Analysis Of Polycyclic Aromatic Hydrocarbons Research Articles

Evaluation of exposure to volatile organic compounds (BTEX) and Polycyclic Aromatic Hydrocarbons (PAHs) in gas station workers and oxidative stress assessment in Karaj city

Gas stations are one of the sources of benzene, toluene, ethylbenzene and xylene (BTEX) and polyromantic hydrocarbons (PAHs). The present study was conducted with the aim of evaluating the level of breathing exposure of gas station workers to BTEX, PAHs and oxidative stress caused by exposure to these compounds in Karaj city. Oxidative stress and reactive oxygen species (ROS) is one of the mechanisms involved in the toxicity caused by exposure to gas vapors. In this study, all 25 gas stations in the city of Karaj were investigated. Personal sampling and analysis of BTEX and PAHs was done according to National Institute for Occupational Safety and Health (NIOSH) 1501 and 5515 methods, respectively. Finally, oxidative stress markers were investigated in 25 gas station workers and 25 control group. The results showed that the mean age and employment history of gas station workers are 39.96 ± 9.55 and 12.84 ± 6.92, respectively. Also, no significant difference was reported between gas station workers and control subjects in terms of oxidative stress parameters including the level of ROS, oxidized glutathione (GSSG) content, malondialdehyde (MDA) and reduced glutathione (GSH) content. The concentration values of personal exposure of gas station workers to BTEX and PAHs are lower than the occupational exposure limits (OEL). Although the level of oxidative stress parameters in gas station workers is higher than the control group, this difference is not statistically significant (p>0.05). It is recommended to take personal protection measures in case of chronic exposure.

Flexible and designable metal–organic framework-based electrospun nanofibrous for highly sensitive recognition of polycyclic aromatic hydrocarbons in water samples

In this study, a novel functionalized electrospun nanofibrous material was developed through a straightforward and robust approach that combines polydopamine (PDA) mediation and hydrothermal growth. This material was utilized as a SPME probe for polycyclic aromatic hydrocarbons (PAHs) analysis. Under optimal extraction conditions, the proposed method exhibited higher enrichment factors (1362–4563) and lower detection limits (0.003–0.35 ng mL−1), with relative standard deviations (RSDs) below 6.7 %. Applied to water samples, the stability and reproducibility of the nanofibrous have been validated with the intra- and inter-assay RSD in 2.3–9.8 % and 1.5–9.9 %, respectively. Acceptable recoveries of 87.1–109.2 % were achieved. Furthermore, the developed SPME-GC method was successfully applied to the analysis of PAHs in water samples.

Development of new PDMS in tube extraction microdevice for enhanced monitoring of polycyclic aromatic hydrocarbons and their derivatives in water

Contamination by polycyclic aromatic hydrocarbons (PAHs) is an urgent environmental concern, given its atmospheric dispersion and deposition in water bodies and soils. These compounds and their nitrated and oxygenated derivatives, which can exhibit high toxicities, are prioritized in environmental analysis contexts. Amid the demand for precise analytical techniques, comprehensive two-dimensional chromatography coupled with mass spectrometry (GCxGC/Q-TOFMS) has emerged as a promising tool, especially in the face of challenges like co-elution. This study introduces an innovation in the pre-concentration and detection of PAHs using an extraction fiber based on polydimethylsiloxane (PDMS), offering greater robustness and versatility. The proposed technique, termed in-tube extraction, was developed and optimized to effectively retain PAHs and their derivatives in aqueous media, followed by GCxGC/Q-TOFMS determination. Fiber characterization, using techniques such as TG, DTG, FTIR, and SEM, confirmed the hydrophobic compounds retention properties of the PDMS. The determination method was validated, pointing to a significant advancement in the detection and analysis of PAHs in the environment, and proved effective even for traces of these compounds. The results showed that the detection limits (LOD) and quantification limits (LOQ) ranged from 0.07 ng L−1 to 1.50 ng L−1 and 0.33 ng L−1 to 6.65 ng L−1, respectively; recovery ranged between 72 % and 117 %; and the precision intraday and interday ranged from 1 % to 20 %. The fibers were calibrated in the laboratory, with exposure times for analysis in the equilibrium region ranging from 3 to 10 days. The partition coefficients between PDMS and water were also evaluated, showing logarithm values ranging from 2.78 to 5.98. The fibers were applied to the analysis of real water samples, demonstrating high capacity. Additionally, given the growing demand for sustainable methods, the approach presented here incorporates green chemistry principles, providing an efficient and eco-friendly solution to the current chemical analysis scenario.

