Distribution Of Polycyclic Aromatic Compounds Research Articles

Emission characteristic, spatial distribution, and health risk of polycyclic aromatic compounds (PAHs, NPAHs, and OPAHs) from light-duty gasoline and diesel vehicles based on on-road measurements

Vehicle exhaust is the primary source of polycyclic aromatic compounds (PACs). Real road tests using a portable vehicle measurement system on light-duty gasoline vehicles and light-duty diesel trucks were conducted to investigate gas- and particle-phase polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs (NPAHs), and oxy-PAHs (OPAHs) in vehicle exhaust with different emission standards, fuel types, and altitudes. The results showed that with the tightening of emission standards, the overall emission factors (EFs) of PACs decreased. Compared with China V diesel vehicles, the emissions of PAHs, OPAHs, and NPAHs from China VI diesel vehicles were 75.1 %, 84.4 %, and 61.2 % lower, respectively. With a ~100 m increase in altitude, the EFs of PAHs, OPAHs, and NPAHs of diesel vehicles increased 1.88, 1.92, and 1.59 times due to incomplete combustion. In addition, the EFs of PAHs and OPAHs in gasoline vehicles were lower than those in diesel vehicles. In contrast, the proportion of PAHs with highly toxic components, such as dibenzo[a,h]anthracene (DahA) and benzo[a]pyrene (BaP), and the EFs of gas-phase NPAHs in gasoline vehicles were higher than those in diesel vehicles. Furthermore, the emissions of 1,8-DNP from diesel vehicles cannot be disregarded. 1,8-DNP was the main gas-phase NPAHs emitted by China VI and China V diesel vehicles, accounting for 49.3 % and 26.0 %, respectively. Moreover, gas-phase PACs contributed more to the EFs than particle-phase PACs, whereas particle-phase PACs have greater toxic effects. Although the EFs of PAHs are more than 100 times those of NPAHs, the toxic equivalent concentrations (TEQBaP) of PAHs in diesel and gasoline vehicles were approximately 6.5 times and 35 times those of NPAHs. The spatial distribution characteristics revealed that PACs emissions were mainly concentrated in urban areas and highways, and the differences in the toxicity of PACs emissions between different cities depended on the proportion of diesel vehicles. The average TEQBaP of PAHs and NPAHs in Haidong, Haibei, Huangnan, Hainan, Guoluo, and Yushu was 8.42 μg/m3 and 0.36 μg/m3, respectively, while those of Xining and Haixi were 0.24–0.29 μg/m3 and 0.09–0.108 μg/m3 higher, respectively. This study provides a comprehensive understanding of the emission characteristics, health risks, and spatial distribution of PACs from diesel and gasoline vehicle PACs in urban areas.

Historic distribution of Polycyclic Aromatic Compounds (PAC) in a Skagerrak fjord, Swedish west coast as reflected in a high-resolution sediment record and compared to the Environmental Quality Standards (EQS)

We present the historic distribution of Polycyclic Aromatic Compounds (PAC) in a Skagerrak fjord, a relatively unexploited area, on the Swedish west coast. PACs encompass various compounds, including PAHs, alkyl-PAHs, nitro-PAHs, and oxy-PAHs. These compounds, have environmental implications due to their harmful properties. Using a high-resolution sediment record, PAC variations including standard PAHs, nitro-PAHs and oxy-PAHs were investigated over the last approximately 170 years, comparing them with other European records. The sediment record reveals a significant increase in PAC levels during the 1940s–1950s, followed by peaks in the 1960s and 1970s, and a subsequent decrease in the 1980s. These trends align with industrial growth and evolving stronger environmental regulations in the region. The highest recorded concentration of PACs (1950–1970) reached levels comparable to present-day polluted urban environments. The study also compared PAH levels with EQS values. Results indicated that PAH levels exceeded EQS standards, potentially posing risks to sediment-dwelling organisms.

