High Molecular Weight Polycyclic Aromatic Hydrocarbons Research Articles

The study of three beaches of South-West Cameroon polluted by polycyclic aromatic hydrocarbons

The US Environmental Protection Agency (US-EPA) published a priority list of 16 polycyclic aromatic hydrocarbons (PAHs), which are compounds that are studied in a variety of matrices due to their wide range of risks. Environmental compartments can be contaminated with PAHs from different sources, such as wastewater from industries and petroleum spills. For the case of Cameroon, there are no recorded data concerning the sources, distributions, and toxicity levels of PAHs in water and sediment from Cameroon beaches which are found in South-West, Littoral, and South Regions. In this work, only three beaches from South-West Region were studied regarding the sources, distributions, and toxicity levels of PAHs in water and sediment. The analyzed samples came from Bobende coastal beach, Down-beach, and Cape-Limboh beach. To achieve the analyses, liquid-liquid extraction and gas chromatography enabled the identification and quantification of PAH compounds from sediments and marine water. Out of the 16 PAHs listed by US-EPA, twelve were identified and quantified among which four of them were light molecular weight PAHs (acenaphthylene, fluorene, phenanthrene, and anthracene). Anthracene in the Cape-Limboh sample presented the highest concentration (477.57ng/kg weight of dry sediment) of LMW-PAHs. Eight identified and quantified PAHs of high molecular weight as a whole, three absent PAHs (benzo[a]anthracene, dibenzo[a,h]anthracene, and benzo[g,h,i]perylene) in the Cape-Limboh sample, while only one is absent in the Bobende samples (dibenzo[a,h]anthracene) and Down Beach (benzo[g,h,i]perylene). According to the ratios used for the determination of the sources of PAHs, it came out that the source of PAHs from all beaches is pyrolytic. In all samples, BaA is the only high molecular weight PAH presenting serious toxicity and ecological risk.

Sediment remediation using submerged plants mitigated the bioaccumulation of organic contaminants in benthic organisms in simulated freshwater aquaculture ponds

Few studies have investigated whether growing submerged plants can provide significant mitigation of both polycyclic aromatic hydrocarbons (PAHs) and antibiotics (ATBs) in sediments and cultured aquaculture products. In this study, Corbicula fluminea was selected as the indicator organism in the laboratory simulation experiment, and four remediation systems using Vallisneria natans L. (VN), Hydrilla verticillate L. (HV), Elodea nuttallii P. (EL) and Control Check (CK) were constructed individually. The accumulated concentrations (Cb) and changes in both bioavailability (Cfree) and bulk burden (Cs) of 16 PAHs and four ATBs were analyzed before, during, and after the experiment. Compared with the CK group, the introduction of VN, HV, and EL reduced: Cb of ΣPAHs by 43%, 32%, and 27%, respectively; ΣATBs by 68%, 49%, and 39%, respectively, in Corbicula fluminea; the corresponding cancer risk of ΣPAHs by 19%, 8.9%, and 13%, respectively; and the target hazard quotients of ΣATBs by 73%, 48%, and 41%, respectively. The freely dissolved concentrations of ΣPAHs and ΣATBs (Cfree) in the experimental groups decreased by 38%− 58% and 37%− 70%, respectively. More ATBs than PAHs were reduced in biota, with VN showing the highest efficiency. Reduction in Cfree was more related to reduction in Cb than reduction in Cs. In terms of Cb reduction, Cfree was more indicative for ATBs than PAHs. Analyses of the bacterial community revealed that the introduction of submerged plants significantly increased the abundance of Sphingomonas and Mycobacterium, with specific degradation effects observed for high molecular weight PAHs in the sediment.

Health Risk Assessment of Polycyclic Aromatic Hydrocarbons in Charbroiled Meat Commonly Consumed in Port Harcourt Metropolis