Characterization of carbonaceous components and PAHs on ultrafine particles in Phnom Penh, Cambodia.

This study investigated seasonal fluctuations in particulate matter (PM) concentrations, including carbon and polycyclic aromatic hydrocarbon (PAH) components, in Phnom Penh, Cambodia, focusing on ultrafine particles (UFPs or ≤ 100nm). UFP levels were notably higher during the dry season, averaging 23.73 ± 3.7µg/m3 compared to 19.64 ± 3.4µg/m3 in the wet season, attributed to increased emissions from vehicles and agricultural burning. In contrast, lower concentrations during the wet season were due to scavenging effect of rain. When compared to other Southeast Asian cities, UFP levels in Phnom Penh were significantly higher during the dry season, surpassing those in cities like Bangkok and Kuala Lumpur. Seasonal variations in carbonaceous components showed higher elemental carbon (EC) and total carbon (TC) during the dry season, with EC/TC ratios suggesting substantial influence from vehicular emissions and biomass burning. PAH analysis revealed seasonal disparities, with higher concentrations of benzo[b]fluoranthene (BbF) and benzo[k]fluoranthene (BkF) during the wet season, whereas fluoranthene (Flu) and pyrene (Pyr) were consistently present, indicating diverse PAH sources. The Flu/(Flu + Pyr) ratios, indicative of biomass burning, were higher in the dry season. Correlations between PAHs and carbon components confirmed combustion as a significant source of PAHs, aligning with global trends. This emphasizes the need to address distinct PM sources during various season in Phnom Penh.

Nectarine core-derived magnetite biochar for ultrasound-assisted preconcentration of polycyclic aromatic hydrocarbons (PAHs) in tomato paste: A cost-effective and sustainable approach

A novel ultrasound-assisted magnetic solid-phase extraction coupled with gas chromatography–mass spectrometry (US-MSPE-GC/MS) was developed to detect trace amounts of polycyclic aromatic hydrocarbons (PAHs) in tomato paste, using a magnetic biochar adsorbent derived from nectarine cores. The highest extraction recovery was attained under 10 mg adsorbent mass, 30 min extraction time, 9 % (w/v) sodium chloride, and elution with 200 μL of dichloromethane. Under optimum conditions, the method demonstrated excellent linearity (R2 > 0.992) across a wide concentration range (0.01-100 ng g−1) with high sensitivity (LODs: 0.028-0.053 ng g−1, LOQs: 0.094-0.176 ng g−1) and good repeatability (RSDs <5.96 %). The application of the US-MSPE-GC/MS method was tested on four brands of real tomato paste and no PAHs were detected in unspiked samples, indicating no background contamination. This method showed high relative recoveries 88.03-98.52 %) and good reproducibility (<9.19 %.) at two concentration levels, confirming its effectiveness for PAH analysis in real samples.

