Source apportionment of polycyclic aromatic hydrocarbons (PAHs) in small craft harbor (SCH) surficial sediments in Nova Scotia, Canada

Quantifying the impact of anthropogenic emissions and aquatic environmental impacts on sedimentary mercury variations in a typical urban river

In urban and industrial regions, sedimentary mercury (Hg) serves as the crucial indicator for Hg pollution, posing potential risks to ecology and human health. The physicochemical processes of Hg in aquatic environments are influenced by various factors such as anthropogenic emissions and aquatic environmental impacts, making it challenging to quantify the drivers of total mercury (THg) variations. Here, we analyzed the spatiotemporal variations, quantified driving factors, and assessed accumulation risks of sedimentary THg from the mainstream of a typical urban river (Haihe River). THg in the urban region (37-3237 ng g-1) was significantly higher (t-test, p < 0.01) than in suburban (71-2317 ng g-1) and developing regions (156-916 ng g-1). The sedimentary THg in suburban and developing regions increased from 2003 to 2018, indicating the elevated atmospheric deposition of Hg. Together with the temperature, grain size of sediments, total organic carbon (TOC), the pH and salinity of water, 40 components of parent and substituted polycyclic aromatic hydrocarbons (PAHs) were first introduced to quantify the driver of sedimentary THg based on generalized additive model. Results showed that anthropogenic emissions, including three PAHs components (31%) and TOC (63%), accounted for 94% of sedimentary THg variations. The aquatic environmental impacts accounted for 5% of sedimentary THg variations. The geo-accumulation index of THg indicated moderate to heavy accumulation in the urban region. This study demonstrates that homologous pollutants such as PAHs can be used to trace sources and variations of Hg pollution, supporting their co-regulation as international conventions regulate pollutants.

Polycyclic aromatic hydrocarbons in surface water of rivers in Sergipe State, Brazil: A comprehensive analysis of sources, spatial and temporal variation, and ecotoxicological risk

This study conducted in Sergipe State, Brazil, aimed to investigate the presence of polycyclic aromatic hydrocarbons (PAHs) in the surface water of five rivers, determining their sources, spatial and temporal variations, and ecotoxicological risks. Correlation and principal component analyses were utilized to identify the relationship between PAH concentrations and water sample properties. Results indicated higher PAH concentrations during the rainy season, attributed to increased run-off and sediment resuspension. The composition of PAHs suggested a main petroleum source with organic material combustion in minor scale. Ecological risk assessment revealed potential risks to the ecosystem, emphasizing the need for continuous monitoring of PAHs pollution. This study highlights the importance of understanding and mitigating PAHs contamination in rivers to protect aquatic ecosystems.

Global producer responsibility for plastic pollution

Brand names can be used to hold plastic companies accountable for their items found polluting the environment. We used data from a 5-year (2018-2022) worldwide (84 countries) program to identify brands found on plastic items in the environment through 1576 audit events. We found that 50% of items were unbranded, calling for mandated producer reporting. The top five brands globally were The Coca-Cola Company (11%), PepsiCo (5%), Nestlé (3%), Danone (3%), and Altria (2%), accounting for 24% of the total branded count, and 56 companies accounted for more than 50%. There was a clear and strong log-log linear relationship production (%) = pollution (%) between companies' annual production of plastic and their branded plastic pollution, with food and beverage companies being disproportionately large polluters. Phasing out single-use and short-lived plastic products by the largest polluters would greatly reduce global plastic pollution.

Tar pollution event (2021) at the Southeastern Levantine oligotrophic basin, short-term impacts and operational oceanography perspectives

The Levantine basin (LB) in the Southeastern Mediterranean Sea is a high-risk oil pollution hot spot owing to its dense maritime traffic and intense oil and gas exploration and exploitation activities. In February 2021 the Israeli LB shorelines were impacted by an exceptional tar pollution event (~550 tons; average distribution: ~3 kg tar m-1 front beach) of an unknown oil spill source. Here we report on the immediate numerical modelling assessment of the oil spill propagation and tar distribution; operational use of underwater gliders for tracking water column anomalies of dissolved polycyclic aromatic hydrocarbons (PAHs) and turbidity signals; the beached tar composition and amounts and the short-term response of the microbial population along the ~180 km shoreline. This pollution event emphasizes the need for improving the early warning systems for oil spills and implementing continuous operational monitoring at high-risk, ecologically sensitive and valuable resource areas like the Israeli LB waters.

Pollution patterns and their effects on biota within lotic and lentic freshwater ecosystems: How well contamination and response indicators correspond?

