High Molecular Weight Polycyclic Aromatic Hydrocarbons Research Articles

Enhanced analysis of PAHs in tea using GC–MS/MS with hydrogen carrier gas

A green multiresidue method for PAH analysis was developed using hydrogen as the carrier gas, avoiding harmful solvents and integrating waste-reducing strategies such as µSPE. The use of hydrogen carrier gas in gas chromatography coupled with tandem mass spectrometry (GC–MS/MS) was explored for the enhanced detection of polycyclic aromatic hydrocarbons (PAHs) in black tea. The study demonstrated that hydrogen, as a carrier gas, offers better chromatographic properties than helium or nitrogen. This leads to improved separation of critical pairs using a short run time method. A fast extraction method using micro solid-phase extraction (µSPE) as a clean-up step was developed to analyze 24 PAHs. The extraction method was optimized using a 4 mL 1:1 mixture of ethyl acetate and acetone. The method was validated and demonstrated good recoveries, ranging from 73 % to 113 % for most PAHs, with lower recoveries (50–63 %) observed for high molecular weight PAHs. Reproducibility was also high, with relative standard deviation (RSD) values below 15 %. Linearity and matrix effects were also evaluated, yielding excellent results, with no PAH exhibiting strong matrix effects. Real sample analysis of black tea from various brands and origins revealed the presence of multiple PAHs with concentrations ranging 9.5–39.2 µg/Kg, some exceeding the maximum residue levels set by the European Union. These findings highlight the need for efficient methodologies to monitor PAHs in food products.

Effects of carbon dioxide addition on soot dynamics in ethylene/air inverse diffusion flames: An experimental and computational analysis

The effects of carbon dioxide (CO2) addition to ethylene (C2H4)/air inverse diffusion flames (IDFs) to the air stream on soot formation characteristics are investigated with the addition ratio of 0-13.64%. The planar laser-induced fluorescence (PLIF) and planar laser-induced incandescence (PLII) techniques, in conjunction with CoFlame and Chemkin code simulations were utilized to assess the distributions of Polycyclic Aromatic Hydrocarbons (PAHs) and Soot Volume Fraction (SVF). The findings indicate that increasing CO2 addition results in a gradual decrease in the mole fraction of hydroxyl (OH) radicals and flame temperature, accompanied by a reduction of approximately 15% in the reaction zone height in experimental observations and 19% in simulations. The inhibition of soot formation is evident through a consistent decline in the normalized total SVF, a decrease in the peak volume fraction of radial soot distribution, and reduced total SVFs observed across different flame sections at varying heights. In the meanwhile, increasing the CO2 doping ratio significantly reduces the peak signal intensity of PAHs, particularly affecting high molecular weight PAHs (A3-A4, A2-A3) with reductions of up to 75.5%. Furthermore, reductions are noted in the rates of soot inception and subsequent surface growth, accompanied by an upward displacement of the initial inception and growth location. The condensation of PAHs controls the soot surface growth. The thermal and chemical effects of CO2 were differentiated by employing the virtual substance FCO2. The results suggest that the thermal effect of CO2 lowers flame temperature, reduces combustion intensity, and consequently inhibits soot nucleation. The chemical effect of CO2 competes for H radicals through the reverse reaction of CO+OH <=> CO2+H. This process suppresses the formation and growth of PAHs, consequently leading to a reduction in soot production.

Characterization, source profiles and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in urban dust of 14 Chinese cities

ABSTRACT Data for 16 USEPA priority PAHs were collected in urban dust from 14 cities in China between 2008 and 2022, and concentration, profile composition, and human health risk were investigated. The mean concentration of PAHs was 6.60 mg kg−1, ranging from 2.88 mg kg−1 to 13.88 mg kg−1, and it was higher than other important cities in neighboring countries of China. Among different individual PAHs, mean fluoranthene (Flr) was dominant, accounting for 15.04%, and low molecular weight PAH (LMW) was almost a third of high molecular weight PAH (HMW). The results of PAH composition profiles suggested that the proportion of different rings of PAHs increased in order: 2-ring PAHs (4.40%)< 6-ring PAHs (15.73%)< 3-ring PAHs (17.77%)< 5-ring PAHs (22.54%)< 4-ring PAHs (39.56%). The results of the source appointment suggested that pyrogenic sources and mixed sources, particularly wood, grass, coal, and diesel combustion, were the main sources of PAHs in urban dust. The results of the health risk assessment illustrated that children were more vulnerable to PAHs, and ingestion was the dominant exposure pathway to PAHs (78.152%, 67.519%, 73.206%, and 72.957% of children, adolescents, adults, and the total lifetime cancer risk (TLCR)). PAH pollution in urban dust from different cities in China was a commonly existing phenomenon, but the mean and maximum of TLCR were acceptable according to the standard established by USEPA (10−4). Based on Monte Carlo simulations, body weight (BW) was the most important uncertain input in three age groups (60.75%-91.22% contribution).