Polycyclic aromatic hydrocarbons in fish from four lakes in central and eastern China: Bioaccumulation, pollution characteristics, sources, and health risk assessment

Polycyclic aromatic hydrocarbons (PAHs) are highly concerning environmental pollutants due to their toxicity, persistence, and bioaccumulation. In this paper, concentrations and compositions of 16 United States Environmental Protection Agency (USEPA) priority control PAHs in the fish collected from four lakes in central and eastern China were analyzed. 18 species of fish were collected from four typical lakes, namely Taihu Lake, Danjiangkou Reservoir, Yuncheng Salt Lake, and Nansi Lake. Quantitative analysis of PAHs were carried out with gas chromatograph/mass spectrometer, and 13 out of 16 PAHs were identified, with the main components being pyrene, chrysene, naphthalene, and benzo(b)fluoranthene. The accumulation of PAHs in fish from Taihu Lake, Danjiangkou Reservoir, Yuncheng Salt Lake, and Nansi Lake was 28.75–47.27, 26.60–31.93, 33.56–39.30, and 27.22–43.01 ng·g−1, respectively. The toxic equivalents of high-cyclic PAHs in fish of the four lakes were significantly higher than those of low-cyclic and middle-cyclic PAHs (P < 0.05). In Taihu Lake, Danjiangkou Reservoir, and Nansi Lake, the toxicity equivalents were predominantly contributed by benzo[a] pyrene (BaP), while in Yuncheng Salt Lake, dibenzo(a,h) anthracene (DahA) was the main contributor. The residents in central and eastern China exposed to PAHs had a negligible non-cancer risk (non-carcinogenic risk values <1) and a potential low cancer risk. It was noteworthy that the Pleuronichthys cornutus and Lateolabrax japonicus from Yuncheng Salt Lake could pose carcinogenic risks (>10−4) to humans, with benzo[b]fluoranthene (BbF) having the highest risk contribution rate. Source analysis indicated that the main source of PAHs in fish was combustion sources. BaP, DahA, and BbF could become potential pollutants of concern in the field of ecotoxicology. The results of this study on PAHs bioaccumulation, pollution characteristics, sources and health risks in fish from four lakes would provide a scientific basis for local governments to formulate targeted environmental management policies, pollution control measures, and public health strategies.

Assessment of polycyclic aromatic hydrocarbon (PAH) levels and health risks in kitchen dust from wood, kerosene, and gas cooking systems in Cumilla, Bangladesh

This study investigates the presence of polycyclic aromatic hydrocarbons (PAHs) in kitchen dust from households in the Cumilla District of Bangladesh, utilizing three different cooking systems: wood, kerosene, and gas. Sixty dust samples were collected from various kitchen surfaces and analyzed for 18 PAH compounds. The extraction and analysis of PAHs were performed using gas chromatography-mass spectrometry (GC-MS) with selective ion monitoring (SIM) mode. The results indicated significant variations in PAH concentrations across different cooking systems, with the highest levels observed in kitchens using wood stoves, followed by kerosene and gas stoves. Diagnostic ratios were used to identify the sources of PAHs, revealing a combination of pyrogenic and petrogenic origins. Health risk assessments, including Incremental Lifetime Cancer Risk (ILCR) and Hazard Index (HI), were conducted to evaluate the potential risks associated with PAH exposure. The findings demonstrated a higher carcinogenic risk associated with wood stove systems, while kerosene and gas systems posed comparatively lower risks. The study's findings have practical implications for public health and policy development, as they underscore the need for continuous monitoring of indoor PAH levels and the development of policies to mitigate exposure, highlighting the critical importance of addressing indoor pollution to ensure public health safety.

FEAST: Feedback in Emerging extragAlactic Star ClusTers: JWST Spots Polycyclic Aromatic Hydrocarbon Destruction in NGC 628 during the Emerging Phase of Star Formation

We investigate the emergence phase of young star clusters in the nearby spiral galaxy NGC 628. We use JWST NIRCam and MIRI observations to create spatially resolved maps of the Paα 1.87 μm and Brα 4.05 μm hydrogen recombination lines, as well as 3.3 and 7.7 μm emission from polycyclic aromatic hydrocarbons (PAHs). We extract 953 compact H ii regions and analyze the PAH emission and morphology at ∼10 pc scales in the associated photodissociation regions. While H ii regions remain compact, radial profiles help us to define three PAH morphological classes: compact (∼42%), extended (∼34%), and open (∼24%). The majority of compact and extended PAH morphologies are associated with very young star clusters (<5 Myr), while open PAH morphologies are mainly associated with star clusters older than 3 Myr. We observe a general decrease in the 3.3 and 7.7 μm PAH band emission as a function of cluster age, while their ratio remains constant with age out to 10 Myr and morphological class. The recovered PAH3.3μm/PAH7.7μm ratio is lower than values reported in the literature for reference models that consider neutral and ionized PAH populations and analyses conducted at galactic physical scales. The 3.3 and 7.7 μm bands are typically associated with neutral and ionized PAHs, respectively. While we expected neutral PAHs to be suppressed in proximity to an ionizing source, the constant PAH3.3μm/PAH7.7μm ratio would indicate that both families of molecules disrupt at similar rates in proximity to H ii regions.

