Identification Of Hydrocarbons Research Articles

Toxicity, mutagenicity, and source identification of polycyclic aromatic hydrocarbons in ambient atmosphere and flue gas.

This study aimed to assess the characteristics of particulate matter (PM) and polycyclic aromatic hydrocarbons (PAHs) from various stationary and mobile emission sources in Taiwan, with a focus on source apportionment and associated health risks. The northern power plant, equipped with bag filters operating at 150°C, had significantly lower FPM and CPM levels (0.44 and 0.13mg/m3, respectively) compared to the central and southern power plants, which used electrostatic precipitators operating at 250°C (FPM, 1.45-8.35mg/m3; CPM, 2.37-3.73mg/m3). Additionally, emissions from diesel vehicles under both idle and high-speed conditions exhibited higher FPM levels (3.46-4.67mg/m3) than gasoline vehicles (0.19-0.40mg/m3). In terms of PAH toxicity, diesel vehicle emissions had significantly higher BaP-TEQ (87.3ng/m3) and BaP-MEQ (25.9ng/m3) levels compared to power plants (BaP-TEQ, 5.49ng/m3; BaP-MEQ, 2.65ng/m3). The highest ambient concentrations of PM2.5, BaP-TEQ, and BaP-MEQ were recorded at traffic sites, with values of 48 ± 36µg/m3, 0.29ng/m3, and 0.11ng/m3, respectively. Differences in PAH distributions between stationary and mobile sources were influenced by factors such as pollution control technologies, combustion temperatures, and fuel types. Diesel vehicle emissions were dominated by benzo[g,h,i]perylene (BghiP), indeno[1,2,3-cd]pyrene (IND), benzo[a]pyrene (BaP), and benzo[b]fluoranthene (BbF) under idle conditions, while phenanthrene (PA), pyrene (Pyr), and BghiP were prevalent under high-speed conditions. Source apportionment conducted using principal component analysis (PCA) and positive matrix factorization (PMF) identified diesel and gasoline vehicles as the dominant contributors to atmospheric PAHs in Taiwan, accounting for 38% of the total, followed by coal-fired power plants at 35%. The highest lifetime excess cancer risk (ECR) of 2.5 × 10⁻5 was observed in traffic-dense areas, emphasizing the public health implications of vehicle emissions. The study adds credibility to the source apportionment findings, and the health risk analysis highlights variations across different regions, including traffic, urban, rural, and background zones.

Characterization of Adsorbed Hydrocarbons in Deposit Sands and Well Fracture in the Burgos Basin

Objective: The objective of this research is to determine the potential adsorption by the solids carried by the hydrocarbon production stream to the surface by characterization to identify its origin. Theoretical framework: In the natural gas producing wells of the Burgos Basin, there is the presence of solids in the production fluids, these can be from the reservoir or from fracture. The reservoir solids are created from the carbonates, sandstones and shales inside the well, the fracture solids are better known as props, they are mixed with the drilling fluid so that inside the well they act as packs in the fractures where the hydrocarbon can flow for extraction. In this Basin, horizontal hydraulic fracturing is used for the extraction of hydrocarbons, the solids present adsorb part of the hydrocarbons and are contaminated with them. Method: Sand samples from 4 wells were used, which were extracted with Soxhlet equipment to separate the organic content of the sand. Using ASTM (2003) and US EPA (1996) methods D5369-93 and 3540C-3541 as a reference. Subsequently, the hydrocarbon concentrate was fractionated using the method reported in the manual of soil analysis techniques of Fernández et al., (2006) who adapted the methods 3600C, 3610B and 3611B of the US EPA (1996). The analytical method consisted of reading the spectra of each fraction in a UV-Visible Shimadzu UV-1800 spectroscopy equipment and by FT-IR spectrophotometry, in a Nicolet iS10 equipment, with a DTGS KBr detector. The physical characterization of the sands was performed by recording the particle size using the API-RP56 standard. Finally, X-ray diffraction is used to determine the phases of the sands by the method 05LA-34080109-DRX-MP-01. Results and discussion: The amount of total hydrocarbon extracted from the sands was in a range of 2,975-0,060 gr. The identification of hydrocarbons extracted by Uv-Visible and FTIR showed functional groups of aliphatic, polycyclic and nitrogen compounds. The particle size of the sands was measured between 45-311 nm. And finally RX identified the type of sand to analyze, being well 1: reservoir sand, well2: fracture sand, well 3: fracture sand and well 4: reservoir sand. Implications of the research: This research presents a study on the classification of the type of sands that are being dragged to the surface with the hydrocarbon stream of well production. These are data that show a fact that occurs and gives the certainty of what happens at the bottom of the well. Originality/value: The analysis of the results allows decisions to be taken to prevent corrosion and plugging problems of surface equipment, which can cause explosions such as the one of September 19, 2012 in the PEMEX gas pipeline at the Km 19 Measuring Center in Reynosa, Tamps. Mexico.

