Polycylic Aromatic Hydrocarbons Research Articles

The IR Compactness of Dusty Galaxies Sets Star Formation and Dust Properties at z ∼ 0–2

The surface densities of gas, dust, and stars provide a window into the physics of star formation that, until the advent of high-resolution far-IR/submillimeter observations, has been historically difficult to assess among dusty galaxies. To study the link between IR surface densities and dust properties, we leverage the Atacama Large Millimetre/Submillimetre Array archive to measure the extent of cold dust emission in 15 z ∼ 2 IR-selected galaxies selected on the basis of having available mid-IR spectroscopy from Spitzer. We use the mid-IR spectra to constrain the relative balance between dust heating from star formation and active galactic nuclei (AGNs), and to measure emission from polycylic aromatic hydrocarbons (PAHs), small dust grains that play a key role in the photoelectric heating of gas. In general, we find that dust-obscured star formation at high IR surface densities exhibits similar properties at low and high redshift, namely, local luminous IR galaxies (LIRGs) have comparable PAH luminosity to total dust mass ratios as high-z galaxies, and star formation at z ∼ 0–2 is more efficient at high IR surface densities despite the fact that our sample of high-z galaxies is closer to the main sequence than local LIRGs. High star formation efficiencies are coincident with a decline in the PAH-to-IR luminosity ratio reminiscent of the deficit observed in far-IR fine-structure lines. Changes in the gas and dust conditions arising from high star formation surface densities might help drive the star formation efficiency up. This could help explain the high efficiencies needed to reconcile star formation and gas volume densities in dusty galaxies at cosmic noon.

How has COVID-19 medical face mask altered the dynamics of pollutants from incinerated wastes?

The COVID-19 pandemic caused the disposal of an unprecedentedly huge amount of medical face masks, part of which were burnt or incinerated alongside other solid wastes. In this study, we investigated how the presence of the common medical masks may have altered the nature and quantities of pollutants normally associated with the burning of solid wastes. It was found that the addition of increasing amount of face masks (at 1.82%, 3.71% and 5.67% by mass) to solid wastes had no influence on the types of pyrogenic PAHs (polycylic aromatic hydrocarbons) present in the combustion residues. However, presence of the masks at 5.67% led to a drastic reduction in PAHs concentration (∑16PAHs = 0.83 ± 0.047 mg/kg, compared to the concentration measured when the face masks were not incorporated, ∑16PAHs = 4.65 ± 0.23 mg/kg). Mixtures containing 3.71% and 5.67% of masks caused increases in total suspended particulate matter (TPM) by 475.6% and 796.4%, respectively. Presence of the masks at 3.71% and 5.67% also led to emission of poisonous carbon (II) oxide gas above the environmental safe limit of 29 mg/m3. Furthermore, addition of face masks led to higher concentrations of highly toxic metals (As, Cd, Pb and Cu) in the combustion residues of the solid wastes. Overall, this study demonstrates that medical face masks are better incinerated separately, rather than combining them with regular solid wastes. The findings are invaluable for ongoing management of used face masks in health facilities around the world, and in event of any future global or regional pandemic.

Excitation energies of polycylic aromatic hydrocarbons by double-hybrid functionals: Assessing the PBE0-DH and PBE-QIDH models and their range-separated versions.

A family of non-empirical double-hybrid (DH) density functionals, such as Perdew-Burke-Ernzerhof (PBE)0-DH, PBE-QIDH, and their range-separated exchange (RSX) versions RSX-0DH and RSX-QIDH, all using Perdew-Burke-Ernzerhof(PBE) exchange and correlationfunctionals, is applied here to calculate the excitation energies for increasingly longer linear and cyclic acenes as part of their intense benchmarking for excited states of all types. The energies for the two lowest-lying singlet 1La and 1Lb states of linear oligoacenes as well as the triplet 3La and 3Lb states, are calculated and compared with experimental results. These functionals clearly outperform the results obtained from hybrid functionals and favorably compare with other double-hybrid expressions also tested here, such as B2-PLYP, B2GP-PLYP, ωB2-PLYP, and ωB2GP-PLYP. The study is complemented by the computation of adiabatic S0-T1 singlet-triplet energy difference for linear acenes as well as the extension of the study to strained cyclic oligomers, showing how the family of non-empirical expressions robustly leads to competitive results.