Contiguous hourly variations and relativeness of polycyclic aromatic hydrocarbons and their chlorinated derivatives in urban PM2.5

The time-resolved analysis of ambient polycyclic aromatic hydrocarbons (PAHs) has been frequently performed in various sites, whereas that of chlorinated PAHs (ClPAHs) is limited. This study performed the time-resolved analysis of PAHs and ClPAHs in hourly PM2.5 spots collected using a tape filter at three stations in urban cities. The hourly concentrations of the total PAHs and ClPAHs exhibited specific variations in each station, attributable to the different sources and origins. According to PAH diagnostic ratio analysis, the hours at which the ClPAH concentrations were elevated showed the contributions of coal, petroleum combustions, and aged particles. The network analysis of the datasets was performed to visualize the association of each compound with the sampling time and station. PAHs were prevalent in all the stations at every time, whereas the impacts of ClPAHs were limited to certain stations and times. This suggests that the ClPAHs in the air could be attributed to specific sources, dissimilar to the ubiquitous sources of PAHs.

Polycyclic Aromatic Hydrocarbons (PAHs) in Grilled Marshmallows.

The aim of this study was to assess potential health risks among children and adolescents consuming various grilled marshmallows using a survey and to determine polycyclic aromatic hydrocarbons (PAHs) in these food products. PAH analysis in grilled marshmallows included a dilution stage with deionized water and liquid-liquid extraction with cyclohexane and solid-phase extraction (SPE). PAH fractions were initially analyzed via high-performance thin-layer chromatography, and PAH concentrations were determined via gas chromatography with a tandem mass detector using the selective reaction monitoring (SRM) mode. This study on the consumption of grilled marshmallows was conducted among approximately 300 children and adolescents. The preliminary results indicated that "raw" marshmallows did not contain PAHs. However, the obtained data suggested the exposure of young people to carcinogenic PAHs from grilled marshmallows (63.5% of them consumed marshmallows). Carcinogenic benzo(a)pyrene (BaP) was determined in all samples. The profile of PAH concentrations in the extracts isolated from various grilled types of marshmallows was similar (r2 > 0.8000), regardless of the grilling method. Compared to the white sugar confection, higher concentrations of PAHs were determined in multicolored marshmallows. The lack of social awareness about exposure to carcinogenic substances is alarming.

Honeycomb-like triazine-based conjugated microporous polymers exhibiting simultaneous and ultrasensitive detection of fifteen polycyclic aromatic hydrocarbons using solid-phase microextraction technique