Aquatic environments are often severely polluted with chemical substances of anthropogenic origin, which can pose a potential threat to aquatic organisms and human health. In this study, patterns and sources of heavy metals (HMs, 6 metals) and polycyclic aromatic hydrocarbons (PAHs, 16 hydrocarbons), contamination indicators, environmental genotoxicity measures and metrics of ecological status in lotic and lentic ecosystems were collated for the first time. Chemical analysis has confirmed previously reported long-term contamination at certain study sites. The sediments of Lake Talkša, located in a city and characterized by exclusive anthropogenic pressure, exhibited the highest levels of contamination by both HMs and PAHs. Through positive matrix factorization (PMF) analysis, vehicle and industrial emissions were identified as the primary sources of HMs and PAHs. Our results revealed that frequencies of genotoxic aberrations were higher in river sites compared to lakes, with the highest genotoxic risk observed in the Nemunas River below industrial cities Alytus and Kaunas. Surprisingly, even the severely contaminated Lake Talkša showed only a "moderate" grade of genotoxic risk, highlighting the potential for adaptation of biota to long-term contamination especially in lentic ecosystems. The ecological quality status assessed by macroinvertebrate metrics, which may be sensitive to observed high biological contamination, appeared to be unrelated to contamination patterns. Consequently, to obtain the robust information on anthropogenic contamination and its effects, a combination of various assessment methods and metrics should be employed.

Risk assessment of sediment PAH, BTEX, and emerging contaminants in Chanomi Creek Niger Delta, Nigeria

This study assessed the levels of polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, ethylbenzene, and xylene (BTEX), and emerging contaminants in Chanomi Creek. Sediment samples were collected between March 2019 and July 2020 to evaluate the concentrations of PAH, BTEX, and emerging contaminants using GC-MS and GC-FID with Headspace extraction. Results indicated mean PAH concentrations were 22.691 ± 15.09 µg/kg. The highest individual PAH concentrations were fluorene (7.085 µg/kg), naphthalene (4.517 µg/kg), and phenanthrene (3.081 µg/kg). Carbazole (0.828 µg/kg) was discovered as a novel environmental toxin with dioxin-like toxicity and widespread prevalence in sediments. The most common congener (25%) was ethylbenzene, followed by toluene and ortho- and meta-xylene (21%) and benzene (13%). The analysis of diagnostic ratios revealed that the main factors responsible for the presence of PAHs in the study area are the residential use of firewood, emissions from industrial activities, bush burning, and petroleum slicks. The risk assessment indicated that most PAHs exceeded the permissible risk quotient values, suggesting a moderate to high ecological risk. However, cutaneous exposure to PAHs and BTEX was found to have minimal impact on human health, with no significant hazards identified in adults and children. Nevertheless, the study revealed low cancer risks associated with PAH and BTEX compounds for both age groups. The continued discharge of PAHs and BTEX compounds into Chanomi Creek could have significant long-term negative effects on human and aquatic health. Thus, contamination risk awareness programs and the development of stringent contextual thresholds for identified contaminants could enhance environmental and public health protection.

Using positive matrix factorization to unmix PAH fingerprints in contaminated sediments

Some of the challenges to apportioning PAH-related remedy costs at contaminated sediment sites include the lack of source samples, different PAH signatures associated with the same source, historical PAH sources long removed, mixing of urban sediment by boat traffic, and, in turn, PAHs mixing and weathering. Unmixing of PAH fingerprints in sediment sites to PAH source classes (petrogenic, pyrogenic, and runoff) is typically a first step to tracking PAH upland sources and ultimately, responsible parties. This work demonstrates using positive matrix factorization (PMF) as a method to unmix PAH fingerprints to its source classes.A large PAH dataset (over 700 samples) assembled from contaminated urban sediment sites was used as an input to PMF. Using a 3-factor PMF analysis, a petrogenic, pyrogenic, and runoff/weathered PAH end-member fingerprints were identified. Different numerical mixing percentages of the PMF-identified end-member sources were able to replicate the sediment-measured PAH fingerprints, with the percent contribution of each of the end members to each sediment sample calculated. The demonstrated work provides a method to satisfy the unmixing of PAH fingerprints to its source classes, as a step towards apportioning of PAH contamination.

Effect of humic acid-modified attapulgite on polycyclic aromatic hydrocarbon adsorption and release from paddy soil into the overlying water in a rice-crab coculture paddy ecosystem and the underlying process