This study was designed to assess polycyclic aromatic hydrocarbons (PAHs) concentrations in four selected commonly consumed charbroiled meats (Micropogonias undulatus, Gallus gallus domesticus, Sus scrofa domesticus, Bos Taurus) and their potential health risks associated with consumption. The charbroiled samples (croaker fish, chicken, pork and beef) respectively were analyzed with Gas Chromatograph GC (Agilent 6890N) coupled with mass detector (Agilent 5975) in accordance with standard analytical method for PAHs. The levels of PAHs in croaker fish, chicken, pork and beef collected from Mile 4 are significantly lower at p<0.05 in comparison to the concentrations of PAH in croaker fish, chicken, pork and beef collected from Choba. The highest mean individual concentration was recorded for Benzo (a) pyrene in croaker fish (0.733±0.015mg/kg) and pork (0.733±0.021mg/kg) from Choba and Mile 4 respectively and were above the maximum permissible limits as recommended by the USEPA. Low molecular weight PAHs (LMW PAHs) were generally predominant compared to High molecular weight PAHs (HMW-PAHs). This suggests that the sources of these PAHs in the samples analyzed were mainly of pyrogenic and petrogenic origin at the Choba and Mile 4 sites respectively. Estimated Daily Dose (EDD), Hazard Quotient (HQ), Hazard Index (HI) and Life Time Excess Carcinogenic Risk (LECR) showed that ingestion of charbroiled croaker fish and chicken across the study areas were above the set standard limits. Hence there is a potential risk of consumption. However, Hazard indexes < 1 described by the EPA across all samples analyzed indicated non-carcinogenic threat from the consumption of charbroiled meat.

Liquid Chromatographic Separation of MM 302 Da Polycyclic Aromatic Hydrocarbons in Synthetic Mixtures Using Chiral Stationary Phase Material

High molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) are an example of a family of compounds that exist with isomeric mixtures. While multi-instrument techniques may isolate many isomeric PAHs at qualitative and quantitative levels, complete separation of this class of environmental pollutant has not yet been attained, leaving ample room for method improvement. In this research, the separation of 21 commercially available isomers of MM 302 Da was studied using polysaccharide-based chiral immobilized materials as stationary phase. Isocratic, normal phase runs were performed using mixed concentrations and combinations of 302 Da PAH isomers. Retention times and calibration data were determined using a chiral chromatographic setup. Selectivity values are given for all the evaluated HMW-PAH isomers, retention and intensity factors were also calculated based on the directions outlined in Environmental Protection Agency Method 550.1, along with chromatographic peak resolution values. With the use of chiral separation, a total of 16 HMW-PAH peaks are visible on the chromatogram of the 21 MM 302 Da PAH synthetic mixture. This group of molecules does not possess chiral centers in the classical sense; however, larger molecules such as these may possess pseudochiral characteristics, providing a little-researched opportunity for separation strategy of formerly considered achiral molecules to be separated using chiral stationary phases. The resolution of this method makes it suitable for the identification and quantitation of MM 302 Da PAH isomers fractionated from a larger complex sample. The potential for this approach with other classes of high molecular weight achiral molecules is yet to be explored.

Chemical fingerprints and implicated cancer risks of Polycyclic aromatic hydrocarbons (PAHs) from fine particulate matter deposited in human lungs

Exposure to fine particles (PM2.5) and associated PAHs are frequently linked with lung cancer, which makes the understanding of their occurrence and health risk in human lungs urgently important. Using the ultrasonic treatment and sequencing centrifugation (USC) extraction method coupled with gas chromatography-tandem mass spectrometry (GC - MS/MS) analysis, we revealed the molecular fingerprints of PM-accumulated PAHs in human lungs from a cohort of 68 patients with lung cancer in a typical air-polluted region, China. Sixteen priority PAHs can be grouped by concentrations as ∼ 1 × 104 ng/g (ANT/BkF/ACE/DBA/BgP/PHN/PYR), 2–5 × 103 ng/g (BaP/FLE/NaP/BbF), and ∼ 1 × 103 ng/g (IND/Acy/CHR/FLT/BaA). The sum concentration of 16 PAHs was approximately equaled to 13% of those in atmospheric PM2.5, suggesting significant pulmonary leaching of PAHs deposited in lungs. Low- and high-molecular weight PAHs accounted for ∼ 41.8% and ∼ 45.1% of the total PAHs, respectively, which indicated that atmospheric PM2.5, tobacco and cooking smoke were likely to be important sources of pulmonary PAHs. The evident increasing concentrations of NaP and FLE in pulmonary PM were significantly correlated with smoking history among smokers. The implicated carcinogenic potency of PM-accumulated PAHs among the participants aged 70–80 was 17 times that among participants aged 40–50 on the basis of BaP equivalent concentration (BaPeq) evaluation. The particulate enrichment factor (EFP), the PAH content in pulmonary PM relative to the bulk lung tissue, was equaled to 54 ∼ 835 and averaged at 436. The high value of EFP suggested that PAHs were essentially accumulated in pulmonary PM and exhibited a pattern of “hotspot” distribution in the lungs, which would likely increase the risk of monoclonal tumorigenesis. The chemical characteristics of PM-accumulated PAHs in human lungs together with their implicated lung cancer risks could provide significant information for understanding health effects of particulate pollution in the human body.