Diagnostic Ratios and Ecological Risk of Non-carcinogenic Polycyclic Aromatic Hydrocarcarbons (ncPAHs) in Egi Crude Oil Communities, Nigeria

The loadings of PAHs, its diagnostic ratios and ncPAHs at three cluster communities in Egi sub district of Niger-Delta with geographic coordinates of latitude 150 32ʹ 50ʺ N and longitude 60 34ʹ 42ʺ E were ascertained using Gas Chromatography (GC-FID, HP 5890 Series). The diagnostic ratios showed that Obagi had an LMW/HMW ratio of 0.2340, Ibewa's was 0.2222, and Obite's was 0.2549. In Obagi, the proportion of Low Molecular Weight (LMW) PAHs compared to High Molecular Weight (HMW) PAHs was 19%, while in Obite it was 18%, and in the Ibewa cluster it was 20%. The sediments of the Obagi, Obite, and Ibewa cluster sites exhibited a significant abundance of PAHs derived from pyrogenic sources, as evidenced by the presence of LMW/HWM ratios below 1. The identified ncPAHs include: Naphthalene, Acenaphthene, Acenaphthylene, Fluorene, Anthracene, Phenanthrene, Fluoranthene, Pyrene and Benzo(ghi)perylene. According to the results obtained the Obite cluster area exhibited the lowest concentrations (1.503mg/Kg) amongst the ncPAHs, while the Obagi study zone demonstrated the highest concentrations (1.5733mg/Kg). Among the nc(PAHs) examined, benzo (g,h,i) perylene exhibited the highest concentrations (2.086mg/Kg) across all locations, whereas acenaphthylene displayed the lowest concentration (0.123mg/kg) across the three cluster areas. However, none of the three study locations had any ncPAHs that are above the maximum permissible limit. Results from the application of risk quotient models (RQNCs and RQMPCs) to assess the ecological risk of ncPAHs as presented indicated that all the sites where these rivers' sediments were tested had RQNCs values for specific ncPAHs below 1, implying that these ncPAHs pose little or no danger to ecosystems. Also, the RQMPC score is less than 1, it means that the contamination from individual ncPAHs chemicals do not necessitate immediate remediation. Because the RQNCs and RQMPCs for a single PAH molecule are both less than 1, the contamination it generates might be considered low risk. Thus, few measures of control or correction would be required. The ecological risk of non-carcinogenic PAHs using RQMPCs and RQNCs indicated a very negligible risk which could be due to factors like heavy flooding that washed away soil surfaces. Application of Detoxification by chemical reaction technology should be used as future remediation method if there is need.

Passive sampling of polycyclic aromatic hydrocarbons with low-density polyethylene: Equilibration limitations in aqueous suspensions

Polyethylene (PE) and other polymers are widely and successfully used as passive samplers for organic pollutants in the environment. This study provides high-resolution experimental data from batch shaking tests on the uptake, reversibility, and linear equilibrium partitioning of polycyclic aromatic hydrocarbons (PAHs) using two different PE sheets of 30 µm and 80 µm thickness. Kinetics for phenanthrene are well described by a mechanistic first-order model with mass transfer limited by an aqueous boundary layer (with a mean thickness of 170 µm). Equilibration in laboratory batch systems during uptake and desorption is very rapid with characteristic times of 1–2 h but this depends on the boundary condition, e.g., the ratio of PE mass to water volume. Therefore, equilibration of PE in other setups, e.g., in soil slurries or sediment suspensions, may take orders of magnitude longer because the boundary condition for PE changes from finite to infinite bath conditions (soil or sediment particles may keep the concentration in water almost constant). Solid precipitates for high molecular weight PAHs explain partition coefficients below expected values because of kinetic limitations in such a system. Nevertheless, passive sampling can be employed safely if such limitations are considered; furthermore, partition coefficients can be estimated accurately by empirical relationships (e.g., within 0.1 log unit) based on molecular weight, octanol/water partition coefficients, or subcooled liquid solubilities.

