Polycyclic aromatic hydrocarbons (PAHs) in water and sediment from a river basin: sediment-water partitioning, source identification and environmental health risk assessment

Impact of wildfire ash on skin and gut microbiomes and survival of Rana dybowskii

Climate change and human activities escalate the frequency and intensity of wildfires, threatening amphibian habitats and survival; yet, research on these impacts remains limited. Wildfire ash alters water quality, introduces contaminants, and may disrupt microbial communities, impacting gut and skin microbiota; however, the effects on gut and skin microbiota remain unclear. Rana dybowskii were exposed to five concentrations (0 g L-1, 1.25 g L-1, 2.5 g L-1, 5 g L-1, and 10 g L-1) of aqueous extracts of wildfire ashes (AEAs) for 30 days to assess AEAs' metal content, survival, and microbiota diversity via Illumina sequencing. Our results showed that the major elements in ash were Ca > K > Mg > Al > Fe > Na > Mn, while in AEA they were K > Ca > Na > Mg > As > Al > Cu. A significant decrease in amphibian survival rates with increased AEA concentration was shown. The beta diversity analysis revealed distinct shifts in microbiota composition. Notably, bacterial genera associated with potential health risks showed increased abundance in skin microbiota, emphasising the potential for ash exposure to affect amphibian health. Functional prediction analyses revealed significant shifts in metabolic pathways related to health and disease, indicating that wildfire ash exposure may influence amphibian health through changes in microbial functions. This study highlights the urgent need for strategies to mitigate wildfire ash impacts on amphibians, as it significantly alters microbiota and affects their survival and health.

Accumulation of typical persistent organic pollutants and heavy metals in bioretention facilities: Distribution, risk assessment, and microbial community impact

Bioretention facilities have proven highly effective in removing pollutants from runoff. However, there is a concerning paucity of research on the contamination characteristics and associated risks posed by refractory pollutants in these facilities following long-term operation. This research focuses on the distribution, sources, microbial community impact, and human health risks of pollutants in eight bioretention facilities that have been operational for 5-11 years. The results showed that the distribution of Cu, Zn, and Cd was closely related to anti-seepage measures. PAHs, PCBs, and OCPs primarily accumulated in the surface, with concentrations ranging from 7.42 to 20.34 mg/kg, 31.8-77.3 μg/kg, and 60.5-163.6 μg/kg, respectively. Their concentrations inversely correlate with the depth of the media. Although the majority of contaminants remained below their respective risk thresholds, their concentrations typically exceeded those of background soil values, indicating an enrichment phenomenon. Source analysis revealed that PAHs primarily originate from oil combustion, PCBs were linked to their related industrial products, DDTs had their main sources in technical DDx and residues from the use of dicofol, while HCHs were traced back to historical residues from agricultural activities. Microbial α-diversity (Chao 1 and Shannon) decreased by 8.3-23.4% and 0.8-4.4%, respectively, in different facilities after long-term operation. The most dominant microbial phylum in the facilities was Proteobacteria (all relative abundances >48%). The total relative abundance of dominant genera was 6.7-34.3% higher than the control site, and Pseudomonas, a typical POPs-heavy metal degrading bacterium, had the highest relative abundance (>1.2%). Cu, Zn, and Cd present no non-carcinogenic risks and have low potential ecological risks. However, the lifetime cancer risk for PAHs is 10-6 ∼10-4 in most facilities and is of concern. The cancer risk for PCBs is acceptable, while OCPs pose a low cancer risk only for children.

Occurrence of halogenated organic contaminants in surface sediments of the Yangtze River estuary and its adjacent marine area

Halogenated organic contaminants, such as chlorinated and brominated polycyclic aromatic hydrocarbons (Cl/Br-PAHs), are some of the most important emerging environmental pollutants. However, empirical data on Cl/Br-PAHs in estuarine and marine ecosystems are limited, rendering assessments of Cl/Br-PAH contamination in estuarine and offshore environments uncertain. Here the occurrence, sources, and ecological risks of 7 Cl-PAHs and 18 Br-PAHs were determined in surface sediments of the Yangtze River Estuary (YRE), a highly urbanized and industrialized area, and its adjacent marine area. The concentrations of Cl-PAHs ranged from 4.50 to 18.38 ng g-1 (average 7.19 ng g-1), while those of Br-PAHs ranged from 4.80 to 61.18 ng g-1 (average 14.11 ng g-1). The dominant Cl-PAH and Br-PAH in surface sediment were 9-chlorofluorene (17.79%) and 9-bromofluorene (58.49%), respectively. The distributions and compositions of Cl/Br-PAHs in the surface sediments varied considerably due to complex hydrodynamic and depositional conditions in the YRE and its adjacent marine area, as well as differences in physicochemical properties of different Cl/Br-PAHs. Positive matrix factorization revealed that the primary sources of Cl/Br-PAHs in the study area were e-waste dismantling (33.6%), waste incineration (23.2%), and metal smelting (11.0%). According to the risk quotient, the Cl/Br-PAHs in sediments posed no toxic risk to aquatic organisms.

PAHs and hopanes in the surface sediments of Qatar coast and their ecological risks: Comparison with regional and global coastal regions

The distribution, characteristics, sources and ecological risks of polycyclic aromatic hydrocarbons (PAHs) and hopanes in the surface sediments collected along the Qatar coast were investigated. Concentration of ∑14PAHs and hopanes ranged between 0.076 and 7.04 ng g-1 (mean: 2.60 ng g-1), 100 and 700 ng g-1 (mean: 205 ng g-1), respectively. Sediment samples were dominated by high molecular weight PAHs composition (4-6 rings). Diagnostic ratios of PAH concentrations showed both petrogenic and pyrogenic origins of PAHs, with a higher percentage of pyrogenic sources. The ecological risk levels of PAHs were estimated using sediment quality guidelines (SQG), mean probable effect level quotient values (PEL-Q), carcinogenic toxic equivalent quantity (TEQ), and risk quotient (RQ) evaluation methods. The calculated TEQ values (0.00012-0.85 ng g-1) were lesser than those in other locations around the globe, and were also within the safe level (600 ng g-1) suggested by the Canadian soil quality guidelines.

Oil spill in an amazon blackwater environment: Biochemical and physiological responses of local fish species

The accidental spill of petroleum asphalt cement (PAC) in São Raimundo (SR Harbor, located on the Rio Negro (Manaus, Amazonas, Brazil) was monitored through the analysis of polyciclic aromatic hydrocarbons (PAHs) in water and a set of biomarkers in fishes (exposure biomarkes: PAHs-type metabolites concentrations in bile; the activities of ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) in liver. Effect biomarkers: lipid peroxidation concentration (LPO) in liver, acetylcholinesterase activity in brain, and genotoxic DNA damage in erythrocytes). Two fish species, Acarichthys heckelii and Satanoperca jurupari, were collected 10, 45, and 90 days after the PAC spill in São Raimundo. At the same time, fish were collected from the Tupé Sustainable Development Reserve (Tupé) which served as a reference area. The sampling periods were related to the rising waters of the natural flood pulse of the Rio Negro. Higher concentrations of PAHs in water were observed at 10 and 45 days and returned to the values of TP 90 days after the PAC spill, a period in which harbor waters rose about 0.2 m. Unlike the PAHs in water, biomarker responses in both fish species significantly increased following the PAC spill in SR. Hepatic ethoxyresorufin-O-deethylase (EROD), PAH-like metabolites in bile, and erythrocyte DNA damage increases, together with inhibition of acetylcholinesterase (AChE) activity in the brain were the most evident responses for both fish species. The calculated pyrolytic index showed mixed sources of PAHs (petrogenic and pyrolytic). The applied PCA-FA indicated important relationships between dissolved organic carbon (DOC) and PAHs concentrations in water, where DOC and PAHs concentrations contributed to biomarkers responses for both fish species in all collection periods.