Remediation of PAH-contaminated soil using a combined process of soil washing and adsorption by nano iron oxide/granular activated carbon composite

This study investigated the application of magnetic granular activated carbon (MGAC) in soil washing process for the removal of polycyclic aromatic hydrocarbons (PAHs) from real contaminated soil. The magnetic composite was prepared using a facile-modified co-precipitation method. The presence of the synthesized magnetite (Fe3O4) nanoparticles on the composite surface was confirmed by the SEM and XRD characterization tests. The surface area and total pore volume of MGAC were determined to be 837.9 m2/g and 0.5 cm3/g, respectively, which were approximately 10% smaller than those for the bare GAC. The Langmuir model fitted the adsorption isotherm data the best; therefore, monolayer adsorption was predominant in the treatment process with MGAC. The maximum PAH adsorption capacity of MGAC was obtained at 153.5 µg/mg for the total PAHs, which was nearly 20% lower than that of bare GAC (190.3 µg/mg). The soil washing parameters were optimized, and the results demonstrated that the total PAH removal reached a maximum of 47.4% at an MGAC dose of 2% (w/w), washing time of 24 h, a liquid-to-soil ratio of 15:1, stirring speed of 100 rpm, pH of 8.3, and a temperature of 25 °C. For low molecular weight (LMW) PAHs, the removal from soil ranged from 34.6% to 57.7%, whereas the removal percentage of high molecular weight (HMW) PAHs was determined to be between 27.9 and 67.1 %. This indicated that the optimized soil washing with MGAC had a better efficiency for some HMW PAHs than the LMW PAHs. According to the thermodynamic studies, the adsorption of PAHs onto MGAC in the soil washing process was non-spontaneous (ΔG° > 0) and endothermic (ΔH° > 0) with increased randomness at the solid/solution interface of MGAC as temperature increases. The obtained results confirmed the efficiency of the magnetized activated carbon as adsorbent in soil washing to remove the hazardous PAH compounds from soil.

Two-dimensional gas chromatography coupled to isotope ratio mass spectrometry for determining high molecular weight polycyclic aromatic hydrocarbons in sediments

The accuracy of compound-specific isotope analysis (CSIA) of trace-level pollutants in complex environmental samples has always been limited by two main challenges: poor chromatographic separation and insufficient amounts of analytes. In this study, a two-dimensional gas chromatography-isotope ratio mass spectrometry (2DGC-IRMS) system was constructed for compound-specific δ13C analysis of high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) in estuarine/marine sediments. This construction occurred through hyphenating an extra gas chromatography system (GC) to a conventional GC-IRMS using a commercially available multi-column switching-cryogenic trapping system (MCS-CTS). Compared with the previous 2DGC-IRMS strategy, which utilizes a Deans Switch device, the newly implemented 2DGC-IRMS scheme resulted in online purification of target analytes as well as enriched them online via duplicate injection and cryogenic trapping in CTS; this resultingly lowered the limits of detection (LOD) of CSIA. To improve the sample transfer efficiency to the IRMS, a broader-bore and longer fused-silica capillary was utilized to replace the original sample capillary running from the sample open split to the IRMS. A ẟ13C analysis of PAH standards showed accurate ẟ13C values, and high precisions (standard deviations 0.13–0.37%) were achieved, with the LOD of HMW-PAHs reduced to at least 1.0 mg/L (i.e., 0.07 to 0.09 nmol carbon per compound on-column). The successful application of this newly developed 2DGC-IRMS scheme provides a practical solution for the reliable CSIA of trace-level pollutants in complex environmental samples that cannot be measured using the conventional GC-IRMS system.

Metabolism of benzo[a]pyrene after low-dose subchronic exposure to an industrial mixture of carcinogenic polycyclic aromatic hydrocarbons in rats: a cocktail effect study.