Chemical speciation and oxidative potential of PM10 in different residential microenvironments: Bedroom, living room and kitchen

Exposure to particulate matter (PM) and its chemical constituents in residential microenvironments has become a major health concern worldwide. The oxidative potential (OP) has been proposed as a metric for estimating the PM capacity to induce oxidative stress and, consequently, health effects. In the present study, PM10 was daily monitored simultaneously in the bedroom, living room and kitchen of three dwellings for one week in a small town of Portugal, to perform a detailed characterisation of its organic and inorganic constituents and the determination of the OP. Bedrooms (B) were found to be a hotspot of PM10 concentrations (B1 = 22.7 μg m−3; B2 = 19.5 μg m−3; B3 = 68.1 μg m−3). PM10-bound elements varied significantly between microenvironments in all dwellings. Lower molecular weight polycyclic aromatic hydrocarbons (PAHs) were found to be between 14 and 72 times higher than high molecular weight PAHs in bedrooms. The mean volume-normalised OP determined by the dithiothreitol and ascorbic acid assays varied within the 0.01–0.38 nmol min−1 m−3 and 0.03–0.53 nmol min−1 m−3 ranges, respectively. Quinones, oxy-aromatic, aromatic and alkyl-aromatic compounds stood out in bedrooms. Strong and significantly positive relationship between OP and black carbon, Cu and Br were observed, indicating common redox active species mainly associated with traffic emissions. Sr, Fe, Zn and Zr presented higher concentrations in dwelling 3, exhibiting excellent positive correlation with OP, indicating that the Sahara dust intrusion recorded in that house may have contributed to the formation of more redox active species thought to drive antioxidant depletion responses.

Chemical Fingerprinting, PAHs Characterization and Ecological Risks of Carcinogenic PAHs in Surficial Sediments of Egi Crude Oil Producing Communities, Niger-Delta, Nigeria

In order to do PAHs rings analysis, its source identification, extent to which cPAHs present and what kind of ecological risk they pose, the surface sediments from various freshwaters in the Egi crude oil producing cities in the Niger Delta, Nigeria were analyzed. Sediments collected from the research areas for PAHs loadings (in mg/kg dry weight) ranged from 0.020 to 1.790, 0.050 to 1.880, and 0.020 to 1.640, respectively for Obite, Obagi, and Ibewa cluster areas, as measured by gas chromatography-mass spectrometer. In these clusters, the respective average concentration of the three dominant carcinogenic PAHs were Indeno(1,2,3-cd)pyrene (1.170.0mg/kg), Dibenz[a,h]anthrancene (0.870.0 mg/kg), and Dibenz[a,h]anthrancene (1.3670 mg/kg) for Ibewa, Obagi and Obite cluster areas. The findings showed that dominant PAHs rings are of high molecular weight (HMW) PAHs in these sediments are, 5 member rings, which are benzo(b)fluoranthene, Benzo(k)fluoranthene, and Benzo(a)pyrène, and 6-member ring which are, Indeno(1,2,3-cd)pyrene, Dibenz[a,h]anthrancene, and Benzo[ghi] perylene, respectively. Their fingerprints points majorly to pyrogenic sources, combustion of coal, biomass, petroleum, and other related anthropogenic petroleum activities as the primary source of PAHs in the environment. Notably, the RQNCs and RQMPCs for single PAHs molecule are both less than 1, it means the contamination it generates is considered of low ecological risk. Again, the research area experiences frequent flooding, it is believed that this contributes to the low ecological risk of PAHs chemical pollution. Consequently, the area is deemed to be quite safe.

Eco-friendly electrospun nanofibers for air filtration enhanced by TiO2 nanoparticles reactive phases for superior capturing the emitted polycyclic aromatic hydrocarbons (PAHs)

