Polycyclic Aromatic Hydrocarbons In Sediments Research Articles

Assessment of parent and alkyl -PAHs in surface sediments of Iranian mangroves on the northern coast of the Persian Gulf: Spatial accumulation distribution, influence factors, and ecotoxicological risks

Spatial patterns, potential origins, and ecotoxicological risk of alkylated (APAH) –and parent –(PPAH) polycyclic aromatic hydrocarbons (PAHs) were studied in mangrove surface sediments along the northern coasts of the Persian Gulf, Iran. The mean total concentrations (ngg-1dw) ∑32PAH, ∑PPAHs and ∑APAHs in sediments were 3482 (1689-61228), 2642 (1109-4849), and 840 (478-1273), respectively. The spatial variability was similar among these PAH groups, with the highest levels occurring in Nayband National Marine Park (NNMP). Physicochemical environmental factors, such as sediment grain size, and total organic carbon (TOC) contents, are significant factors of PAH distribution. These findings suggest that PAH pollution level is moderate-to-high, supporting the current view that mangrove ecosystems are under intensive anthropogenic impacts, such as petrochemical, oil and gas loads, port activities, and urbanization. Non-parametric multidimensional scaling (NPMDS) ordination demonstrated that NNMP mangrove is the critical site exhibiting high loading of PAH pollutants. Here, for the first time in this region, Soil quality guidelines ( SQGs), Toxic equivalency quotient (TEQ), Mutagenic equivalency quotient (MEQ), and composition indices comprising Mean maximum permissible concentration quotient (m-MPC-Q), and Mean effect range median quotient (m-ERM-Q ) methods were used to have a comprehensive risk assessment for PAH compounds and confirmed medium-to-high ecological risks of PAHs in the study area, particularly in the western part of the Gulf, highlighting the industrial impacts on the environment.

Risk Assessments of Polycyclic Aromatic Hydrocarbons in the Surface Sediments of Drinking Water Sources in Ifite Ogwari, South-East Nigeria

ABSTRACT Surface water is the main source of drinking water in Ifite Ogwari, Anambra State, South-East Nigeria. In aquatic environments, sediment functions as both a source and a sink of polycyclic aromatic hydrocarbons (PAHs). To determine the level of pollution, health concerns to people and the environment, and potential sources of PAHs in the surface water sediments in Ifite Ogwari, sediment samples were collected from 9 surface water sources used for drinking by Ifite Ogwari people and were analyzed using a Gas Chromatography/Flame Ionization Detector (GC-FID). In all sediment samples, only 11 PAHs out of 16 United States Environmental Protection Agency (USEPA) priority PAHs were detected while 5 were below detectable limits. The concentration of benzo[a]anthracene was high but detected in only 2 sediment samples while fluoranthene has a relatively close concentration across all samples. Benzo[k]fluoranthene has the highest concentration compared to other PAHs in the samples while benzo[a]pyrene has the lowest concentration across all samples. Atammele sediment was analyzed as the most carcinogenic followed by Isiachala with concentrations of 84.23 ng/µL and 51.92 ng/µL respectively. Ube stream sediment has the lowest concentration of PAHs (11.74 ng/µL). Ecological risk of the PAHs revealed a sediment-to-sediment variation in the risk profile. Human health risk assessment depicts that hazard index and total cancer risk for adults and children ranged from 2.3E-07 - 2.57E-05 and 4.85E-07 - 5.43E-05 respectively. Pyrogenic activities are the main source of PAHs in the sediments. The results provide a guide for monitoring PAHs pollution and protecting drinking water sources.

