrocarbons (HMW PAHs) in the sediment. Structurally, the predominant taxa in the AEW metagenome are Proteobacteria (50.35%), Alphaproteobacteria (43.31%), Brevundimonas (49.96%), and Leptolyngbya boryana (14.93%), while in the sediment (AES) metagenome, Proteobacteria (53.03%), Gammaproteobacteria (28.66%), Azospirillum (6.51%), and Acidihalobacter prosperus (7.56%) were preponderant. Statistical analysis of the two microbiomes (AEW, AES) revealed significant statistical differences (P < 0.05) at all the hierarchical levels. Functional characterization of the two metagenomes revealed extensive adaptations of the sediment microbiome to various environmental stressors as evident in the high numbers of putative genes involved in the degradation of diverse classes of aromatic hydrocarbons, efflux, detoxification, and transport of heavy metals, and metabolism of organic/inorganic nutrients. Findings from this study revealed that the estuary sediment is the sink for most of the anthropogenic pollutants and harbors the more adapted microbiome that could serve as a potential bioresource for the bioremediation of the perturbed estuary.

Impact of Thermal Process on Polycyclic Aromatic Hydrocarbons in Rabbit Meat

Abstract Rabbit meat represents food with a chemical composition beneficial to the human body. Due to its protein content and low fat levels, it is widely used in the diet of people with various health problems. Through preparation and heat treatments, some components lose their value, and these treatments can also increase the content of compounds that can be toxic to the human body. The sensory characteristics obtained after frying and smoking are appreciated by most consumers. The highest average values are for phenanthrene, both in smoked and fried meats and in raw rabbit meat. Among the hydrocarbons analyzed, benzo(a)anthracene is in the lowest quantity, This study shows the influence of some cooking, frying and smoking processes on the content of polycyclic aromatic hydrocarbons in rabbit meat.

Development of a comprehensive air risk index and its application to high spatial-temporal health risk assessment in a large industrial city.

Particulate matter (PM) contains various hazardous air pollutants (HAPs) that can adversely affect human health, highlighting the need for an integrated index to represent the associated health risks. In response, this study developed a novel index, the comprehensive air-risk index (CARI), for Ulsan, the largest industrial city in South Korea. This index integrates toxicity-weighted concentrations of polycyclic aromatic hydrocarbons (PAHs) and heavy metals using their inhalation unit risks. CARI was categorized into four risk levels based on probabilistic health risks. Over eight years (2013-2020) in Ulsan, the risk from PAH exposure showed a decreasing trend, whereas the risk from heavy metals remained stable, reflecting different emission patterns and major source types. PAHs and heavy metals contributed 38.1% and 61.9% to CARI, respectively, highlighting the greater impact of heavy metals on human health. Unlike the monthly variations in PM2.5 concentrations, CARI values tended to increase in the summer and decrease in the spring and fall, indicating the impact of local emissions, particularly from petrochemical and non-ferrous industrial facilities. Moreover, a machine learning model enhanced the spatio-temporal resolution of CARI, showing that 'unhealthy' days were 2.4 times more frequent in industrial areas than in urban areas. In conclusion, CARI is a promising tool for assessing health risks in industrial cities and for developing risk-based management plans. Furthermore, we propose the development of a national-scale real-time CARI system by enhancing the spatio-temporal resolution of HAP data through the use of machine learning.

Neural network potential-based molecular investigation of thermal decomposition mechanisms of ethylene and ammonia

This study developed neural network potentials (NNPs) specifically tailored for pure ethylene and ethylene-ammonia blended systems for the first time. The NNPs were trained on a dataset generated from density functional theory (DFT) calculations, combining the computational accuracy of DFT with a calculation speed comparable to reactive force field methods. The NNPs are employed in reactive molecular dynamics simulations to explore the thermal decomposition reaction mechanisms of ethylene and ammonia. The simulation results revealed that adding ammonia reduces the activation energy for ethylene decomposition, thereby accelerating ethylene consumption. Furthermore, the addition of ammonia uncovers a new reaction pathway for hydrogen radical consumption, which reduces the occurrence of H-abstraction reactions from ethylene by hydrogen radicals. The inhibition effect of ammonia addition on soot formation mainly acts in two aspects: on the one hand, ammonia decomposition products react with carbon-containing species, ultimately producing C1N products, thereby decreasing the carbon numbers involved in soot formation. This significantly reduces the concentrations of C5C9 molecules and key polycyclic aromatic hydrocarbons (PAHs) precursors like C2H2 and C3H3. On the other hand, ammonia promotes the ring-opening reactions of six-membered carbon rings at high-temperature conditions, thereby reducing the formation of PAHs precursors. The results show that with the addition of ammonia, six-membered carbon rings tend to convert into seven-membered carbon rings at lower temperatures, while at higher temperatures, they are more likely to transform into three- and five-membered carbon rings. These variations in the transformation of six-membered carbon rings may also affect soot formation. The insights gained from understanding these fundamental chemical reaction mechanisms can guide the development of ethylene-ammonia co-firing systems.