The electrospinning nanofibrous filters have attracted much attention owing to their distinctive physicochemical properties. This work focused on designing a novel, straightforward prototype model and fabricating eco-friendly electrospun nanofiber filters as promising air filtration. The synthesized electrospun nanofiber is composed of cellulose acetate (CA) and thermoplastic polyurethane (TPU), which was enhanced by TiO2 nanoparticles to improve the capturing of low, medium, and high molecular weight PAHs. The fabricated CA:TPU/TiO2 and their derivatives were analyzed using FT-IR, XRD, TEM, SEM, TGA, and mechanical characteristics. Different concentrations of TiO2 (2 %, 4 %, 6 %, 8 %) were evaluated. The determinations of PAHs were achieved using gas chromatography-mass spectrometry (GC–MS) with a TG-5MS column. The newly designed prototype has two air pathways with identical specifications; therefore, it could simultaneously evaluate the efficiency of two filters. In Motobas dumpsite (agricultural sources), the results indicated that the highest efficiency of electrospun nanofiber filters was CA:TPU/TiO2 6 %, captured 3041 µg/m3 of total PAHs, and also in the incinerator stack (industrial sources) was CA:TPU/TiO2 6 % captured 9401 µg/m3 of total PAHs. The concentrations of low molecular weight PAHs were greater than the high molecular weight in all sites, and the electrospun CA:TPU/TiO2 was the most effective catalyst for air purification.

Characterization and health risk assessment of n-alkanes and PAHs in sediments from Shalateen (Halayeb Triangle), Egyptian Red Sea Coast

In this paper, the concentrations, origins, and carcinogenic potential of n-alkanes and polycyclic aromatic hydrocarbons (PAHs) collected from Shalateen sediments (Sh), Red Sea, Egypt were discussed. Individual n-alkanes has fluctuated from a minimum of 17.7 μg/g dw recorded for C-9 at Sh-54 to a maximum of 2.02 × 104 μg/g dw recorded for C-12 at Sh-B1. Total n-alkanes have fluctuated from 252–1.41 × 104 μg/g with a mean of 4.84 × 104 μg/g dw. C-12 had the highest average value, and C-19 had the lowest. The total ΣPAH concentrations in sediments from Shalateen as determined by gas chromatography-mass spectrometry/mass spectrometry (GC-MS/MS) ranged from 43.2 to 270 ng/g dw (averaging 95.2 ng/g dw). Carbon preference index (CPI) values were <1, consistent with the prevalence of even-C alkanes vs. the odd-C homologues. High molecular weight (HMW) PAHs were the most abundant substances affecting the collected samples. The cancer risk ranged from 2.25 × 10−5 to 4.78 × 10−2, indicating a moderate cancer risk associated with PAHs. The primary sources of PAHs in sediments included emissions from burning gasoline and diesel, biomass, and natural gas. The current study is considered one of the most important and unique with regard to the amounts and distributions of n-alkanes and PAHs in sediments along the coasts of Shalateen. It is the first baseline data documentation (GC MS/MS approach) of n-alkanes and PAHs in the Shalateen region.

Ecological and Geochemical Assessment of the State of Soils in the City of Baikalsk According to the Content of Polycyclic Aromatic Hydrocarbons

The pollution of the topsoils of the city of Baikalsk (Irkutsk region) under the influence of industrial emissions and wastes of the Baikal Pulp and Paper Mill (BPPM) was studied. The content of 16 individual PAH structures in samples of urban and background soils taken during the soil geochemical survey in the summer of 2019 was analyzed. Relatively low levels of PAH content were found in the lignin sludge from the BPPM and СHP ash. The concentration of total PAHs in CHP ash reaches 46 mg/ kg with a predominance of low molecular weight compounds (the proportion of naphthalene and its homologues is 24% and 34% of the total PAHs, respectively), among high molecular weight PAHs, 5-nuclear benzo(b)fluoranthene dominates (16%). In lignin sludge, the amount of PAHs is 7.16 mg/kg with the predominance of benzo(b)fluoranthene (83%). In the soils of Baikalsk, the average total content of PAHs (38.4 mg/kg) is 5 times higher than the background content. In urban soils, 4–5-nuclear fluoranthene (61.1%) and benzo(b)fluoranthene (29.4%) prevail. This makes it possible to attribute soil pollution to the fluoranthene type. The soils of the motor transport (total PAH 105 mg/kg) and industrial (59.5 mg/ kg) zones are the most polluted, where the most contrasting PAH anomalies were formed. In descending order of the amount of PAHs, the land use zones of the city form a series: motor transport industrial residential one-storey railway transport residential multi-storey recreational zone. Several local anomalies in the amount of PAHs are distinguished, forming two large pollution halos in the western and eastern parts of the city. The leading factors in the accumulation of high molecular weight PAHs in soils are acid-alkaline conditions and soil organic matter, while the accumulation of low molecular weight polyarenes is mainly controlled by pH. The environmental hazard of pollution of Baikalsk soils with polyarenes is due to benzo(b)fluoranthene, its contribution is 83.5%.