Polycyclic Aromatic Hydrocarbon (PAH) Levels in Clarias gariepinus Dried with Traditional and Modern Smoking Kiln

The study compared the polycyclic aromatic hydrocarbon content of Clarias gariepinus dried by traditional and modern smoking methods at the teaching and research farm of the Department of Fisheries and Aquaculture Management, Nnamdi Azikiwe University Awka, Nigeria. The traditional method involved using firewood while the modern method involved using charcoal charged smoking kiln to dry the fish. Laboratory analysis of 16 polycylic aromatic hydrocarbons was done by gas chromatography. The traditionally smoked fish contained significantly higher (P<0.05) concentrations of fluorene (0.63µg/ kg), anthracene (9.02µ/kg), Phenanthrene (3.34 µg/kg), pyrene (55.05 µg/kg) and benzo (a) anthracene (17.55 µg/kg) than the modern smoked fish. The average PAH concentration in traditionally smoked fish (14.568 µg/kg) was significantly higher (P<0.05) than the average PAH concentration in the modern smoked fish (4.404 µg/kg). However the maximum acceptable concentration for most PAHs was not exceeded in the smoked fish samples, therefore fish studied was declared wholesome for human consumption. Recommendation of efforts geared towards processing fish with methods using charcoal smoke instead of wood smoke was upheld in order to reduce the levels of PAHs in smoke dried fish.

Physiological Responses of the Bivalves Mytilus galloprovincialis and Ruditapes decussatus Following Exposure to Phenanthrene: Toxicokinetics, Dynamics and Biomarkers Study.

The aim of the current study was to assess the multifaceted effects of the polycylic aromatic hydrocarbon phenanthrene, mainly used in the colouring, explosive, and pharmaceutical industries, on the physiology of two bivalve species with economic value as seafood, namely, the Mediterranean mussel Mytilus galloprovincyalis and the European clam Ruditapes decussatus. The current study assessed how the phenanthrene affected several biomarkers and biometric endpoints in both bivalves, based on an in vivo experiment in silico approach. The bivalves were exposed during four time slots (i.e., 7, 15, 21, and 28 days) to two concentrations of phenanthrene in water (50 µg/L and 100 µg/L). For the clam R. decussatus, an additional contamination of sediment was applied due their typical benthic lifestyle (50 µg/kg and 100 µg/kg). The phenanthrene significantly reduced the ability of bivalves to tolerate desiccation and their Median Lethal Time, and also inhibited the activity of the enzyme acetylcholinesterase in a time-dependent manner. The activity of catalase indicated that bivalves also experienced oxidative stress during the first 21 days of the experiment. The significant decline in catalase activity observed during the last week of the experiment for the mussel M. galloprovincyalis supported a depletion of enzymes caused by the phenanthrene. The phenanthrene has also toxicokinetic and toxicodynamic properties, as assessed by the in silico approach. Overall, the results obtained suggest that the bivalves Ruditapes decussatus and M. galloprovincyalis can be used as a sentinel species in monitoring studies to assess the environmental impact of phenanthene in marine ecosystems. The significance of our findings is based on the fact that in ecotoxicology, little is known about the chronic effects, the simultaneous use of multiple species as bioindicators, and the interactions molecular modelling.

Isolation and Identification of Anthracene Utilizing Proteus vulgaris from Oil Spill Contaminated Soil at NNPC Depot Kano State Nigeria