Phenanthrene (Phe), a typical polycyclic aromatic hydrocarbon (PAH) pollutant, poses an enormous safety risk to rice-crab coculture (RC) paddy ecosystems. In this study, humic acid-modified purified attapulgite (HA-ATP) with a composite structure was successfully fabricated to adsorb PAHs released from paddy soil to overlying water in RC paddy ecosystems in Northeast China. The maximum crab bioturbation intensities for dissolved Phe and particulate Phe were 64.83nullng/L·(cm²·d) and 214.29nullng/L·(cm²·d), respectively. The highest concentration of dissolved Phe released from paddy soil to overlying water due to crab bioturbation reached 80.89nullng/L, while the corresponding concentration of particulate Phe reached 267.36nullng/L. The dissolved organic carbon (DOC) and total suspended solid (TSS) concentrations in overlying water increased correspondingly and were strongly correlated with dissolved Phe and particulate Phe concentrations, respectively (P < 0.05). When 6% HA-ATP was added to the surface layer of paddy soil, the efficiency of the adsorption of Phe release was 24.00%-36.38% for particulate Phe and 89.99%-91.91% for dissolved Phe. Because HA-ATP has a large adsorption pore size (11.33 nm) and surface area (82.41nullm²/g) as well as many HA functional groups, it provided multiple hydrophobic adsorption sites for dissolved Phe, which was conducive to competitive adsorption with DOC in the overlying water. In contrast to that adsorbed by DOC, the average proportion of dissolved Phe adsorbed by HA-ATP reached 90.55%, which reduced the dissolved Phe concentration in the overlying water. Furthermore, even though the particulate Phe was resuspended by crab bioturbation, HA-ATP immobilized particulate Phe due to its capacity to inhibit desorption, which achieved the goal of reducing the Phe concentration in the overlying water. This result was confirmed by research on the adsorption-desorption characteristics of HA-ATP. This research provides an environmentally friendly in situ remediation method for reducing agricultural environmental risks and improving rice crop quality.

Characterization, risk assessment, and source estimation of PM10-bound polycyclic aromatic hydrocarbons during wintertime in the ambient air of Basrah City, Iraq

In this study, the concentration and structure of polycyclic aromatic hydrocarbons (PAHs) associated with the ambient PM₁₀ in Basrah City, Iraq have been investigated for the first time. From December 2021 to February 2022, PM₁₀ samples were collected on quartz fiber filters, extracted using an optimized extraction protocol, and analyzed for the sixteen US EPA priority PAHs. The results indicated that 4- and 5-ring PAHs represent 52% of the total detected PAHs. The most abundant PAHs over the study period were chrysene (1.2 ± 1.5 ng m^-3), fluorene (0.9 ± 1.4 ng m^-3), and benzo[b]fluoranthene (0.7 ± 0.9 ng m^-3). Source identification suggested that PM₁₀-bound PAHs primarily originated from pyrogenic and petrogenic activities in Basrah City. In addition, the cancer risk associated to PAH exposure was assessed based on benzo[a]pyrene equivalent concentration and was found ranging from 0.07 to 6.32 ng m^-3; hence, it exceeded the threshold limit of 1.0 ng m^-3 established by the European legislation (EU, 2014). Benzo[a]pyrene was determined to be main contributor to total carcinogenic power of the detected PAHs, accounting for 50.3%, followed by dibenz[a,h]anthracene (22.3%). Similarly, benzo[a]pyrene represented a major contributor to PAH associated mutagenicity, accounting for 43.5% of the total.

State of polycyclic aromatic hydrocarbon (PAH) contamination in the Saint John Harbour, New Brunswick, Canada

This study examined the concentrations and compositions of polycyclic aromatic hydrocarbon (PAH) contaminants in the surficial sediments of the Saint John Harbour (SJH) and assessed PAH exposure to local aquatic biota. Our findings suggest that sedimentary PAH contamination is heterogeneous and widespread in the SJH, with several sites exceeding the Canadian and NOAA recommended guidelines for the protection of aquatic life. Despite high concentrations of PAHs at some sites, there was no indication that local nekton was affected. Lack of a biological response may be due in part to a low bioavailability of sedimentary PAHs, presence of confounding factors (e.g., trace metals), and/or adaptation of local wildlife to the historic PAH contamination in this region. Overall, although no indication of effects to wildlife was observed with the data collected in the present study, continued efforts should be made to remediate highly contaminated areas and reduce the prevalence of these compounds.

Occurrence and source of PAHs in Miankaleh International Wetland in Iran

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

Distribution and source assignments of polycyclic aromatic and aliphatic hydrocarbons in sediments and biota of the Lafayette River, VA

The Lafayette River comprises a tidal sub-estuary constrained by an urban watershed that is bounded by residential areas at its upper reaches and port activity at its mouth. We determined the concentrations and distributions of polycyclic aromatic hydrocarbons (PAHs) and aliphatic n-alkanes across 19 sites from headwaters to river mouth in surface sediments (0-2 cm). Potential atmospheric sources were investigated through the analysis of wet and dry deposition samples and intact coals from a major export terminal nearby. The potential consequences for human consumption were examined through analysis of native oyster (Crassostrea virginica) and blue crab tissues (Callinectes sapidus). A suite of up to 66 parent and alkyl-substituted PAHs were detected in Lafayette sediments with total concentrations ranging from 0.75 to 39.00 µg g^-1 dry wt. Concentrations of aliphatic n-alkanes (n-C₁₆ - n-C₃₁) ranged from 4.94 to 40.83 μg g^-1 dry wt. Source assignment using diagnostic ratios and multivariate source analysis suggests multiple sources contribute to the hydrocarbon signature in this metropolitan system with automotive and atmospheric transport of coal dust as the major contributors. Oyster tissues showed similar trends as PAHs observed in sediments indicating similar sources to water column particles which ultimately accumulate in sediments with crabs showing altered distributions as a consequence of metabolism.