Occupational Exposure of On-Shift Ottawa Firefighters to Flame Retardants and Polycyclic Aromatic Hydrocarbons.

Firefighters can be exposed to complex mixtures of airborne substances, including hazardous substances released during structural fires. This study employed silicone wristbands (SWBs) as passive samplers to investigate potential exposure to polycyclic aromatic hydrocarbons (PAHs) and flame retardants (FRs). SWBs were deployed at different areas of four fire stations, in four truck cabins, and at an office control location; they were also donned outside the jackets of 18 firefighters who responded to fire calls. Overall, office areas had significantly lower PAHs than fire station areas. Vehicle bays and truck cabins had significantly higher concentrations of low molecular weight (LMW) PAHs than sleeping and living room areas. For organophosphate ester flame retardants (OPFRs), tri-n-butyl phosphate (TnBP) and tris(1-chloro-2-propyl) phosphate (TCPP) were detected in all the samples; 2-ethylhexyl diphenyl phosphate (EHDPP) was more frequently detected in the fire station areas. Triphenyl phosphate (TPP) concentrations were highest in the truck cabin and office areas, and tris(1,3-dichloro-2-propyl)phosphate (TDCPP) was highest in truck cabins. Thirteen of 16 PAHs and nine of 36 OPFRs were detected in all the SWBs worn by firefighters, and tris (2-butoxyethyl) phosphate (TBEP) was the predominant OPFR. Levels of LMW PAHs were significantly lower when firefighters did not enter the fire. LMW PAHs, HMW (high molecular weight) PAHs, and EHDPP were significantly elevated when heavy smoke was reported. This work highlights the potential for occupational exposure to PAHs and flame retardants in some fire station areas; moreover, factors that may influence exposure during fire suppression. Whilst firefighters' occupational exposure to PAHs is likely related to fire suppression and exposure to contaminated gear and trucks, exposure to OPFRs may be more related to their presence in truck interiors and electronics.

Plant Defense Mechanisms against Polycyclic Aromatic Hydrocarbon Contamination: Insights into the Role of Extracellular Vesicles.

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants that pose significant environmental and health risks. These compounds originate from both natural phenomena, such as volcanic activity and wildfires, and anthropogenic sources, including vehicular emissions, industrial processes, and fossil fuel combustion. Their classification as carcinogenic, mutagenic, and teratogenic substances link them to various cancers and health disorders. PAHs are categorized into low-molecular-weight (LMW) and high-molecular-weight (HMW) groups, with HMW PAHs exhibiting greater resistance to degradation and a tendency to accumulate in sediments and biological tissues. Soil serves as a primary reservoir for PAHs, particularly in areas of high emissions, creating substantial risks through ingestion, dermal contact, and inhalation. Coastal and aquatic ecosystems are especially vulnerable due to concentrated human activities, with PAH persistence disrupting microbial communities, inhibiting plant growth, and altering ecosystem functions, potentially leading to biodiversity loss. In plants, PAH contamination manifests as a form of abiotic stress, inducing oxidative stress, cellular damage, and growth inhibition. Plants respond by activating antioxidant defenses and stress-related pathways. A notable aspect of plant defense mechanisms involves plant-derived extracellular vesicles (PDEVs), which are membrane-bound nanoparticles released by plant cells. These PDEVs play a crucial role in enhancing plant resistance to PAHs by facilitating intercellular communication and coordinating defense responses. The interaction between PAHs and PDEVs, while not fully elucidated, suggests a complex interplay of cellular defense mechanisms. PDEVs may contribute to PAH detoxification through pollutant sequestration or by delivering enzymes capable of PAH degradation. Studying PDEVs provides valuable insights into plant stress resilience mechanisms and offers potential new strategies for mitigating PAH-induced stress in plants and ecosystems.

Biodiversity of multi-trophic biological communities within riverine sediments impacted by PAHs contamination and land use changes