Catalyst screening for conversion of Chlorella sp. to aromatic fuel additives: A sustainable strategy for CO2 capture

Developing biofuels with characteristics similar to current fossil fuels and compatibility with existing petroleum infrastructure (drop-in biofuels) is gaining prominence, aligning with global efforts towards carbon-neutral economies and decarbonization of the transportation sector. The originality of the current study involves two directions: first, the use of Chlorella sp. microalgae, cultivated under simulated post-combustion gas, as a raw material for producing drop-in biofuel precursors; and second, an investigation of the catalytic activity of hierarchical zeolites in the deoxygenation and denitrogenation of volatile pyrolysis products, enhancing hydrocarbon content. To accomplish this, a micro-furnace-type temperature-programmable pyrolyzer coupled with chromatographic separation and mass spectrometry detection (Py-GC/MS) was utilized to assess the upgrading effectiveness of distinct zeolites (faujasite-type, MFI-type, and mordenite-type) on volatile pyrolysis products. All tested zeolites effectively reduced oxygenated and nitrogenated compounds in the volatile pyrolysis products, enhancing their suitability for producing renewable fuel. This supports sustainable development goals by promoting affordable, clean energy and climate action. HMor yielded the highest hydrocarbon content (98.5 %), followed by HZSM-5 (97.6 %) and HY (85.5 %). Catalytic upgrading significantly increased the concentration of aromatic hydrocarbons (at least 66.3 %), with MFI-type zeolites showing the highest selectivity for valuable BETX compounds (benzene, ethylbenzene, toluene, xylene). Hydrocarbons in the gasoline range, with up to 91.7 %, predominantly align with the needs of the transportation fuel market. The principal component analysis illustrates that using MFI-type zeolites promoted the lowest selectivity for PAHs, constituting precursors for coke formation, which is advantageous for ensuring a longer catalyst lifespan. Our results are promising and encourage the conversion of microalgal biomass into renewable fuel additives for formulating drop-in biofuels, as hydrocarbon-rich volatile pyrolysis products could be directly integrated into existing biorefineries. Thus, microalgal biomass cultivated using flue gas as the carbon source can be viewed as a versatile and promising resource for producing renewable fuel additives, contributing to developing a sustainable, low-carbon future.

Combustion Temperature and Soil Organic Horizons Composition Influence on the PAHs Content (Laboratory Experiment Results)

Fire induced changes in the content and composition of polycyclic aromatic hydrocarbons (PAHs) in organic horizons of the boreal zone soils are considered. Experiment of combustion under oxygen deficient conditions were conducted. The organic horizons of soils as peat (sphagnum oligotrophic) and two types of forests (lichen pine and green-moss spruce) were selected. The PAHs content was determined by high-performance liquid chromatography. It was found that combustion conditions, composition of organic horizons and combustibility significantly affect the content and composition of PAHs. The formation of PAHs occurs to a greater extent at 300°C. Compared with the original samples, the content increases from 2.7 to 9.7 times. Compared with the peak PAHs content (in 300°C) samples, a decrease from 5.8 to 33.0 times is found at 500°C. It is likely that the significant decrease in the content of polycyclic aromatic hydrocarbons is due to the decomposition of substances to simpler ones. The ratio of low molecular to high molecular weight PAHs is indicated. The obtained ratio greater than 1.0 can serve as an indicator of pyrogenic origin of polyarenes.