Source identification and ecological risks of parent and substituted polycyclic aromatic hydrocarbons in river surface sediment-pore water systems: Effects of multiple factors

Substituted polycyclic aromatic hydrocarbons (SPAHs) have shown higher health and ecological risks than the corresponding parent PAHs (PPAHs) from laboratory studies, their variations in freshwater system, especially in surface sediment and pore water, remain inadequate understanding. In this study, we revealed the coexistence, ecological risk, and multiple factors affecting variations and sources of PPAHs and SPAHs (nitrated PAHs (NPAHs), oxygenated PAHs (OPAHs)) in the surface sediment-pore water system from a typical urban river in Northern China. The concentration ranges of Σ₂₆PPAHs, Σ₁₀NPAHs, and Σ₄OPAHs in the surface sediments were 153.0-5367.4, not detected (N.D.)-105.4, and 42.2-1177.0 ng·g^-1 dry weight, and fell within 0.6-38.8, N.D.-297.9, and N.D.-212.6 ng·mL^-1 in the pore waters. The t-distributed stochastic neighbor embedding (SNE) coupled with the partitioning around medoids (PAM) elucidated spatiotemporal the variations in PAHs, emphasizing the impacts of industrial activities and sewage discharges. Besides the geochemical and hydrochemical conditions, SPAHs were affected by the potential secondary formation, especially during the wet season. The method comparisons indicated the advantages of principal component analysis-multivariate linear regression (PCA-MLR) and n-alkanes model on source identification. PAHs mainly originated from fossil fuel combustion and vehicular exhaust. The top risk quotient (RQ) values for PAHs occurred in the urban and industrial sections. A majority of the surface sediment samples emerged with low to moderate exposure risks, while all the pore water samples showed high exposure risks. The RQs of OPAHs were significantly higher (p < 0.01) than those of PPAHs. The results suggested the secondary formation of SPAHs as an important role in ecological risks of PAHs in the urban river system.

Accumulation of heavy metal(loid)s and polycyclic aromatic hydrocarbons in the sediment of the Prahovo Port (Danube) and associated risks

The current study investigated the concentrations, possible sources, toxicity, and ecological risk of eight heavy metal(loid)s (As, Cd, Cr, Cu, Hg, Ni, Pb, Zn) and sixteen priority polycyclic aromatic hydrocarbons (PAHs) in surface sediments in the port of Prahovo (Danube, Serbia). Among the examined HMs, the most abundant was Cu (38.3 mg/kg), followed by Zn. The Σ16PAHs concentrations ranged from 25 to 112.5 µg/kg, with 4-ring PAHs (17.3 µg/kg) being the most dominant in the study area. The mean and maximum values of HMs and PAHs obtained in this study were below the national regulatory limits and within environmental criteria. Particularly significant correlations between As, Cd, Cr, Ni, Pb, Zn, 5-, 6-ring PAHs, as well as between Pb and Hg, indicated their similar anthropogenic sources, pathways, and adsorption mechanisms. These findings were confirmed by cluster analysis and principal component analysis. Diagnostic ratios demonstrated that contamination in inner port stations was characterized by pyrogenic sources, while PAHs of petrogenic origin prevailed in samples near the port entrance. The mean ERM quotient (mERMq), toxic risk index (TRI), and toxic equivalent quotient (TEQ) were also calculated to assess the toxicity of the investigated HMs and PAHs in sediments. Positive matrix factorization suggested four potential sources as the main components of sediment contamination, whereas the risk assessment indicated a low or relatively insignificant risk of adverse biological effects from the combined toxicity of HMs and PAHs for the entire study area.