BackgroundSince the severe hazard to the ecosystem and widespread distribution through biological and man-made ways of polycyclic aromatic hydrocarbons (PAHs), it is very urgent to establish the ultrasensitive analytical method to quantitatively and directly monitor PAHs in real samples. However, because of the complicated environmental matrix and their trace concentration, the pre-concentration process is a necessary step to analyze of these compounds. In this study, solid phase microextraction (SPME) technique was proposed to separate and enrich fifteen trace PAHs from environmental samples. ResultsIn this work, a honeycomb-like triazine-based conjugated microporous polymers (T-CMPs) were prepared by Yamamoto reaction and firstly used as SPME coating material for the ultrasensitive direct-immersion-SPME of PAHs prior to high performance liquid chromatography-fluorescence detector (HPLC-FLD). The synthesized T-CMPs was characterized using various spectroscopy and electron microscopy techniques. The unique porous network of T-CMPs might deliver abundant adsorption sites for PAHs. Orthogonal experimental design (OED) was used to investigate the influence of four experimental parameters on the enrichment ability. Under optimal situation, a wide linear range (which lasted from 0.003 to 1000 μg L−1) with the coefficients of determination (R2) varying 0.9981 to 0.9993 was obtained. The limits of detection (LODs) for the analytes varied from 0.001 to 1.650 μg L−1, and the limits of quantification (LOQs) were between 0.003 and 4.960 μg L−1. The proposed method was effectively employed to the simultaneous and ultrasensitive detection of fifteen PAHs in industrial wastewaters. The relative recoveries for PAHs analysis varied from 74.6 % to 105 % with the relative standard deviations (RSD) of 0.1 %–7.5 % in real water samples. SignificanceThe prepared SPME coating material exhibited a simultaneous, high extraction and adsorption capacity for fifteen PAHs due to its honeycomb-like porous structure, ultra-large specific surface area, strong π-π stacking, and hydrophobic interactions. The present research developed a novel strategy for the construction of SPME fiber coating composites and demonstrated great application potential in the field of sample pretreatment and environmental analytical chemistry.

Characterization of Microplastics and Adsorbed/Dissolved Polycyclic Aromatic Hydrocarbons in the Biggest River System in Saitama and Tokyo, Japan.

This study presents a comprehensive characterization of microplastics (MPs) and adsorbed/dissolved polycyclic aromatic hydrocarbons (PAHs) in the Arakawa River, the largest river system in Saitama and Tokyo, Japan. The MPs were sampled at various points along the river, revealing an average number density of 2.21 ± 1.48 pieces/m3, with a predominant size range of 0.5-1 mm. Polymer analysis indicated that polyethylene (PE) comprised the highest proportion of MPs (55.9%), followed by polypropylene (PP) (22.4%) and polystyrene (PS) (21.7%). Seasonal fluctuations in MPs concentration were observed, with the highest values in winter and the lowest in summer. An analysis of adsorbed PAHs revealed a median partition coefficient (Kd) value of 3.58 × 104 L/kg for MPs, indicating their affinity for PAHs. Further PAHs analysis revealed that the PAHs with the highest mean values were bicyclic naphthalene, pyrene, and fluoranthene. A comparison with coastal MPs showed differences in PAH composition, with higher proportions of high-ring PAHs observed in coastal samples. The study also investigated the distribution of PAHs in the dissolved and suspended states in the river, finding that similar PAHs were distributed in both states, with the PAHs present in MPs being about 1/10,000 of those in the dissolved and suspended states. The study underscores the importance of the continued monitoring and management of MPs and associated pollutants in river ecosystems.

Computational assessment of soot models in ethylene/air laminar diffusion flames

To improve the accuracy of soot formation and evolution predictions, several physical and chemical models have been developed over the last decades. These models include (i) detailed chemical kinetic mechanisms describing both gas-phase chemistry related to combustion processes and reaction pathways leading to large-sized aromatic molecules, which are needed for modelling soot formation, and (ii) soot models providing a comprehensive description of soot particle dynamics and interactions with gas-phase chemical species. Accordingly, in this work, two detailed soot models, the method of moments (MOM) and the discrete sectional method (DSM), are evaluated in ethylene/air laminar diffusion flames, and their corresponding results are compared with experimental measurements. Furthermore, the NBP and KM2 chemical kinetic mechanisms are assessed and compared with each other by examining key chemical species related to soot formation and evolution. To compute gas mixture’s radiative properties, the weighted sum of grey gases model considering a grey medium is also utilised. Finally, the contributions of the soot precursors known as PAH (polycyclic aromatic hydrocarbon) to soot formation are also analysed. The main results show that the discrepancies in PAH concentrations obtained with different chemical kinetic mechanisms can be significant. In addition, compared to MOM ones, DSM results obtained here show a better agreement with experimental data. Finally, the analysis of PAH shows that those with two (A2) to four (A4) aromatic rings impact the most on soot modelling. Specifically, contributions of A4 were found to be more significant at lower heights above the burner, whereas A2 was found to be more impactful downstream as the flame develops. Maximum contributions of A2 and A4 to the soot inception rate were 66% and 85%, respectively, whereas the maximum summed contribution of PAH with five (A4R5) to seven (A7) aromatic rings accounted for only 13% of the inception rate.

