Spatiotemporal PAH levels in surface water of the Southeastern Black Sea; baseline study from the Giresun shores

Chemo-metric appraisal on the distribution of polycyclic aromatic hydrocarbons in marine environment of Alang Ship Breaking Yard, India

This study investigated the comparative assessment of 15 priority USEPA polycyclic aromatic hydrocarbons (PAHs) in marine sediments and seawater at the world's largest shipbreaking yard Alang, Gujarat. The ∑PAHs concentration was found in between 0.30 and 31.35 μg/g in marine sediment and 0.02 to 3.22 μg/L found in seawater among all sampling spots. Furthermore among all PAHs fluoranthene showed a higher concentration followed by pyrene, indeno [1,2,3-cd]pyrene, and benz[a]anthracene in marine sediment. Four-ring compounds present higher compared to 2-3 rings, 5 rings, and 6 rings of PAHs from selected study areas. Diagnostic ratios were also applied for the possible sources of identification and present study area contaminated by both pyrogenic and petrogenic sources. The analysed data were also used for correlation study with seawater physicochemical parameters to identify positive correlations for their occurrences. The Nap, Flu, Flt, Pyr and BaA having the strong positive correlation with the seawater quality. Dibenz[a,h]anthracene showing zero coefficient with measured sea water quality. Hierarchical cluster analysis indicates, the control sampling spot is significantly different from other spots and this pattern was found in both sediments and water.

Distribution, sources and bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) in oysters of Sal estuary Goa, India

Present study aimed to unfurl occurrence and accumulation of Polycyclic Aromatic Hydrocarbons (PAHs) in water and oysters of Sal estuary (Goa, India). The highest total PAHs concentration were observed at mid estuary (SSJ2) region for water (594.36 μg L-1) and oyster (12,022.2 ng g-1 dry weight) respectively. Which is under high anthropogenic pressure and tidal influence. The lowest concentration of total PAHs were displayed by upper estuarine (SSJ1) region (1.04 μg L-1) for water and oyster (7019.1 ng g-1 dry weight) as it is well surrounded by mangroves and is relatively pristine. Diagnostic ratios suggested mixed source as primary PAHs source in the study area. According to EFSA guidelines, Exposure Daily Intake (EDI) values and Target Hazard Quotient (THQ) were within permissible limits thus risk to develop chronic systematic effects is low. Although, present scenario demonstrates low health risk, long term exposure might be detrimental. High prevalence low molecular weight PAHs were noted in water column while, significant accumulation of high molecular weight PAHs in oysters were due to hydrophobic and lipophilic characteristic of PAHs, which increases with molecular weight.

Polycyclic aromatic hydrocarbons in intertidal surface sediments of mangrove wetlands in Dongzhai Harbor, Haikou, China: Understanding sources, distribution, and ecological risk

Polycyclic aromatic hydrocarbons (PAHs) can be stored for long periods in soil or sediments, especially in sediments containing large amounts of organic matter, because of their special properties. Due to the high organic matter content in mangrove forests, this area serve as natural reservoir or a "sink" for persistent organic pollution. For this reason, sediment and soil samples were obtained from the mangrove wetland in Dongzhai Harbor, Hainan, to examine the distribution of PAHs concentration, source, and ecological danger. The PAHs content varied from 69.94 to 1481.91 ng·g-1 and presented a mean of 244.44 ng·g-1. The maximum PAHs concentration of 1481.91 ng·g-1 occurred at station DZ-03 which located at the innermost of the harbor. The PAHs concentrations in the other stations ranged within 69.94-356.66 ng·g-1, and the average value was 131.95 ng·g-1, which denotes a medium to low pollution level. The diagnostic ratio approach and principal component analysis revealed that the primary source of PAHs was the combustion of coal and biomass. The majority of the PAHs at Station DZ-03 showed high potential danger according to the ecological risk assessment. At the other stations, Ace and BghiP pose danger while the potential risk of the other PAHs was low. TEQBaP revealed high concentrations at Station DZ-03 and low concentrations at the other stations, where the overall potential ecological risk was low. Nevertheless, PAHs emissions should still be given attention, and the burning of fossil fuels and biomass should be reduced to decrease the potential ecological risk.

Comprehensive research of some semi-volatile organic compounds (SVOCs) at very low levels in Lake and marine waters in Antarctica on-site by SBSE thermal desorption GC-MS/MS: Distribution, source apportionment, ecological and human health implication

Antarctica is not immune to pollution, and Semi-volatile organic compounds (SVOCs) in Antarctica's water systems can reach the continent through long-range atmospheric transport, ocean currents, and human activities. The aim of this study was investigated the distribution of SVOCs, including PAHs, PCBs, and OCPs, in Antarctic lake and marine waters, assesses their potential sources, and evaluates the ecological and human health risks. The collected water samples were pretreated on-site in Antarctica using the stir bar sorptive extraction (SBSE) method. Water samples (500 mL) were extracted overnight (16 h), the SVOCs retained in the stir bars were analyzed by Thermal Desorption gas chromatography-tandem mass spectrometry (GC-MS/MS) in a competent laboratory in Türkiye. The method successfully extracted compounds with log Kow values above 2. A total of 33 water samples were analyzed, revealing ΣPAH concentrations between 0.484 and 2.570 ng/L (mean: 1.168 ng/L), ΣPCB between 0.099 and 0.343 ng/L (mean: 0.219 ng/L), and ΣOCP between 0.162 and 1.338 ng/L. Naphthalene, benz(a)anthracene, phenanthrene, and fluorene were the predominant PAHs, while PCB 101, PCB 52, PCB 28, biphenyl, cypermethrin, and beta-HCH were dominant among PCBs and OCPs. Elevated concentrations were observed at M4, L4, L5, and L9. Diagnostic ratios suggest petrogenic sources, particularly fossil fuel combustion and ship transportation emissions. Risk assessment showed that RQ values for SVOCs were below 1 in all samples, indicating negligible environmental risk. Furthermore, BaPeq values confirmed no immediate carcinogenic threat. Health risk analysis suggested that exposure to these pollutants does not pose significant non-carcinogenic or carcinogenic risks to children or adults based on regulatory criteria.