Temporal and spatial distribution of polycyclic aromatic hydrocarbons (PAHs) in the Danube River in Hungary

The Danube is a significant transboundary river on a global scale, with several tributaries. The effluents from industrial operations and wastewater treatment plants have an impact on the river's aquatic ecosystem. These discharges provide a significant threat to aquatic life by deteriorating the quality of water and sediment. Hence, a total of 16 Polycyclic Aromatic Hydrocarbons (PAHs) compounds were analyzed at six locations along the river, covering a period of 12 months. The objective was to explore the temporal and spatial fluctuations of these chemicals in both water and sediment. The study revealed a significant fluctuation in the concentration of PAHs in water throughout the year, with levels ranging from 224.8 ng/L during the summer to 365.8 ng/L during the winter. Similarly, the concentration of PAHs in sediment samples varied from 316.7 ng/g in dry weight during the summer to 422.9 ng/g in dry weight during the winter. According to the Europe Drinking Water Directive, the levels of PAHs exceeded the permitted limit of 100 ng/L, resulting in a 124.8% rise in summer and a 265.8% increase in winter. The results suggest that the potential human-caused sources of PAHs were mostly derived from pyrolytic and pyrogenic processes, with pyrogenic sources being more dominant. Assessment of sediment quality standards (SQGs) showed that the levels of PAHs in sediments were below the Effect Range Low (ERL), except for acenaphthylene (Acy) and fluorene (Fl) concentrations. This suggests that there could be occasional biological consequences. The cumulative Individual Lifetime Cancer Risk (ILCR) exceeds 1/104 for both adults and children in all sites.

Seasonal variation and concentration of PAHs in Lake Balaton sediment: A study on molecular weight distribution and sources of pollution

The temporal and spatial variations of 16 Polycyclic Aromatic Hydrocarbons (PAHs) were examined at multiple sites around Lake Balaton from February 2023 to January 2024. The results indicated that the concentrations of PAHs in sediment were high during the winter months, 448.35 to 619.77 ng/g dry weight, and low during the summer months, 257.21 to 465.49 ng/g dry weight. The concentration of high molecular weight PAHs (HMWPAHs), consisting of 5–6 rings, was greater than that of low molecular weight PAHs (LMWPAHs), which had 2–3 rings. The total incremental lifetime cancer risk (ILCR) for both dermal and ingestion pathways was high for both adults and children during the four seasons, with the highest records as the following: winter > spring > summer > autumn. The ecological effects of the 16 PAHs were negligible except for acenaphthylene (Acy) and fluorene (Fl), which displayed slightly higher concentrations during the autumn and spring, respectively.

Sourcing aliphatic and polycyclic aromatic hydrocarbons (PAHs) in Jinga shrimp (Metapenaeus affinis) muscle tissues and surface sediments (study case: Northwest Persian Gulf).

This study addresses the sources of aliphatic hydrocarbons (AHs) and polycyclic aromatic hydrocarbons (PAHs) in the surface sediments of the northwestern Persian Gulf and the muscle tissues of Jinga shrimp (Metapenaeus affinis), a commercially important aquatic species. In November 2018, 28 Jinga shrimp samples were systematically collected from four key fishing areas in Behrgan and Khormusi: Imam Khomeini Port (S1), Mahshahr Port (S2), Sejafi (S3), and Behrgan Wharf (S4). Additionally, sediment samples were collected from these locations, and AHs and PAHs concentrations were analyzed using gas chromatography-mass spectrometry (GC-MS). The average aliphatic concentration in Jinga shrimp was 4800.32 (μg g-1 DW), exceeding the sediment samples' 2496.69 (μg g-1 DW) estimate. Hydrocarbon component analysis revealed EPA priority list (PAH-16) and measured PAHs (PAH-29) concentrations in Jinga shrimp ranging from 1095.8 to 2698.3 (ng g-1 DW) and in sediments from 653.6 to 1019.5 (ng g-1 DW). Elevated AHs and PAHs in Jinga shrimp, compared to sediments, suggest a petrogenic source, notably at station S4 near Behrgansar and Nowruz oil fields. Low molecular weight (LMW) compounds dominated in both shrimp and sediment PAHs. Aliphatic composition profiles in shrimps closely mirrored sediment profiles, illustrating an even-to-odd carbon dominance gradient. Diagnostic ratio examinations of hydrocarbons indicated pervasive petroleum derivatives in the environment. This study establishes a direct correlation between hydrocarbon concentrations in shrimp and sediment samples and the corresponding aliphatic groups, PAH-16, and PAH-29. The findings underscore the potential of Jinga shrimp as a reliable indicator of hydrocarbon pollution in the northwestern Persian Gulf.