Effects of several typical plastic combustion residues on gasoline

Abstract In order to solve the interference caused by polymer materials on gasoline accelerants in arson cases, the characteristics of residues after combustion of some typical plastics are studied. Comparing it to the combustion residue of gasoline, we discussed the interference in gasoline detection. The results show that the combustion products of these plastics mainly interfere with the alkanes and aromatic hydrocarbons in gasoline. Polyethylene, polystyrene, and polyvinyl chloride mainly produce C9-C16 branched-chain and straight-chain alkanes. Polystyrene and ABS resin generated C5 and C6 alkanes, also generated C1-benzene, C2 - benzene, and styrene. It mainly affects the identification of aromatic hydrocarbons in gasoline combustion residues. Understanding the types and characteristics of products in the combustion residues of these plastics can provide powerful evidence for fire investigators and criminal technicians in physical evidence identification.

A novel microwave pretreated hot air drying (PMt-HD) process for improving drying efficiency and drying quality of Z. bungeanum

The traditional drying method of Fresh Z. bungeanum has the problems of long drying time and serious loss of nutrients, which seriously restricts its efficient and high-value utilization. This study utilized a self-developed penetrating microwave infrared hot air rolling bed dryer (PMIHRBD) to optimize the drying process and compare microwave hot air drying, microwave pretreated hot-air drying (PMt-HD), and freeze drying with hot air drying (HD). The results showed that the drying time of PM10-HD was 48% shorter than that of HD, and the contents of TFC, TPC and TAC were increased by 17.6%, 23.7% and 20.7%, the yield of essential oil was increased by 59.6%, and the antioxidant activity was significantly enhanced. According to the identification of VOCs, hydrocarbons, esters and alcohols played a major role in the formation of Z. bungeanum odor, and HD samples had similar characteristics to PM10-HD samples. For flavor, PM10-HD showed a higher five-flavor richness than other drying processes. In summary, PM10-HD provided a fast and efficient drying process for harvesting high quality Z. bungeanum.

The cosmic timeline implied by the JWST reionization crisis

Context. JWST’s discovery of well-formed galaxies and supermassive black holes only a few hundred million years after the big bang, and the identification of polycyclic aromatic hydrocarbons (PAHs) at z = 6.71, seriously challenge the timeline predicted by ΛCDM. Moreover, the implied bright UV-irradiation of the early Universe suggests a reionization history much too short to comply with the observed evolution of the hydrogen ionization fraction, xHII(z). Aims. A recent analysis of reionization after JWST concludes that the ΛCDM timeline simply cannot accommodate the combined JWST-Planck observations even if exotic fixes are introduced to modify the standard reionization model. In this paper, we argue that this so-called ‘photon budget crisis’ is more likely due to flaws in the cosmological model itself. We aim to reanalyze the data in the context of established astrophysics with Rh = ct as the background cosmology, an approach that has already been shown to mitigate the tension created by the too-early appearance of galaxies, quasars and PAHs. Methods. We employ the standard reionization model using the JWST-measured UV luminosity function in the early Universe and the timeline and physical conditions in both ΛCDM and Rh = ct. The former has already been fully probed and discussed elsewhere, and we here merely redo the calculation to ensure consistency with their pioneering work. We then contrast the predicted reionization histories in these two scenarios and compare them with the data. Results. We confirm that the reionization history predicted by ΛCDM is in significant tension with the observations, and demonstrate that the latter are instead in excellent agreement with the Rh = ct timeline. Conclusions. Together, the four anomalies uncovered by JWST, including the newly discovered reionization crisis discussed in this paper, provide strong evidence against the timeline predicted by ΛCDM and in favor of the evolutionary history in Rh = ct.