Mangrove guardians: Unearthing the enrichment patterns of PAHs in the Zhangjiang estuary ecosystem

Understanding the bioaccumulation of PAHs in mangrove plants is crucial as it reflects the ecosystem's ability to mitigate pollution and minimize its impacts on surrounding environments. The Zhangjiang Estuary mangrove ecosystem is a vital ecological asset in Fujian Province, however, the interactions between contaminants, such as polycyclic aromatic hydrocarbons (PAHs), and mangrove plant tissues remain underexplored. This study investigates the different bioaccumulation patterns and machanism of 26 PAHs in three mangrove species (Kandelia obovata, Aegiceras corniculatum, and Avicennia marina). PAHs concentrations in mangrove and estuarine sediments ranged from 55.68 to 247.76 ng/g and 119.16 to 346.03 ng/g, while Σ26PAHs in the mangrove plants ranged from 13.03 to 172.17 ng/g, which was dominated by two- and five-ring PAHs. The bioconcentration factors (BCFs) of plant tissues showed a wide range, from 0 to 330.17, stems exhibited the highest PAHs concentrations compared to roots and leaves, with BCFs in stems following average enrichment factors: two-ring PAHs (37.23 ± 13.33) > alkylated PAHs (9.40 ± 4.66) > three-ring PAHs (3.09 ± 2.20) > six-ring PAHs (2.29 ± 0.36) > five-ring PAHs (0.52 ± 0.06) > four-ring PAHs (0.03 ± 0.01). The BCFs in roots showed strong positive correlations with logKow and Koc values, while the trends in stems and leaves were reversed, suggesting that roots showed high affinity for hydrophobic compounds, while stems and leaves preferred more water-soluble PAHs. The bioaccumulation capacity was highest in Aegiceras corniculatum, followed by Kandelia obovata and Avicennia marina. Additionally, alkylated PAHs were more enriched than their parent compounds, indicating selective uptake potential in mangrove plants. These findings underscore the critical role of mangrove species in mitigating PAHs contamination through selective absorption and accumulation. The results provide valuable insights into the application of mangrove ecosystems in bioremediation and offer guidance for environmental management in coastal regions.

Fecundity of the snapping shrimp Alpheus estuariensis (Caridea: Alpheidae) after the oil spill in three mangroves of tropical Brazil

This study examined the impacts of oil spills since 2019 by analyzing polycyclic aromatic hydrocarbons (PAHs) in sediments and their effects on the fecundity of the shrimp Alpheus estuariensis. Samples were collected from mangroves in three Pernambuco locations: Catuama, Suape Bay, and Carneiros Beach. Ovigerous females were identified, and their eggs were counted and classified by embryonic stage. Sediment PAH levels were analyzed in freeze-dried and homogenized samples. A total of 107 females were analyzed, with varying distributions across sites. In the dry season, Carneiros showed the highest average fecundity (309 eggs), followed by Suape (238) and Catuama (154), without statistical differences. During the rainy season, Carneiros had significantly higher fecundity (605 eggs) compared to Catuama (176) and Suape (173). PAH concentrations were highest at Catuama (79 ng g-1), followed by Suape (72 ng g-1), and Carneiros (19 ng g-1). Fecundity was inversely related to PAH levels, with Carneiros showing the highest fecundity and lowest PAHs. Four years post-spill, high- molecular- weight PAHs (4-6 rings) were prevalent, posing carcinogenic and mutagenic risks. Diagnostic ratios indicated that PAHs primarily originated from pyrolytic processes, particularly combustion, highlighting biomass burning as a significant source. These findings emphasize the necessity for ongoing monitoring of impacted areas using model species to understand long-term environmental impacts on Brazil's northeastern coast.

Ecological effects and health risks of potentially toxic elements in Cyctoceria barbata and sediment

A comprehensive study was conducted to evaluate the levels, sources, potential ecological risks, and impacts on public health of potential toxic elements (PTEs) in the sediments and C. barbata in 8 cities located on the Turkish coast of the Black Sea. In all the measuring stations, the enrichment factors (EF) for Ni, Zn and Cu metals in the sediments were in the "minimal enrichment" class. All PTEs have shown "low ecological risk" at all stations according to the ecological risk index (Eri). As a result of the geo-accumulation index (Igeo) analysis, As, Cd, Cr, Cu, Ni, and Zn were evaluated as "practically uncontaminated" at all sampling points. It was determined that the sediments at all stations were rated as "no heavy metal pollution" according to the pollution load index (PLI) result, "low toxicity level" according to the toxic units (TUs) result, and "low ecological risk" according to the potential ecological risk index (PERI) result. According to the biological risk index (BRI) results, sediments in Artvin, Rize, Giresun, Ordu, Sinop and Kastamonu were evaluated as "low priority side" and in Trabzon and Samsun as "medium-low priority side". Since the metal pollution indeks (MPI) level was >1 in all stations, it is thought that C. barbata may pose a significant risk to human health if consumed.