Characterization, source apportionment, and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in urban soils from 23 cities in China

Concentrations, composition profiles, sources, and health risks of 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) in urban soils from 23 cities across China based on metadata collected from previous studies between 2005 and 2021 were investigated. ΣPAH concentrations in urban soils from 23 cities across China ranged from 0.1231 to 17.2000 mg/kg (mean = 2.7171 ± 3.8276 mg/kg). Overall PAH contamination in urban soils across China was moderate compared to that in global cities. Based on energy consumption and climate conditions, the spatial distributions of mean ΣPAH concentrations in Northeast China were highest, followed by those in North China, West China, East China, and South China. Individual PAH composition profiles decreased in the order: 4-ring PAHs (41.36%) > 5-ring PAHs (21.77%) > 3-ring PAHs (18.53%) > 6-ring PAHs (14.00%) > 2-ring PAHs (2.27%). Diagnostic ratios and positive matrix factorization (PMF) revealed that PAHs in urban soils were mainly derived from fossil fuel combustion (from coal, natural gas, and biomass), especially in North, Northeast, and East China, with smaller contributions from petrogenic sources. Health risk assessment results suggest that although there are potential cancer risks from PAHs, risks were acceptable. Toxic equivalent concentration (TEQ) and the corresponding oral cancer slope factor (CFS₀) contributed most to the uncertainty of total risks. This study will help develop strategies to reduce PAH risk management in urban soils in China.

Characterization, source apportionment and risk assessment of PAHs in urban surface dust in Shenyang city, China

Characteristics, profile composition, ecological and human health risk of polycyclic aromatic hydrocarbons in surface dust collected from Shenyang city, China, were investigated. Concentrations of 16 USEPA priority PAHs ranged between 371.57 and 3300.04 μg/kg (mean 1244.76 ± 715.25 μg/kg). Fluoranthene was the most abundant individual PAHs, followed by pyrene, and high molecular weight PAHs, more than three times of low molecular weight PAHs, were the predominant components. Profiles of PAHs showed that 4-ring PAHs were dominant, followed by 3-ring and 5-ring PAHs, and indicated that combustion sources accounted for the most PAHs. Results of diagnostic ratios and positive matrix factorization all suggested that pyrogenic sources were the most important source of PAHs in urban dust, followed by natural gas combustion and petrogenic sources, and traffic emissions would play an increasingly critical role with the increasing of vehicles. Health risk assessment suggested children were the most vulnerable to PAHs compared to adolescents and adults. Ingestion was the most important exposure pathway. The total lifetime cancer risk of 43.33% of sampling sites was higher than 10^-6, but the TLCR at all sites was much lower than the highest acceptable risk established by USEPA (10^-4).

Source Identification and Superposition Effect of Heavy Metals (HMs) in Agricultural Soils at a High Geological Background Area of Karst: A Case Study in a Typical Watershed

Exogenous sources and the superposition effect of HMs in agricultural soils made the idenfication of sources complicated in a karst area. Here, a typical watershed, a research unit of the karst area, was chosen as the study area. The smaller-scale study of watersheds allowed us to obtain more precise results and to guide local pollution control. In this study, sources of HMs in agricultural soil were traced by a CMB model. Superposition effects were studied by spatial analysis of HMs and enrichment factor (EF) and chemical fraction analysis. The average concentrations of Cd, Pb, Cr, Cu, Ni and Zn in surface soils were 8.71, 333, 154, 51.7, 61.5 and 676 mg∙kg^-1, respectively, which exceeded their corresponding background values. The main sources of Cd, Pb and Zn in agricultural soil were rock weathering, atmospheric deposition and livestock manure, and their contributions were 47.7%, 31.0% and 21.2% for Cd; 7.63%, 78.7% and 13.4% for Pb; and 17.0%, 52.3% and 28.1% for Zn. Cr mainly derived from atmospheric deposition (73.8%) and rock weathering (20.0%). Cu and Ni mainly came from livestock manure (81.3%) and weathering (87.5%), respectively, whereas contributions of pesticides and fertilizers were relatively limited (no more than 1.04%). Cd, Pb, Zn and Cu were easily enriched in surface soils near the surrounding pollution sources, whereas Cr and Ni were easily enriched in the high-terrain area, where there was less of an impact of anthropogenic activities. The superposition of exogenous sources caused accumulation of Cd, Pb and Zn in topsoil, contaminated the subsoil through leaching and improved bioavailability of Cd and Pb, causing high ecological risk for agricultural production. Therefore, Cd and Pb should be paid more attention in future pollution control.

Multiple contaminant ecological risk evaluation in small craft harbour sediments in Nova Scotia, Canada

Small craft harbours are vital for the fishing industry and have high socioeconomic and cultural importance for surrounding communities. Presence of potential contaminants of concern in small craft harbour sediments can have significant impacts in biota and humans, including fishing activities and the local economy. While single contaminant sediment concentrations may be below sediment quality guidelines, the interaction of multiple contaminants in sediments may potentially exacerbate chemical ecological risk. An ecological risk evaluation for four classes of contaminants (i.e., petroleum hydrocarbons, polychlorinated biphenyls, polycyclic aromatic hydrocarbons and metals) was conducted in 31 small craft harbours in Nova Scotia, Canada, using two approaches (i.e., mean probable effect level quotient and number and frequency of sediment quality guideline exceedances). Most small craft harbours showed a low ecological risk to marine biota, with only two small craft harbours suggesting high risk. While urgent action is not needed, monitoring is recommended for these small craft harbours to confirm that pollution is not increasing, and to potentially identify and control contamination sources.