Microbial biodegradation of polycyclic aromatic hydrocarbons (PAHs) like Anthracene, represent an efficient, time, and cost-effective way for bioremediation of the polluted environment. This study was aimed at isolating, identifying and characterizing bacteria with potential to degrade and utilize anthracene as a sole carbon source. A bacteria was isolated from oil spilled contaminated site located in Kano, using an enrichment method on mineral salt media (MSM) following serial dilution (10-1-10-6). Characterization was done by studying the effects of temperature and pH on mineral salt media (MSM) containing anthracene. The isolate was then identified morphologically, biochemically and molecularly based on 16S rRNA partial gene sequence analysis. The morphological and microscopic examination of the isolate from this research shows that the isolate was creamy in color, motile, gram negative, short rod and non-spore forming respectively. The biochemical test of the isolate was found to be positive for these parameters (methyl red, catalase, motility, indole and urease) and negative for (citrate and oxidase). The 16S rRNA sequence and Phylogenetic analysis using neighbor joining tree and 1000 boos trap revealed that, the isolate was closely related (on the same clade) to Proteus vulgaris with accession number MW766369. Characterization was done by studying the effects of temperature and pH. The isolated bacterium was optimal at a temperature of 35ºC and pH 7.5. This isolate is a promising strain that could be used in bioremediation of polycylic aromatic hydrocarbons polluted environment.

Concentrations and Risk of Polycyclic Aromatic Hydrocarbons (PAHs) in Oil and Tomato-Based Sauces from Selected Brands of Canned Fish Consumed in Nigeria

The concentrations of the 16 US EPA polycylic aromatic hydrocarbons (PAHs) were investigated in oil and tomato-based sauces from some popular brands of canned fish products (mackerel, sardine and tuna) commonly consumed in Nigeria. The aim of the study was to provide data on the PAH compositions and likely risks arising from ingestion of these oil and tomato-based sauces. The PAH content in these oils and sauces was determined by gas chromatography-mass spectrometry. The concentrations of PAHs in these samples varied from 101 to 698 µg kg−1 for tomato sauces from canned mackerel, 168 to 733 µg kg−1 for oils from canned sardines, and 204 to 459 µg kg−1 for oils from canned tuna. The benzo(a)pyrene and PAH4 (benzo(a)anthracene [BaA] + Chrysene [Chry] + benzo(a)pyrene [BaP] + benzo(b)fluoranthene [BbF]) concentrations in the majority of the samples exceeded their respective limits as specified by the European Union regulations. The benzo(a)pyrene carcinogenic (BaPTEQ) and mutagenic (BaPMEQ) potency values ranged from not detected (nd) to 288 µg kg−1 and nd-217 µg kg−1 respectively. The probable cancer risk arising from consumption of oils and tomato sauces from these canned fish products were above the acceptable risk value of 10−6, which indicates that there is a considerable risk associated with the consumption of sauces and oils from these canned fish products.

Sources and pollution path identification of PAHs in karst aquifers: an example from Liulin karst water system, northern China

Karst water, with constituting major sources for water supply worldwide, is vulnerable and prone to be polluted. In this study, it is reported that karst water polycylic aromatic hydrocarbons (PAHs) pollution is caused by the infiltration of surface runoff in the bared carbonate areas, which is of universal significance for the protection of groundwater resources in karst region. Hydro-geochemistry, stable isotopes (δD, δ18O and 87Sr/86Sr) and characteristic ratio method were conducted together to illustrate the concentration, distribution, sources and pollution path of polycyclic aromatic hydrocarbons in groundwater in the Liulin karst water system of northern China. The results showed that total concentration of polycyclic aromatic hydrocarbons ranged from 39.25 to 16,830 ng/L in groundwater, with Naphthalene being the dominant component, and the median value increased gradually along the flow path. The highest polycyclic aromatic hydrocarbons concentrations in karst water were mainly observed in the coal mining and the discharge areas. Based on the characteristic ratios, the polycyclic aromatic hydrocarbons in the study area mainly come from local incomplete combustion of woods, fossil fuels, coal and liquid fuels. The slight shift of δD and δ18O and moderate 87Sr/86Sr ratios suggest that the polycyclic aromatic hydrocarbons in karst water is mainly polluted by surface runoff during rain events in the bared karst region. The leakage of river water may partly contribute to the polycyclic aromatic hydrocarbons in some karst water, which normally located close to the karst water - river water mixing line. This study provides a new technical method for tracing the sources and identifying the pollution paths of organic pollution in a karst water system.