Sedimentary spatial variation, source identification and ecological risk assessment of parent, nitrated and oxygenated polycyclic aromatic hydrocarbons in a large shallow lake in China

Because polycyclic aromatic compounds (PACs) are persistent, universal, and toxic pollutants, understanding the potential source and ecological risk thereof in lakes is critical to the safety of the aquatic environment. Here, a total of 25 sedimentary samples were collected from Lake Taihu, China, in 2018. The total concentrations of 16 parent polycyclic aromatic hydrocarbons (PAHs), 15 nitrated PAHs (NPAHs), nine oxygenated PAHs (OPAHs), and five hydroxy-PAHs (OH-PAHs) ranged from 294 to 1243, 3.0 to 54.5, 188 to 1897, and 8.3 to 51.7 ng/g dw, with the most abundant compounds being fluoranthene, 1,8-dinitropyrene, 6H-Benzo[cd]pyren-6-one, and 2-phenylphenol, respectively. The spatial distribution of PACs in sediments of Lake Taihu showed elevated concentrations from east to west due to economic development and transportation. The positive correlations between most paired PAHs indicate that these compounds likely originated from similar sources. The total organic carbon and organic matter contents affected the distribution characteristics of PACs in sediments. Diagnostic ratios, principal component analysis-multiple linear regression (PCA-MLR), and positive matrix factorization (PMF) were integrated to identify the sources. PACs had various sources including combustion, petroleum leakage, traffic emissions, hydroxyl metabolism, and other oxidation pathways in sediments of Lake Taihu. The PMF (R2 > 0.9824), which showed better optimal performance compared with PCA-MLR (R2 > 0.9564) for PAHs and derivatives, is recommended as the preferred model for quantitative source analysis. Ecological risk assessment showed that the risk quotient values of OPAHs in sediments were much higher than those of other PACs and should be given special attention.

Alkylated Polycyclic Aromatic Hydrocarbons Are the Largest Contributor to Polycyclic Aromatic Compound Concentrations in the Topsoil of Huaibei Coalfield, China.

Alkyl polycyclic aromatic hydrocarbons (APAHs) are more toxic and persistent than their parent compounds. Here, the concentrations, composition profiles, and spatial distribution of polycyclic aromatic compounds (PACs) in 127 topsoil samples from Huaibei coalfield were analyzed. The PAC concentrations in different functional areas were significantly different: mining area > industrial area > residential area > agricultural area. APAHs were the major contributors to PACs, accounting for 71–83% of total PACs. Alkylnaphthalenes and alkylphenanthrenes were the primary APAH components, accounting for 83–87% of APAHs. Principal component analysis showed that petrogenic source, coal and biomass combustion, and vehicle emissions were the primary sources of PACs. By comparing the fingerprint information of soil, coal, and coal gangue, it was hypothesized that the petrogenic source of PAC pollution in typical mining areas and surrounding areas are coal particle scattering and coal gangue weathering. Some coal mining and industrial areas potentially pose risks to children, whereas others do not. There are limited evaluation criteria for alkyl PAHs; hence, the estimated risk is likely lower than the actual risk. In addition to the conventional 16 PAHs, it is critical to consider a broader range of PACs, especially APAHs.

Effect of the Wildfires on Sandy Podzol Soils of Nadym Region, Yamalo-Nenets Autonomous District, Russia

Active land disturbance of soil and environments appears even in remote landscapes of tundra and forest tundra. Wildfires become a frequent factor of soil degradation and intensification of permafrost degradation, also affecting the global balance of carbon, especially content and distribution of polycyclic aromatic compounds. Mature unaffected by fire sandy-textured podzols soils were investigated in comparison with the same soil strongly affected by surface fire in the end of August 2016 in surroundings of the Pangody settlement, Nadym district, Yamal region. Data obtained showed an intensive morphological transformation of the topsoil layers, decreasing total organic matter and apparently increasing the humus enrichment by nitrogen. Wildfires also result in complete transformation of the fractional composition of the polycyclic aromatic compounds. The sum of PAHs increases intensively as well as benzo(a)pyrene content in soils. Therefore, soils of the cryolithozone become more faced to the wildfires during the last decades. Even one-time fire effect results in serious transformation of soil geochemical state.

Suspended particulate matter collection methods influence the quantification of polycyclic aromatic compounds in the river system.