Polycyclic aromatic hydrocarbons (PAHs) are interesting environmental pollutants for understanding cocktail effects. High-molecular-weight-PAHs (HMW-PAHs) are classified as probable or possible carcinogens; only benzo[a]pyrene (B[a]P) is a certain carcinogen in humans. Their toxicity depends on their metabolic activation. While 3-hydroxybenzo[a]pyrene (3-OHB[a]P) represents its detoxification pathway, trans-anti-7,8,9,10-tetrahydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene (tetrol-B[a]P) represents the carcinogenicity pathway. The objective was to study the metabolism of B[a]P and HMW-PAHs during chronic low-dose exposure to B[a]P or a PAH mixture. Rats were exposed orally 5 times/week for 10weeks to low-levels of B[a]P (0.02 and 0.2mg.kg-1.d-1) or to an industrial mixture extracted from coal tar pitch (CTP) adjusted to 0.2mg.kg-1.d-1 B[a]P. Urinary levels of monohydroxy-, diol-, and tetrol-PAH were measured during weeks 1 and 10 by HPLC-fluorescence and GC‒MS/MS. After 1 week, the percentages of B[a]P eliminated as 3-OHB[a]P and tetrol-B[a]P were not different depending on the dose of B[a]P, whereas they were reduced by half in the CTP group. Repeated exposure led to an increase in the percentages of the 2 metabolites for the 0.02-B[a]P group. Moreover, the percentage of B[a]P eliminated as 3-OHB[a]P was equal in the 0.2-B[a]P and CTP groups, whereas it remained halved for tetrol-B[a]P in the CTP group. The percent elimination of HMW-PAH metabolites did not vary between weeks 1 and 10. Thus, dose, duration of exposure and chemical composition of the mixture have a major influence on PAH metabolism that goes beyond a simple additive effect. This work contributes to the reflection on determination of limit values and risk assessments in a context of poly-exposures.

Occurrence and source of PAHs in Miankaleh International Wetland in Iran

We examined the occurrence and sources of 16 priority PAHs in the water and sediment samples of the Miankaleh Wetland (Coastal Biosphere Reserve), famous for harbouring huge flocks of migrating birds. The water and sediment samples collected from various locations were visualized and processed using a self-organizing map, positive matrix factorization and GIS. All the sediment samples, and >90% of the water samples, showed some degree of PAHs contamination. Higher PAH levels occur near the Chopoghi Channel, powerplants, sewage outfalls, and near fishing operations. Compared with previous study in this area, the PAHs concentration in the sediments of aquatic ecosystem of Miankaleh Wetland is increasing. The levels of PAH contamination seem too low to account for the mass deaths of migratory birds, and botulinus contamination seems the likely cause. Fugacity calculations show that the sediments act as a sink for PAHs. According to PMF and SOM analyses, three origins of PAHs were recognized: (i) fossil fuel and vehicular emissions with high-molecular weight PAHs (4–5 ring); (ii) municipal and industrial sewages characterized by low-molecular weight PAHs (2–3 ring) typical of petrogenic sources; and (iii) port activity characterized by prevalence of petrogenic influence and petroleum-related activities (combustion PAHs and low-molecular weight PAHs) consistent with port activity. This wetland needs serious attention because of continuous input of pollutants. The results and the methods used in this study may assist in improving coastal wetlands management.

Study of the effect of methanol/biodiesel fuel mixtures on the generation of soot particles and their oxidation reactivity

When diesel engines burn different fuels, the chemical composition of the emitted combustion particles changes, leading to changes in the oxidation characteristics of these particles and determining the regeneration strategy and service life of after treatment devices. In order to investigate the influence of methanol/biodiesel fuel mixtures on the chemical composition and oxidation activity of emitted soot matter, a test bench was built using a four-cylinder diesel engine, and soot matter in the exhaust was collected. Tests used mixed fuel with different methanol mixing ratios. By using a high-performance liquid chromatograph, a thermogravimetric analyzer, and other equipment, the changes of chemical composition and oxidation characteristics of particles were studied. The results show that as the methanol mixing ratio increases, the mass concentration of organic carbon (OC), bicyclic, and tricyclic polycyclic aromatic hydrocarbons (PAHs) in the particles increase, the mass concentration of elemental carbon (EC) and high molecular weight PAHs decreases, the concentration of nitrate ions first increases and then decreases, the activation energy decreases, and the oxidation activity increases. In general, the chemical composition of combustion particulates from methanol/biodiesel changes, and the oxidation activity is greatly improved. This research work can provide a reference for the coating design and regeneration strategy for optimizing diesel particulate filters (DPFs).