Strong observational support for the [formula omitted] timeline in the early universe

JWST’s recent discovery of well-formed galaxies and supermassive black holes only a few hundred Myr after the big bang seriously challenges the timeline predicted by ΛCDM. Now, the latest identification of polycyclic aromatic hydrocarbons (PAHs) at z=6.71, together with these earlier inconsistencies, makes the time compression problem in this model quite overwhelming. We consider the timeline associated with the formation and growth of PAH grains based on current astrophysical models and argue that their appearance at z=6.71 favors the structure formation history in Rh=ct rather than that of Planck-ΛCDM. We estimate the time at which they must have started growing in each case, and then trace their history through various critical events, such as the end of the ‘dark ages’, the beginning of Pop III star formation, and the onset of reionization. Together, these three distinct discoveries by JWST, viz. high-z galaxies, high-z quasars and the surprisingly early appearance of PAHs, all paint a fully consistent picture in which the timeline in ΛCDM is overly compressed at z≳6, while strongly supporting the expansion history in the early Universe predicted by Rh=ct.

Examination and Chemical Analysis by GC-MS of Syzygium Cumini Extract(Bark)

The investigation focused on the analysis of the hexane extract obtained from the bark of Syzygium cumini originating from India. Through chromatographic techniques, both traditional column chromatography and gas chromatography mass spectrometry (GC-MS), the oily fraction of the bark was examined, leading to the identification of numerous ester and hydrocarbon compounds. While the initial hexane eluate yielded waxy substances, which were challenging to separate through column chromatography due to their limited quantity, GC-MS analysis facilitated the identification of 39 compounds. These compounds were matched with existing literature through comparisons of retention times, Kovats indexes, and interpretation of mass spectra. Many of these identified compounds find applications across industries such as perfumery, flavoring, deodorants, antiseptics, and pharmaceuticals. This study aimed to elucidate the chemical composition of the hexane extract from S. cumini bark, particularly focusing on the identification of hydrocarbons and esters. Key words: Syzygium cumini (bark), esters, hydrocarbons, signals, peak gas chromatography -mass spectrometry

Recovery of enhanced gasoline-range fuel from catalytic pyrolysis of waste polypropylene: Effect of heating rate, temperature, and catalyst on reaction kinetics, products yield, and compositions

The present study focuses on the recovery of superior-quality pyrolytic oil (PO) from the pyrolysis of waste polypropylene (WPP). The optimum heating rate, temperature and catalyst dosing were identified from experimental pyrolysis runs in a batch pyrolyzer. The thermal pyrolysis at 550 0C at 20 0C/min produced 83.5% PO, the maximum yield. The activated zeolite and kaolin catalyst prepared from the low-cost natural zeolite and kaolin clay were used for catalytic pyrolysis. The specific surface areas were determined to be 16.45 and 13.62 m2/g, with pore sizes 18.5 and 20.6 nm for zeolite and kaolin, respectively. The catalytic dosing of 12% zeolite and 10% kaolin was found to be the most optimum towards maximum PO yield. The FTIR and GC-MS analysis provided the qualitative and quantitative identification of various hydrocarbons (HCs) in PO. The HCs were classified as diesel-range (DHC) and gasoline-range (GHC) based on the carbon numbers. The catalyst zeolite and kaolin enhanced the yield of GHC components in PO by 6.45 and 7.7%, respectively. The catalyst considerably reduced the density, viscosity and improved the flash and pour points of PO. Finally, the reaction mechanism and reaction kinetics of pyrolysis reaction were determined from thermogravimetric data obtained under identical reaction conditions as in batch pyrolyzer. A shift of the reaction mechanism with lower activation energy was identified in the presence of a catalyst. The detailed characterization of gaseous products and solid residues were also performed.

Source identification of polycyclic aromatic hydrocarbons (PAHs) in soils around crude oil contaminated area in Ohaji/Egbema, Imo State