Potential sources and toxicity risks of polycyclic aromatic hydrocarbons in surface sediments of commercial ports in Taiwan

The accumulation of pollutants in the semi-enclosed waters of ports has long been a concern. This study assessed the pollution status, sources, and toxicity risks of 16 polycyclic aromatic hydrocarbons (PAHs) in surface sediments of 7 major ports in Taiwan. Total PAHs concentrations in sediments ranged between 8.4 and 572.5 ng/g dw, with an average of 112.4 ± 136.5 ng/g dw. The 3- and 4-ring PAHs (63 %) were the major constituents of PAHs in the sediments. Diagnostic ratios and positive matrix factorization analyses indicated that PAHs in sediments were mainly contributed by biomass combustion (45.0 %), coal combustion (31.5 %), and vehicle emissions and related fossil fuels (23.5 %). The results of ecological risk assessment showed a low-medium risk of PAHs in the sediments outside the port, whereas most of the sediments within the port presented a medium-high risk. An assessment of the possible human health risks indicated that PAHs were present at acceptable levels.

An Advanced PMF Model Based on Degradation Process for Pollutant Apportionment in Coastal Areas

With increasing stress posed to the marine ecosystem and coastal communities, prevention and control of coastal pollution becomes urgent and important, in which the identification of pollution sources is essential. Currently, the pollutant source apportionment in coastal areas is mainly based on receptor models, such as the positive matrix factorization (PMF) model. Nevertheless, these models still lack consideration of the changes of pollutant behaviors (e.g., the degradation of pollutants) which cause the differences in pollutant compositions. Subsequently, the source apportionment via receptor models only based on the monitoring data may not be consistent with the one in pollution sources. To fill this gap, a pollutant degradation model was firstly developed in this study. Accordingly, the degradation model was inversed to estimate the pollutant concentrations at their emitting sources, based on the monitoring concentration in the coastal area. Finally, the estimated concentrations were fed to the PMF model for pollutant source apportionment, advancing the PMF model with degradation process. To demonstrate the feasibility and accuracy of the developed model, a case study of source appointment was carried out based on the polycyclic aromatic hydrocarbons (PAHs) in the sediments of the Pearl River Estuary. The results indicated the same types of emission source identified by the original and advanced PMF models, which were oil spill, biomass and coal combustion, and traffic emission. Nevertheless, the contributions of sources were significantly varied between the two models. According to the analyses based on emission inventory, the offsets of the results from the original PMF model were −55.4%, 22.7%, and 42.2% for the emission sources of oil spill, biomass and coal combustion, and traffic emission, respectively. Comparatively, the offsets for the advanced PMF model narrowed down to −27.5%, 18.4%, and −4.4%. Therefore, the advanced PMF model is able to provide satisfactory source apportionment for organic pollutants in coastal areas, and thus further provide a scientific basis for marine pollution prevention and control.

Spatiotemporal characterization of petroleum hydrocarbons and polychlorinated biphenyls in small craft harbour sediments in Nova Scotia, Canada

Previous characterization of polycyclic aromatic hydrocarbons (PAHs) and metals has been conducted in small craft harbour (SCH) sediments in Nova Scotia, Canada, but petroleum hydrocarbons (PHCs) and polychlorinated biphenyls (PCBs) have not been spatiotemporally assessed. This study characterized the distribution of over 500 PHCs and PCBs samples in 31 SCHs sediments between 2000 and 2017. Federal and regional sediment quality guidelines were used to determine exceedances. Results showed exceedances for diesel and oil resembling PHCs, expected given their longer permanence in sediments and lower volatility. However, only 7% of the samples exceeded 500 ppm, threshold where benthic impairment is observed, showing low risk. PCBs do not pose high risk to biota since only six samples exceeded the higher effect level and 25% of them exceeded the lower effect one. Monitoring is recommended for SCHs with significant exceedances, as well as collectively assessing all contaminants characterized in SCHs.

Spatial occurrence and sources of PAHs in sediments drive the ecological and health risk of Taihu Lake in China

To study the spatial occurrence, sources, and ecological risks of 16 PAHs, surface sediments had been collected from seven major areas of Taihu Lake, China in April 2021. Results showed that the concentrations of ∑₁₆PAHs varied between 1381.48 and 4682.16 ng g⁻¹, and the contents of BghiP in each sample were the highest. The PAHs concentrations in the sediments near the lakeshore were much higher than those in the central area of the lake. The sedimentary ∑₁₆PAHs were mainly composed of molecular-weight monomers and 4-ring PAHs showed superiority (35.69–45.02%). According to the ratio of PAH monomer, the sedimentary PAHs in Taihu Lake were dominantly derived from the combustion. Through the biological toxicity assessment and the BaP equivalent (BaPE), great biological risks of PAHs monomers i.e. DahA and IcdP were found. Both concentrations of ∑₁₆PAHs and dominant 4–6-ring monomers accompanied by carcinogenic risks in many areas of Taihu Lake increased. It is necessary to strengthen monitoring and take measures to control the input of organic pollutants.