A review on sources and distribution of polycyclic aromatic hydrocarbons (PAHs) in wetland ecosystem: focusing on plant-biomonitoring and phytoremediation

In the contemporary era, rapid global urbanization, coupled with intense industrial development, has led to a continuous influx of carcinogenic pollutants like PAHs, into the ecosystems. Owing to their long-range transportation potential, PAHs have driven their way from a regional scale to a global platform and become readily available in air, water, sediment, and biota of the most ecologically diverse ecosystems, like wetlands. The wetland ecosystems, due to their susceptibility to anthropogenic activities, face a heightened vulnerability to anthropogenic PAHs pollution. This PAHs pollution load adversely influences the unique biodiversity of wetlands. Hence, it is a pertinent to implement immediate and continuous monitoring programs to assess the present and ongoing PAHs pollution status. In this context, the use of plants for biomonitoring emerges as a potential alternative tool to the traditional monitoring process which also offers simultaneous mitigation mechanism and provides sustainability through detoxification. Therefore, sources and distribution of PAHs in wetland sediment and water are discussed in this review work to highlight the major sources of PAHs pollution and their distribution which would aid in proper strategic planning for phytoremediation the present study focuses on phytoremediation studies of wetland PAHs reported so far emphasizing its potential as a sustainable solution for addressing and mitigating PAHs pollution in wetlands. Various phytoremediation mechanisms are pointed out case to case to understand the plants' potential in bioremediation technique.

Environmental and health risk assessment of polycyclic aromatic hydrocarbons and toxic elements in the red sea using Monte Carlo simulation

This research evaluates the environmental and health risks linked to potentially toxic elements (PTEs) and PAHs along the western coast of the Gulf of Suez, Egypt. This study investigated the concentration of 16 PAH compounds in the Suez Gulf, revealing significantly higher levels than the EU (0.20 µg/L) and US (0.030 µg/L) standards. The average total PAH concentration across eight locations was significantly higher, with the Suez area having the highest concentration at 479 µg/L. Pyrene (Pyr) was the dominant PAH with a concentration of 443 µg/L in Suez, while acenaphthylene (Ace) had the lowest concentration at 0.120 µg/L in Northern Zaafarana. Carcinogenic PAHs (CAR) ranged from 8.67 µg/L at Ras Gharib to 29.62 µg/L at Suez, highlighting the urgent need for regulatory measures. Confirmatory ratios pointed to industrial and shipping influences as petrogenic sources. Elevated total organic carbon (TOC) levels in Suez Bay indicated aggravated organic pollution, exacerbated by oil rigs and refineries. The ecological risk assessment highlighted substantial risks, particularly in Suez, necessitating immediate interventions to combat PAH contamination and preserve the environmental balance of the Red Sea. The dominant metals in water samples were arranged in descending order as follows: Pb > Fe > Cr > Cu > Zn > Mn > Cd > Ni. The study evaluated environmental and human health risks using a multifaceted approach, including cluster analysis, principal component analysis, and various indices (HPI, RI, MI, HQ, HI, and CR). Most water samples exhibited high pollution risks, surpassing permissible limits for HPI (> 100) and MI (> 6). Notably, HI oral values indicated significant non-carcinogenic risks for adults and children. While HI values for adults suggested low-risk dermal contact, those for children showed a substantial proportion in the high-risk category. Most water samples displayed CR values exceeding 1 × 10-4 for Cd, Cr, and Pb, indicating vulnerability to carcinogenic effects in both age groups. Monte Carlo simulations reinforced these findings, revealing a significant carcinogenic impact on children and adults. The identified clusters, reflective of industrial, petroleum-related, and urban runoff contamination sources, were consistently validated and clarified through PCA, enhancing the reliability of the findings. In light of these results, urgent and comprehensive water treatment measures are imperative to mitigate carcinogenic and non-carcinogenic health risks. These insights provide a foundation for implementing targeted management strategies to effectively address the challenges of heavy metal contamination in the Red Sea.

Tailor-made ammonia nitrogen risk management with machine learning models for aquatic environments in the Mainland of China

Efficient management of pollutant risks in water bodies is crucial for public health and aquatic ecosystem sustainability. However, the toxicities of pollutants, such as ammonia nitrogen (NH3-N), are often affected by multiple water quality factors, including the pH and water temperature. Extensive spatial and temporal variability in these factors hinders tailor-made management of risk. This study used high-frequency monitoring data collected over 1 year to evaluate the long-term NH3-N risk in China's aquatic ecosystems. High accuracy and interpretability were achieved by decomposing NH3-N risk into the contributions of key influencing factors using random forest models and Shapley Additive Explanations. Two distinct types of NH3-N risk hotspots were identified across 18 cities: 15 cities with high NH3-N concentrations and 3 cities with low environmental carrying capacity due to high pH levels or elevated water temperatures. For the former, rapid NH3-N abatement measures are necessary to bring NH3-N concentrations back below the environmental capacity. For the latter, it is recommended that NH3-N related industries are relocated to regions with high environmental capacities because fragile environments are not suitable for such industries. Importantly, this study investigated methods for attributing pollutant risks in the context of non-linear influencing factors, and the risk of NH3-N was predicted to increase by 6.1 % by the end of 2100 in the context of increasing temperatures under the SSP 2-4.5 scenario. The methodology is also adaptable and suitable for integration into global ecosystem risk management efforts to balance development and aquatic ecological sustainability.

Hydrocarbons in waters and bottom sediments of the coastal areas of the Caucasian sector of the Black Sea (2021-2023)

The current level of aliphatic and polycyclic aromatic hydrocarbons was determined in suspended particulate matter of waters (mainly in surface waters) and in upper layer of bottom sediments of coastal areas in the Caucasian sector of the Black Sea of the Russian Federation (September 2021, May and September 2022, March 2023). IR method was used to determine the aliphatic hydrocarbons, and the method of high performance liquid chromatography was employed for PAHs. The average concentration of aliphatic hydrocarbons was ≈20 μg/L and for polycyclic aromatic hydrocarbons ≈130 ng/L in suspended particulate matter in open surface waters of Gelendzhik and Golubaya bays. Their content naturally increased as they approached the coast. Despite the decrease in hydrocarbon concentrations in surface waters in recent years, the Kerch Strait and Novorossiysk remain the most polluted areas as before. Higher concentrations in the waters of the Taman Peninsula may be caused by the seepage of hydrocarbons from the sedimentary layer. Hydrocarbons are accumulated in bottom sediments, that leads to their rising portion in total organic carbon (e.g., aliphatic hydrocarbons up to 14.2 % in the Tuapse region and 13.1 % in the Novorossiysk region). Along with contamination from anthropogenic sources, natural processes also affect the hydrocarbon levels such as high biological productivity of the area and fluid flows from the sediment layer.