Systematic underestimation of polycyclic aromatic hydrocarbon aqueous concentrations in rivers

Polycyclic aromatic hydrocarbons (PAHs) are a widespread group of organic contaminants whose presence in water bodies is cause of severe concern. With few exceptions, the majority of PAHs is hydrophobic, presents a high adsorption affinity, and is thus primarily transported within river systems during high-flow events together with suspended particulate matter (SPM). Evidence exists of analytical challenges related to the incomplete extraction of PAHs adsorbed to solids and thus to a potential negative bias in the chemical analysis of PAHs in bulk water samples with high SPM content. Despite this, partly due to the elevated efforts required to collect representative samples containing sufficient SPM for the separate PAH analysis in this matrix, several investigations rely on the analysis of aqueous samples. This study tests the hypothesis that surveys based exclusively on bulk water may lead to a systematic underestimation of the real contamination level and transport of PAHs in rivers. Six high-turbidity events were examined in three Austrian rivers applying time-integrated sampling and simultaneously analyzing PAHs in total bulk water, filtered water, SPM, and supernatant. Despite an unavoidable degree of uncertainty in such challenging sampling scheme, the results indicate that measurements performed with best available standard methods in bulk water samples determined in average only about 40% of the theoretically expected total PAHs concentrations derived from the analyses in SPM. Such deviation has important implications for the reliable assessment of the compliance with environmental quality standards as well as for surveys aimed to estimate riverine loads, validate emission models, and understand the transport dynamics of PAHs in rivers. Whereas the first objective, e.g., in European countries, is alternatively achieved via monitoring in biota, the latter ones require efforts directed to complement monitoring campaigns with separate sampling of SPM, with monitoring of suspended solids transport to appropriately select and interpret the results of water samples and to improve the chemical analysis of PAHs in bulk water samples with high solids content.

Quantitative analysis of four PAHs in oily sludge by surface-enhanced Raman spectroscopy (SERS) combined with partial least squares regression (PLS) based on a novel nano-silver-silicon coupling substrate

Polycyclic aromatic hydrocarbons (PAHs) present in oily sludge generated by the petroleum and petrochemical industries have emerged as a prominent concern within the realm of environmental conservation. The precise determination of PAHs holds immense significance in both petroleum geochemistry and environmental protection. In this study, a combination of surface-enhanced Raman spectroscopy (SERS) and solid–liquid extraction was employed for the screening of PAHs in oily sludge. Methanol was utilized as the extraction solvent for PAHs, while nanosilver-silicon coupling substrates were employed for their detection. The SERS spectrum was acquired using a portable Raman spectrometer. The nano silver-silicon coupling substrate exhibits excellent uniformity, with relative standard deviations (RSDs) of Phenanthrene, Fluoranthrene, Fluorene and Naphthalene (Phe, Flt, Flu and Nap) being 2.8%, 1.08%, 1.41%, and 5.44% respectively. Moreover, the limits of detection (LODs) achieved remarkable values of 0.542 μg/g, 0.342 μg/g, 0.541 μg/g, and 5.132 μg/g. The quantitative analysis of PAHs in oily sludge was investigated using SERS technology combined with partial least squares (PLS). The optimal PLS calibration model was optimized by combining spectral preprocessing methods and using the SiPLS (Synergy interval partial least squares)-VIP (Variable Importance in Projection) hybrid variable selection strategy. The prediction performance of the D1st (First derivative)-WT (Wavelet transform)-SiPLS-VIP-PLS model was deemed satisfactory, as evidenced by high R2P values of 0.9851, 0.9917, and 0.9925 for Phe, Flt, and Flu respectively; additionally, the corresponding MREP values were found to be 0.0580, 0.0668, and 0.0669 respectively. However, for Nap analysis, the D1st-WT-PLS model proved to be a better calibration model with an R2P value of 0.9864 and an MREP (Mean relative error of prediction) value of 0.0713. In summary, SERS technology combined with PLS based on different spectral pretreatment methods and mixed variable selection strategies is a promising method for quantitative analysis of PAHs in oily sludge, which will provide new ideas and methods for the quantitative analysis of PAHs in oily sludge.