Microplastics and associated polycyclic aromatic hydrocarbons in surface water and sediment of the Bay of Bengal coastal area, India: sources, pathway and ecological risk

In the aquatic environment around the world, microplastic contamination has been a common and ongoing issue. Particularly, the ability of microplastics to absorb persistent organic pollutants (POPs) and then transmit these POPs to aquatic creatures has attracted a lot of interest. A stereomicroscope was used to detect the size, shape, and color of the microplastics (MPs), and Fourier Transform Infrared (FTIR) spectroscopy was used to identify the polymer composition of the MPs. To address MP transit, destiny, and mitigation, a study of MP pollution coastal areas is required. In the current study, MP pollution in the collected sample from upper layer of water and sediment of the Digha and Puri beaches along the coast of BOB was evaluated. The average concentration with SD of MPs observed in water was 5.3 ± 1.8 items/L whereas, in sediments, it was 173.4 ± 40.1 items/kg at Digha beach. The mean MPs abundance in the Puri beach was 6.4 ± 1.7 items/L in the water and 190.4 ± 28.0 items/kg in the sediments. The investigated total 16-PAHs concentrations were 164.7 ng/g, 121.9 ng/g, 73.6 ng/g, and 101.3 ng/g on the MPs surface of foam, fragment, fibers, and film respectively in the studied MPs sample. Smaller than 1000 µm size of MPs are distributed in the largest concentration. Fibers, films, fragments, and foam were the most common shapes of MPs. The molecular structure of MPs in water and sediment samples was analysed i.e., polyesters (PEs), polypropylene (PP), polyethylene (PE), polymethyl methacrylate (PMMA), polystyrene (PS), polyamide (PA), polycarbonates (PC), and polyurethane (PU). The obtained result offers an accurate assessment of the PLI, and the investigated polymer facilitates determining the polymer hazard levels, which emphasizes the risk associated with it.

Advances in Water, Air and Soil Pollution Monitoring, Modeling and Restoration

Global pollution demands continuous attention and concerted efforts to reduce its effects [...].

Harnessing the power of bacterial laccases for xenobiotic degradation in water: A 10-year overview

Industrialization and population growth are leading to the production of significant amounts of sewage containing hazardous xenobiotic compounds. These compounds pose a threat to human and animal health, as well as the overall ecosystem. To combat this issue, chemical, physical, and biological techniques have been used to remove these contaminants from water bodies affected by human activity. Biotechnological methods have proven effective in utilizing microorganisms and enzymes, particularly laccases, to address this problem. Laccases possess versatile enzymatic characteristics and have shown promise in degrading different xenobiotic compounds found in municipal, industrial, and medical wastewater. Both free enzymes and crude enzyme extracts have demonstrated success in the biotransformation of these compounds. Despite these advancements, the widespread use of laccases for bioremediation and wastewater treatment faces challenges due to the complex composition, high salt concentration, and extreme pH often present in contaminated media. These factors negatively impact protein stability, recovery, and recycling processes, hindering their large-scale application. These issues can be addressed by focusing on large-scale production, resolving operation problems, and utilizing cutting-edge genetic and protein engineering techniques. Additionally, finding novel sources of laccases, understanding their biochemical properties, enhancing their catalytic activity and thermostability, and improving their production processes are crucial steps towards overcoming these limitations. By doing so, enzyme-based biological degradation processes can be improved, resulting in more efficient removal of xenobiotics from water systems. This review summarizes the latest research on bacterial laccases over the past decade. It covers the advancements in identifying their structures, characterizing their biochemical properties, exploring their modes of action, and discovering their potential applications in the biotransformation and bioremediation of xenobiotic pollutants commonly present in water sources.

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.

Occurrence, multiphase partition and risk assessment of organic amine pesticides in drinking water source of Xiang River, China

The extensive use of organic amine pesticides (OAPs) in agricultural practices has resulted in the contamination of water environments, posing threats to ecosystems and human health. This study focused on the Xiang River (XR), a representative drinking water source, as the research area to investigate the occurrence characteristics of 34 OAPs. Diphenylamine emerged as the most prevalent OAP in surface water due to industrial and agricultural activities, while cycloate dominated in sediments due to cumulative effects. Generally, the concentration of OAPs in a mixed tap water sample was lower than those in surface water samples, indicating OAPs can be removed by water plants to a certain extent. The water-sediment distribution coefficients (kd) of ΣOAPs were much less than 1 L/g, the majority of OAPs maintained relatively high concentrations in water samples instead of accumulating in sediments. Furthermore, risk assessment revealed that carbofuran showed a moderate risk to the aquatic environment, with a risk quotient of 0.23, while other OAPs presented minor risks. This study provided crucial insights for regional pesticide management and control in the XR basin, emphasizing the importance of implementing strategies to minimize the release of OAPs into the environment and protect human health.

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.

Floating plastics as integrative samplers of organic contaminants of legacy and emerging concern from Western Mediterranean coastal areas

This study investigates the role of floating plastics as integrative samplers of organic contaminants. To this end, plastics items were collected in two Western Mediterranean coastal areas: the Mar Menor lagoon, and the last transect of Ebro river. Floating plastics were identified and characterized by attenuated total reflection Fourier-transform infrared spectrometry. Then, organic contaminants were extracted from plastic items by ultrasonic extraction with methanol, and the concentrations of 168 regulated and emerging contaminants were analysed. These compounds were analysed by stir bar sorptive extraction coupled to gas chromatography-mass spectrometry (GC-MS), except for bisphenol analogues, which were analysed with a ultraperformance liquid chromatography pump coupled to a triple quadrupole mass spectrometer (UHPLC-MS/MS), and pharmaceutical compounds, determined by UPLC coupled to hybrid triple quadrupole-linear ion trap mass spectrometer (UPLC-MS/MS). All the contaminants groups considered were detected in the samples, being particularly relevant the contribution of plastic additives. The most frequently detected contaminants were UV-filters, PAHs, pharmaceuticals and synthetic musks. Apart from plasticizers, the individual contaminants octocrylene, homosalate, galaxolide, salycilic acid and ketoprofen were frequently detected in plastics items. The results pointed out to urban and touristic activities as the main sources of pollution in the coastal areas investigated. The utility of floating plastics as integrative samplers for the detection of organic contaminants in aquatic ecosystems has been demonstrated.

Polycyclic aromatic hydrocarbon (PAH) source identification and a maternal transfer case study in threatened killer whales (Orcinus orca) of British Columbia, Canada

The northeastern Pacific (NEP) Ocean spans the coast of British Columbia (Canada) and is impacted by anthropogenic activities including oil pipeline developments, maritime fossil fuel tanker traffic, industrial chemical effluents, agricultural and urban emissions in tandem with stormwater and wastewater discharges, and forest wildfires. Such events may expose surrounding marine environments to toxic polycyclic aromatic hydrocarbons (PAHs) and impact critical habitats of threatened killer whales (Orcinus orca). We analyzed skeletal muscle and liver samples from stranded Bigg's killer whales and endangered Southern Resident killer whales (SRKWs) for PAH contamination using LRMS. C3-phenanthrenes/anthracenes (mean: 632 ng/g lw), C4-dibenzothiophenes (mean: 334 ng/g lw), and C4-phenanthrenes/anthracenes (mean: 248 ng/g lw) presented the highest concentrations across all tissue samples. Diagnostic ratios indicated petrogenic-sourced contamination for SRKWs and pyrogenic-sourced burdens for Bigg's killer whales; differences between ecotypes may be attributed to habitat range, prey selection, and metabolism. A mother-fetus skeletal muscle pair provided evidence of PAH maternal transfer; low molecular weight compounds C3-fluorenes, dibenzothiophene, and naphthalene showed efficient and preferential exposure to the fetus. This indicates in-utero exposure of PAH-contamination to the fetus. Our results show that hydrocarbon-related anthropogenic activities are negatively impacting these top predators; preliminary data found here can be used to improve oil spill and other PAH pollution management and regulation efforts, and inform policy to conserve killer whale habitats in the NEP.