Characterization of polycyclic aromatic hydrocarbons in mangrove sediments from Ifiekporo Creek, Warri, Nigeria

The occurrence and level of polycyclic aromatic hydrocarbons (PAHs) in mangrove sediment from Ifiekporo Creek in Warri, Delta State, Nigeria, were assessed in this study. The extraction of PAHs from the sediment samples was achieved using the PAH analytical test method (USEPA 8270). This method measures the individual concentrations of extractable PAHs in samples. The PAHs were quantified within the C11-C22 subgroup. The basic GC parameters for the analysis of polyaromatic hydrocarbons were analysed using a gas chromatography‒mass selective detector (GC‒MSD). The individual PAH concentrations in the mangrove sediment samples ranged from 850 µg/kg−1 to 3470 µg/kg−1. PAH source apportionment employing isomeric ratios and multivariate statistics indicated both pyrogenic and petrogenic source inputs in the sediment samples. The order of PAH homology in the sediment was 3-ring > 2-ring > 4-ring. The sediment samples were mostly dominated by LMW PAHs. The results of the ecological risk assessment in the study area indicate that there is low ecological risk associated with PAH exposure in sediment. These results provide data on the concentrations and compositional patterns of PAHs, which is useful for understanding the effects, sources, fates, and transport of PAHs in sediment in the study area, as well as for providing relevant information for environmental quality management and forensic studies.

[Spatial-temporal Distribution and Source Analysis of Polycyclic Aromatic Hydrocarbons in the Sediments of Poyang Lake].

The concentrations, spatial-temporal distribution, and influencing factors of 16 polycyclic aromatic hydrocarbons (PAHs) in the sediments of Poyang Lake were studied, and a quantitative source analysis of PAHs in different areas of the lake was conducted. PAHs were widespread within the sediments. The concentrations of ∑16PAHs in the surface sediments of all sites ranged from 203 to 2 318 μg·kg-1. The concentrations of PAHs in the surface sediments of the lake body were higher than those in the surface sediments of the inlet rivers. The ratio of PAHs in Poyang Lake was 4 rings > 5 rings > 6 rings > 3 rings > 2 rings; the composition of 4-ring PAHs was dominant, and its content accounted for 86.11% of ∑16PAHs. The 2- and 3-ring and some 4-ring PAHs, including Flua and Pyr, were more susceptible to SOM, and the 4 through 6-ring PAHs were more susceptible to ORP and heavy metals and other environmental factors. Spatially, the higher concentration of ∑16PAHs occurred in the area of the lake adjacent to Duchang County and Poyang County, where the terrain was relatively closed, and the water exchange with the surrounding area was less than that in other sections, which was not conducive to the migration, transformation, and degradation of pollutants. In the temporal distribution, the changes in PAHs concentration level and the development of GDP in Jiangxi Province showed high consistency, and the influence of economic development and human activities might have been the main reason for the increasing PAHs concentration level. The main sources of PAHs in surface sediments of Poyang Lake included petroleum pollution and oil and coal and biomass combustion sources, and there were some spatial differences in PAHs sources in different regions. This study can provide a reference for PAHs pollution in surface sediments of Poyang Lake, which is important for the ecological environmental protection and management of Poyang Lake.

Variations in the concentration, inventory, source, and ecological risk of polycyclic aromatic hydrocarbons in sediments of the Lake Chaohu

In this study, the ecological risk assessment of PAHs pollution, the existing S-T model was improved and applied to this PAHs pollution assessment in surface sediment in Lake Chaohu. The potential sources and contributions of PAHs in the surface sediment were estimated by molecular diagnostic ratio (MDR) and positive matrix factorization (PMF). The results showed that the average concentration of 16 priority PAHs in the surface sediment was 718.16 ng/g in 2009 and 334.67 ng/g in 2020. In 2020, PAHs concentration has decreased compared to 2009 and the dominant composition has changed from high- to low-molecular-weight PAHs. The estimated PAHs mass inventory of the top 2 cm surface sediment was 2712 tons in 2009 and 1263 tons in 2020. Ecosystem risk assessment by improved S-T models suggested that the overall ecosystem risk of the studied regions was acceptable.