Characterization and risk assessment of polycyclic aromatic hydrocarbons from the emission of different power generator

Epileptic power supply in Sub-Saharan countries of Africa has warranted the use of power generators as an alternative source of power supply. Exhaust emission from these generators is associated with Polycyclic Aromatic Hydrocarbon (PAHs). Hence, this study focused on the determination of levels of PAHs in the emission of different brands of power generators used in Nigeria. Exhaust emissions of different power generators were sampled using a filter-sorbent sampling system with polyurethane foam (PUF) as an adsorbent material. Analysis of PAHs was carried out using a Gas Chromatograph coupled to a mass selective detector (GC- MS) operated on Electron Ionization (EI) mode. The results showed the ∑ PAHs range 14.91–26.0 μgm−3. Bap was the most abundant of all the compounds with a concentration of 2.6 μgm−3 with a range of 2.08–3.07 μgm−3. The Incremental Life Cancer Risk (ILCR) values of all the generator's emission sampled are higher than 10− 4 for both children and adult which indicate a high potential cancer risk from inhalation of emission from these generators while Hazard Quotient (HQ) values from all the power generating set in this study are all above 1 which indicated high associated non-carcinogenic. The study revealed the levels of PAHs associated with the emission of power generators in Nigeria.

Optimization of parameters affecting the recovery in the analysis of polycyclic aromatic hydrocarbons in natural waters by HPLC-fluorescence

To improve the recovery percentages in the analysis of PAH (polycyclic aromatic hydrocarbons) in natural waters, parameters such as standard stability, filtration, storage time and matrix effect were optimized for five PAH by HPLC-FD. For aqueous standards, with the addition of 10% acetonitrile, good linearity was found for naphthalene, acenaphthene, anthracene, pyrene, and chrysene curves up to the second day of standards preparation. In filtration, the best results were obtained using the AP10 and Nylon filters with 10% acetonitrile, with recovery ranges of 98-72% and 93-56%, respectively. In contrast, lower values were obtained with cellulose filters in a polyethylene holder without the addition of 10% acetonitrile with recoveries of 52-0%. A 23 factorial design established, for natural water, that the most important factors were: storage time for naphthalene and acenaphthene, with area losses at 48 hours and the use of organic solvent for anthracene, pyrene and chrysene, with area gain for 20 % acetonitrile. For liquid-liquid extraction in standards, recoveries of 62-45% were found in aqueous matrix without acetonitrile and 98-35% with 20% acetonitrile + 2.5% NaCl, at 24 hours of preparation.

Beyond the Drinking Water Directive: The use of reporter gene assays as an added tool for effect-based monitoring of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in drinking water sources