Impacts of shipyard oil leakage on the PAHs and PCBs occurrence in Xiangshan Bay, China

Here, we studied the shipyard impacts on the distribution of PAHs and PCBs in the semi-enclosed Xiangshan Bay, an important mariculture zone in China. The results showed that the shipyard caused a pollution plume for PAHs but not for PCBs. As characteristic pollutants of oil leakage, the PAHs had concentrations of up to 55.82 ng L-1 in the water, 2235.04 ng g-1 in suspended particulate matter (SPM), and 1489.60 ng g-1 in sediment. The PAHs in water and SPM were dominated by phenanthrene and pyrene that were mostly derived from lubricant and diesel, while those in sediments were dominated by the high-molecular-weight PAHs, such as indeno[1,2,3-c,d]pyrene. In contrast, the PCBs concentrations reached up to 10.17 ng L-1, 79.72 ng g-1, and 124.33 ng g-1 in the seawater, SPM, and sediment samples, respectively, and they did not show spatial patterns affected by the shipyard. Moreover, the health risk assessment indicated that the shipyard discharge caused a substantial PAHs ecological risk to the adjacent and downstream water environment. Therefore, point source discharge in semi-enclosed bays should be paid close attention to due to the strong pollutant transport effect.

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.

Investigation of the concentration, origin and health effects of PAHs in the Anzali wetland: The most important coastal freshwater wetland of Iran

This study investigated the concentration of PAHs in 19 water samples, 34 sediment samples and 22 fish samples of Anzali Wetland, located in north of Iran. The average concentration of ∑PAHs in the wetland sediment was 89.19 μg/kg (8.28-806.64) and 78.31 ng/L (5.14-253.37) in the wetland water. Also, the average concentration of ∑PAHS in the muscle of the investigated fish in the wetland was 23 μg/kg (56.1 to 7.6). The source apportionment of PAHs in water and sediment considering isomeric ratios and statistical methods reveals the predominance of petrogenic origin of the compounds in water and pyrogenic origin in sediment. Overall, the level of contamination in fish is relatively low to moderate, considering ∑PAHs. The findings present clear evidence of low to moderate level of contamination in the wetland, the PAHs contamination however could cross their ecological thresholds in future unless control measures are taken to protect the wetland.

Estimation of Polycyclic Aromatic Hydrocarbons in Groundwater from Campania Plain: Spatial Distribution, Source Attribution and Health Cancer Risk Evaluation

The aim of this study was to evaluate the concentrations of polycyclic aromatic hydrocarbons (PAHs) in 1168 groundwater samples of the Campania Plain (Southern Italy), taken using a municipal environmental pressure index (MIEP), and to analyze the distribution of these compounds to determine source PAHs using ratios of isomers diagnostic. Lastly, this study also aimed to estimate the potential health cancer risk in groundwaters. The data indicated that the highest concentration of PAHs was found in groundwater from Caserta Province and the contents of BghiP, Phe, and Nap were detected in the samples. The spatial distribution of these pollutants was evaluated using the Jenks method; moreover, the data indicated that incremental lifetime cancer risk ILCR_ingestion ranged from 7.31 × 10^-20 to 4.96 × 10^-19, while ILCR_dermal ranged from 4.32 × 10^-11 to 2.93 × 10^-10. These research findings may provide information about the Campania Plain's groundwater quality and aid in the development of preventative measures to lessen PAH contamination in groundwater.

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

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

Persistent organic pollutants influence the marine benthic macroinvertebrate assemblages in surface sediments of Nayband National Park and Bay, Northern Persian Gulf, Iran

Macroinvertebrate communities have been influenced by chemical substances, originated from petrochemical developments, that caused many problems in the marine biota. This study investigated the surface sediments of Nayband National Park and Bay (northern Persian Gulf) for polycyclic aromatic hydrocarbons (PAHs) and total petroleum hydrocarbons (TPHs) in terms of their distribution, source, and impacts on benthic macroinvertebrate assemblages. To this end, a total of 180 surface sediment samples from 20 stations were collected using Van-Veen grab sampler during winter 2018. The concentration of PAHs, TPHs, total organic carbon (TOC). and total organic matter (TOM) were evaluated, and grain size measurements were conducted on sediment samples in this study. Benthic macroinvertebrates were then identified in terms of presence and distribution. The results indicated that coarse granulometric fractions of sands were prevalence in all samples stations. The total concentration of PAHs ranged from 47.57 to 657.68 ng/g and TPHs 5.72 to 42.16 µg/g dw. The risk of ΣPAHs and TPHs in the sediments was relatively low to moderate according to the sediment quality guidelines. Analysis of the results revealed a significant negative correlation between ΣPAHs (R-value =  - 0.917; P < 0.01), TPHs (R-value =  - 0.849; P < 0.01) and macrofaunal abundance. Findings demonstrated that the species richness and abundance were at the lowest levels in stations where concentrations of PAHs, TPHs, TOC, and TOM were in the highest values, suggesting that these contaminants could negatively influence the benthic organisms in Nayband National Park and Bay. The results of correspondence analysis (CA) and principal component analysis (PCA) analysis showed that sedimentary habitats in Nayband National Park and Bay are being negatively affected by PAHs and TPHs, released from Pars Special Economic Energy Zone (PSEEZ). Moreover, the marine biotic index (AMBI) and Shannon-Weiner Diversity (H') results suggest that Nayband National Park and Bay can be classified as slightly to moderate polluted area. In conclusion, Northern Persian Gulf is significantly affected by oil industry developments and petrochemical activities. The unique ecosystem like Nayband National Park and Bay has been in a cautious status in terms of the PSEEZ pollutants and the levels of PAHs and TPHs concentration, warning that urgent environmental programs should be considered to protect the diversity and ecology of this valuable marine systems.

Occurrence, distribution and risk assessment of microplastics and polycyclic aromatic hydrocarbons in East lake, Hubei, China

The pollution of microplastics (MPs) and polycyclic aromatic hydrocarbons (PAHs) in the environment is a global problem, which has attracted extensive attention of many researchers. In present study, MPs and PAHs are investigated to study the impact of human activities and their possible relationship in China's second largest urban lake, East Lake. The abundance of MPs are 3329.19 ± 2059.26 particles/m³ and 2207.56 ± 1194.04 particles/kg in water and sediment, respectively. MPs are predominantly characterized by fibers, polypropylene (PP) and polyethylene (PE), colorlessness in water and sediment. The abundance of MPs in water with frequent human activities is higher, which is reversed in sediments, indicating that disturbance is not conducive to the enrichment of MPs in sediments. The concentration of 16 PAHs are 36.95 ± 13.76 ng/L and 897.08 ± 232.34 ng/g in water and sediment, respectively. PAHs in water are mainly 2-3-ring, while there are 4-ring PAHs in sediments. The good corresponding relationship between MPs and PAHs indicates that human activities have an important impact on the distribution of pollutants compared to the interaction of pollutants. In addition, the significant positive correlation between lakeshore length and water MPs abundance indicates that surface runoff may be an important source of water MPs. The pollution load index shows that MPs in sediment has reached moderate to severe pollution level, while the water is slightly polluted level. The potential ecological risk assessment results show that more than half of the sediment sites are at dangerous to very dangerous ecological risk level.