River ecosystems currently face a significant threat of degradation and loss of biodiversity resulting from continuous emissions of persistent organic pollutants and human activities. In this study, multi-trophic communities were assessed using DNA metabarcoding in a relatively stable riverine sediment compartment to investigate the biodiversity dynamics in the Beiluo River, followed by an evaluation of their response to polycyclic aromatic hydrocarbons (PAHs) and land use changes. A total of 48 bacterial phyla, 4 fungal phyla, 4 protist phyla, 9 algal phyla, 31 metazoan phyla, and 12 orders of fish were identified. The total concentration of PAHs in the Beiluo River sediments ranged from 25.95 to 1141.35 ng/g, with low molecular weight PAHs constituting the highest proportion (68.67%), followed by medium (22.19%) and high (9.14%) molecular weight PAHs. Notably, in contrast to lower trophic level aquatic communities such as bacteria, algae, and metazoans, PAHs exhibited a significant inhibitory effect on fish. Furthermore, the diversity of aquatic communities displayed obvious heterogeneity across distinct land use groups. A high proportion of cultivated land reduced the biodiversity of fish communities but increased that of metazoans. Conversely, an elevated proportion of built-up land reduced metazoan biodiversity, while simultaneously enhancing that of fungi and bacteria. Generally, land use changes exert both indirect and direct effects on aquatic communities. The direct effects primarily influence the abundance of aquatic communities rather than their diversity. Nevertheless, PAHs pollution may have limited potential to disrupt community structures through complex species interactions, as the hub species identified in the co-occurrence network did not align with those significantly affected by PAHs. This study indicates the potential of PAHs and land use changes to cause biodiversity losses. However, it also highlights the possibility of mitigating these negative effects in riverine sediments through optimal land use management and the promotion of enhanced species interactions.

A quantitative comparison of economic viability, volatile organic compounds, and particle-bound carbon emissions from a diesel engine fueled with biodiesel blends

Despite the environmental advantages of biofuel blends, detailed studies on emissions of polycyclic aromatic hydrocarbons (PAHs), n-alkanes, and particle-bound carbon from diesel engines, particularly when fueled with biodiesel, remain limited. This study addresses these gaps by analyzing biodiesel blends from neem, linseed, and jatropha oils produced via mechanical extraction and assessing their impact on volatile organic compounds and particle-bound carbon emissions in diesel engine. Economic evaluations of production costs, engine modifications, and payback periods are also conducted. The result shows that jatropha biodiesel exhibits a calorific value of 35.7 MJ/kg, while neem biodiesel shows superior oxidative stability due to its low iodine value. Additionally, linseed biodiesel displays favorable cold flow properties due to its high density and cetane value. Compared to D100, the N10 and N30 blend notably reduced high molecular weight PAH emissions by 10.7 % and 38.4 %, respectively, with the N30 blend achieving a remarkable 76 % reduction in formaldehyde emissions. Conversely, the J10 blend increased specific PAHs, while the J30 blend reduced PAHs by 21.3 %. Both L10 and L30 blends showed reduced naphthalene emissions, with the J30 blend notably reducing elemental carbon (EC) by 31.4 %, although organic carbon (OC) slightly increased. In contrast, the N30 blend decreased both EC and OC emissions, demonstrating a dose-dependent relationship between biodiesel concentration and emissions reduction. Overall, Jatropha biodiesel blends offer the best balance of economic efficiency and emission reductions, resulting in shorter payback periods and lower carcinogenic risks. Neem and linseed blends also provide environmental benefits but with varying economic implications, highlighting the trade-offs between production costs and long-term sustainability.

Polycyclic aromatic hydrocarbons in ship breaking area and associated ecological risk assessment: evidence from the Sitakund ship-breaking area in Bangladesh.

Ship-breaking yards are recognized for releasing hazardous polycyclic aromatic hydrocarbons (PAHs), leading to severe environmental pollution in the sediment of ship-breaking areas. This study assessed the concentrations of 16 priority PAHs in surface sediments collected from the intertidal zone adjacent to the Sitakund ship-breaking yards. The samples underwent Soxhlet extraction and detection using PerkinElmer GC-Clarus 690 and MS-Clarus SQ8C with an Elite-5MS capillary column (30m × 0.25mm ID × 0.25µm). The study utilized PAH concentrations to reveal spatial distribution patterns, identify point sources, and assess potential toxicity. The total PAH concentration ranged from 1899.2 to 156,800.08ngg-1 dw, while the concentration of 7 carcinogenic PAHs ranged from 822.03 to 1899.15ngg-1 dw. High molecular weight PAHs dominated among the 16 PAHs, whereas low molecular weight PAHs, such as 2-ring PAHs, were negligible. Source characterization based on different molecular ratios suggested that PAHs in the area originated from pyrolytic processes related to ship dismantling, fishing activities, and water transportation for people. The observed PAH concentrations exceeded both national and international standards for sedimentary PAH levels, indicating significant ecological risks. The total TEQcarc values of sediment samples varied from 564.41 to 10,695.12ngg-1, with a mean value of 3091.25ngg-1. The study's findings underscore the immediate biological damage that PAH contamination in the Sitakund ship-breaking area could cause, emphasizing the need for effective control measures to ensure ecological and human safety.