Distribusi Spasial dan Analisis Risiko Ekologi Senyawa Polisiklik Aromatik Hidrokarbon (PAH) di Perairan Cilincing – Teluk Jakarta

<p><strong>Spatial distribution and ecological risk analysis of Polycyclic Aromatic Hydrocarbons in Cilincing waters – Jakarta Bay</strong>. Within a few decades, Polycylic Aromatic Hydrocarbon (PAH) pollution increases in marine environment in seawater, sediment, and organism. Generally, this pollutant comes from industrial and household waste, agricultural runoff, shipping activities, and input from atmospheric deposition. This study aims to determine the concentration, spasial distribution, source, and ecological risks analysis in Cilincing waters, Jakarta Bay. Samples of seawater, total suspended solid (TSS), and sediment were collected on April 2019 at ten stations. Samples were stored at 4<sup>o</sup>C afterward analyzed in the laboratory. All samples were then extracted with dichloromethane and n-hexane solvents. They were then fractionated with n-pentane: dichloromethane, and the results were injected into a Gas Chromatography-Mass Spectrometer (GCMS) instrument. The highest concentration of PAH compounds in seawater, TSS, and sediment samples are 208.74 ng.L<sup>1-</sup>; 5.90 ng.L<sup>1-</sup>; and 63.63 ng.g<sup>1-</sup> dry weight (dw) respectively. The highest spatial distribution of PAHs in seawater and TSS samples were detected in station 1, 9, and 10, whilst in sediment sample was in station 5 and 6. The ratio of ∑Low Molecular Weight (LMW)/∑High Molecular Weight (HMW), Fluo/(Fluo + Pyr), and An/(An + Phe) revealed that the source of PAH pollution dominated from pyrogenic, especially petroleum combustion from vehicle engine. The total concentration of ∑PAH-9 in sediment was 31.21 ng.g<sup>1-</sup>dw which was lower than Effects Range Low (ERL), Effects Range Median (ERM), Threshold Effect Levels (TEL), and Probably Effect Levels (PEL) values referred to sediment quality guideline. These results were indicated low potential of causing an adverse biological effect.</p>

Highly radiating hydrogen flames: Effect of toluene concentration and phase

Adapting hydrogen as a carbon-free fuel for industrial applications requires new, innovative approaches, especially when radiant heat transfer is required. One possible option is to dope hydrogen with bio-oils, containing aromatics that help produce highly sooting flames. This study investigates the potential doping effects of toluene on a hydrogen-nitrogen (1:1 vol) flames. Flames with 1–5% toluene, based on the mole concentration of hydrogen, are measured using a combination of techniques including: still photographs and laser-based techniques. Toluene was mixed with hydrogen-nitrogen fuel mixture as either a vapour carried by nitrogen, or as a dilute spray. Spray flames are found to produce substantially more polycylic aromatic hydrocarbons, with significantly more soot near the nozzle exit plane, than the prevaporised flames. Increasing the dopant concentration from 1 to 3% of the hydrogen has a marked effect on soot loading in the flame, although the further increasing the dopant concentration to 5% has a far smaller effect on the soot produced in the flame. Simulations of laminar flames using detailed chemical kinetics support the above findings and reveal details of the competition between soot precursor formation and hydrocarbon oxidation. Correlations of formation rates are non-linear with toluene concentration in cases where toluene represents less than 10% of the fuel, although expected linear relationships are noted beyond this regime up to 1:1 toluene/hydrogen blends. The study provides insight and explanation into effects of toluene as a dopant, comparison between flame doping in gaseous or liquid phases and suggests that flame doping and blending should be treated as different regimes for their global effect on flame sooting characteristics.