Prospects of emerging PAH sources and remediation technologies: insights from Africa

Remediation of polluted environmental media is critical to realization of the goals of the United Nations Decade on Ecosystem Restoration (UNDER) project. Many natural-resource dependent economies in Africa are characterized by numerous contaminated sites resulting from conventional and artisanal natural-resource mining. Alongside these extractive activities, there are refining, processing, and power plant operations, agriculture, urban, and infrastructure developments that contribute to increased discharges of toxins into the environment, particularly polycyclic aromatic hydrocarbons (PAHs), which are carcinogenic in nature. As a result, human and environmental receptors (i.e., air, water, soil, and biota) face increasing risk of exposure to higher concentrations of PAH. Evidence exists of widespread PAH contamination and in some instances where corrective action has been taken, residual contaminant levels exceeding regulatory thresholds remain in the environment due to the use of inappropriate and unsustainable remedial methods. Considering the long-term harmful effects of PAH on human and ecosystem health, land use, and the complexity of Africa's environmental deterioration, it is essential to explore remediation strategies that benefit both the environment and the economy. This review examined the status, opportunities, and challenges related to the application of emerging green technologies to remediate PAH-contaminated sites in five African countries (South Africa, Nigeria, Angola, Egypt, and Kenya). This paper concludes that bioremediation presents a sustainable option, considering its low net emissions and environmental footprints, and its low economic cost to Africa's poor communities and overburdened economy. However, an integration of biological and physico-chemical approaches could address various compounds and concentrations of PAH contamination.

Polycyclic aromatic hydrocarbons (PAHs): Updated aspects of their determination, kinetics in the human body, and toxicity

Polycyclic aromatic hydrocarbons (PAHs) are legacy pollutants of considerable public health concern. Polycyclic aromatic hydrocarbons arise from natural and anthropogenic sources and are ubiquitously present in the environment. Several PAHs are highly toxic to humans with associated carcinogenic and mutagenic properties. Further, more severe harmful effects on human- and environmental health have been attributed to the presence of high molecular weight (HMW) PAHs, that is PAHs with molecular mass greater than 300 Da. However, more research has been conducted using low molecular weight (LMW) PAHs). In addition, no HMW PAHs are on the priority pollutants list of the United States Environmental Protection Agency (US EPA), which is limited to only 16 PAHs. However, limited analytical methodologies for separating and determining HMW PAHs and their potential isomers and lack of readily available commercial standards make research with these compounds challenging. Since most of the PAH kinetic data originate from animal studies, our understanding of the effects of PAHs on humans is still minimal. In addition, current knowledge of toxic effects after exposure to PAHs may be underrepresented since most investigations focused on exposure to a single PAH. Currently, information on PAH mixtures is limited. Thus, this review aims to critically assess the current knowledge of PAH chemical properties, their kinetic disposition, and toxicity to humans. Further, future research needs to improve and provide the missing information and minimize PAH exposure to humans.

Distribution, sources and ecological risk assessment of polycyclic aromatic hydrocarbons in waters and sediments from Olt River dam reservoirs in Romania

This study provides important data on the distribution, sources and ecological risks of polycyclic aromatic hydrocarbons (PAHs), in surface waters and sediments collected from dam reservoirs on middle and lower course of the Olt River, the main tributary of the Danube, until the discharge into the Black Sea. A wide variation range of total PAHs concentrations in water (from 1.3 to 46.2 ng/L) and sediment (from 1.78 to 614.04 μg/kg) samples was emphasized by the results. The highest average PAHs concentration in water was recorded in the cold season and the lowest in the summer. In sediments, no differences were observed depending on the sampling period. Spatial distribution of PAHs in waters and sediments was correlated with the main anthropogenic activities along the river course. Regardless of the method used to attribute PAH sources (diagnostic ratios of specific PAHs, principal component analysis and hierarchical cluster analysis), it was confirmed that the potential anthropogenic sources of PAHs were both pyrogenic (incomplete combustion of biomass and coal) and pyrolytic (incomplete combustion of liquid fossil fuels and vehicle exhaust emissions), with a dominant pyrolytic input. Ecological risk assessment based on environmental quality standards, mean effect range-median quotient (m-ERM-Q), toxic equivalency factors (TEFs) and risk quotient (RQ) methods indicated potentially low ecological risks from PAHs. The ecological status of the Olt river waters poses no potential risk, and pollution of surface sediments can be classified as low polluted, except for two sites near industrial activities classified as moderately polluted. Therefore, a regular monitoring of PAHs concentration in the waters and sediments should be performed to prevent further contamination of PAHs in the studied area, especially in densely populated industrial areas.

Concentrations and source identification of priority polycyclic aromatic hydrocarbons in sediment cores from south and northeast Thailand

In this study, the environmental fate of carcinogenic polycyclic aromatic hydrocarbons (PAHs) in tropical lake sediments and their potential sources have been discussed. 15 PAHs (i.e. ΣPAH) have been investigated in two lakes, namely Songkhla Lake (SKL) and Nong Han Kumphawapi Lake (NHL), which are located at the southern and north-eastern parts of Thailand, respectively. Since these two lakes are registered as important wetlands under the Ramsar convention (United Nations Educational, Scientific and Cultural Organization: UNESCO), the quantitative identification of potential contributors of PAHs is an inevitable analytical tool for launching an evidence-based policy. The ΣPAH concentrations observed in SKL and NHL sediments (n = 135) were in the range of 19.4–1,218 ng g⁻¹ and 94.5–1,112 ng g⁻¹, respectively. While the exponential decline of ΣPAH contents were detected in SKL sediments, NHL showed a trend of enhancing PAH contents with depth. The averaged benzo [a]pyrene (B [a]P) contents of surface sediments in both lakes were much below the value stipulated by the United States Environmental Protection Agency (US-EPA) guidelines for carcinogen risk assessment. Based on numerous multivariate statistical techniques coupled with source apportionment analysis, “biomass burning” and “anthropogenic activities” are two potential contributors of the PAHs detected in the study areas. To achieve the long-term conservation of nature with related ecosystem services and cultural values, it is therefore important to promote decision-making based on ecotoxicological studies of carcinogenic substances.

Investigation of monthly residues of polycyclic aromatic hydrocarbons in water and sediment samples from Kirikkale Kizilirmak River Basin

Polycyclic aromatic hydrocarbons (PAHs) contain two or more benzene rings and are categorized as general environmentally harmful pollutants. PAHs occur because of various combustion and pyrolysis processes with different environmental and anthropogenic sources. The Kizilirmak River is one of the major important water sources used for drinking water and irrigation purposes in Turkey. There are important industrial facilities around the river and PAH pollution is important in terms of environmental health. This study was carried out to determine the residues of PAHs in water and sediment samples according to month and to identify the pollution sources. Thus, water and sediment samples were collected from five different stations in the Kirikkale basin of the Kizilirmak River every 15 days for a year. In this way, 120 water and 120 sediment samples were collected over a year and analyzed in terms of 16 priority PAHs according to the Environmental Protection Agency. The monthly average of the water and sediment samples was calculated. Analyses were carried out with high-performance liquid chromatography based on solid phase extraction. GC-MS was used for confirmation. Acenaphthene, acenaphthylene, benzo[b]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, and dibenzo[a,h]anthracene were not found in the water samples. The total PAH levels in water and sediment were detected in the range of 0.04 to 1.545 μg/L and 43.15-386.115 μg/kg, respectively. PAHs found in water and sediment samples had pyrogenic and petrogenic origin and pollution changed significantly between autumn and winter. As a result, precautions should be taken in terms of preventing environmental pollution.