ABSTRACT This study aims to determine the source of polycyclic aromatic hydrocarbons (PAHs) in the soils surrounding an area in Ohaji/Egbema, Imo State, that has been contaminated by crude oil. Soil samples were collected in the study area using a soil auger at a depth of 0–20 cm at three sampling locations (sample A, sample B, and sample C) in the Mmahu community in Ohaji/Egbema. In each of the sampling locations, twenty sub-samples were collected from twenty sampling points and pooled together to form representative samples for each of the sampling locations. Prior to GC-MS analysis, the composite samples were air-dried, sieved through a 2-mm mesh, and then kept in pet bottles that had been previously cleaned. The GC-MS investigations were carried out using a Shimadzu Model 2010 GC-MS (Shimadzu, Japan) fitted with an HP-5 MS fused silica column. This was used to quantify the 16 USEPA priority PAHs in the studied soils. The sum of the 16 USEPA priority PAHs in the sample locations ranged from 0.0192 mg/kg in the control sample to 10.73 mg/kg in sample A. Compared to high molecular weight PAHs (4–6 rings), the total concentration of low molecular weight PAHs (2–3 rings) was found to be substantially greater. According to the PAH molecular diagnostic ratio, all sampling points had low to high molecular mass ratios >1, which suggests that the origin of the PAH contamination was petrogenic. The petrogenic source of contamination was attributed to oil spillage around the study area. The knowledge of source identification of PAHs in soils helps in the determination of the most appropriate remediation strategy in order to prevent further contamination and minimise the risks to human health and the environment.

Day–night variation, size distribution, source identification, and health risk of polycyclic aromatic hydrocarbons in particulate matter in Ulsan, South Korea

Particulate matter (PM) in 11 different sizes was collected at a semi-rural site in Ulsan, a multi-industrial city in South Korea, over one year from 2019 to 2020 to investigate the temporal patterns in size distribution and potential sources of polycyclic aromatic hydrocarbons (PAHs). The mean concentration of Σ21 PAHs was higher in winter (0.29 and 0.45 ng/m3 for coarse and fine PM, respectively) than in summer (0.06 and 0.07 ng/m3). Although there was no statistically significant difference between day and night for the concentration of individual PAHs in both coarse and fine PM, the concentrations were generally higher during the day than at night. During the day, Σ21 PAHs had two distinct peaks (0.056–0.10 μm and 3.20–5.60 μm) in winter, but they tended to partition to larger particles (1.00–1.80 μm and >18.0 μm) in summer. This result suggests that the volatilization of PAHs in smaller particles was enhanced by high-temperature conditions in summer, followed by their condensation onto larger particles. At night, Σ21 PAH peaks were mainly around the size of 0.7 μm (droplet mode), suggesting the importance of heterogeneous-aqueous reactions. The results of the conditional bivariate probability function and concentration-weighted trajectory indicate that the high concentrations of PAHs in summer and winter were more affected by local pollution and long-range atmospheric transport, respectively. The results of the health risk assessment demonstrate that PAHs in fine PM contributed significantly to cancer risk compared to those in coarse PM. In conclusion, investigating the size distribution of PAHs in particles is necessary to understand their environmental behaviors and evaluate potential health risks.

Seasonal variation, source identification, and health risk assessment of atmospheric polycyclic aromatic hydrocarbons (PAHs) in Ulsan, South Korea

Gaseous and particulate 21 PAHs were monitored at a residential site in Ulsan, South Korea, over three seasons (December 2013–August 2014). The mean concentrations of Σ21 PAHs were highest in winter (16.2 ± 8.2 ng/m3), followed by spring (8.37 ± 4.53 ng/m3) and summer (6.23 ± 2.53 ng/m3). The mean gaseous concentration of Σ21 PAHs (7.39 ± 4.39 ng/m3) was 2.7 times higher than that of particulate PAHs (2.70 ± 3.38 ng/m3). To identify the sources of PAHs (both types of sources and their areas), diagnostic ratios, principal component analysis, and concentration-weighted trajectory (CWT) were used. The results showed that pyrogenic sources (e.g., coal combustion) were the primary emission sources of PAHs in winter and spring. In summer, the influence of both coal and heavy oil combustion was dominant, suggesting that PAHs could be transported from industrial areas of Ulsan (e.g., petrochemical and nonferrous industrial complexes) by seasonal winds. Regarding emission source areas, the CWT analysis revealed that in winter and spring, PAHs in Ulsan could be attributed to emissions from regional areas, e.g., China and North Korea. The PAH concentrations were also used to assess the health risks associated with the inhalation of these compounds for adults aged 18–70. The results showed that the cancer risks from Σ19 PAHs and Σ13 PAHs did not exceed the guideline set by the US EPA (10−6), indicating no cancer risks for this target group. However, it is worth noting that certain PAHs, which are not listed as priority PAHs by the US EPA, make significant contributions to the benzo[a]pyrene equivalent and the associated cancer risks. Therefore, it is necessary to investigate not only the priority PAHs but also other PAH species to fully evaluate their effect on human health.