Occurrence characteristics and source appointment of polycyclic aromatic hydrocarbons and n-alkanes over the past 100 years in southwest China

The extensive anthropogenic activities and their potential impacts during the Anthropocene have led to a research focus on the sedimentary record. In the present study, the occurrence and temporal variations in the fluxes and compositions of n-alkanes and polycyclic aromatic hydrocarbon (PAHs) were investigated in ²¹⁰Pb-dated sediment cores from a small catchment near the outflow Tanglangchuan in the western Dianchi Lake, China. The continuing organic contamination (i.e. PAHs and n-alkanes) from inputs to outputs has been of concern. To trace the sources and driving forces, multi indicators were applied. Results showed that the total organic carbon (TOC) contents and C/N ratios varied in the range of 4.20-12.30 mg g^-1 dw and 8.64-15.65, respectively, indicating algae- and terrestrial plant-derived organic matter (OM). The flux of Σn-alkanes ranged from 0.67 to 38.86 μg cm^-2 a^-1 with a peak in 2013. The long-chain n-alkanes (Σn-alk_26-35) and short-chain n-alkanes (Σn-alk_12-20) accounted for 44.02%-49.38% and 35.32%-41.49% of the Σn-alkanes, respectively. A bimodal distribution of n-alkanes was displayed in the sediments implying the sedimentary OM may be derived from a mixed source of endogenous and exogenous origin. The posterior peak (≥n-C₂₆) compounds in the highest abundance were n-C₃₁ or n-C₃₃ with a significant odd-numbered C predominance, representing terrestrial plant-derived OM. Whereas n-C₁₆ was rich in all sediment profiles reflecting crude oil or incompletely combusted fossil fuel-derived source. The indicators analysis showed an increasing trend of the contribution from terrestrial plants and wet to drought climate during 1873-2019. The sedimentary flux of ΣPAHs ranged between 11.71 and 1231.54 ng cm^-2 a^-1 and the percent of high-ring PAHs rose annually indicating enhanced anthropogenic activities. In the past 147 years, the results of present study highlight the influence of the agricultural and industrial economy on the catchment outlets.

Baseline occurrence, distribution and sources of PAHs, TPH, and OCPs in surface sediments in Gorgan Bay, Iran

Baseline polycyclic aromatic hydrocarbons (PAHs), total petroleum hydrocarbons (TPH) and organochlorine pesticides (OCPs) in surface sediments were measured in Gorgan Bay, Iran. Total PAHs, TPH, and OCPs concentrations ranged between 13.70 and 23.68 ng g^-1, 2.97 to 11.51 μg g^-1 dry weight, and below detection to 1.41 ng g^-1, respectively. Benzo [k] fluoranthene and anthracene had the highest (BkF; 19.77 ± 0.08 ng g^-1), and lowest (Ant; 4.38 ± 1.72 ng g^-1) individual PAH concentrations, respectively. The most abundant OCPs were β-Endosulfan, followed by methoxychlor and endrin. PAH isomeric ratios in sediments revealed that contamination originated from mixed sources, with a strong indication of pyrogenic sources. Ecological risk assessments based on sediment quality guidelines (SQGs) suggested that individual PAHs and OCPs posed low ecological risks in Gorgan Bay.

Bioaccumulation and function analysis of glutathione S-transferase isoforms in Manila clam Ruditapes philippinarum exposed to different kinds of PAHs

This study analyzed the function of different glutathione S-transferase (GST) isoforms and detoxification metabolism responses in Manila clam, Ruditapes philippinarum, exposed to 4 kinds of polycyclic aromatic hydrocarbons (PAHs) single, and their mixtures for 15 days under laboratory conditions. 13 kinds of GSTs in R. philippinarum were classified, and the results of tissue distribution indicated that 12 kinds of GSTs (except GST sigma 3) expressed most in digestive glands. We detected the mRNA expression levels of aryl hydrocarbon receptor signaling pathway, and detoxification system in digestive glands of clams exposed to benzo[a]pyrene (BaP), chrysene (CHR), benzo[a]anthracene (BaA), benzo[b]fluoranthene (BbF), and BaP + CHR + BaA + BbF, respectively. Among these genes, we selected GST-sigma, GST-omega and GST-pi as potential indicators to BaP; GST-sigma, GST-A and GST-rho to CHR; GST-pi, GST-sigma, GST-A, GST-rho and GST-microsomal to BaA; GST-theta and GST-mu to BbF; while GST-pi and GST-mu to the mixture of BaP, CHR, BaA and BbF. Additionally, the bioaccumulation of PAHs in tissues increased remarkably over time, and showed an obvious dose-effect. Under the same concentration, the bioaccumulation in single exposure group was higher than that in mixture group, and the bioaccumulation of PAHs in tissues with different concentrations of stress was irregular. The results revealed the metabolic differences and bioaccumulation rules in clams exposed to four kinds of PAHs, and provided more valuable information for the PAHs risk assessment.