Distribution, source, and health risk assessment of polycyclic aromatic hydrocarbons in the soils from a typical petroleum refinery area in south China

The ubiquity of polycyclic aromatic hydrocarbons (PAHs) in soils in petroleum refining areas is an important problem affecting human and ecological safety. In this study, 103 topsoil (0-0.50 m) samples were collected from a retired petroleum refinery area in Guangdong province, south China. The PAHs concentrations were determined by ultrasonic extraction and gas chromatography-mass spectrometry detection methods. Twelve PAHs controlled priority listed by the US Environmental Protection Agency (USEPA) were investigated. The results revealed that the concentration of Ʃ₁₂PAHs ranged from 2100 to 5200 µg kg^-1, with a mean value of 3741.66 µg kg^-1. The site was dominated by high rings PAHs (4-, 5-, and 6-ring), contributing 81.96% to Ʃ₁₂PAHs. The concentrations of 9 kinds of PAHs exceeded the Dutch soil quality standard. Besides, the PAHs were primarily distributed in the storage tank area and with high levels of contamination. The results of hierarchical cluster analysis (HCA) and principal component analysis (PCA) indicated that coal combustion was the source of PAHs in topsoil, followed by petroleum dripping and traffic emissions. The incremental lifetime cancer risk (ILCR) modeling illustrated that soil ingestion was the major pathway of PAH exposure for both adults and children. Notably, the total noncarcinogenic human health risk due to PAHs was within the limit of 1, while the carcinogenic risks alone caused by benzo(a)pyrene via soil ingestion to adults and children were obviously beyond the USEPA limit (1.00E -06). Therefore, PAHs in the petroleum refinery areas have potential carcinogenic hazards to human health, the area should be remediated before reuse.

Socio-psychological determinants of Iranian rural households' adoption of water consumption curtailment behaviors

Dealing with a growing population and a shortage of drinking water is a major challenge for politicians and planners. A key factor in ensuring a sustainable water supply is water conservation at the household level, which can increase productivity and save water resources. Therefore, promoting water consumption curtailment behavior will contribute significantly to reducing the global water crisis, especially in arid and semi-arid regions. Water consumption curtailment behaviors depend on individuals’ encouragement to choose and adopt voluntary behaviors and cannot be enforced by any political or planning power. In order to encourage water conservation those social and psychological factors should be considered that influence individuals to participate or adopt water consumption curtailment behaviors. Therefore, the study of factors influencing rural households' water consumption curtailment behaviors is of great importance. This study aimed to describe the socio-psychological factors influencing water consumption curtailment behaviors among rural households in southwestern Iran. The extended theory of planned behavior (ETPB) was used as a theoretical framework in this study along with descriptive norms (DN), moral norms (MN), habits, and justification. Data were collected using a questionnaire and analyzed using structural equation modeling (SEM). The results showed that ETPB can explain 35% and 54% of intention and water consumption curtailment behaviors among rural households in Iran. Our findings may assist policymakers in reducing domestic water consumption.

Polycyclic Aromatic Hydrocarbons (PAHs) in the Dissolved Phase, Particulate Matter, and Sediment of the Sele River, Southern Italy: A Focus on Distribution, Risk Assessment, and Sources

The Sele River, located in the Campania Region (southern Italy), is one of the most important rivers and the second in the region by average water volume, behind the Volturno River. To understand the distribution and sources of polycyclic aromatic hydrocarbons (PAHs) in the Sele River, water sediment samples were collected from areas around the Sele plain at 10 sites in four seasons. In addition, the ecosystem health risk and the seasonal and spatial distribution of PAHs in samples of water and sediment were assessed. Contaminant discharges of PAHs into the sea were calculated at about 1807.9 kg/year. The concentration ranges of 16 PAHs in surface water (DP), suspended particulate matter (SPM), and sediment were 10.1–567.23 ng/L, 121.23–654.36 ng/L, and 331.75–871.96 ng/g, respectively. Isomeric ratio and principal component analyses indicated that the PAH concentrations in the water and sediment near the Sele River were influenced by industrial wastewater and vehicle emissions. The fugacity fraction approach was applied to determine the trends for the water-sediment exchange of 16 priority PAHs; the results indicated that fluxes, for the most part, were from the water into the sediment. The toxic equivalent concentration (TEQ) of carcinogenic PAHs ranged from 137.3 to 292.6 ngTEQ g⁻¹, suggesting that the Sele River basin presents a definite carcinogenic risk.

A review on polycyclic aromatic hydrocarbons distribution in freshwater ecosystems and their toxicity to benthic fauna

Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds, found ubiquitously in all environmental compartments. PAHs are considered hazardous pollutants, being of concern to both the environmental and human health. In the aquatic environment, PAHs tend to accumulate in the sediment due to their high hydrophobicity, and thus sediments can be considered their ultimate sink. Concurrently, sediments comprise important habitats for benthic species. This raises concern over the toxic effects of PAHs to benthic communities. Despite PAHs have been the subject of several reviews, their toxicity to freshwater benthic species has not been comprehensively discussed. This review aimed to provide an overview on PAHs distribution in freshwater environments and on their toxicity to benthic fauna species. The distribution of PAHs between sediments and the overlying water column, given by the sediment-water partition coefficient, revealed that PAHs concentrations were 2 to 4 orders of magnitude higher in sediments than in water. The sediment-water partition coefficient was positively correlated to PAHs hydrophobicity. Toxicity of PAHs to benthic fauna was addressed through Species Sensitivity Distributions. The derived hazardous concentration for 5% of the species (HC₅) decreased as follows: NAP (376 μg L^-1) > PHE > PYR > FLT > ANT (0.854 μg L^-1), varying by 3 orders of magnitude. The hazardous concentrations (HC₅) to benthic species were inversely correlated to the hydrophobicity of the individual PAHs. These findings are pertinent for environmental risk assessment of these compounds. This review also identified future challenges regarding the environmental toxicity of PAHs to freshwater benthic communities, namely the need for updating the PAHs priority list and the importance of comprehensively and more realistically assess the toxicity of PAHs in combination with other stressors, both chemical and climate-related.

Fire and rain: A systematic review of the impacts of wildfire and associated runoff on aquatic fauna

Climate and land-use changes are expected to increase the future occurrence of wildfires, with potentially devastating consequences for freshwater species and ecosystems. Wildfires that burn in close proximity to freshwater systems can significantly alter the physicochemical properties of water. Following wildfires and heavy rain, freshwater species must contend with complex combinations of wildfire ash components (nutrients, polycyclic aromatic hydrocarbons, and metals), altered light and thermal regimes, and periods of low oxygen that together can lead to mass mortality events. However, the responses of aquatic fauna to wildfire disturbances are poorly understood. Here we provide a systematic review of available evidence on how aquatic animals respond to and recover from wildfire disturbance. Two databases (Web of Science and Scopus) were used to identify key literature. A total of 83 studies from across 11 countries were identified to have assessed the risk of wildfires on aquatic animals. We provide a summary of the main ecosystem-level changes associated with wildfires and the main responses of aquatic fauna to such disturbances. We pay special focus to physiological tools and biomarkers used to assess how wildfires impact aquatic animals. We conclude by providing an overview of how physiological biomarkers can further our understanding of wildfire-related impacts on aquatic fauna, and how different physiological tools can be incorporated into management and conservation plans and serve as early warning signs of wildfire disturbances.

Toxicity assessment of typical polycyclic aromatic hydrocarbons to Daphnia magna and Hyalella azteca in water-only and sediment-water exposure systems