Exploring source-specific ecological risks of PAHs near oil platforms in the Yellow River Estuary, Bohai Sea

The Yellow River Estuary (YRE) is one of highly remarkable regions profoundly impacted by human activities, with numerous oil platforms dispersed throughout. In this area, offshore oil exploitation may pose significant ecological risks. To comprehensively evaluate the quantitative impacts of oil field exploitation on the marine coastal ecosystem, this study investigated the occurrence, sources, and ecological risks associated with 16 polycyclic aromatic hydrocarbons (PAHs) in seawater and sediment near oil platforms in the YRE. We found that 1) The concentrations of PAHs decreased from the surface seawater to sediments; 2) The ecological risk level of PAHs in seawater exceeded that in sediments; 3) terrestrial sources (combustion), rather than offshore oil drilling activities, significantly influenced regional ecological risks through processes of atmospheric deposition and surface runoff. These findings provide essential data for future estuarine research efforts while supporting mitigation measures aimed at addressing marine environmental pollution related to oil production activities.

Identification of key anthropogenic and land use factors and ecological risk assessment of dissolved polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in an urbanized estuary in China

This study investigated dissolved PAHs and OCPs in Quanzhou Bay estuaries, assessed their ecological risk, and examined anthropogenic impacts on contaminant distribution. Results showed that dissolved ∑24PAH concentrations ranged from 117 to 709 ng/L (mean: 358 ng/L), with dominance of 2-ring PAHs (Naphthalene, 1-Methylnaphthalene, and 2-Methylnaphthalene). Dissolved DDT levels ranged from 0.06 to 0.49 ng/L (mean: 0.28 ng/L), while HCBz concentrations varied from 0.02 to 0.44 ng/L (mean: 0.20 ng/L). PAHs were higher in the north due to urbanization and transport, while OCPs showed higher levels in the south due to historical agricultural use. Rural areas, water bodies, and wetlands significantly influenced the behavior of PAHs according to Spearman correlation and lasso regression analyses. Quanzhou Bay was categorized as a low to medium risk area based on dispersion simulation and ecological risk assessment, highlighting implications for future sustainable development and policy planning. CAPSULE: The coupled relationship between human activities and the distribution of dissolved PAHs and OCPs in urbanized estuaries was explored using statistical methods and GIS technology, providing valuable insights into environmental processes and pollutant control policies.

PAHs contamination in ports: Status, sources and risks

Polycyclic aromatic hydrocarbons (PAHs) constitute important organic contaminants that have been degrading coastal ecosystems over the years. Evaluating PAH status in port ecosystems aligns with societal goals of maintaining clean habitats and sustainability. This comprehensive review systematically analyzed 123 articles, exploring the global distribution, sources, and ecological risks linked to PAH contamination in ports, focusing on water, sediment, and biota. The mean concentrations of 16 PAHs in water, sediment, and biota across worldwide ports were 175.63 ± 178.37 ng/L, 1592.65 ± 1836.5 μg/kg, and 268.47 ± 235.84 μg/kg, respectively. In line with PAH emissions and use in Asia, Asian ports had the highest PAH concentrations for water and biota, while African ports had the highest PAH concentrations for sediment. The temporal trend in PAH accumulation in sediments globally suggests stability. However, PAH concentrations in water and biota of global ports exhibit increasing trends, signaling aggravating PAH contamination within port aquatic ecosystems. Some ports exhibited elevated PAH levels, particularly in sediments with 4.5 %, 9.5 %, and 21 % of the ports categorized as very poor, poor, and moderate quality. Some PAH isomers exceeded guidelines, including the carcinogenic Benzo(a)pyrene (BaP). Coal, biomass, and petroleum combustion were major sources for PAHs. The structure of ports significantly influences the concentrations of PAHs. PAH concentrations in sediments of semi-enclosed ports were 3.5 times higher than those in open ports, while PAH concentrations in water and biota of semi-enclosed ports were lower than those in open ports. Finally, risk analyses conducted through Monte Carlo simulation indicated moderate to high risks to aquatic species, with probabilities of 74.8 % in water and 34.4 % in sediments of ports worldwide. This review underscores the imperative to delve deeper into the accumulation of PAHs and similar pollutants in ports for effective management and environmental protection.

Release of PAHs from sediments to seawater under wave: Indoor microcosms and level IV fugacity models

Estuaries and coasts are located at the land-sea interface, where sediment liquefaction due to strong wave action results in significant material exchange at the sediment-seawater system. Polycyclic aromatic hydrocarbons (PAHs), as organic pollutants, are distributed across various media. Herein, the impact of wave was studied on the release of PAHs through indoor microcosmic experiments combined with a level IV fugacity model. Comparison revealed that the release amount and rate of PAHs during static consolidation stage were minimal, whereas wave action substantially enhanced the release. Particularly the sediments in a liquefied state, the PAHs release in Stage III was 1.55-1.86 times that in Stage II, reaching 84.73 μg/L. The loss of soil strength and strong hydrodynamic effects resulted in a substantial release of PAHs into seawater along with suspended solids. Due to volatility of 2-ring PAHs and difficult desorption of 6-ring PAHs, 3-5-ring PAHs are the main contributors to releases into seawater. The model results also indicated that the three PAHs had different fates in the sediment-seawater system, with sediment serving as an important "reservoir" for benzo[a]pyrene entering seawater, while functioning as both a "sink" and a "source" for pyrene.