Hygienic aspects of ensuring chemical safety of using new health-saving technologies for the utilization of biogas at solid municipal waste landfills

Introduction. Environmental health issues are currently among the most important for the population of large administrative and industrial centers. Improving the quality of the environment and creating comfortable living conditions for humans using environmentally friendly methods is one of the current topical areas in environmental hygiene. Materials and methods. The assessment of the effectiveness and chemical safety of the application of a new technology for the collection, purification, neutralization, and disposal of landfill gas for the content of a wide range of organic compounds C5–C20 at a municipal solid waste landfill was carried out using a chromato-mass spectrometric method that allows identifying and quantifying with sensitivity at and below hygienic standards a wide range of organic compounds C5–C20 in air with an unknown composition of pollutants. Results. As a result of the operation of the new landfill gas purification system at the solid waste landfill, the total concentration of pollutants, including marginal and aromatic hydrocarbons, oxygen-containing compounds (alcohols, carboxylic acids), organic sulfur-containing compounds, and sulfur dioxide decreased. As a result of the operation of the new landfill gas purification technology, 100% purification from odourous dialkyl sulfides and nitrogen-containing compounds has been achieved. However, at the outlet of the system, compounds not detected at the inlet were identified, which can be considered as products of combustion and transformation of hydrocarbons that are part of landfill gas, the presence of which indicates to the use of an oxidative process in the process of its disposal. Limitations. The study is limited to the application of the method of investigation of organic compounds with the molecular formula C5–C20. Conclusion. For an adequate assessment of the quality and chemical safety to human health of health-saving technologies, an important condition is the use of physical-chemical studies that identify and quantify dozens of pollutants simultaneously, which makes it possible to take into account the multiple componentness of the chemical composition and the possibility of adverse side effects in the form of toxic transformation of products affecting humans in real environmental pollution conditions.

Leaf ecological traits (morphology and gas exchange) and polycyclic aromatic hydrocarbons concentrations in shrubs and trees: A meta-analysis approach

The leaves of trees and shrubs can capture atmospheric pollutants such as polycyclic aromatic hydrocarbons (PAHs), and the capacity of uptake depends on the leaf traits. Although numerous studies have measured PAH concentrations in leaves of woody plants and the variability in leaf traits, few have investigated the relationship between these factors. We conducted a literature review to summarize the available information on this topic and found that five types of leaf traits have been studied, with those associated with leaf morphology and gas exchange being the most common. However, the results of the studies are often contradictory. To address these discrepancies, we conducted a meta-analysis to examine how PAH uptake by woody species is affected by leaf ecological traits associated with morphology (leaf area, specific leaf area [SLA], leaf thickness and leaf width/length ratio [W/L]) and with gas exchange (stomatal conductance, leaf carbon isotopic signature [δ13C] and stomatal density). The meta-analysis included studies involving at least two different species with comparable PAH concentrations. Many of the studies did not examine the relationship between ecological traits and PAH concentration, and those that did often involve different traits. We therefore used the TRY Plant Trait Database data as the standard source of trait data. Relationships were analyzed by determining differences regarding PAHs and traits and calculating Spearman correlations and their significance. The leaf morphology traits were more closely correlated with PAH concentrations than the gas exchange traits. Thus, morphological traits such as SLA and leaf area can be considered significant predictors of PAH uptake, especially for particulate-associated PAHs. Gas exchange traits showed less consistent correlations, indicating the complexity of factors influencing PAH uptake in leaves. This study highlights the importance of considering multiple leaf traits in order to better understand and predict PAH uptake in woody plants.

Harnessing microbial synergy: A comprehensive evaluation of consortia-mediated bioremediation strategies for petroleum refinery wastewater treatment