Polycyclic aromatic hydrocarbons (PAHs) in blood serum of adults living in high and low-traffic volume areas in Malaysia: A comparative cross-sectional study

Ambient polycyclic aromatic hydrocarbons (PAHs) originate predominantly from fuel combustion of motor vehicles and have the potential to affect human health. However, there is insufficient knowledge regarding serum PAHs health risks among the Malaysian population. This study aims to compare PAH concentrations, distributions, correlations, and health risks in 202 blood serum samples drawn from residents living in high-traffic volume areas (Kuala Lumpur) and low-traffic volume areas (Hulu Langat) in Malaysia. Solid phase extraction and gas chromatography-mass spectrometry (GC-MS) were employed to extract and analyze blood serum samples. Questionnaires were distributed to obtain sociodemographic and contributing factors of serum PAHs. The mean total PAHs concentration in serum of the Kuala Lumpur group was 54.44 ng g−1 lipids, double the Hulu Langat group's concentration (25.7 ng g−1 lipids). Indeno(1,2,3-cd)pyrene (IcP) and acenaphthene (ACP) feature the most and least abundant compounds in both study groups. The mean concentrations of IcP and ACP in the Kuala Lumpur and Hulu Langat groups were 26.8 vs 12.68 and 0.27 vs 0.14 ng g−1 lipids, respectively. High-molecular-weight PAHs (HMW-PAHs) composed 85% of serum total PAHs in both groups. Significant correlations were found (i) between the individual serum PAH congeners (p < 0.01) and (ii) between serum PAHs and total lipids (p < 0.01). According to the questionnaire data, high traffic volume and outdoor hobbies were the only contributory factors that confirmed significant relationships with serum PAHs (p < 0.001). Health risk assessment was computed using benzo(a)pyrene (BaP) equivalent (BaPeq) and demonstrated that the Kuala Lumpur group has twofold greater carcinogenic risk than the Hulu Langat group (16.11 vs 7.76 ng g−1 lipids). Our study reveals that traffic volumes notably impact serum PAH levels and general health among the Malaysian population.

Assessing the Impact of Pre-Soaking to Enhance Laundering Efficacy of Firefighter Turnout Gear.

Firefighters are exposed to hazardous chemicals at fire scenes, including polycyclic aromatic hydrocarbons (PAHs) among many others, which pose significant health risks. Current laundering practices are ineffective at removing persistent contaminants from turnout gear, necessitating further research to optimize cleaning methods. This study explores the impact of presoaking prior to the laundering process and the factors that can affect its effectiveness, including the presoaking duration and detergent concentration, in PAH removal when laundering. For this, contaminated fabric swatches were subjected to various presoaking durations (1, 3, and 12 h) and detergent concentrations (99:1 and 90:10 water-to-detergent ratios) before undergoing bench-scale washing. The cleaning efficacy was assessed for 16 PAH compounds, including both low-molecular-weight (LMW) PAHs and high-molecular-weight (HMW) PAHs. Moreover, the removal mechanisms of PAHs from turnout gear were fundamentally explained using partition coefficients and standard affinities with different parameters during washing. The results demonstrate that 3 h and 12 h of presoaking lead to 2.8 and 4.3 times greater HMW PAH removal, respectively. After 12 h of presoaking in a 90:10 water-to-detergent ratio, 97% of the LMW PAHs and 78% of the HMW PAHs were removed, compared to only an 11% removal of the HMW PAHs with a 99:1 ratio. Additionally, direct washing with a 90:10 ratio achieved comparable efficacy to that of presoaking with the same water-to-detergent ratio, indicating the crucial role of detergent concentration during laundering. These findings offer valuable insights for optimizing firefighter safety practices, emphasizing the role of presoaking and the appropriate methods to perform presoaking to mitigate firefighters' occupational exposure risks to toxic substances and ensure gear reliability.