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) are legacy organic micropollutants (OMPs) that are sporadically detected in drinking water (DW) sources. The European Drinking Water Directive requires EU member states to monitor 5 PAHs in DW and its sources. The Dutch national regulations require 6 additional PAHs to be monitored and 7 polychlorinated biphenyls (PCBs). These indicator compounds act as representatives for large compound classes. PCBs alone comprise 209 congeners, it is evident that conventional chemical target analysis (GC-tQ-MS) alone is not sufficient to monitor these entire compound classes. This study investigated the application of reporter gene assays as effect-based methods (EBMs) to monitor PAHs and PCBs in DW sources. Herein, it was assessed what added value the bioassays can bring compared to the current approach of chemical target analysis for PCBs and PAHs. Regulated and non-regulated PAHs and PCBs were tested in four bioassays to determine the relative potency factors (RPFs) for these compounds. Non-regulated congeners were found to be active in the PAH-CALUX and anti-AR CALUX. An assessment of surface water (SW) spiked with standard mixtures containing PAHs and PCBs confirmed the predictable behavior of the PAH-CALUX. Moreover, the bioassay was able to detect AhR-mediated activity caused by non-regulated PAHs and PCBs, whereas this would have been missed by conventional chemical target analysis. Last, a field study was conducted in Dutch DW sources at six sampling moments. The PAH-CALUX detected AhR-mediated activity at all sampling moments and an ecological effect-based trigger (EBT) value was exceeded on multiple accounts. Combined application of GC-tQ-MS and the PAH-CALUX ensures compliancy with monitoring legislation and provides additional insights into potential hazards to humans and the environment.

Identification and health risk evaluation of soil contaminated by polycyclic aromatic hydrocarbons at shale gas extraction sites based on positive matrix factorization

The impact of shale gas extraction on surrounding environmental media remains unclear. In this study, the current state of contamination by polycyclic aromatic hydrocarbons (PAHs), which are high-frequency contaminants of shale gas, was investigated in the soil surrounding emerging shale gas development sites. The source analysis of PAHs was conducted in the soils of shale gas extraction sites using positive matrix factorization (PMF). The health risk assessment (HRA) was calculated for ingestion, dermal contact, and inhalation exposures, and the priority sources of PAHs in the soil were jointly identified by PMF and HRA to refine the contribution level of different individual PAHs to the carcinogenic risk. The results showed that both Sichuan and Chongqing mining site soils were contaminated to different degrees. Shale gas extraction has an impact on the surrounding soil, and the highest contributing source of PAHs in the mining site soil of Sichuan was anthropogenic activity, accounting for 31.6%, whereas that in the mining site soil of Chongqing was biomass combustion and mixed automobile combustion, accounting for 35.9%. At the two mining sites in Sichuan and Chongqing, none of the three exposure pathways (ingestion, dermal contact, and inhalation) posed a carcinogenic risk to children, whereas the dermal exposure pathway posed a carcinogenic risk to adults. Health risk assessments based on specific source assignments indicate that when managing soil pollution, the control of fossil fuel combustion and vehicular emissions should be prioritized.

Differentiated cognition of the effects of human activities on typical persistent organic pollutants and bacterioplankton community in drinking water source

Accelerated urbanization in developing countries led to a typical gradient of human activities (low, moderate and high human activities), which affected the pollution characteristics and ecological functions of aquatic environment. However, the occurrence characteristics of typical persistent organic pollutants, including organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs), and bacterioplankton associated with the gradient of human activities in drinking water sources is still lacking. Our study focused on a representative case – the upper reaches of the Dongjiang River (Pearl River Basin, China), a drinking water source characterized by a gradient of human activities. A comprehensive analysis of PAHs, OCPs and bacterioplankton in the water phase was performed using gas chromatography-mass spectrometry (GC-MS) and the Illumina platform. Moderate human activity could increase the pollution of OCPs and PAHs due to local agricultural activities. The gradient of human activities obviously influenced the bacterioplankton community composition and interaction dynamics, and low human activity resulted in low bacterioplankton diversity. Co-occurrence network analysis indicated that moderate human activity could promote a more modular organization of the bacterioplankton community. Structural equation models showed that nutrients could exert a negative influence on the composition of bacterioplankton, and this phenomenon did not change with the gradient of human activities. OCPs played a negative role in shaping bacterioplankton composition under the low and high human activities, but had a positive effect under the moderate human activity. In contrast, PAHs showed a strong positive effect on bacterioplankton composition under low and high human activities and a weak negative effect under moderate human activity. Overall, these results shed light on the occurrence characteristics of OCPs, PAHs and their ecological effects on bacterioplankton in drinking water sources along the gradient of human activities.