While the equilibrium partitioning (EqP) method has been demonstrated to effectively predict the adverse effects of nonionic organic chemicals in sediment on benthic organisms by sediment toxicity tests, only a limited number of studies have been performed both in water-only and whole-sediment toxicity tests using the same species and verified the validity of EqP-based toxicity assessment. To further examine the validity of the EqP method for application in a wide range of hydrophobicity, we conducted sorption/desorption experiments and both water-only and sediment toxicity tests using a popular aquatic crustacean species, Daphnia magna (48 h), and benthic species Hyalella azteca (96 h) for six typical polycyclic aromatic hydrocarbons (PAHs) with three to five rings and an amine derivative: anthracene, phenanthrene, fluoranthene, pyrene, benzo[a]pyrene, dibenzo[a,h]anthracene, and 1-aminopyrene. The linear sorption coefficient was determined and ranged from 2.7 × 10² (phenanthrene) and 1.2 × 10⁴ L/kg (benzo[a]pyrene) highly depending on the hydrophobicity while the aqueous concentrations were stable after 24 h in the desorption test. As result of acute toxicity tests in the water-only exposure system, anthracene and dibenz[a,h]anthracene were found to be nontoxic to both species, while median effect/lethal concentrations (EC₅₀/LC₅₀) were determined as ranging from 0.66 (benzo[a]pyrene) to 330 μg/L (phenanthrene), and from 11 (1-aminopyrene) to 180 μg/L (phenanthrene) for D. magna and H. azteca, respectively. Among these compounds, three PAHs with three, four, and five rings each, and 1-aminopyrene were subjected to sediment-water toxicity tests. In the sediment-water tests, the LC₅₀ of phenanthrene and pyrene was three to six times higher than that of the water-only tests for H. azteca while the EC₅₀ was 1.1 to 2.0 times higher for D. magna. In contrast, the EC₅₀/LC₅₀ of benzo[a]pyrene (BaP) in the sediment-water toxicity test was more than 5 times higher than that in the water-only test for both H. azteca and D. magna. The EC₅₀/LC₅₀ values of 1-aminopyrene were similar in both the sediment-water and the water-only toxicity tests, ranging narrowly from 21 to 28 μg/L and 8.8 to 11 μg/L for D. magna and H. azteca, respectively. The EC₅₀/LC₅₀ based on the body residue (ER₅₀/LR₅₀) was investigated for two of the representative PAHs, pyrene, and BaP. The ER₅₀/LR₅₀ of pyrene in both species was 2.3 and 11 times higher in the water-only toxicity test for D. magna and H. azteca, respectively, while those of BaP in the sediment-water toxicity test were not calculated for the sediment-water toxicity tests, and the highest body concentration in the sediment-water tests was lower than the ER₅₀/LR₅₀ in the water-only toxicity test. Although the experimental results were comparable with the predicted sediment toxicity values based on the EqP method for the selected PAHs in this study, there is a risk of phenanthrene and pyrene being slightly underestimated (1.4-1.9 fold for phenanthrene and 3.7-6.1 fold for pyrene) by the EqP method for H. azteca. These results reaffirm that the bioavailability of poorly water-soluble chemicals is important for sediment toxicity and that the exposure pathway should be further investigated to avoid under- and overestimation via the EqP method.

WITHDRAWN: Usage of deep learning in environmental health risk assessment

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Distribution, sources, and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in surface sediments from Daya Bay, South China

In this study, the concentrations of 16 kinds of polycyclic aromatic hydrocarbons (PAHs) in surface sediments of Daya Bay were determined and analyzed. Results showed that 16 PAHs were detected in all the samples, and the total PAH concentration ranged from 70.18 to 128.04 ng g-1, with an average of 103.17 ng g-1. The cyclic number distribution of PAHs in the sediments was mainly 4 and 5 rings. Six classic PAH ratios named Ant/(Ant + Phe), Fla/(Fla + Pyr), [InP/(InP + BghiP)], [BaA/(BaA + Chr)], BaA/BghiP, and LMW/HMW, and principal component analyses showed that the main source of PAHs in this region was combustion (biomass, coal, and petroleum combustion), and the secondary source was petroleum. The ecological risk analysis of PAHs by using effect range low/median method and mean effects range-median quotient method showed that all of PAHs are lower than the effect range low (ERL) level and the effects range-median quotient (M-ERM-Q) value of all stations is 0.0027-0.0067, with an average value of 0.0046. Thus, it can be seen that PAHs are at a low-risk level in surface sediments of Daya Bay.

Fate and Occurrence of Polycyclic Aromatic Hydrocarbons and Their Derivatives in Water and Sediment from Songhua River, Northeast China

The Songhua River is one of the most populated and oldest industrial areas in Northeast China. To understand the sources and distribution of polycyclic aromatic hydrocarbons and their derivatives, such as 16 priority (PAHs), 33 methylated (Me-PAHs), and 12 nitrated (NPAHs) in river water and sediment, were noticed. The concentrations of ∑PAHs, ∑Me-PAHs, and ∑NPAHs in river water scaled from 135 to 563, 9.36 to 711, and 1.26 to 64.7 ng L−1, with mean values of 286, 310, and 17.9 ng L−1, and those in sediments were from 35.8 to 2000 ng g−1, 0.62 to 394 ng g−1, and 0.28 to 176 ng g−1 (dry weight) with mean values of 283, 103, and 21.7 ng g−1. The compositions proved that two-ring and three-ring compounds of PAHs, NPAHs, and four-ring, six-ring of Me-PAHs were prevalent in water samples; in contrast, four-ring dominated in sediments. Principal components analysis (PCA) and diagnostic ratios confirmed that pollutant source was mixed petrogenic and pyrogenic origin. The fugacity fraction (ƒƒ) was also calculated to explain the trend of sediment–water exchange, high ƒƒ values found in summer, for most HMW PAHs and Me-PAHs that these substances acted as a secondary source of emissions from sediment to water. The risk assessment for water was categorized as high.

Environmental status of an Italian site highly polluted by illegal dumping of industrial wastes: The situation 15 years after the judicial intervention

In 2008 the Italian government classified the Bussi sul Tirino area (Central Italy) as Site of National Interest destined to remediation which, unfortunately, has not yet begun. The decision followed >20 years of illegal dumping of industrial wastes, lasting from 1984 to 2005, that generated the biggest illegal toxic waste disposal site in Europe. The contamination profile of the site was mainly characterized by PCDD/Fs, PCBs, PAHs, chlorinated solvents, Hg, and Pb. Due to the health concern of the population and local authorities, an extensive monitoring and biomonitoring campaign was carried out in 2017-2018, checking the site-specific pollutants in local food (free-range hens' eggs, milk from grazing sheep and goats, wild edible mushrooms, and drinking water), environmental (air and freshwaters) and biological (human urine) matrices. A total of 314 samples were processed, obtaining 3217 analytical data that were compared with regulatory limits, when available, and values reported by international literature. The sum PCDD/Fs and DL-PCBs ranged from 0.24 to 3.6 pg TEQ g^-1 fat, and from 0.46 to 8.3 pg TEQ g^-1 fat, respectively in milk in eggs, in line with the maximum levels established by CE Regulations except for an egg sample. As regards PAHs, all our results were lower than the literature data, as well as for Hg and Pb. Outdoor air showed levels of chlorinated solvents ranging from <LOD to 36 μg m^-3, and freshwaters from 0.21 to 2.8 μg L^-1. All drinking water samples resulted compliant with the maximum levels established by the current EU directive. Despite the severe pollution of the illegal dumping site and the remediation not yet carried out, the local environment and the population living in Bussi and surroundings seem not to be affected by significant exposure to the toxics characterizing the landfill.

Concentrations, distribution and risk of polycyclic aromatic hydrocarbons in sediments from seven major river basins in China over the past 20 years

Polycyclic aromatic hydrocarbons (PAHs) in river sediments in China have been extensively investigated. However, most previous studies only reported information about specific locations. As a result, the distribution and changes of these chemicals in sediments nationwide remain unknown. Based on published data during 1997-2020, we conducted a systematic meta-analysis to understand the concentration, risk and the spatiotemporal variation of PAHs in river sediments from the seven major river systems in China. The report provides a national picture of PAHs in river sediments of China. Among the seven river systems, higher concentrations of sediment PAHs are found in the basins of Liaohe River and Haihe River. In the study sediments, high-molecular-mass (4-6-ring) PAHs were predominated, reflecting the widespread combustion of coal and fossil fuels across China. In addition, PAH source assessment also suggests that raw coal and crude oil are important contributors to PAH concentrations in the rivers in northeastern China. Over the past 20 years, there is no downward trend in the concentrations of Σ₁₆PAHs in sediments in the seven river basins; but the contribution of high-temperature combustion to the pollution has declined. In addition, our calculated risks from sediment PAHs seem to decline between 1997-2006 and 2007-2017 periods, although the differences were not statistically significant (p > 0.05). Of note, the data collection and the risk assessment methods used in this preliminary survey may result in some uncertainty. Our results suggest that the PAHs in river sediments in China still need to be paid attention to due to the complexity of their sources and harms to aquatic organisms.