Distribution, sources and ecological risks of PAHs and n-alkanes in water and sediments of typically polluted estuaries: Insights from the Xiaoqing River

Seasonal water and sediment samples were collected from the Xiaoqing River estuary and the neighboring sea to study the spatial and temporal distributions, sources and ecological risks of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes. The results showed significant spatial and temporal differences in the concentrations of PAHs and n-alkanes under the influence of precipitation, temperature, and human activities. The concentrations of PAHs in water were lower in the wet season than in the dry season, and those in sediments were higher in the wet season than in the dry season. The concentrations of n-alkanes were higher in the rainy season than in the dry season for both water and sediments. The spatial distributions of PAHs and n-alkanes were estuarine > offshore. The concentration ranges of ∑PAHs in water and sediments were 230.66-599.86 ng/L and 84.51-5548.62 ng/g, respectively, in the wet season and 192.46-8649.55 ng/L and 23.39-1208.92 ng/g, respectively, in the dry season. The proportion of three-ring PAHs in water (57.03% and 78.27% in the wet and dry seasons, respectively) was high, followed by two-ring PAHs (27.31% and 13.59% in the wet and dry seasons, respectively). The proportion of four-ring PAHs was higher in sediments (24.79% and 32.20% in the wet and dry seasons, respectively). The ecological risk of PAHs assessed using the toxicity equivalent quotient and risk quotient was at moderate to moderately high risk levels. The high concentration of n-alkane fraction C16 (611.65-75594.58 ng/L) in the water is indicative of petroleum or other fossil fuel inputs. The main peaks of n-alkanes in river sediments were C27, C29 and C31, indicating higher inputs of plant sources. The sediments in the estuary showed dominance of both short-chain C16 and long-chain C25-C31, indicating a combined input of higher plants and petroleum. The diagnostic ratios of PAHs and n-alkanes indicated that their sources were mainly oil/coal/biomass combustion and petroleum spills attributed to frequent vehicular, vessel and mariculture activities. Given the potential ecological risks of PAHs and n-alkanes in water and sediments, future studies should focus on their bioaccumulation and biotoxicity.

Occurrence, removal, and risk assessment of polycyclic aromatic hydrocarbons and their derivatives in typical wastewater treatment plants

Wastewater treatment plants (WWTPs) have a certain removal capacity for polycyclic aromatic hydrocarbons (PAHs) and their derivatives, but some of them are discharged with effluent into the environment, which can affect the environment. Therefore, to understand the presence, sources, and potential risks of PAHs and their derivatives in WWTPs. Sixteen PAHs, three chlorinated polycyclic aromatic hydrocarbons (ClPAHs), three oxidized polycyclic aromatic hydrocarbons (OPAHs), and three methylated polycyclic aromatic hydrocarbons (MPAHs) were detected in the influent and effluent water of three WWTPs in China. The average concentrations of their influent ∑PAHs, ∑ClPAHs, ∑OPAHs, and ∑MPAHs ranged from 2682.50 to 2774.53 ng/L, 553.26-906.28 ng/L, 415.40-731.56 ng/L, and 534.04-969.83 ng/L, respectively, and the effluent concentrations ranged from 823.28 to 993.37 ng/L, 269.43-489.94 ng/L, 285.93-463.55 ng/L, and 376.25-512.34 ng/L, respectively. The growth of heat transport and industrial energy consumption in the region has a significant impact on the level of PAHs in WWTPs. According to the calculated removal efficiencies of PAHs and their derivatives in the three WWTPs (A, B, and C), the removal rates of PAHs and their derivatives were 69-72%, 62-71%, and 68-73%, respectively, and for the substituted polycyclic aromatic hydrocarbons (SPAHs), the removal rates were 41-49%, 31-40%, and 33-39%, respectively; moreover, the removal rates of PAHs were greater than those of SPAHs in the WWTPs. The results obtained via the ratio method indicated that the main sources of PAHs in the influent of WWTPs were the combustion of coal and biomass, and petroleum contamination was the secondary source. In risk evaluation, there were 5 compounds for which the risk quotient was considered high ecological risk. During chronic disease evaluation, there were 11 compounds with a risk quotient considered to indicate high risk. PAHs and SPAHs with high relative molecular masses in the effluent of WWTPs pose more serious environmental hazards than their PAHs counterparts.

Influence of oil extraction on concentration distributions, migration, secondary formation and carcinogenic risk of NPAHs and OPAHs in air and soil in an oilfield development area in China

Oil extraction leads to environmental pollution from the oilfields and dweller activities, however, knowledge of the concentration distributions, migration, secondary formation and toxicity of nitrated/oxygenated polycyclic aromatic hydrocarbons (N/OPAHs) in oilfield regions is limited. In this research, atmospheric and soil samples in 7 different location types in an important oil industrial base in China were gathered. The ΣNPAHs and ΣOPAHs in the air ranged from 0.05 to 2.47 ng/m3 and 0.14-22.72 ng/m3, respectively, and in soil ranged from 0.22 to 17.81 ng/g and 9.69-66.86 ng/g, respectively. Both NPAHs and OPAHs in the atmosphere exhibited higher concentrations during winter. The atmospheric NPAH concentrations decreased exponentially with distance from urban area especially in the summer, revealing the impact of vehicles on the air in the Yellow River Delta area. High NPAH and OPAH concentrations were found only in soil near oil extraction facilities, indicating that the impact of oil extraction is limited to the soil near the extraction facilities. The air-soil exchanges of N/OPAHs were assessed through fugacity fraction analysis, and NPAHs were in the equilibrium-deposition state and OPAHs were in the net-deposition state in the winter. Higher incremental lifetime cancer risk (ILCR) occurred at the urban, industrial, and oilfield sites in the atmospheric samples, and the soil samples had the largest ILCR values in the oilfield sites. However, ILCR values for both air and soil did not exceed the threshold of 10-6.