Sediment records and multi-media transfer and fate of polycyclic aromatic hydrocarbons in Dianchi Lake over the past 100 years

This study analyzed the fate and transfer of PAHs through multiple media in Dianchi Lake and the sediment records of polycyclic aromatic hydrocarbons (PAHs) in sediments. The model simulation results showed the simulated concentrations to be in good agreement with the measured values. The concentration and total amount of PAHs were the highest in the sediment, which is an important sink for PAHs in lake systems. The main transport direction of the PAHs in the three phases was from the atmosphere to the water to the sediment. Advection and emission inputs were the primary input pathways for PAHs in the atmosphere, and advection output was the main removal path. The main input sources pathways for PAHs in sediments was the sedimentation of particulate matter in water, with diffusion and degradation being the primary methods of removal. Advection and atmospheric dry and wet deposition were the main sources of PAHs in water, with particulate deposition being the primary removal process. The range of PAHs was 336–3520 ng/g in sediments in Dianchi Lake, with an average of 1569 ng/g, peaking in 2012. Among the predicted future PAH concentrations in the sediments under the five shared socioeconomic pathways (SSPs), the lowest PAH concentration was found under SSP3 from 2025 to 2035, whereas the lowest PAH concentration was found under SSP4 from 2035 to 2050. In the sustainable path of SSP1, although the concentration of PAH pollutants showed an increasing trend in the short term, the increase in PAHs concentration in sediments slowed in the long run.

History of organic pollution in montane lake Issyk-Kul, Kyrgyzstan, Central Asia, inferred from a sediment core

In arid regions, montane lakes are valuable water sources and play important ecological roles. However, recent human-induced inputs of organic pollutants are threatening lake ecology in such regions and becoming a matter of great concern. To investigate pollutant histories and sources, we measured polycyclic aromatic hydrocarbons (PAHs) and n-alkanes in a dated sediment core that spans the last ∼350 years, from montane Lake Issyk-Kul (Kyrgyzstan, Central Asia). Results showed that organic pollutants were delivered to Lake Issyk-Kul in four stages and that their concentrations increased from Stage I (∼1670–1800 CE) to Stage IV (∼2000–2010 CE). Furthermore, we tracked the sources of sedimented PAHs using their ratios combined with n-alkanes data. Ratios of PAHs Ant/(Ant + Phe), Flt/(Flt + Pyr) and Bap/BghiP indicated that inputs during Stage II (∼1800–1970 CE) and Stage III (∼1970–2000 CE) came mainly from high-temperature combustion of coal and vehicle emissions. PAHs in Stage I and Stage IV, however, were mainly derived from low-temperature combustion and petrogenic sources. Diagnostic PAH ratios, combined with the natural n-alkane ratio (NAR＜0) and unresolved complex mixtures (UCM), showed that the sources of PAHs in Stage I were mainly from erosion of bedrock and partly influenced by forest wildfires, different from the source during Stage IV, which was mainly from refined petroleum caused by accidental spills. Our assessment of the contamination history of the lake indicates that toxicity risk to the waterbody from sediment PAHs is low, but recent discharges arising from traffic deserve attention.

Distribution characteristics, source analysis and risk assessment of polycyclic aromatic hydrocarbons in sediments of Kuye River: a river in a typical energy and chemical industry zone.

This study systematically analyzed the distribution characteristics, sources, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in Kuye River sediments, located in an energy and chemical industry base in northern Shaanxi, China. The results that revealed the concentrations of 16 PAHs in the sediment ranged from 1090.04 to 32,175.68ng∙g-1dw, with the four-ring PAHs accounting for the highest proportion. Positive matrix factorization analysis (PMF) revealed the main sources of PAHs as incomplete fossil fuel combustion, biomass combustion, and traffic emissions. The total toxic equivalent concentration of BaP, risk quotient, and lifetime carcinogenic risk of PAHs suggested moderate to high contamination of PAHs in the area. The higher incremental lifetime carcinogenic risk (ILCR) indicated that PAH ingestion was the primary route of impact on public health, with children potentially being more susceptible to PAH exposure. This study can provide valuable theoretical support for implementing pollution prevention measures and ecological restoration strategies for rivers in energy and chemical industry areas.