Urinary 1-Hydroxypyrene levels among children with asthma in Chennai, South India

Aim: To explore the potential relationship between exposure to Polycyclic Aromatic Hydrocarbons (PAHs) and asthma exacerbation among children and also to explore the potential exposure sources of PAHs at the household level. Methods: Case-control study was conducted at a tertiary care hospital in Chennai among 60 participants after obtaining approval from the Institutional Ethics Committee. The study was conducted from March till May 2018. Informed consent was obtained from the participants. The participants were included based on their clinical diagnosis of asthma and few participants were as used as control based on no documented history of wheeze and PEFR levels. All the participants were male children aged between 9-12 years and exclusion was done if they were reported to having congenital heart disease, surgery or chronic lung disease. They were interviewed with a standardized questionnaire to ascertain their exposure to PAHs sources. Urinary 1-OHP levels were analyzed using HPLC to determine their exposure. Results: Participants with asthma showed a higher concentration of 1-OHP (7.56mg/g) in their urine. Second-hand exposure to tobacco smoke, consumption of charred or grilled foods, use of indoor air pollutants and exposure to traffic fumes were identified as contributive factors to elevated 1-OHP levels. Conclusion: Exposure sources at household levels may play a major role in exacerbating asthma. Significant PAHs exposure was contributed through dietary habits. Further exposure monitoring studies are needed to quantify the impact of PAH exposure on respiratory health. Keywords: Polycylic Aromatic Hydrocarbons; Asthma; 1-Hydroxypyrene

Inhibition of hERG Potassium Channels by the Polycylic Aromatic Hydrocarbon Phenanthrene

Polycyclic aromatic hydrocarbons (PAHs) may contribute to cardiotoxic effects of hydrocarbon-based pollution. Phenanthrene (Phen) is an abundant PAH in polluted air and water. For example, Phen is a constituent PAH of crude oil spills and has been shown to increase ventricular action potential duration of fish ventricular myocytes. This action is associated with inhibition of the rapid delayed rectifier K+-current. Ether-à-go-go Related Gene encoded potassium channels (ERG) mediate IKr in multiple species including fish and human, and block of human ERG (hERG) channels by structurally diverse drugs can result in acquired long QT syndrome in humans. The purpose of this study was to investigate the action of Phen on hERG, using whole-cell patch-clamp recording from HEK 293 cells expressing wild-type (WT) or mutant hERG channels. Under conventional voltage-clamp, WT hERG current (IhERG) tails at −40 mV following an activating protocol were inhibited with an IC50 of 16.8 ± 1.7 µM, Hill slope: 1.0 ± 0.1 (mean ± SEM; n= at least 5 for 5 different concentrations). Phen (10 µM) inhibition of IhERG was voltage-dependent and was associated with leftward shift of voltage-dependent activation (V0.5 shift of −10.1 ± 0.9 mV; n=16). The extent of observed IhERG inhibition also varied with duration of the activating voltage command. IhERG carried by the attenuated inactivation N588K hERG mutant was markedly less sensitive to Phen and the F557L mutation in the S5 domain also reduced Phen inhibition. Thus, the observed IKr block with Phen appears to involve a direct inhibitory effect of the compound on (h)ERG channels that is contingent on channel gating. Intact inactivation gating and availability of the F557 residue appear to be significant influences on this inhibitory action. Funded by the British Heart Foundation PG/17/77/33125

Biodegradasi Senyawa Toksik Naftalena Pencemar Lingkungan Menggunakan Isolat Fungi Indigen Provinsi Riau

<em>Napthalene is two ring aromatic of a group Polycylic Aromatic Hydrocarbons (PAHs) that is one priority pollutans established in nature which can cause carcinogenic. The aim of this study is determine the effectiveness of three isolates of indigenous fungi from Riau Province to degrade naphthalene. The growth and the ability of isolates to degrade naphthalene were examined into liquid MM (Minimal Medium) containing 0.2 mM naphthalene for 16 days incubation.The potential of fungi isolates during the degradation process was influenced by several parameters, including biomass, pH and the percentage of degradation which was measured at 0, 4, 8, 12 and 16 days of incubation. The results showed that the three isolates could use the naphthalene substrate as an energy source. The three isolates can degraded naphthalene each 51.28% oleh Aspergillus sp. LBKURCC151, 55.13% oleh Aspergillus sp. LBKURCC152 dan 48.72% oleh Penicillium sp. LBKURCC153. LBKURCC152. In conclusion, Aspergillus sp. LBKURCC152 is the best isolate for naphthalene degradation in this research</em>