Deposition of atmospheric polycyclic aromatic hydrocarbons in rural areas: Current data and historical record from an ombrotrophic peatland

Atmospheric concentrations of 18 polycyclic aromatic hydrocarbons (PAHs) were measured in a rural area in northern Spain. Both the gas phase and particulate fraction were determined to evaluate the types and abundance of PAHs taken up by vegetation and the historical record of PAH deposition in an ombrotrophic peatland over the last 300 years. The total atmospheric PAH concentration was ca. 2.5 ng m−3, a value that is slightly lower value than those found in other rural areas, consistent with those of remote areas (Pyrenees, Alps, and Caledonian Mountains), and much lower than those recorded in urban areas. The particulate fraction showed a greater content of high molecular weight PAHs, whereas the gas phase was enriched in low molecular weight homologues. The concentration of total PAHs in the gas phase was higher than that in the particulate fraction (ca. 80%) and similar to that found in other localities in remote areas. PAHs showed seasonal variability. In this regard, the highest concentrations in the gas phase occurred in winter and autumn, whereas in the particulate fraction they were found in winter and spring. Of note, the concentrations of PAHs increased in the particulate fraction during the years in which fires occurred. The PAH content in peat-forming plants in this area showed a similar distribution to that of the gas phase. The historical record of the depositional fluxes of PAHs in an ombrotrophic peatland in the study area, which was dated radiometrically, allowed to reconstruct the changes in pollutant content between 1775 and the present. In general, the PAHs detected were of pyrogenic origin (fossil fuels and wood combustion). The concentrations of these pollutants increased from uniform background levels at the turn of the second half of the 19th century, which were linked to industrial development, to maximum values during the first half of the 20th century until the beginning of the 21st century, when the extraction and combustion of coal was extensive close to the study area. In contrast, in the uppermost part of the record, PAH concentrations decreased. This reduction is attributed to the implementation of environmental policies, although the concentrations of these pollutants were still greater than during the preindustrial period. To gain a detailed understanding of the deposition and evolution of PAHs in the study area, here it is reported on a new method that integrates current atmospheric data on PAHs with information on their accumulation in plants and the historical peat record of a rural area in Spain. The methodology described herein could be applied to other scenarios in the context of PAH pollution.

Spatiotemporal Distribution and Driving Factors of Polycyclic Aromatic Hydrocarbons (PAHs) in Inland Sediments of China

This study reviewed the spatial and temporal distributions of polycyclic aromatic hydrocarbons (PAHs) during 2000-2010 in inland sediments of China and quantified the underlying socioeconomic determinants based on the structural equation model and gravity model. We found that PAHs concentrations in the sediments of eight different regions followed the order of Northern coast>Northeast>Eastern coast>Southern coast>Middle Yellow River>Middle Yangtze River>Southwest>Northwest. The Southern coast, Middle Yangtze River, and Southern coast regions showed large contributions to the high-molecular weight PAHs, whereas the Northeast, Northwest, and Middle Yellow River regions showed high contributions to the low-molecular weight PAHs. PAHs concentrations continuously increased from the year 2000 followed by a gradual decline after 2006, with significant differences in the year when PAHs levels reached their peak. PAHs concentrations of sediment in developed regions declined in recent years following a continuous increase in the 2000s; however, they still increased rapidly in developing regions owing to fast economic development. In addition, the increment rate of PAHs concentrations in sediment at the remote or less-developed regions was slower than that at the developed regions. Urbanization and industrialization had an important effect on PAHs in the sediments, and the largest influencing factor was the economic development.

Environmental and human health risk assessment of polycyclic aromatic hydrocarbons in the Musa estuary (northwest of Persian Gulf), Iran

A comprehensive investigation of PAHs' occurrence and distribution in the water, sediment, and fish samples of Musa estuary was conducted. Concentrations of 16 PAHs in water, sediment and two commercial fish ranged from 0.14 to 0.66 ng/l, 67.21 to 82.92 ng/g dw, 50.25 to 99.39 ng/g fdw in J. belangerii, and 40.14 to 76.93 ng/g fdw in B. orentalis, respectively. High molecular weight PAHs (HMW-PAHs) were generally predominant compared to low molecular weight PAHs (LMW-PAHs). Additionally, the study of the PAHs fingerprints, using specific ratios, suggests the predominance of a pyrolytic origin for observed PAHs. 4-ring PAHs were observed more in the two species, whereas the PAHs in sediments were dominated by three and five ring compounds. The Incremental lifetime Cancer Risk (ILCR) for fish was ≤10 E 10−5, showed a minimal possible risk of cancer for children and adult.