Sources, Occurrences, and Risks of Polycyclic Aromatic Hydro-Carbons (PAHs) in Bangladesh: A Review of Current Status

Polycyclic aromatic hydrocarbons (PAHs) pollution has emerged as a significant environmental issue in Bangladesh in the recent years, driven by both economic and population growth. This review aims to investigate the current trends in PAHs pollution research, covering sediments, water, aquatic organisms, air particles, and associated health risks in Bangladesh. A comparative analysis with PAHs research in other countries is conducted, and potential future research directions are explored. This review suggests that the research on PAHs pollution in Bangladesh is less well studied and has fewer research publications compared to other countries. Dominant sources of PAHs in Bangladesh are fossil fuel combustion, petroleum hydrocarbons, urban discharges, industrial emissions, shipbreaking, and shipping activities. The concentrations of PAHs in sediments, water, air particles, and aquatic organisms in Bangladesh were found to be higher than those in most of the other countries around the world. Therefore, coastal sediments showed higher PAHs pollution than urban areas. Health risk assessments reveal both carcinogenic and non-carcinogenic risks to residents in Bangladesh due to the consumption of aquatic organisms. According to this investigation, it can be concluded that there are considerably higher PAHs concentrations in different environmental compartments in Bangladesh, which have received less research attention compared with other countries of the world. Considering these circumstances, this review recommends that future PAHs pollution research directions should focus on aquatic ecosystems, shipbreaking areas, air particles, and direct exposure to human health risks. Therefore, this study recommends addressing the identification of PAH sources, bioaccumulation, biomagnification in the food web, and biomarker responses of benthic organisms in future PAHs pollution research.

Anthropogenic contribution, transport, and accumulation of Polycyclic Aromatic Hydrocarbons in sediments of the continental shelf and slope in the Mediterranean Sea

A multidisciplinary approach, involving geochemical, sedimentological and oceanographic analyses, was employed to examine the distribution of Polycyclic Aromatic Hydrocarbons (PAHs) in a strongly anthropized area of the marginal Adriatic Sea (Mediterranean basin). The investigation into PAH distribution considered the grain size and biogeochemical properties of the sediments, as well as in relation to the main oceanographic processes and river inputs. Both biogeochemical and hydrographical inputs regulated the sedimentation of organic particles, influencing the distribution of PAHs. The results indicated PAH levels in 116 marine surface sediments ranging from 4 to 235 ng g−1 (average 55 ng g−1). The distribution of PAHs in Adriatic Sea surface sediments aligned with a higher clayey sedimentation in the deeper basin areas of the Middle Adriatic Depression.

Hydrocarbon-based parameters for the identification of oil contamination in an area with brown coal mining: Emphasis on pyrogenic index and alkylated PAHs

The aim of the study was to propose hydrocarbon-based parameters that can ben used to identify oil derived contamination in an area with a long-term load of coal mining industry. Aliphatic hydrocarbons and PAHs have been quantified for bottom sediments in the Bílina River, Czechia. Presented data demonstrate that all river sediments are highly contaminated with PAHs. The results showed that the distribution of PAHs was not possible to interpret by using the standard evaluation due to multisource long-term sedimentation of petroleum by-products, coal tars, and accidents of processing industry in the river system. The presence of petroleum derived hydrocarbons has been initially screened by the bulk parameter TEH and confirmed by the occurrence of steranes, hopanes and the unresolved complex mixture (UCM) in the chromatograms. The identification of the biomarkers 25-Norhopane and Gammacerane point out onsite microbial degradation of parent hydrocarbon compounds. The interpretation of the ratios Fl/Py, An/P, BaAn/Ch were not decisive to prove petrogenic origin of PAHs in the river sediments. However, using the combined evaluation of TEH together with the ratio of low molecular over high molecular weight PAHs, pyrogenic index and the presence of specific oil derived biomarkers allowed to prove the presence of petroleum contamination. Environmental implicationDue to oil spill accidents and intensive coal mining over the years, polycyclic aromatic hydrocarbons (PAHs) have been present in extreme amounts in bottom sediments of a tributary of the Elbe River, so called the Bílina River. Due to its hydrophobic and carcinogenic character, mutual understanding of the fate of alkylated PAHs homologues are usually overlooked within EPA PAHs 16 monitoring programme. This study pays attention to alkylated PAHs homologues and conventional diagnostic ratios when identifying oil derived contamination.