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.

Risk assessment of trace metals and polycyclic aromatic hydrocarbons in seawater of typical bays in the Bohai Sea

The ecological risks of trace metals (Cu, Zn, As, Cd, Pb, and Hg) and PAHs in seawater from three typical bays of the Bohai Sea (the Liaodong Bay, Bohai Bay, and Laizhou Bay) were comprehensively assessed by recompiling 637 sites. Results highlighted that scrutiny should be given to the ecological risks of Cu (3.80 μg/L) in the Bohai Bay and Hg (0.23 μg/L) in the Laizhou Bay. Conversely, the Liaodong Bay exhibited negligible ecological risks related to trace metals. The risks of ΣPAHs in the Liaodong Bay, Bohai Bay, and Laizhou Bay were moderate, with mean concentrations of 368.16 ng/L, 731.93 ng/L, and 187.58 ng/L, respectively. The source allocation of trace metals and PAHs required consideration of spatial variability and anthropogenic factors, which greatly affected the distribution and composition of these pollutants. The combined ecological risks in the Bohai Bay (6.80 %) and Laizhou Bay (5.43 %) deserved more attention.

Distribution, sources, partition behavior and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in the waters and sediments of Lake Ulansuhai, China

This study represents the first comprehensive investigation of 16 polycyclic aromatic hydrocarbons (PAHs) in the waters and sediments of Lake Ulansuhai. It explores their occurrence, sources, transport behavior, and associated risks to human health and ecosystems. The results revealed that concentrations of ∑PAHs in dissolved phase and sediment with no significant seasonal differences. In contrast, ∑PAHs concentrations in suspended particulate matter were significantly higher during the ice-free period compared to the ice period. Spatially, the northern part of Lake Ulansuhai displayed higher PAHs content. Diagnostic isomeric ratios and PMF models indicated that the PAHs were primarily derived from combustion sources. The distribution of PAHs within water-sediment demonstrated that non-equilibrium status. Fugacity calculations indicated that 2-4 rings PAHs acted as secondary sources of sediment emissions. Toxicity assessment, indicated that PAHs posed no significant carcinogenic risk to humans. Risk quotient values showed that PAHs as low to high ecological risk.

Distribution and sources of polycyclic aromatic hydrocarbons in surface sediments of the East China marginal seas: Significance of the terrestrial input and shelf mud deposition

To investigate the distribution, sources, influencing factors, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in East China Marginal Seas (ECMSs) sediments, we measured the concentrations of 16 PAHs in 104 surface sediment samples collected from the ECMSs in 2014 and 2016. Total PAH concentration (∑PAHs) ranged from 4.49 to 163.66 ng/g dry weight (dry w), with 65.98 ± 33.00 (mean ± SD) ng/g dry w. The highest PAH concentrations and total organic carbon were observed in areas with fine-grained sediments in the Bohai Sea (BS), Yellow Sea (YS), and coastal East China Sea (ECS), indicating the prominent influence of regional hydrodynamics and sediment properties. The dominant PAH congener in BS and YS was BbF, whereas coastal ECS was Phe. The heterogeneity of PAH sources implies that terrestrial PAH input and shelf mud deposition have crucial roles in the source-sink processes of PAHs in a strongly human-influenced marginal sea.

PAH levels in sediments from a coastal area heavily subjected to anthropogenic pressure (Asturias, north of Spain)

Ninety-two sediment samples collected along the Asturias coastline (north of Spain), were studied based on their concentrations of 16PAHs. Concentrations of Σ16PAH showed an average of 12.650 mg kg-1 d.w., which is higher than most other studies conducted around the world. The origins of PAHs present in the sediments are mainly from fuel combustion in industrial processes. The main source of PAH to the coastal system seems to be the Nalón River, which played a significant past role related to different industrial activities, highlighting thermal power stations located in the basin. On the other hand, the Avilés Estuary, hotspot of the regional heavy metallurgical industry was the area with the highest concentrations of Σ16PAH, with an average of 5 to 6 times higher than the rest studied. The risk assessment of Σ16PAH concentrations in the study area showed a high potential risk of contamination transfer to other environmental compartments.

Spatiotemporal distribution, source analysis and ecological risk assessment of polychlorinated biphenyls (PCBs) in the Bohai Bay, China

As a class of persistent organic pollutants (POPs), the spatial and temporal distribution of polychlorinated biphenyls (PCBs) in seawater is important for environmental assessment. Surface water samples were collected from 35 stations during summer and 36 stations during autumn of 2020 in the Bohai Bay. The concentration, composition, distribution and sources of PCBs were analyzed to assess the ecological impact of PCBs. The average concentration of ∑18PCBs was 124.6 ng/L (range of 28.1-445.5 ng/L) in summer and 122.8 ng/L (range of 21.0-581.4 ng/L) in autumn. PCBs in surface seawater of the Bohai Bay showed high near-shore and low far-shore characteristics, indicating the serious influence of land-based sources such as port activities and river inputs. Proportion analysis showed that Tetra-PCBs and Penta-PCBs were the major constituents in most stations. It was assessed as moderate and high risk (MRQ > 0.1) by mixture risk quotient (MRQ) and concentration addition (CA) model in surface seawater of the Bohai Bay. Principal component analysis (PCA) was used to explain the sources of PCBs in the Bohai Bay. PCBs in the Bohai Bay may come from commercial PCBs and their incineration products, municipal landfills, wood and coal combustion, and industrial activities, etc.