EXPERIMENTAL RESEARCH ON THE PRESENCE OF HYDROCARBONS IN THE SOIL OF THE NORTH CONSTANTA ZONE

This experimental research engages in an investigation of sediment quality, with a focus on the identification and quantification of hydrocarbons and other contaminants that may adversely affect the health of the marine and terrestrial ecosystem in the Black Sea region. The purpose of this experimental research is to contribute to the understanding of the dynamics of hydrocarbon pollution and its impact on the marine and terrestrial environment in the Black Sea area.

Impact of Atmospheric Conditions and Source Identification of Gaseous Polycyclic Aromatic Hydrocarbons (PAHs) during a Smoke Haze Period in Upper Southeast Asia.

Gaseous polycyclic aromatic hydrocarbons were measured in northern Thailand. No previous studies have provided data on gaseous PAHs until now, so this study determined the gaseous PAHs during two sampling periods for comparison, and then they were used to assess the correlation with meteorological conditions, other pollutants, and their sources. The total concentrations of 8-PAHs (i.e., NAP, ACY, ACE, FLU, PHE, ANT, FLA, and PYR) were 125 ± 22 ng m-3 and 111 ± 21 ng m-3, with NAP being the most pronounced at 67 ± 18 ng m-3 and 56 ± 17 ng m-3, for morning and afternoon, respectively. High temperatures increase the concentrations of four-ring PAHs, whereas humidity and pressure increase the concentrations of two- and three-ring PAHs. Moreover, gaseous PAHs were estimated to contain more toxic derivatives such as nitro-PAH, which ranged from 0.02 ng m-3 (8-Nitrofluoranthene) to 10.46 ng m-3 (1-Nitronaphthalene). Therefore, they could be one of the causes of local people's health problems that have not been reported previously. Strong correlations of gaseous PAHs with ozone indicated that photochemical oxidation influenced four-ring PAHs. According to the Pearson correlation, diagnostic ratios, and principal component analysis, mixed sources including coal combustion, biomass burning, and vehicle emissions were the main sources of these pollutants.

Distribution and source identification of polycyclic aromatic hydrocarbons (PAHs) with PCA-MLR and PMF methods in the topsoil of Chengdu at SW, China

In spite of extensive studies on the features of polycyclic aromatic hydrocarbons (PAHs) as typical persistent organic pollutants (POPs) in cities, lack of understanding on the distribution and source characteristics of PAHs in big city with basin climate that can easily accelerate the pollution. Therefore, we sampled and analyzed PAHs from forty-five topsoil samples evenly distributed in Chengdu and the data shows that: (1) concentrations of ∑16PAHs in the study area ranged from 88.56 to 4448.34 ng/g, with a mean value of 739.07 ng/g, which is a lower level compared to similar cities, the distribution and proportion of LMW-PAHs show that the migration of pollution is blocked by the topography of the basin; (2) principal component analysis-multiple linear regression (PCA-MLR) and positive matrix factorization (PMF) indicated that combustion of fossil fuels and biomass is the most important source of PAHs in Chengdu; (3) the toxic equivalency factors of benzo[a]pyrene indicated a low risk of ∑16PAHs in all areas in Chengdu; (4) the inherited lifetime carcinogenic risk (ILCR) showed a relatively low level of potential risk in the region, while female inhabitants in several regions seem to suffer from higher health risks. Overall, our case study of PAHs in the topsoil at Chengdu city at SW China indicates that the PCA-MLR analysis is useful to identify the source of PAHs in the urban region with complicated pollution source.

An Approach to Define and Quantify Porosity System in Heterogeneous Carbonate Reservoirs through Textural Analysis using High-Resolution Resistivity Image in the Bassein Formation of Mumbai Offshore Basin, India

Summary In evaluating the porosity system of the Bassein formation, high-resolution resistivity image (FMI) data have been used. Major features observed from the FMI data are the presence of low-angle fractures and solution channels of varying length and thickness. Against the layers with very-low-density neutron porosity, solution channels are seen as conductive features. These mud-filled solution channels can actively participate in production. Being very small-scale features, these types of porosities are not identifiable from conventional log data. To define and quantify porosity types such as vugs, solution channel, and matrix porosity, the resistivity image data are processed and image-based porosity is calculated. A core thin-section study is carried out and is used for calibration of the image-derived porosity system. Using resistivity image data, we have computed porosity types, for example, vugs, connected matrix and resistive, and their contribution to total porosity. Identification of hydrocarbons in reservoir layers with their porosity contribution (porosity partitioning) gives better insight into hydrocarbon production in these low-porosity layers which are producing after acid job.