The growing global demand for energy has led to the expansion of oil and gas industries, putting our environment at risk of pollution. The unregulated discharge of petroleum refinery wastewater (PRW), accidental spills, and ineffective policies have led to severe contamination and increased environmental and health consequences making management and mitigation a priority for everyone. This study evaluated the performance of two biological treatment methods - free-cell microbial consortium and immobilized microbial system - in the remediation of PRW using physicochemical, 2,6-dichlorophenollindophenol (DCPIP), Gas chromatography (GC) and Fourier-transform infrared spectroscopy (FTIR) techniques. The effectiveness of the two microbial consortia in reducing concentrations of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) in the wastewater was compared to determine the most efficient method for treating PRW. The physicochemical result revealed cocktails of contaminants while Alcaligenes faecalis strain SLW6 and strain IAM 12369, and Providencia vermicola strain OP1, showed high degradative capacities. The immobilized and free-cell microbial systems significantly reduced the concentrations of PAHs, and HMs pollutants in the wastewater, with the former showing slightly better removal efficiencies for PAHs (92.97 % vs 87.34 %), heavy metals (99.17 %), and oil weight reduction (87.76 % vs 82.25 %) after the 28-day biodegradation period respectively. GC and FTIR analyses confirmed the formation of various degraded products, demonstrating the microbial consortia's effectiveness in degrading complex organic compounds. The findings highlight the potential of microbial consortia-mediated remediation as an eco-friendly and sustainable approach for treating PRW, contributing to protecting water resources and promoting sustainable practices in the petroleum industry.

Tourism activities significantly contributed to atmospheric pollutants in a remote town of Tianshan revealed by the continuous observation of two years

The large reduction in tourism activities in 2020 provided a unique opportunity to investigate their contribution on atmospheric pollutants in Bayanbulak, a remote town in Tianshan, China. In this scenic and sensitive region, we measured total suspended particulates (TSP) along with concentrations of polycyclic aromatic hydrocarbons (PAHs), organic carbon (OC), elemental carbon (EC) and water-soluble inorganic ions (WSIIs) during the lockdown in 2020 and compared these to levels in the pre-pandemic period of 2019. The study revealed significant reductions in PAHs, OC, EC, and some WSIIs concentrations during the tourist season (May–October) of 2020 compared with 2019, whereas variations between non-tourist seasons were less pronounced. Furthermore, by comparing pollutant characteristics in tourist seasons of these two years, we found that 5- and 6-ring groups were main PAH constituents in 2019, while 5- and 3-ring groups contributed more to total PAHs in 2020. OC/EC ratio increased from 2019 to 2020, indicating an increase of biomass burning contribution after the lockdown. Using positive matrix factorization, we determined that emissions from tourism-related transportation and combustion of natural gas and coal (mainly for cooking) contributed 21.9% and 46.6%, respectively, to certain atmospheric pollutants in 2019, whereas they decreased significantly to 3% and 19.4% in 2020 with dust and biomass contributions increased substantially. The levels of PAHs, OC, and EC from tourism-related sources were as high as 9.31 ng m−3, 1.28 μg m−3 and 0.11 μg m−3 and decreased by 54.37%, 25.16%, and 9.54%, respectively, compared to 2019. Hence, the impact of tourism must be considered during the assessment of local air pollutant emissions, particularly in remote areas.

Characterization of AhR-mediated potency in sediments from Kongsfjorden, Svalbard: Application of effect-directed analysis and nontarget screening

In this study, we aimed to identify the major aryl hydrocarbon receptor (AhR) agonists in surface sediments (S1–S10, n = 10) from Kongsfjorden, Arctic Svalbard, using effect-directed analysis. High AhR-mediated potencies were observed in the mid-polar fractions and RP-HPLC subfractions (F2.6–F2.8; log KOW 5–8) in the sediments of sites S2 and S3, which are located near abandoned coal mine areas, as assessed by the H4IIE-luc bioassay. The concentrations of traditional polycyclic aromatic hydrocarbon (t-PAHs), emerging PAHs, alkyl-PAHs, and styrene oligomers ranged from 6.1 to 2100 ng g−1 dry weight (dw), 0.5–1000 ng g−1 dw, 47 to 79,000 ng g−1 dw, and 4.2–130 ng g−1 dw, respectively, with elevated levels in S2 and S3. Principal component analysis coupled with multiple linear regression suggested that t-PAHs in sediments primarily originated from coal, petroleum combustion, and coal combustion. Twenty-four target AhR agonists accounted for 3.2%–100% (mean = 47%) of the total AhR-mediated potencies in S2 and S3. Nontarget screening via GC-QTOFMS in the highly potent fractions identified 48 AhR agonist candidates through four-step selection criteria. Among these, 27 compounds were identified as coal-derived substances. VirtualToxLab in silico modeling predicted that most of the 48 tentative AhR agonist candidates could bind to AhR. Overall, our findings indicate significant contamination of the Kongsfjorden sediments by coal-derived substances, highlighting the need for further studies to assess the ecological risks associated with these contaminants.