In this study, we compared the influence of two different collection methods, filtration (FT) and continuous flow field centrifugation (CFC), on the concentration and the distribution of polycyclic aromatic compounds (PACs) in suspended particulate matter (SPM) occurring in river waters. SPM samples were collected simultaneously with FT and CFC from a river during six sampling campaigns over 2years, covering different hydrological contexts. SPM samples were analyzed to determine the concentration of PACs including 16 polycyclic aromatic hydrocarbons (PAHs), 11 oxygenated PACs (O-PACs), and 5 nitrogen PACs (N-PACs). Results showed significant differences between the two separation methods. In half of the sampling campaigns, PAC concentrations differed from a factor 2 to 30 comparing FT and CFC-collected SPMs. The PAC distributions were also affected by the separation method. FT-collected SPM were enriched in 2-3 ring PACs whereas CFC-collected SPM had PAC distributions dominated by medium to high molecular weight compounds typical of combustion processes. This could be explained by distinct cut-off threshold of the two separation methods and strongly suggested the retention of colloidal and/or fine matter on glass-fiber filters particularly enriched in low molecular PACs. These differences between FT and CFC were not systematic but rather enhanced by high water flow rates.

Temporal variation in the deposition of polycyclic aromatic compounds in snow in the Athabasca Oil Sands area of Alberta.

Atmospheric deposition of polycyclic aromatic compounds (PACs) via and onto snow, and their releasing during spring snowmelt has been a concern in the Athabasca Oil Sands Region of Alberta. This study was designed to evaluate the concentrations, loadings, and distribution of PACs in springtime snowpack and how they have changed since the first study in 2008. Snowpack samples were collected in late winters 2011-2014 at varying distances from the main developments. PAC concentration and deposition declined exponentially with distance, with pyrenes, chrysenes, and dibenzothiophenes dominating the distribution within the first 50km. The distribution of PACs was different between sites located close to upgraders and others located close to mining facilities. Overall, PAC loadings were correlated with priority pollutant elements and water chemistry parameters, while wind direction and speed were not strong contributors to the variability observed. Total PAC mass deposition during winter months and within the first 50km was initially estimated by integrating the exponential decay function fitted through the data using a limited number of sites from 2011 to 2014: 1236kg (2011), 1800kg (2012), 814kg (2013), and 1367 (2014). Total loadings were estimated to have a twofold increase between 2008 and 2014, although the increase observed was not constant. Finally, kriging interpolation is presented as an alternative and more robust approach to estimate PAC mass deposition in the area. After a more intensive sampling campaign in 2014, the PAC mass deposition was estimated to be 1968kg.

Univariate and multivariate characterization of heavy fuel oil weathering and biodegradation in soil

Polycyclic aromatic compounds (PACs) of petrogenic origin are widespread contaminants of the environment. We investigated the weathering and biodegradation of fuel oil PACs in microcosms that contained natural soil or natural soil primed by adding bioremediated soil to a 2% concentration. In the primed soil, lag-phases were shorter, and biodegradation was more pronounced. To describe PAC degradation, changes in the relative distribution of PACs and changes in isomer ratios, that are specific for biodegradation, were determined by univariate and multivariate techniques. A multivariate approach based on normalized areas or isomer ratios, in combination with principal component analysis, provided the most detailed description of weathering and biodegradation. In particular, the sequence of degradation of PACs was more transparent when using the multivariate approach. We also identified new diagnostic ratios of dimethylphenanthrenes for use in the study of moderately and severely biodegraded samples.