Riverine transport and water-sediment exchange of polycyclic aromatic hydrocarbons (PAHs) along the middle-lower Yangtze River, China

We examined the riverine transport of polycyclic aromatic hydrocarbons (PAHs) based on their spatial-temporal distributions in water and sediments from the mainstream along the middle and lower Yangtze River. According to the fugacity fraction (ff) estimation, sediments performed as a secondary emission source of two-, three-, and four-ringed PAHs and as a sink for five- and six-ringed congeners, leading to higher ecological and human health risks especially towards the lower reaches. The higher PAH levels observed in the more developed delta and megacities were highly linked to economic parameters. This was further supported by the source apportionment performed using the principal component analysis-multiple linear regression (PCA-MLR) model, which showed major contributions of coal and coke combustions along with vehicle emissions. The spatial-temporal distribution revealed that water runoff was the major contribution to PAHs transport along the middle-lower Yangtze River, whereas a sharp decrease in sediment discharge due to the dam impoundment along the upper reaches would lead to an increase in the catchment retention effect of PAHs. Hence, the biogeochemical processes of PAHs and their impacts on the fragile ecosystems as a consequence of the further modification of the sedimentary system in rivers need to be fully explored.

Bioremediation of Diesel Contaminated Marine Water by Bacteria: A Review and Bibliometric Analysis

Oil pollution can cause tremendous harm and risk to the water ecosystem and organisms due to the relatively recalcitrant hydrocarbon compounds. The current chemical method used to treat the ecosystem polluted with diesel is incompetent and expensive for a large-scale treatment. Thus, bioremediation technique seems urgent and requires more attention to solve the existing environmental problems. Biological agents, including microorganisms, carry out the biodegradation process where organic pollutants are mineralized into water, carbon dioxide, and less toxic compounds. Hydrocarbon-degrading bacteria are ubiquitous in the nature and often exploited for their specialty to bioremediate the oil-polluted area. The capability of these bacteria to utilize hydrocarbon compounds as a carbon source is the main reason behind their species exploitation. Recently, microbial remediation by halophilic bacteria has received many positive feedbacks as an efficient pollutant degrader. These halophilic bacteria are also considered as suitable candidates for bioremediation in hypersaline environments. However, only a few microbial species have been isolated with limited available information on the biodegradation of organic pollutants by halophilic bacteria. The fundamental aspect for successful bioremediation includes selecting appropriate microbes with a high capability of pollutant degradation. Therefore, high salinity bacteria are remarkable microbes for diesel degradation. This paper provides an updated overview of diesel hydrocarbon degradation, the effects of oil spills on the environment and living organisms, and the potential role of high salinity bacteria to decontaminate the organic pollutants in the water environment.

Chemometric tools applied to optimize a fast solid-phase microextraction method for analysis of polycyclic aromatic hydrocarbons in produced water

Chemometric tools are powerful strategies to efficiently optimize many processes. These tools were employed to optimize a fast-solid phase microextraction procedure, which was used for the analysis of polycyclic aromatic hydrocarbons (PAHs) in oil-based produced water using a Headspace-Solid Phase Microextraction technique (HS-SPME/GC-MS). This optimization was achieved with a 2⁴ factorial design approach, where the final conditions for this extraction procedure were 10 μg L^-1, 1 h, 92 °C (at headspace), and 0.62 mol L^-1 for PAHs concentration, fiber exposition to headspace, temperature, and NaCl concentration, respectively. The limit of detection (LOD) in this protocol ranged from 0.2 to 41.4 ng L^-1, while recovery values from 67.65 to 113.10%. Besides that, relative standard deviation (RSD) were lower than 8.39% considering high molecular weight compounds. Moreover, the proposed methodology in this work does not require any previous treatment of the sample and allows to quantify a higher number of PAHs. Notably, naphthalene was the major PAHs compound quantified in all samples of the produced water at 99.99 μg L^-1. Altogether, these results supported this methodology as a suitable analytical strategy for fast determination of PAHs in produced water from oil-based industry.

After remediation - Using toxicity identification evaluation of sediment contamination in the subtropical Erren river basin

This study utilized the freshwater amphipod (Hyalella azteca) for the indication of contamination risk levels of sediment-associated contaminants in the Erren (ER1∼ER10) and Sanye Rivers (SY1∼SY5) which were contaminated by metal scrap and smelting industries for decades. Toxicity identification evaluations involving the manipulation of pore water and whole-sediment samples were conducted to identify causative pollutants. Impacts on the aquatic environment were then evaluated in order to explore how industrial development led to contaminant accumulation in sediments and resulted in biological effects. A whole-sediment TIE indicated that the major toxicant at sampling sites ER8 and SY5 was ammonia and that its toxicity was significantly reduced by the addition of zeolite. Toxicity at sampling sites ER4 and ER9 was induced by ammonia and heavy metals (Zn, Cd, Cr, As), whereas Cr was at toxic levels at ER6. ∑PAHs was another major class of contaminants at site ER2. Metals (Zn, Ni, Pb, Cd, Cr, and As) were identified as major toxic contaminants at three sites (ER3, SY1, and SY3). The application of TIEs confirmed that a causative toxicant can be identified and that its measured toxicity correlated with its concentration. In conclusion, a TIE approach was successful in demarcating most effective contaminant groups (ammonia, heavy metals, and non-polar organic compounds) in whole-sediment cores, their porewaters and potential toxicities from a highly polluted river after remediation in southern Taiwan to an invertebrate animal model H. azteca.

Using Excimeric Fluorescence to Study How the Cooling Rate Determines the Behavior of Naphthalenes in Freeze-Concentrated Solutions: Vitrification and Crystallization

We utilized fluorescence spectroscopy to learn about the molecular arrangement of naphthalene (Np) and 1-methylnaphthalene (MeNp) in frozen aqueous solutions. The freezing induces pronounced compound aggregation in the freeze-concentrated solution (FCS) in between the ice grains. The fluorescence spectroscopy revealed prevalent formation of a vitrified solution and minor crystallization of aromatic compounds. The FCS is shown as a specific environment, differing significantly from not only the pure compounds but also the ice surfaces. The results indicate marked disparity between the behavior of the Np and the MeNp; the cooling rate has a major impact on the former but not on the latter. The spectrum of the Np solution frozen at a faster cooling rate (ca 20 K/min) exhibited a temperature-dependent spectral behavior, whereas the spectrum of the solution frozen at a slower rate (ca 2 K/min) did not alter before melting. We interpret the observation through considering the varied composition of the FCS: Fast freezing leads to a higher water content expressed by the plasticizing effect, allowing molecular rearrangement, while slow cooling produces a more concentrated and drier environment. The experiments were conceived as generalizable for environmentally relevant pollutants and human-made freezing.

Gas ebullition from petroleum hydrocarbons in aquatic sediments: A review

Gas ebullition in sediment results from biogenic gas production by mixtures of bacteria and archaea. It often occurs in organic-rich sediments that have been impacted by petroleum hydrocarbon (PHC) and other anthropogenic pollution. Ebullition occurs under a relatively narrow set of biological, chemical, and sediment geomechanical conditions. This process occurs in three phases: I) biogenic production of primarily methane and dissolved phase transport of the gases in the pore water to a bubble nucleation site, II) bubble growth and sediment fracture, and III) bubble rise to the surface. The rate of biogenic gas production in phase I and the resistance of the sediment to gas fracture in phase II play the most significant roles in ebullition kinetics. What is less understood is the role that substrate structure plays in the rate of methanogenesis that drives gas ebullition. It is well established that methanogens have a very restricted set of compounds that can serve as substrates, so any complex organic molecule must first be broken down to fermentable compounds. Given that most ebullition-active sediments are completely anaerobic, the well-known difficulty in degrading PHCs under anaerobic conditions suggests potential limitations on PHC-derived gas ebullition. To date, there are no studies that conclusively demonstrate that weathered PHCs can alone drive gas ebullition. This review consists of an overview of the factors affecting gas ebullition and the biochemistry of anaerobic PHC biodegradation and methanogenesis in sediment systems. We next compile results from the scholarly literature on PHCs serving as a source of methanogenesis. We combine these results to assess the potential for PHC-driven gas ebullition using energetics, kinetics, and sediment geomechanics analyses. The results suggest that short chain <C₁₀ alkanes are the only PHC class that alone may have the potential to drive ebullition, and that PHC-derived methanogenesis likely plays a minor part in driving gas ebullition in contaminated sediments compared to natural organic matter.