Characterization of scrubber water discharges from ships using comprehensive suspect screening strategies based on GC-APCI-HRMS

An extended suspect screening approach for the comprehensive chemical characterization of scrubber discharge waters from exhaust gas cleaning systems (EGCSs), used to reduce atmospheric shipping emissions of sulphur oxides, was developed. The suspect screening was based on gas chromatography coupled with high-resolution mass spectrometry (GC-HRMS) and focused on the identification of polycyclic aromatic hydrocarbons (PAHs) and their alkylated derivatives (alkyl-PAHs), which are among the most frequent and potentially toxic organic contaminants detected in these matrices. Although alkyl-PAHs can be even more abundant than parent compounds, information regarding their occurrence in scrubber waters is scarce. For compound identification, an in-house compound database was built, with 26 suspect groups, including 25 parent PAHs and 23 alkyl-PAH homologues. With this approach, 7 PAHs and 12 clusters of alkyl-PAHs were tentatively identified, whose occurrence was finally confirmed by target analysis using GC coupled with tandem mass spectrometry (GC-MS/MS). Finally, a retrospective analysis was performed to identify other relevant (poly)cyclic aromatic compounds (PACs) of potential concern in scrubber waters. According to it, 18 suspect groups were tentatively identified, including biphenyls, dibenzofurans, dibenzothiophenes and oxygenated PAHs derivatives. All these compounds could be used as relevant markers of scrubber water contamination in heavy traffic marine areas and be considered as potential stressors when evaluating scrubber water toxicity.

Spatial distribution, source identification and flux estimation of polycyclic aromatic hydrocarbons and organochlorine pesticides in basins of the Eastern Indian Ocean

Although polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) have been recorded worldwide, information on their presence in the Eastern Indian Ocean (EIO), especially south of 10°S, remains limited. We investigated the distribution and depositional fluxes of PAHs and OCPs, and the major sources and ecological risks of PAHs in EIO surface sediments from the Central Indian Ocean (CIOB) and Wharton Basin (WB). The concentration of Σ18 PAHs and ∑10 OCPs had an average value (± SD) of 138.4 ± 52.34 and 0.8 ± 0.20 ng g−1, respectively. PAHs may mainly affected by traffic emission and biomass and wood combustion. Persistent organic pollutant accumulation rate (PAR) and depositional flux (DF) values showed that abundant PAHs might lost during top-down transport. The low trans- chordane (CHL)/cis-CHL ratio and PAR of OCPs may indicated few OCPs were inputted into the EIO recently. The results of binary isotope mixing modeling indicate the predominance of marine organic matter (MOM) in total organic carbon (TOC) of sediments. Fluoranthene (Flour) and pyrene (Py) might have potential biological effects in the EIO. The study provided background values for PAHs and OCPs in the Indian Ocean, and preliminarily revealed the fate of POPs in the open oceans.

Temporal and spatial distributions, source identification, and health risk assessment of polycyclic aromatic hydrocarbons in PM2.5 from 2016 to 2021 in Shenzhen, China.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants in the atmosphere that have drawn intense attention due to their carcinogenicity and mutagenicity. In this work, 1424 air samples were collected between January 2016 and December 2021 in three areas of Shenzhen, China to determine the concentrations of PM2.5 and PAHs and their spatiotemporal variation. Human health risks due to the daily intake and uptake of PAHs and the resulting incremental lifetime cancer risk (ILCR) were also evaluated. PAHs were detected frequently in the samples at concentrations between 0.28 and 32.7ng/m3 (median: 1.04ng/m3). PM2.5 and PAH concentrations decreased from 2016 to 2021, and the Yantian area had lower median concentrations of PM2.5 (23.0μg/m3) and PAHs (0.02ng/m3) than the Longgang and Nanshan areas. The concentrations of PM2.5 and PAHs were significantly higher in winter than in summer. Analysis of diagnostic ratios indicated that petroleum combustion was the dominant source of airborne PAHs in Shenzhen. The estimated daily intake (EDI) and uptake (EDU) of PAHs by local residents decreased gradually with increasing age, indicating that infants are at particular risk of PAH exposure. However, the incremental lifetime cancer risks (ILCRs) were below the threshold value of 10-6, indicating that inhalation exposure to PAHs posed a negligible carcinogenic risk to Shenzhen residents. While promising, these results may underestimate actual PAH exposure levels, so further analysis of health risks due to PAHs in Shenzhen is needed.