Pyrolysis of Waste Tires with Copper Nitrate

Influence of copper(π)nitrate(CN) on the pyrolysis of waste tires in 50 cm3 static batch reactor in a nitrogen atmosphere are studied. The products of pyrolysis was investigated with in situ Fourier transform infrared (FT-IR) spectroscopy as well as off-line gas chromatography/Mass spectrometry (GC-MS). The combination of FT-IR and GC/MS analysis was able to elucidate the effects of CN. Comparing with the conditions in no salt nitrate, CN can obviously increase hydrogen yields and remarkably reduce the emission of hydrogen sulfide. At the same time, the addition of CN can change the distribution of polycyclic aromatic compounds such as phenanthrene, triphenylene, naphthalene etc. The composites and properties of the derived gases, pyrolytic oils and specific surface area and pore distribution of solid char were determined. The results showed that the gaseous mixture mainly are H2, C2H6, C3H8, CO2, CH4, C3H6, CO in sequence of the yields. The liquid mixture emphasis on the distribution of polycyclic aromatic compounds (PAHs). The pore distribution indicated that nearly 98% of pore volume is made up of less than 1.3 × 10−8 m of radius.

Distribution of PACs in surficial sediments and bioavailability to mussels, Mytilus edulis of Halifax Harbour

Surficial sediments and blue mussels were collected around the perimeter of Halifax Harbour. Samples were analysed for the levels and fingerprint of polycyclic aromatic compounds (PACs). The objective was to explore the relationship between contaminant profiles in sediments and in mussels and to explore the possibility of deducing their sources, pattern of deposition and circulation in the harbour. Combustion derived compounds predominated in both sets of samples, with more variability observed in the level of petroleum derived hydrocarbons in mussel samples. Biota-sediment accumulation factors (BSAF, dry/dry wt.) varied throughout the harbour, ranging from means of 0.006 to 1.26, where generally fluoranthene displayed the highest BSAF. Sediments and mussels give complementary views of the geographical distribution of contaminants, they reflect the state of benthic and pelagic habitats. Results observed for Halifax Harbour are discussed from the perspective of published data.

96/01218 Distribution of polycyclic aromatic compounds in coals of high rank

Fossil-bearing deposits in the Transantarctic Mountains, Antarctica indicate that, despite the cold nature of the continent’s climate, a tundra ecosystem grew during periods of ice sheet retreat in the mid to late Neogene (17–2.5 Ma), 480 km from the South Pole. To date, palaeotemperature reconstruction has been based only on biological ranges, thereby calling for a geochemical approach to understanding continental climate and environment. There is contradictory evidence in the fossil record as to whether this flora was mixed angiosperm-conifer vegetation, or whether by this point conifers had disappeared from the continent. In order to address these questions, we have analysed, for the first time in sediments of this age, plant and bacterial biomarkers in terrestrial sediments from the Transantarctic Mountains to reconstruct past temperature and vegetation during a period of East Antarctic Ice Sheet retreat. From tetraether lipids (MBT′/CBT palaeothermometer), we conclude that the mean continental summer temperature was ca. 5 °C, in agreement with previous reconstructions. This was warm enough to have allowed woody vegetation to survive and reproduce even during the austral winter. Biomarkers from vascular plants indicate a low diversity and spatially variable flora consisting of higher plants, moss and algal mats growing in microenvironments in a glacial outwash system. Abietane-type compounds were abundant in some samples, indicating that conifers, most likely Podocarpaceae, grew on the Antarctic continent well into the Neogene. This is supported by the palynological record, but not the macrofossil record for the continent, and has implications for the evolution of vegetation on Antarctica.

Distribution of Polycyclic Aromatic Compounds in Coals of High Rank

Abstract The concentration of 131 polycyclic aromatic compounds (PAC) has been determined by capillary gas chromatography in the solvent extracts of eight bituminous coals with vitrinite reflectance (Rr) in the range of 0.9–1.9%. The distributions of PAC that eluted between naphthalene and coronene are dominated by naphthalenes, biphenyls, fluorenes, phenanthrenes, fluoranthenes, pyrenes and their C1-C3 derivatives, oxygen-containing compounds (dibenzofurans), and sulphur heterocycles (dibenzothiophenes, benzo[b]-naphthothiophenes) which were selectively measured by an electrolytic conductivity detector. Discrepancies in concentration profiles among PAC can generally be related to differences in kinetic rather than thermodynamic stabilities. However, thermodynamic equilibration is indicated in certain instances, e.g., with methylphenanthrenes and methyldibenzothiophenes extracted from coals having reflectance values between 0.9 and 1.3% Rr where the total concentration of each group of isomers remains fai...