Biochar reduces uptake and accumulation of polycyclic aromatic hydrocarbons (PAHs) in winter wheat on a PAH-contaminated soil

Biochar has been used previously for remediation of polycyclic aromatic hydrocarbons (PAHs) in contaminated soils for years, which has achieved remarkable results in improving removal of soil PAHs and reducing PAHs uptake in crops. However, the underlying mechanism of biochar application in reducing the uptake and accumulation of PAHs in winter wheat remains unclear. Pot trials using PAHs-contaminated soils were conducted for whole plant growth period of winter wheat, which were amended with 2% (w/w) bamboo biochar (BB), coconut shell biochar (CB) and maize straw biochar (MSB) or not (CK). Compared with CK, application of the three types of biochar significantly (p < 0.01) reduced grain PAHs concentration, the total equivalent concentration (TEC) values and the incremental lifetime cancer risk (ILCR) of grain PAHs, indicating that application of biochar reduced the exposure risk of PAHs in wheat grain, especially for MSB. Consistently, application of the three types of biochar significantly (p < 0.05) reduced uptake and accumulation of PAHs in root and stem of wheat, which may be due to that application of biochar enhanced the degradation of PAHs in the rhizosphere soil. Compared with CK, application of the three types of biochar significantly (p < 0.05) reduced the concentration of PAHs in the rhizosphere soil by 15.9%, 26.1% and 33.7%, respectively. It was found that the degradation rate of HMW PAHs (high molecular weight PAHs, 5-6 ring PAHs) was significantly (p < 0.05) higher than that of LMW PAHs (low molecular weight PAHs, 2-4 ring PAHs) regardless of types of biochar used. Additionally, application of the three types of biochar significantly increased the relative abundance of dominant bacterial phyla and genera in soil. Redundancy analysis and correlation analysis results also showed that there was a strong correlation between the removal rate of PAHs and dominant bacteria in the rhizosphere soil. The present study indicated that biochar could reduce dietary risk of PAHs in wheat grains mainly by increasing the abundance of bacteria related to PAHs degradation, promoting the biodegradation of PAHs in the rhizosphere soil and consequently reducing PAHs uptake in wheat.

Sources, Compositions, and Health Risks of PM2.5-bound PAHs at the Rural Area along with the “Coal to Gas” Law

The “Coal to Gas” (CTG) policy in north China markedly altered the characteristics of polycyclic aromatic hydrocarbons (PAHs) in PM2.5. Existing researches about CTG impacts on components, sources, and health risks of PM2.5-bound PAHs mainly focused on metropolitan area, whereas they were lacking in rural area of north China. Here, we deployed an intensive observation in winter of 2020 at a rural site in the central area of the Beijing-Tianjin-Hebei (BTH) region. A positive matrix factorization (PMF) model and an incremental lifetime cancer risk (ILCR) model were utilized to examine the PAH sources and health risks. Higher daily average PM2.5 of 81.5 µg m–3 in the sampling period than 75 µg m–3 of the National Air Quality Standard Grade II indicated the air pollution in rural area was still serious. The total PAHs increased obviously from diurnal 86.2 ng m–3 to nocturnal 151 ng m–3 because of the nocturnal high intensity of heating, with the increases of 20.7%, 85.5%, and 76.3% for low, medium, and high molecular weight PAHs, respectively. Vehicular exhaust (VE), coal burning (CB), industrial source (IS), biomass burning (BB), and oil spill and leakages (OSL) were the main PAH contributors, with the average daily contributions of 32.7%, 21.5%, 18.3%, 15.9%, and 11.6%, respectively. Lower CC contribution of 27.6% in winter of 2020 than 27.6% in winter of 2019 indicated the positive role of CTG policy. However, the nocturnal CC fraction increased by 680% compared with the diurnal value, and CC had become the largest contributor in the nighttime. BB contribution was up to 18.3%, evidencing that biomass utility should be managed in term of the biomass burning was prohibited in BTH rural area. Moreover, the nocturnal average BaPeq equivalent concentration exhibited higher levels than those in the daytime. The nocturnal ILCR values of adults and children was 9.35 × 10–6 and 2.66 × 10–6, exceeding the acceptable threshold, suggesting there was a potential carcinogenic risk.

Influence of temperature and precipitation on the fate of polycyclic aromatic hydrocarbons: simulation experiments on peat cores from a typical alpine peatland in Central China.