Anthracene removal from water samples using a composite based on metal-organic-frameworks (MIL-101) and magnetic nanoparticles (Fe3O4)

Polycyclic hydrocarbons constitute an important source of very dangerous pollutants. Different materials have been used as adsorbent for their removal, but they present difficulties in the separation process. The use of a material based on metal-organic framework (MOF) with large pores and high surface area and magnetic nanoparticles with superparamagnetic properties is an interesting strategy. In this work a magnetic composite based on MOF (MIL-101) and Fe₃O₄ magnetic nanoparticles (Fe₃O₄/MIL-101) was obtained by a simple synthesis method and used as adsorbent for the removal of anthracene. The composite was characterized by transmission electron microscopy, x-ray powder diffraction and vibrating sample magnetometer. The results showed that kinetic data followed a first-order model and equilibrium data were well fitted by the Langmuir model. The maximum adsorption capacity was 12.7 mg g^-1 at pH 6 in 60 min of exposure. The composite was applied for the adsorption of anthracene in water samples reaching more than 95% of anthracene removal in 1 h of contact. The composite material was effectively separated using an external magnet, and no further centrifugation or filtration processes were needed. This composite is a great alternative to remove polycyclic hydrocarbons from water samples and has potential to extend to the removal of other contaminants.

Distribution, sources, and behavior of PAHs in estuarine water systems exemplified by Salt River, Taiwan

Water, suspended particulate matter (SPM), and sediment samples were collected from Salt River in Taiwan and analyzed the concentrations of 16 types of polycyclic aromatic hydrocarbons (PAHs). The analysis results were used to examine the distribution, source, partition behavior, and potential ecological risks of PAHs in the estuarine water systems. The mean concentration of total PAHs in water, SPM, and sediment samples was 0.485-10.2 μg/L, 26.7-169 mg/kg dw, and 0.343-29.4 mg/kg dw, respectively. The highest concentration was found at the river mouth and decreased toward the river and sea with the tide. The distribution of the diagnostic ratios of PAHs showed that the combustion of coal and petroleum products are the main sources of PAHs in Salt River. The in site organic carbon normalized partition coefficients for SPM-water (K'_oc(SPMW)) and sediment-water (K'_oc(SedW)) were 2.8-4.5 and 4.6-6.0 (log units), respectively, increasing with the number of rings in PAHs. The values log K'_oc(SedW) and log K'_oc(SPM-W) showed a significant linear correlation with their octanol-water partition coefficients (p < 0.01), and their slopes were 0.427 and 0.316, respectively. The fugacity fraction was used to evaluate the exchange of PAHs in water-SPM-sediment systems. Results showed that in SPM, 2-4-ring PAHs tend to be released into water, whereas 5-6-ring PAHs in water tend to be adsorbed onto SPM. The exchange of PAHs between water and sediment occurs in the direction of adsorption onto sediment from water. The assessment of the mean risk quotient, total toxicity equivalence, and mean effect range-median quotient of PAHs showed that the PAHs in the water and SPM of Salt River may have moderate to high ecological risk. In sediment, PAHs in the lower reaches and estuary may pose moderate to high ecological risk, whereas PAHs in the middle and upper reaches show low to moderate ecological risk.

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

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

Bisphenol A (BPA) and polycyclic aromatic hydrocarbons (PAHs) in the surface sediment and bivalves from Hormozgan Province coastline in the Northern Persian Gulf: A focus on source apportionment

This study investigates Polycyclic Aromatic Hydrocarbons (PAHs) and Bisphenol-A (BPA) pollution in coastal sediments and bivalves of Hormozgan Province coastline. The results indicated that the BPA concentration in some bivalves reached up to 340.16 ng g^-1. The mean BPA concentration in the sediment samples was also 787.01 ng g^-1. The ∑PAHs content in sediments ranged from 14.54 to 85.00 ng g^-1, while values for bivalves ranged from 5.37 to 16.40 ng g^-1. Individual PAH concentrations in sediments exceeded those in bivalves for which only LMW PAHs were detected. A combination of techniques including Self-Organizing Maps (SOM), Positive Matrix Factorization (PMF), and Cluster Analysis (CA) were applied and both petrogenic and pyrogenic sources were identified. The risk of PAHs in the sediments was relatively low according to the sediment quality guidelines. The health risk indices suggest that exposure to PAHs through bivalve consumption does not impose harmful health effects upon consumers.

Soil-to-plant transfer of naphthalene and its effects on seedlings pea (Pisum sativum L.) grown on contaminated soil

The aim of this work was to determinate effect of naphthalene at different concentrations on morphological, physiological and some metabolic responses of pea seedlings. The quantification of naphthalene and its by-products were also recorded by Gas Chromatography/ Mass Spectrometry (GC / MS) in soil and in the different plant parts (roots, stems, leaves and fruit). In our controlled laboratory studies, plants exposed to naphthalene were able to efficiently grow and maintain their content of chlorophyll and carotenoids comparatively to the control plants. However, the pollutant slightly increased the amounts of fatty acid peroxides and strongly those of malonyldialdehyde, the product of lipid peroxidation. The glutathione S transferase activity was also increased for all concentrations used especially in leaves. Chromatograms showed that naphthalene has fallen sharply in the soil or even disappeared for the highest concentration from the second to third week. Furthermore, the removal ratio of 67% of the pollutant from the soil was distributed between two metabolites (ion 47 and ion 59) in the leaves for this same concentration in only three weeks of cultivation. In parallel, the amount of pollutant remained higher in unvegetated control soil. These results suggest that seedlings of pea (Pisum sativum L.) can remove naphthalene from contaminated soil and consequently have a high potential to be used as a promising candidate for the phytoremediation of naphthalene-contaminated soil.

Effects of total organic carbon content and leaching water volume on migration behavior of polycyclic aromatic hydrocarbons in soils by column leaching tests

The risk of soils transferring polycyclic aromatic hydrocarbons (PAHs) into groundwater has caused widespread concern. Research on the leaching behavior of PAHs in soil profiles is very important for assessing this risk. Column leaching tests were carried out to provide insight into the effect of TOC and leaching water volume on leaching behavior of PAHs. Four groups were leached intermittently by deionized water under the same leaching rate for 10 d, 30 d, 90 d and 120 d. These four leaching periods are equivalent to 1 yr, 3 yr, 9 yr and 12 yr of rainfall time under natural conditions, respectively. The results showed that residual concentrations of PAHs on the surface of soil (0-5 cm) in three columns after 30 d of leaching were 37.9 μg/g, 18.5 μg/g and 3.7 μg/g, respectively, which was consistent with their TOC contents. According to the correlation analysis, both residual concentrations of ∑₁₆PAHs and PAHs with different ring numbers were significantly correlated with the TOC content at depths of 5-100 cm after 30 d of leaching. With increased leaching water volume, PAH migration rates significantly decreased (from 3.13 μg/g/d to 0.005 μg/g/d) from 10 d to 120 d, which indicates that the initial period of the leaching process has a stronger effect on PAH vertical migration than the later stages of the process. Under long-term leaching, PAHs that were not leached previously were capable of migrating deeper into the soil profile. Therefore, it has the risk of PAH-contaminated soils transferring PAHs into groundwater.