A case study on microlitter and chemical contaminants: Assessing biological effects in the southern coast of the Gulf of Finland (Baltic sea) using the mussel Mytilus trossulus as a bioindicator

Chemical and microlitter (ML) pollution in three Estonian coastal areas (Baltic Sea) was investigated using mussels (Mytilus trossulus). Polycyclic aromatic hydrocarbons (PAH) in mussel tissues were observed in moderate levels with high bioaccumulation factors for the more hydrophilic and low molecular weight PAH (LMW PAH), namely anthracene and fluorene. Tissue concentrations of polybrominated diphenyl ethers (PBDE) and cadmium within mussel populations exceeded the Good Environmental Status thresholds by more than 200% and 60%, respectively. Multiple contamination at the Muuga Harbour site by tributyltin, high molecular weight PAH, including the highly toxic benzo[c]fluorene and PBDE, coincided with the inhibition of acetylcholinesterase activity and a lower condition index of the mussels. The metabolization and removal of bioaccumulated LMW PAH, reflected in the dominance of oxy-PAH such as anthracene-9,10-dione, is likely associated with the increased activity of glutathione S-transferase in caged mussels. Only a few microplastic particles were observed among the ML in mussel tissues, with coloured cellulose-based microfibers being the most prevalent. The average concentration of ML in mussels was significantly higher at the harbour area than at other sites. The integrated biomarker response index values allowed for the differentiation of pollution levels across studied locations representing high, intermediate, and low pollution levels within the studied area.

Spatiotemporal distribution and inter-media transfer of polycyclic aromatic hydrocarbons in Shanghai, China: Historical patterns and future trends

Polycyclic Aromatic Hydrocarbons (PAHs) represent pervasive pollutants, posing health risks in urban environments. It is essential to comprehend the spatiotemporal distributions, composition profiles, and inter-media transfer processes of PAHs in various environmental compartments, influenced by both natural changes and anthropogenic activities. This study integrates historical and future spatiotemporally changing environmental parameters, including climate data, GDP, population data, land-use types, and hydrological variables, into the Multimedia Urban Model (MUM). This integration enables the simulation of spatiotemporal distributions and inter-media transfer fluxes of PAHs among six different media from the 2010s to the 2100s under two distinct Shared Socio-economic Pathways (SSP) scenarios in the megacity of Shanghai, China. The MUM model, featuring diverse gridded parameters, effectively captures PAH concentrations and movement across environmental compartments. Results indicate a decreasing trend in PAHs concentrations in the 2100s compared to the 2010s, with PAH concentrations in water, sediment, vegetation, and organic film covering impermeable surfaces under the SSP3–7.0 scenario higher than those of the SSP1–2.6 scenario. Low molecular weight PAHs dominate in the sediment, water, and air, whereas high molecular weight PAHs prevail in the organic film, vegetation, and soil. Sediment and soil serve as the predominant sinks for PAHs. The primary transport processes for PAH movement include air-film, air-soil, film-water, soil-air, and water-air. Almost all transfer fluxes exhibit a declining trend in future periods except for the air-film transport pathway. The principal input and removal routes for PAHs in Shanghai involve the advection of air and water. The study provides essential insights into the environmental behavior of PAHs and informs targeted pollution control in Shanghai. Additionally, it serves as a technical reference for similar pollution prediction research.

Particulate Matter (PM) and Parent, Nitrated and Oxygenated Polycyclic Aromatic Hydrocarbon (PAH) Emissions of Emulsified Heavy Fuel Oil in Marine Low-Speed Main Engine.

To understand the influences of emulsified fuel on ship exhaust emissions more comprehensively, the emissions of particulate matter (PM), nitrated, oxygenated and parent polycyclic aromatic hydrocarbons (PAHs) were studied on a ship main engine burning emulsified heavy fuel oil (EHFO) and heavy fuel oil (HFO) as a reference. The results demonstrate that EHFO (emulsified heavy fuel oil) exhibits notable abilities to significantly reduce emissions of particulate matter (PM) and low molecular weight PAHs (polycyclic aromatic hydrocarbons) in the gas phase, particularly showcasing maximum reductions of 13.99% and 40.5%, respectively. Nevertheless, burning EHFO could increase the emission of high molecular weight PAHs in fine particles and pose a consequent higher carcinogenic risk for individual particles. The total average (gaseous plus particulate) ΣBEQ of EHFO exhausts (41.5 μg/m3) was generally higher than that of HFO exhausts (18.7 μg/m3). Additionally, the combustion of EHFO (extra-heavy fuel oil) can significantly alter the emission quantity, composition, and particle-size distribution of PAH derivatives. These changes may be linked to molecular structures, such as zigzag configurations in C=O bonds. Our findings may favor the comprehensive environmental assessments on the onboard application of EHFO.