The corresponding relationships between temperature, precipitation, and polycyclic aromatic hydrocarbon (PAH) concentration in a typical ombrotrophic peatland in Dajiuhu, Shennongjia, were quantitatively characterized by field sampling tests validated with simulation experiments. The PAH concentrations of peat cores in Dajiuhu peatland ranged from 262 to 977ng·g-1, with a mean value of 536 ± 284ng·g-1. PAHs were mainly composed of 2-3 ring PAHs, accounting for 31.7% ± 2.00% and 31.7% ± 5.00%, respectively. The concentration of PAHs in peat cores showed a significant decrease with increasing temperature, while the low molecular weight PAHs (LMW-PAHs) were more sensitive to temperature changes compared to the high molecular weight PAHs (HMW-PAHs). Besides, with the increase of quantity and velocity of leaching liquid, PAHs in peat were first transferred in the form of attached large-size particles and then gradually entered the aqueous phase. According to the IPCC projections of global warming, Dajiuhu peatland will release 956 ± 26.3kg·°C-1 PAHs into gas phase during 2030-2052, and a conservative projection based on local temperature trends showed that 459 ± 12.6kg·°C-1 PAHs will be released into gas phase by 2047 in Dajiuhu peatland. The projected release fluxes of PAHs in Dajiuhu peatland with precipitation volume and precipitation velocity are 381 ± 201kg·100mm-1 and 1052 ± 167kg·min·mL-1, respectively, which are primarily from peat into particulate and aqueous phase.

Enhancement of soil high-molecular-weight polycyclic aromatic hydrocarbon degradation by Fusarium sp. ZH-H2 using different carbon sources

High-molecular-weight PAHs (HMW-PAHs) in soil cannot be easily degraded. However, nutrient supplementation could stimulate the growth of exogenously added strains to enhance the degradation of HMW-PAHs in polluted soil. This study evaluated the applicability of Fusarium sp. ZH-H2, a polycyclic aromatic hydrocarbon (PAH)-degrading strain isolated by our research group, for the bioremediation of contaminated soil from the Hebei coal mining area in China. A soil incubation experiment was conducted to investigate the effect of two carbon sources and different carbon, nitrogen, and phosphorus (C:N:P) ratios on the remediation of high-molecular-weight PAHs (HMW-PAHs) in soil by Fusarium sp. ZH-H2, as well as the induction of lignin peroxidase activity. Our findings indicated that the HDF2 treatment (equal parts of humic acid and starch as carbon sources at a 50:1:0.5 C:N:P ratio) enhanced the removal rate of total HMW-PAHs from soil, reaching a maximum removal rate of 37.15 %. The removal rates of Pyr (a 4-ring PAH), BaP (a 5-ring PAH), and BghiP (a 6-ring PAH) were the highest in HDF2 treatment, and the removal rates were 39.51 %, 54.63 %, and 38.60 %, respectively. Compared with the ZH-H2 treatment, different carbon sources and C:N:P ratios significantly induced soil lignin peroxidase activity and the HDF2 treatment also resulted in the highest enzyme activity (up to 34.68 U/L). Furthermore, there was a significant or highly significant linear positive correlation between the removal rate of HMW-PAHs and enzyme activity in all cases. Our findings suggest that the optimal HMW-PAH degradation performance and enhancement of lignin peroxidase activity by ZH-H2 were achieved when both starch and humic acid were used as carbon sources at a C:N:P ratio of 50:1:0.5.

Pyrolysis temperature influences the capacity of biochar to immobilize copper and arsenic in mining soil remediation.

Biochar is a promising material used for multiple remediation approaches, mainly in polluted soils. Its properties can differ depending on feedstock and pyrolysis temperature. In this context, we tested the capacity of three biochar products made from corncob, pyrolyzed at different temperatures (350, 500, and 650°C), to remediate a mining soil affected by high levels of Cu and As. We performed an exhaustive characterization of the biochar. We found that biochar showed a higher surface area with increasing pyrolysis temperature, whereas high molecular weight PAHs were detected in biochar produced at the maximum temperature, thus indicating potential ecotoxicological risks. After the application of biochar to the soil, Cu was partially immobilized, especially when using that obtained at 500°C. This effect is attributed to the structure of this material and an increase in soil pH and organic matter content. Conversely, As was increased in the soluble fraction for all three types of biochar but in a proportion that lacks relevance. On the whole, given its lower PAH content, higher Cu immobilization ratio, and an almost negligible increase in As availability, biochar obtained at 500°C outperformed the other two products with respect to soil recovery. Of note, data on Cu and As availability were doubled-checked using two extraction methodologies. We propose that this operational approach for determining the most suitable pyrolysis temperature will find application in other soil remediation actions.