Assessing the potential risks, sources and the relationship between the dissolved and particulate polycyclic aromatic hydrocarbons (PAHs) in the typical semi-enclosed bay, Bohai Bay of China

This study aimed to investigate the spatial and temporal distribution as well as the partitioning behavior of dissolved and particulate polycyclic aromatic hydrocarbons (PAHs) during the summer and autumn seasons of 2020. It was found that the average concentration of PAHs in surface seawater was significantly higher in autumn (58.16 ng L-1) than in summer (40.47 ng L-1) due to a large amount of input in autumn and more photodegradation and biodegradation affected by higher temperatures in summer. The spatial distribution indicated that the river had a significant dilution effect on PAHs in summer and became a significant input source in autumn. In addition, a large number of oil and gas development platforms were distributed throughout the Bohai Bay, and the discharge of production and domestic sewage contributed to the PAHs pollution level. As a semi-enclosed bay, the water exchange capacity of Bohai Bay was poor, leading to a greater accumulation of PAHs in the marine environment. The diagnostic ratios and PCA-MLR indicated that petroleum was the most important source of PAHs with a contribution of 45%, followed by fuel combustion (39%) such as coal and oil. Photooxidation in seawater resulted in a reduction of BaP/BeP, indicating that seasonal variations in photooxidation had a significant impact on the composition of PAHs (summer: 1.49, autumn: 2.96). The concentration of particulate PAHs was correlated with the concentration of dissolved PAHs and SPM, and the proportion of 3-rings (43.8%) and 4-rings (49.8%) PAHs was significantly higher on SPM. The distribution coefficients Log Kd and φspm-water showed a trend of increasing and then decreasing as the number of rings increased, with the 4-rings Pyr exhibiting the highest value. According to the ecological risk assessment, the ecological risk of total PAHs was low (RQNCs < 800, RQMECs < 1), but the ecological risk of individual PAHs and the carcinogenicity of high-ring PAHs could not be ignored (＞96.5%). This study is significant for investigating the "sources and sinks" of PAHs in the complex marine environment by analyzing the partitioning behavior of PAHs in different phases.

Analysis of PAHs content, source and risk assessment in surface sediments from Laizhou Bay and Bohai Bay

To understand the levels of PAHs and ecological risks to the marine environment in Laizhou Bay and Bohai Bay, 33 sediment samples were collected in the region for analysis. PAH concentrations ranged from 98.22 ng·g-1 (dw) to 239.01 ng·g-1 (dw). PAHs in the region are at low to medium pollution levels compared to studies worldwide. Diagnostic ratios and PCA indicate that PAHs are primarily sourced from fuel combustion. PAHs carried into the Bohai Sea by means of river water and sediment are more likely to settle to the seafloor as opposed to diffuse. This results in a slightly higher proportion of low-ring PAHs than high-ring PAHs. Low-ring PAHs accounted for 56 % of the total. Low-ring PAHs are key contributors to ecosystem risk. The SQGs and RQ∑PAHs show that PAHs do not pose a considerable ecological danger within the region.

The ban on the sale of new petrol and diesel cars: Can it help control prospective marine pollution of polycyclic aromatic hydrocarbons (PAHs) in Shandong Province, China?

The constantly increasing amount of road vehicles causes massive exhaust emissions of pollutants, including polycyclic aromatic hydrocarbons (PAHs), necessitating a global responsibility to implement the policy of the ban on the sale of new petrol and diesel cars. Here, we assessed the policy control efficiency on marine pollution of PAHs in China through scenario modeling and prediction models, based on pollution monitoring, risk assessment, and source apportionment of PAHs in typical bays of Shandong Province. The results showed that in 2021, the pollution risk levels were relatively low (HI: 0.008-0.068, M-ERM-Q: 0.001-0.016, IBR: 1.23-2.69, ILCR: 8.11 ×10-6-1.99 ×10-5), and PAHs were mainly derived from traffic emissions (24.9%-35.2%), coal combustion (25.2%-32.9%), petroleum (17.2%-28.9%), and biomass combustion (17.6%-22.8%). In 2050, the predicted decrease of pollution risk values after the implementation of the policy was significant (12%-26%), and the gap between 2021 and 2050 was also significantly huge (18%-85%) without considering possible substitution of conventional energy. Collectively, this study built systematic approaches for assessing prospective marine pollution of PAHs. However, due to the particularity of Shandong Province, i.e., its national predominance of conventional energy consumption, the policy may be more effective when it comes to other coastal areas worldwide, calling for a larger scale research.

Occurrence and distribution of polycyclic aromatic hydrocarbons (PAHs) in marine organisms from Shenzhen coastal waters and human health risk assessment

This study investigated the levels and composition of 16 priority polycyclic aromatic hydrocarbons (PAHs) in marine organisms from South China Sea and assessed their potential health risks. The results revealed that the pollution levels of total PAHs ranged from 3.56 to 392.21 ng/g dw. Notably, 4-ring PAHs constituted the predominant fraction (58.02 %) of the total PAHs, with pyrene being the most abundant congener across all species. Intriguingly, our findings suggested that consuming these organisms might pose a low non-cancer hazard. Nonetheless, benzo[a]pyrene was detected in most species, with levels ranging from non-detectable to 11.24 ng/g dw. The individual lifetime cancer risk levels associated with seafood consumption in studied regions ranged from 1.10 × 10-5 to 1.52 × 10-5, highlighting a potential cancer risk that warrants special attention. These findings emphasize the need to prioritize carcinogenic compounds over total PAHs and underscore the importance of continuous monitoring of PAH pollution in seafood.