Soil and sediment contamination by unsubstituted and methylated polycyclic aromatic hydrocarbons in an informal e-waste recycling area, northern Vietnam: Occurrence, source apportionment, and risk assessment

Improper processing activities of e-waste are potential sources of polycylic aromatic hydrocarbons (PAHs) and their derivatives, however, information about the environmental occurrence and adverse impacts of these toxic substances is still limited for informal e-waste recycling areas in Vietnam and Southeast Asia. In this study, unsubstituted and methylated PAHs were determined in surface soil and river sediment samples collected from a rural village with informal e-waste recycling activities in northern Vietnam. Total levels of PAHs and MePAHs decreased in the order: workshop soil (median 2900; range 870–42,000 ng g−1) > open burning soil (2400; 840–4200 ng g−1) > paddy field soil (1200; range 530–6700 ng g−1) > river sediment samples (750; 370–2500 ng g−1). About 60% of the soil samples examined in this study were heavily contaminated with PAHs. Fingerprint profiles of PAHs and MePAHs in the soil and sediment samples indicated that these pollutants were mainly released from pyrogenic sources rather than petrogenic sources. The emissions of PAHs and MePAHs in this area were probably attributed to uncontrolled burning of e-waste and agricultural by-products, domestic coal and biomass combustion, and traffic activities. Carcinogenicity and mutagenicity of PAHs in the e-waste workshop soils were significantly higher than those of the field soils; however, the incremental lifetime cancer risk of PAH-contaminated soils in this study ranged from 5.5 × 10−9 to 4.6 × 10−6, implying acceptable levels of human health risk. Meanwhile, concentrations of some compounds such as phenanthrene, anthracene, fluoranthene, benz[a]anthracene, and benzo[a]pyrene in several soil samples exceeded the maximum permissible concentrations, indicating the risk of ecotoxicological effects.

Analysis of Migration of Polycyclic Aromatic Hydrocarbons from Sewage Sludge Used for Fertilization to Soils, Surface Waters, and Plants

In this paper, we discuss the effect sewage sludge (SS) application has on the contamination of polycyclic aromatic hydrocarbons in fertilized soils and groundwater. Morver, the contents of these compounds in plant biomass was analyzed. For six months, composted sewage sludge was introduced into sandy soil. The research was conducted under lysimetric experiment conditions with the possibility of collecting soil leachate in natural conditions. The following doses of sewage sludge were used: 0, 10, 20, 30, and 40 t/ha calculated per experimental object containing 10 kg of sandy soil. The examinations were carried out within a three-year time frame. Dactylis glomerata grass was grown on the fertilized soils. Every year, the content of polycyclic aromatic hydrocarbons (PAHs) was collected from fertilized objects and analyzed in soil leachate, which can contaminate surface water. The following six polycylic aromatic hydrocarbons defined by Polish standards were determined: benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenz(a,h)anthracene, and benzo(g,h,i)perylene, indeno(1,2,3-cd)pyrene. Further, the content of PAHs in soils and the bioaccumulation of these compounds in cultivated plants were evaluated after each year. The results of the study showed that the increase in the dose of sewage sludge used for soil fertilization led to the rise in the amount of polycyclic aromatic hydrocarbons analyzed in the soil. The compounds migrated to cultivated plants. This phenomenon was observed especially in the first year following soil fertilization with sewage sludge. Excessive accumulation of PAHs (especially benzo(a)pyrene) was observed in plant biomass in the first year of a lysimetric experiment after sewage sludge fertilization with doses greater than 10 t/ha. The increase in bioaccumulation of this compound in plant biomass compared to control objects was 138%, 288%, and 505% after application of 20, 30, and 40 t/ha, respectively. Fertilization with sewage sludge did not cause contamination with PAHs in water leachates from the soils.