Determination of 16 particle-phase polycyclic aromatic hydrocarbons in herbal incense by ultrasonic extraction-gas chromatography-mass spectrometry and analysis of emission characteristics

Polycyclic aromatic hydrocarbons (PAHs) have attracted global attention because they are carcinogens and mutagenic to humans. To date, more than 200 PAHs have been found. The United States Environmental Protection Agency (USEPA) has designated 16 PAH species as priority control pollutants due to their highly toxic substances. Herbal incense is frequently used in daily life. As a result, it is critical to investigate its impact on human health and environmental safety. However, research on particle-phase PAHs is very limited and inapplicable. The current research focuses mainly on bamboo incense, which has a simpler formula than herbal incense.In this study, the emission factor and emission characteristics of particle-phase PAHs from herbal incense were described. A method combining ultrasonic and gas chromatography-mass spectrometry (GC-MS) was developed for the simultaneous determination of 16 particle-phase PAHs of herbal incense. The settings for extraction solvent, ultrasonic time, and instrument analysis conditions were optimized. In the test chamber, samples were collected by burning 0.8 g of herbal incense. After combustion, PAHs adsorbing on the particles of herbal incense were collected on a quartz filter. The whole filter sample was sliced and extracted with n-hexane-dichloromethane (1∶1, v/v). A rotary evaporator was used to concentrate the extract. GC-MS was used to analyze the prepared sample. The internal standard method was used to perform quantitative analysis on the target compounds. The linearities of the 16 target PAHs were good between mass concentrations of 0.1-5.0 μg/mL, with correlation coefficients greater than 0.998. The method detection limits (MDLs) of the 16 PAHs ranged from 0.4 to 3.8 ng/g. The 0.625 μg/g and 1.25 μg/g spiked recoveries ranged from 77.4% to 99.5% and 82.0% to 101.3%, respectively. The relative standard deviations (RSDs) of the 16 PAHs were ranged from 0.7% to 7.2% (n=6). The emission factors of particle-phase PAHs from five different kinds of herbal incense ranged from 4.60 to 11.89 μg/g. The highest concentration of phenanthrene (Phe) was found in 16 particle-phase individual PAHs of herbal incense. Fluoranthene (Flu), pyrene (Pyr), chrysene (Chr) and anthracene (Ant) concentration were ranked after Phe. The sum of these five proportions was 73.00%-89.97%. The proportion of Phe in herbal incense particle-phase PAHs was significantly higher than that of other indoor combustion sources. As a result, Phe could be used to identify individual PAHs in the particle-phase of herbal incense. The particle-phase PAHs were mainly distributed on the 3-ring and 4-ring, with a sum of 83.84% to 96.31% on the 3-ring and 4-ring. The proportion of high-molecular weight PAHs in the samples ranged from 44.25% to 63.31%. The proportion of low-molecular weight PAHs in the samples ranged from 36.69% to 55.75%. The incense source could be distinguished from other indoor combustion sources by its distinctive Phe/Flu ratio. The established method has high sensitivity, simple operation, and requires fewer samples. This method is suitable for rapidly detecting PAHs in burning incense. At the same time, it provides scientific data for further studies on the distribution and health effects of particle-phase PAHs of herbal incense.

Sedimentary PAH and oxidative stress biomarkers responses on Namalycastis abiuma (Polychaeta: Nereididae) from an urbanized Amazon estuary

Contamination by polycyclic aromatic hydrocarbons (PAH) in sediments and oxidative stress biomarkers responses (glutathione-S-transferase activity—GST and lipoperoxidation—LPO) on the polychaetes Namalycastis abiuma were screened along the urbanized margin of the Guajará Estuary, Brazilian Amazon coast, during dry and rainy seasons. Total 16 priority PAH concentrations ranged from 17 to 386 ng g−1 dry sediment, with higher values during the dry season. High molecular weight PAHs predominated during dry season and were probably originated from fossil fuel burning. Increased naphthalene and anthracene concentrations were noted when the maximum river flow was recorded and suggest diffuse sources from drainage of contaminated surfaces. Ecotoxicological PAH risks were low according to international sediment quality indices. Nevertheless, PAH toxicity equivalency was around 10-fold higher nearer the oil terminal than alongside the estuary. Highest GST activities at the oil terminal and industrial sites coincided with the rainy season, and combined with hydrochemical and sedimentary conditions thought to promote PAH bioavailability and a prolonged toxicant exposure. LPO approached similar levels in both seasons, suggesting that enzymatic activities were sufficient to uphold the prooxidants exposure. This result indicates that the overall estuarine condition exerts subtle oxidative stress on a keystone species and matches the low PAH ecotoxicological risks. Depositional margins within the mangrove areas and port operation are susceptible to an enhanced PAH accumulation and need special surveillance.