Application of solid-phase microextraction/gas chromatography method for extraction, identification, and comparison of polycyclic aromatic hydrocarbons from industrial and traditional edible oils

Polycyclic aromatic hydrocarbons (PAHs) are a large group of cyclic aromatic hydrocarbons that have been listed as hazardous substances by the US Environmental Protection Agency and the World Health Organization. Edible oils are one of the important food sources of PAHs, which are created during the processes of drying oil seeds or refining edible oils. The aim of this research was to evaluate PAHs (Naphthalene, Fluorene, Phenanthrene, Anthracene, Fluoranthene, Pyrene, Benzo[a]pyrene, and Benz[a]anthracene) in industrially produced edible oils (sunflower, corn, canola, olive and sesame) and traditional oils (press) (yellow animal oil, olive, sesame and sunflower oil) in Iran, and these samples were randomly prepared, sampled and analyzed from the stores of West Azarbaijan province (Urmia, Iran). PAHs were extracted from oily samples by solid phase microextraction method and analyzed by Gas Chromatography-FID. The highest concentration of PAHs (μg/L) were related to different oils as the follow: naphthalene (4.61 in animal yellow oil), Fluorene (0.75 in canola), Phenanthrene (0.21 in canola), Anthracene (0.01 in animal yellow oil), Fluoranthene (2.53 in canola), pyrene (2.67 in canola), Benz[a]anthracene (0.44 in corn) and Benzo[a]pyrene (0.45 in canola). The concentration of Benzo[a]pyrene was compared with the European Union (EU) limit value (μ>2) using one-sample t-test. In industrial canola oil, with an average concentration of 2.593μg/kg, Benzo[a]pyrene was higher than the European Union standard of 2μg/kg. Some of the studied aromatic hydrocarbons could not be detected in some oils.

Sources identification and distribution of aliphatic and aromatic hydrocarbons in coastal sediments of Arica Bay – Chile

ABSTRACT This study assesses the first approach regarding the origin, level of contamination, and spatial and vertical distribution of aliphatic and polycyclic aromatic hydrocarbons in coastal sediments of Arica’s Bay. Twenty-seven aliphatic hydrocarbons (AHs) and eighteen polycyclic aromatic hydrocarbons (PAHs) were studied at three depths in sediment cores collected from six locations in the coastal bay. The spatial distribution pattern of the molecular composition of aliphatic and aromatic hydrocarbons is consistent with the directions of the ocean currents from the northeast to the southwest. PAHs are mainly correlated with anthropogenic input sources to the bay. The total aliphatic hydrocarbons showed a wide concentration range from 112.07 to 2,382.43 ng·g−1 dry wt. while total PAHs ranged from 8.01 to 85.40 ng·g−1 dry wt. The vertical distribution of the total AHs shows a tendency to concentrate between 10–20 and 20–30 cm depth. Specific diagnostic characterisation ratios suggest that the bay sediments mainly consist of a mixture of autochthonous, predominantly marine sources composed of marine bacteria (n-C16, n-C18, and C20) and terrestrial plant derivatives (n-C29 and n-C31) and with a contribution of petrogenic hydrocarbons masked by biogenic hydrocarbons. The vertical distribution of the total polycyclic aromatic hydrocarbons is dominated by low molecular weight (LMW) PAHs of two and three rings, such as fluoranthene (FLT), phenanthrene (PHE), pyrene (PYR), and the highest concentrations are found between 10 and 20 cm depth of the sediment column. The PAH diagnostic ratios revealed a mixture of pyrogenic hydrocarbons (biomass and coal combustion) with petrogenic compounds from the Port of Arica and its neighbouring areas. According to the guidelines of UNEP for AHs and PAHs categorisation, the bay’s sediments may be classified from harmless to harmful due to AHs composition and low PAHs pollution.