Development of a needle trap device packed with zinc based metal-organic framework sorbent for the sampling and analysis of polycyclic aromatic hydrocarbons in the air

This study aimed to present a new method combined of needle trap devices (NTDs) packed with the Zn3(BTC)2 metal-organic framework (Zn-MOF) as a sorbent, for the sampling and analysis of polycylic aromatic hydrocarbons (PAHs) in the air for the first time. The electrochemical method was used to synthesize Zn-MOF sorbent packed inside 22 gauge needle trap. This method was investigated in the laboratory under different condition and applied in the field to determination of PAHs in air. In order to make different concentrations of PAHs in air, a glass chamber under temperature of 120 °C was used. The optimization of the desorption conditions and breakthrough volume was accomplished using the response surface method and Design-Expert software (version 7). According to the results, the best desorption temperature was obtained as 379 °C in 9 min, the limit of detection and limit of quantification for the analytes under investigation were within the ranges of 0.011–0.021 and 0.03–0.07 mg/m3, respectively. Moreover, repeatability and reproducibility of the method were estimated in the ranges of 3.6–9.9 and 5.3–24.1, respectively. By storing the needles at 4 °C, no significant reduction was observed in the amount of analytes after 60 days (P > 0.05). It could be concluded that NTD: Zn-MOF is a reliable and high collection efficiency method had a suitable performance in the sampling of PAHs, compared to the National Institute for Occupational Safety and Health (NIOSH)-5515 method.

Cigarette butts: An overlooked source of PAHs in the environment?

Cigarette butts (CBs) are the most common littered objects in the environment and may contain high amounts of polycylic aromatic hydrocarbons (PAHs) from incomplete tobacco leave burning. But to date there is no comprehensive study on environmental emissions of PAHs by CBs. So the main aim of this study was to compare the concentration levels of 16 PAHs in freshly smoked CBs and CBs from the environment (collected from urban streets and river areas) with different exposure times to the environment. The results showed that the mean concentration levels of 4 PAHs including naphthalene, acenaphthylene, acenaphthene, and fluorene were significantly higher in the freshly smoked CB samples compared to the street samples and were the lowest in the river samples. Considering the number of CBs annually littered, considerable amounts of these 4 PAHs may be released to the environment, which may be a threat to the quality of water resources.

Dynamic changes in optical and chemical properties of tar ball aerosols by atmospheric photochemical aging

Abstract. Following wood pyrolysis, tar ball aerosols were laboratory generated from wood tar separated into polar and nonpolar phases. Chemical information of fresh tar balls was obtained from a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and single-particle laser desorption/resonance enhanced multiphoton ionization mass spectrometry (SP-LD-REMPI-MS). Their continuous refractive index (RI) between 365 and 425 nm was retrieved using a broadband cavity enhanced spectroscopy (BBCES). Dynamic changes in the optical and chemical properties for the nonpolar tar ball aerosols in NOx-dependent photochemical process were investigated in an oxidation flow reactor (OFR). Distinct differences in the chemical composition of the fresh polar and nonpolar tar aerosols were identified. Nonpolar tar aerosols contain predominantly high-molecular weight unsubstituted and alkyl-substituted polycylic aromatic hydrocarbons (PAHs), while polar tar aerosols consist of a high number of oxidized aromatic substances (e.g., methoxy-phenols, benzenediol) with higher O : C ratios and carbon oxidation states. Fresh tar balls have light absorption characteristics similar to atmospheric brown carbon (BrC) aerosol with higher absorption efficiency towards the UV wavelengths. The average retrieved RI is 1.661+0.020i and 1.635+0.003i for the nonpolar and polar tar aerosols, respectively, with an absorption Ångström exponent (AAE) between 5.7 and 7.8 in the detected wavelength range. The RI fits a volume mixing rule for internally mixed nonpolar/polar tar balls. The RI of the tar ball aerosols decreased with increasing wavelength under photochemical oxidation. Photolysis by UV light (254 nm), without strong oxidants in the system, slightly decreased the RI and increased the oxidation state of the tar balls. Oxidation under varying OH exposure levels and in the absence of NOx diminished the absorption (bleaching) and increased the O : C ratio of the tar balls. The photobleaching via OH radical initiated oxidation is mainly attributed to decomposition of chromophoric aromatics, nitrogen-containing organics, and high-molecular weight components in the aged particles. Photolysis of nitrous oxide (N2O) was used to simulate NOx-dependent photochemical aging of tar balls in the OFR. Under high-NOx conditions with similar OH exposure, photochemical aging led to the formation of organic nitrates, and increased both oxidation degree and light absorption for the aged tar ball aerosols. These observations suggest that secondary organic nitrate formation counteracts the bleaching by OH radical photooxidation to eventually regain some absorption of the aged tar ball aerosols. The atmospheric implication and climate effects from tar balls upon various oxidation processes are briefly discussed.