Linking PAHs concentration, risk to PAHs source shift in soil and water in epikarst spring systems, Southwest China

A systematic assessment of the variations in the ecological risk of PAHs and the key emission sources controlling the variations is of great importance to human health and aquatic organisms. PAH concentrations, composition, source, and ecological risk in soils and water in two different periods (2010-2011 and 2019) of three typical epikarst springs in Southwest China were investigated. Results showed that PAH concentrations in soil and water have an overall downward trend (a reduction of 57 % and 93 %, respectively) in the past 10 years, which is consistent with the downward trend in the relative contribution rate of raw coal production (a 66 % reduction). In terms of composition, the proportion of low-ring PAHs decreased, medium-ring and high-ring PAHs increased in the soil profile. The proportion of low-ring PAHs did not change obviously, the proportion of medium-ring PAHs increased, and the proportion of high-ring PAHs decreased in epikarst springs. The source of PAHs changed remarkably over time, the relative contribution of coal combustion to PAHs decreased from 38 % to 20 %, and the vehicle contribution of PAHs increased from 31 % to 44 % in soils. The relative contribution rate of unburned oil and coke oven and biomass combustion change is less. Furthermore, the ecological risk of PAHs in the soils was reduced from moderate risk 2 to moderate risk 1, the risk in epikarst spring was reduced from high risk to moderate risk 2 after 10 years. This study demonstrates that substituting petroleum and coal with green energies can reduce PAH concentrations and risk.

Dissemination and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in water and sediment of Buriganga and Dhaleswari rivers of Dhaka, Bangladesh

Concentration, source, ecological and health risks of sixteen polycyclic aromatic hydrocarbons (PAHs) were estimated for water and sediment samples of two urban rivers namely Buriganga River (BR) and Dhaleswari River (DR). The mean concentration of ∑PAHs in BR water and sediment were 9619.2 ngL-1 and 351.6 ngg-1, respectively. Furthermore, the average PAH concentrations detected in DR water and sediment were 1979.1 ngL-1 and 792.9 ngg-1, respectively. The composition profile showed that 3-ring PAHs were dominant in the water matrix; however, 5-ring PAHs were prevalent in the sediment samples of both rivers. Sources apportion study of PAHs indicated that mixed combustion and petroleum sources are responsible for PAHs contamination in the rivers. Ecological risk study of water suggested that the aquatic lives of both rivers are threatened by Fla, BbF, BkF, DahA, and IcdP, as presented above the threshold level. Comparison with sediment quality guidelines (SQGs) indicated that adverse effects might cause occasionally in the sediment ecosystem in DR at certain sampling sites for Nap, Acy, Fl, Phe, Ant, Pyr, Chr, BaP, and DahA. On the other hand, the presence of Nap, Acy and DahA might occasionally cause adverse biological effects in the BR sediment ecosystem. Estimated hazard quotient (HI > 1) and carcinogenic risk (CRtotal > 10-4) values indicated that local inhabitants living in the vicinity of the rivers are prone to high health risks.

Concentrations, phase exchanges and source apportionment of polycyclic aromatic hydrocarbons (PAHs) In Bursa-Turkey

The present study aimed to determine the pollution levels derived from polycyclic aromatic hydrocarbons (PAHs) in air, plant and soil samples and to reveal the PAH exchange at the soil-air, soil-plant and plant-air interfaces. In this context, air and soil samples were collected in approximately 10-day periods between June 2021 and February 2022 from a semi-urban area in Bursa, an industrial city with a dense population. Also, plant branch samples were collected for the last three months. Total PAH concentrations in the atmosphere (∑₁₆PAH) and soil (∑₁₄PAH) ranged from 4.03 to 64.6 ng/m³ and 13-189.4 ng/g DM, respectively. PAH levels in the tree branches varied between 256.6 and 419.75 ng/g DM. In all air and soil samples, PAH levels were low in the summer and reached higher values in the winter. 3-ring PAHs were the dominant compounds, and their distribution in air and soil samples varied between 28.9%-71.9% and 22.8%-57.7%, respectively. According to the results of diagnostic ratios (DRs) and principal component analysis (PCA), both pyrolytic and petrogenic sources were found to be effective in PAH pollution in the sampling region. The fugacity fraction (ff) ratio and net flux (F_net) values indicated that the direction of movement of PAHs was from soil to air. In order to better understand the PAH movement in the environment, soil-plant exchange calculations were also achieved. The ratio of ∑₁₄PAH values measured to modeled concentrations (1.19<ratio<1.52) revealed that the model worked well for the sampling region and produced reasonable results. The ff and F_net levels showed that branches were saturated with PAHs and the direction of PAH movement was from plant to soil. The plant-air exchange results indicated that the direction of movement of PAHs was from plant to air for low molecular weight PAHs and the opposite was true for compounds with high molecular weight ones.

A holistic approach to the assessment of heavy metal levels and associated risks in the coastal sediment of Giresun, southeast Black Sea

A seasonal study was conducted to assess the levels, sources, and potential ecological risks of heavy metals (HM) in coastal sediments along the Giresun Coast, located on the southeast coast of the Black Sea. The mean concentrations of HMs as mg/kg were ranked as Fe (27646.37) > Al (27348.55) > Mn (571.87) > Zn (94.16) > Cr (60.64) > Cu (45.66) > Pb (41.37) > Ni (27.29) > Co (14.47) > As (7.36) > Cd (0.20), respectively. At all stations through the year, Al, Cr, Mn, Fe, Co, and Ni were in "the minimum enrichment" class as evaluated by the enrichment factor (EF). As assessed by the contamination factor (CF), all HM levels except Pb, Fe and Cu were "low" or "moderately polluted" at all stations and seasons. With the exception of Cd levels, all HMs in all seasons and stations pointed out "low ecological risk" according to the ecological risk index (E_rⁱ). According to the sediment quality guidelines, Ni, Cu and Pb were observed to pose a high ecological risk to habitat. The combined risk assessment indices pointed out low to moderate ecological risk. The study concluded that the region is subject to minimum anthropogenic disturbances in the aquatic environment.