Occurrence characteristics, environmental trend, and source analysis of polycyclic aromatic hydrocarbons in the water environment of industrial zones

The middle reaches of the Yellow River are rich in energy resources, with the Kuye River, a first-class river in this region, serving as a vital hub for the coal chemical industry within China. This study investigated the occurrence patterns, environmental trends, and ecological risks associated with polycyclic aromatic hydrocarbons (PAHs) in the Kuye River Basin, offering insights into the environmental dynamics of regions. The findings indicated that the river sediments primarily contained PAHs with medium to high-molecular weights, exhibiting levels ranging from 402.92 ng/g dw to 16,783.72 ng/g dw, while water bodies predominantly featured PAHs with low to medium molecular weights, ranging from 299.34 ng/L to 10,930.9 ng/L. The source analysis of PAHs indicated that industrial and traffic exhaust emissions were the primary contributors to PAHs in the Kuye basin, with sediments serving as a secondary release source based on fugacity fraction. The content of PAHs in sediment correlated closely with the environmental factors, and the PAHs inventory of the basin was 19.97 tons. The increased overall PAH concentration in the basin posed significant ecological and public health concerns, necessitating urgent attention.

Does mangrove leave falling dominate the bury of polycyclic aromatic hydrocarbons in the mangrove of China?

Mangrove wetlands are vital coastal ecosystems that can absorb and accumulate pollutants. Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants that pose potential risks to ecosystems and human health. However, their source and transport fate in mangrove areas are poorly understood. This study investigates 29 PAHs pollution of water and sediment in Zhangjiangkou Mangrove Wetland, the northernmost large-scale mangrove wetland reserve in China. We examine the distribution, source, transport mechanisms and risk assessment of PAHs. The results show that the concentrations of PAHs in mangrove sediment range from 55.62 to 347.36 ng/g (DW), with 5-ring PAHs being the dominant species. While the concentrations of PAHs in surface water range from 10.61 to 46.39 ng/L, with 2-ring PAHs and alkylated PAHs being the dominant species. The PAHs concentrations in surface water and sediment of river are higher than those in mangrove area, indicating that mangrove water could receive PAHs through tidal exchange. Based on diagnostic ratios (DRs), principal component analysis (PCA), and positive matrix factorization (PMF), we infer that the leaf deposition (48.55%) could be an important pathway of PAHs in mangrove sediment except for river water transport (51.45%), while the PAHs in estuary water originate mainly from point sources such as biomass burning (50.96%) and traffic emission (49.04%). The range of toxic equivalents in surface water and sediment was 2.73–16.09 ng TEQ g−1 and 0.03–3.63 ng/L, respectively. Although the ecological risk assessment suggests that the PAHs pollution in surface water and sediment poses a low risk, we recommend more attention to the protection of the mangrove ecosystem. This study reveals that mangrove leaf falling might be a significant mechanism of PAH sequestration in the mangrove system, which deserves more attention in future research.

Effects of electron acceptors and donors on anaerobic biodegradation of PAHs in marine sediments

Polycyclic aromatic hydrocarbons (PAHs) are typical organic pollutants accumulated in the environment. PAHs' bioremediation in sediments can be promoted by adding electron acceptor (EA) and electron donor (ED). Bicarbonate and sulfate were chosen as two EAs, and acetate and lactate were selected as two EDs. Six groups of amendments were added into the sediments to access their role in the anaerobic biodegradation of five PAHs, containing phenanthrene, anthracene, fluoranthene, pyrene, and benzo[a]pyrene. The concentrations of PAHs, EAs and EDs, electron transport system activity, and microbial diversity were analyzed during 126-day biodegradation in serum bottles. The HA group (bicarbonate and acetate) achieved the maximum PAH degradation efficiency of 89.67 %, followed by the SL group (sulfate and lactate) with 87.10 %. As the main PAHs degrading bacteria, the abundance of Marinobacter in H group was 8.62 %, and the addition of acetate significantly increased the abundance of Marinobacter in the HA group by 75.65 %.