Molecular Compositions and Sources of Organic Aerosols from Urban Atmosphere in the North China Plain during the Wintertime of 2017

ABSTRACT PM2.5 samples were collected from Liaocheng, a typical city in the North China Plain, during a winter haze episode around 2017 Chinese Spring Festival (Lunar New Year, LNY) to investigate the impact of firework on organic aerosols. A comparison of PM2.5 concentrations during different periods, with different air mass origins, and under different pollution situations was done. Organic compounds including normal alkanes (n-alkanes), polycylic aromatic hydrocarbons (PAHs), saccharides, and organic acids in PM2.5 aerosols were determined by GC/MS. Sources were analyzed by diagnostics ratios and principal component analysis/multiple linear regression (PCA/MLR) model. The results showed that fireworks burning has significant impacts on fine particle pollution. During the haze period, a sharp increase in n-alkanes, PAHs, saccharides, and fatty acids were observed, but the influence of fireworks burning on n-alkanes concentration is minor. The concentrations of carcinogenic PAHs during haze and LNY periods were more than three times higher than those in the clean period, indicating that PAHs were more carcinogenic during the two periods. In addition, the estimated ILCR for children and adults were both about three times higher than those in the clean periods, suggesting a moderate potential carcinogenic risk in Liaocheng. The higher concentration and the dominance of levoglucoan in the total saccharides suggested that the biomass burning is the predominance source of saccharides. Both the ratios of C18:1/C18:0 and BaP/BeP were the highest during the haze period, indicating that aerosols in the haze period were more oxidized. According to the source precise molecular tracers and the PCA-MLR model, coal combustion, biomass burning, and vehicle emissions were the major sources of organic compounds in PM2.5 aerosols during the winter in Liaocheng, cooking activity and firework burning had impact on organic aerosols obviously during LNY. Our data provided first analysis of the molecular distributions and sources of organic aerosols during Chinese Spring Festival in Liaocheng and their potential effects on human health.

Effect of ohmic cooking followed by an infrared cooking method on lipid oxidation and formation of polycylic aromatic hydrocarbons (PAH) of beef muscle

In this study, the effects of ohmic cooking alone and a consecutive application of ohmic and infrared cooking on lipid oxidation and polycyclic aromatic hydrocarbon (PAH) formation in beef was investigated. In consecutive cooking, samples were first cooked ohmically at 40, 55 and 70 Volt for 7 minutes, then infrared cooking was applied to each side of ohmically cooked beef samples at 3 different temperatures (325, 375 and 425 °F) for 3 minutes. The thiobarbituric acid reactive substance (TBARS) levels of the samples were found between 0.31 and 1.74 mg MDA/kg. Increasing the voltage level in ohmic cooking caused a significant (P < 0.05) increase in the TBARS value. In the consecutive application of ohmic and infrared cooking, infrared cooking temperature caused a significant (P < 0.05) increase in the TBARS value at the same voltage levels. In this study, working with 40 and 55 Volts for ohmic cooking alone and 40 V-325 °F, 40V-375 °F settings for ohmic-infrared cooking gave a generally acceptable threshold level for TBARS value (1 mg/kg). About 12 polycyclic aromatic hydrocarbons (PAHs) were detected in the cooked beef by ultra-performance liquid chromatography fluorescence detector (UPLC-FD). Benzo(a)pyrene (BaP), which is the most common PAH, was detected at between 1.2514 and 1.4392 μg/kg and 4 PAH (sum of Benzo(a)pyrene, Chrysene, Benz(a)anthracene, Benz(b)fluoranthene) levels were detected at between 1.2514- 3.7844 μg/kg. The results of PAHs were reasonably below the European Commission regulation limits, which are very important and indicate that the cooking processes applied in this study are safe.