Correlation between polycyclic aromatic hydrocarbons and total organic carbon in surface sediments of the Bohai Sea and the North Yellow Sea.

The correlation between polycyclic aromatic hydrocarbons (PAHs) and organic carbon is an important indicator of the marine environment. In this paper, twenty-six surface sediment samples were collected from the Bohai Sea and the North Yellow Sea as the study area, and the contents of sixteen PAHs ranged from 71.34 ng·g-1 to 240.78 ng·g-1 with an average of 143.26 ng·g-1 by gas chromatography. The source analysis indicated the source of PAHs in the surface sediments of the study area was more complex, and the percentage of combustion sources was higher than that of petroleum sources, which might cause less negative ecological risks. The average content of total organic carbon (TOC) was 5.25%, as determined by automatic potentiometric titration, and the content of TOC was higher in the Bohai Sea than in the North Yellow Sea. TOC was significantly correlated with HWM-PAHs but was not correlated with LWM-PAHs, which proved organic matter was more effective in controlling high-molecular-weight PAHs than low-molecular-weight PAHs in the surface sediments of the Bohai Sea and the North Yellow Sea.

Concentrations, sources and risks of polycyclic aromatic hydrocarbons in sediments from the Parnaiba Delta basin, Northeast Brazil

The Parnaíba River is the main river in the Parnaíba Delta basin, the largest delta in the Americas. About 18 polycyclic aromatic hydrocarbons (PAHs) were identified and the environmental risk associated with the sediments was evaluated. The study found that PAHs levels ranged from 5.92 to 1521.17 ng g–1, which was classified as low to high pollution, and that there were multiple sources of pollution along the river, with pyrolytic sources predominating, mainly from urban activity such as trucking, although the influence of rural activity cannot be ruled out. PAHs correlated with black carbon and organic matter and showed high correlation with acenaphthylene, phenanthrene, pyrene, benzo(a)anthracene, chrysene, benzo(ghi)perylene, and ∑PAHs. The benzo(a)pyrene levels were classified as a risk to aquatic life because the threshold effect level and the probable effect level were exceeded. In addition, the sediments were classified as slightly contaminated with a benzo(a)pyrene toxicity equivalent value of 108.43 ng g–1. Thus, the priority level PAH exhibited carcinogenic and mutagenic activity that posed a potential risk to human health.

A Comparison Study on the δD Value of Polycyclic Aromatic Hydrocarbons in Hydrous Pyrolysate of Herbaceous Peat with Different Water Medium

AbstractTo investigate the influence of diagenetic water media on the hydrogen isotopes of individual sedimentary aromatic compounds, a series of hydrous pyrolyses were conducted on herbaceous peat. Polycyclic aromatic hydrocarbons (PAHs) in hydrous pyrolysed samples and their hydrogen isotopic composition characteristics were studied. The aqueous medium demonstrated a significant influence on the hydrogen isotopic composition of the individual PAHs generated during pyrolysis. The results showed that the PAHs formed after pyrolysis in the presence of a saltwater medium with high δD value from a salt lake had a heavy hydrogen isotopic composition. The PAHs formed after pyrolysis in the presence of a fresh water medium with low δD value from a swamp had a light hydrogen isotopic composition. The difference in the average PAH δD value between the two hydrous experiments varied from –174‰ to –109‰, suggesting that the hydrogen isotopic composition of individual sedimentary PAHs can reflect the source of the diagenetic water medium. In addition, a comparative study found that the hydrogen isotopes of PAHs were superior to those of n‐alkanes in the same sample for diagenetic water indications. The results indicated that the exchange of water‐derived inorganic hydrogen and organic hydrogen was more intensive in freshwater experiments than in saltwater experiments. With an increase in the simulation temperature, the average δD value of PAHs generated in the hydrous simulation experiments showed an increasing trend, reflecting that the δD value of sedimentary PAHs formed with the participation of diagenetic water media was still closely related to the thermal maturity of organic matter. Comparative studies showed that the δD values of different types of organic compounds produced by hydrous pyrolysis of peat were in the order, PAHs > n‐alkanes > methane.