An integrated approach using chemical ecological risk assessment and multi-integrated biomarker indexes approach to assess pollution: A case study of Ruditapes philippinarum in four bays on the Shandong Peninsula in China

Considering the ecological risks of polycyclic aromatic hydrocarbons (PAHs) to the marine environment, it is urgent to find scientific and effective monitoring methods. In this study, an integrated approach combining chemical ecological risk assessment and multi-integrated biomarker indexes approach was used to assess the marine environment. Samples included seawater, sediments, and clam Ruditapes philippinarum were collected from four bays on the Shandong Peninsula, China in the four seasons of 2019. The concentrations, composition, potential sources, and ecological risk of PAHs were investigated in seawater and sediments. Risk quotient (RQ) and sediment quality guidelines (SQGs) were calculated to assess the ecological risks of PAHs in seawater and sediment, respectively. And then, clam Ruditapes philippinarum's multi-level biological response, including its ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), superoxide dismutase (SOD), lipid peroxidation (LPO), and acetylcholinesterase (AChE) were investigated in-depth, by which multi-integrated biomarker indexes approach were calculated to evaluate marine environmental quality. Taken together, the results showed that the concentration of PAHs was in good agreement with the response of biomarkers, and the usefulness of the combined use of chemical ecological risk assessment and integrated biomarker indexes to assess PAHs pollution was verified.

Concentrations of polycyclic aromatic hydrocarbons in samples of soil, feed and food collected in the Niger Delta region, Nigeria: A probabilistic human health risk assessment

Polycyclic aromatic hydrocarbons (PAHs) are widely distributed compounds with two or more fused aromatic ring, being some of them classified as carcinogenic. In the present study, the concentrations of 16 PAHs and the sum of them (∑PAHs) were determined in samples of food, feed, plant and soil collected in six different heavily polluted areas (Choba, Khana, Trans Amadi, Eleme, Uyo and Yenagoa) of the Niger Delta Region (Nigeria). Principal component analysis (PCA) was then used to identify groups of variables (PAHs) and groups of samples that were the best in rendering the environmental pollution in that Region of Nigeria. In addition, PAHs food consumption and the derived carcinogenic risks were assessed in a probabilistic way. The highest ∑PAHs (mg/kg) were: 16.7 in cow meat, 8.06 in goat meat, 25.4 in chicken meat, 7.72 in fish, 28.70 in fish feed, 15.3 in chicken feed, 8.42 in plant, and 8.80 in soil. In most of the Nigerian areas, cooked cow meat, chicken and chicken feed presented the highest impact regarding PAHs contamination. The highest intake of PAHs was through meat consumption, with a very high and unassumable carcinogenic risk, which is quite above 10^-5 for some PAHs, including benzo [a]pyrene. The results of the present survey highlight the importance of reducing PAHs content in food, specially in meat, in the Niger Delta region.

Remediation of soils and sediments polluted with polycyclic aromatic hydrocarbons: To immobilize, mobilize, or degrade?

Polycyclic aromatic hydrocarbons (PAHs) are generated due to incomplete burning of organic substances. Use of fossil fuels is the primary anthropogenic cause of PAHs emission in natural settings. Although several PAH compounds exist in the natural environmental setting, only 16 of these compounds are considered priority pollutants. PAHs imposes several health impacts on humans and other living organisms due to their carcinogenic, mutagenic, or teratogenic properties. The specific characteristics of PAHs, such as their high hydrophobicity and low water solubility, influence their active adsorption onto soils and sediments, affecting their bioavailability and subsequent degradation. Therefore, this review first discusses various sources of PAHs, including source identification techniques, bioavailability, and interactions of PAHs with soils and sediments. Then this review addresses the remediation technologies adopted so far of PAHs in soils and sediments using immobilization techniques (capping, stabilization, dredging, and excavation), mobilization techniques (thermal desorption, washing, electrokinetics, and surfactant assisted), and biological degradation techniques. The pros and cons of each technology are discussed. A detailed systematic compilation of eco-friendly approaches used to degrade PAHs, such as phytoremediation, microbial remediation, and emerging hybrid or integrated technologies are reviewed along with case studies and provided prospects for future research.

Dustfall-bound polycyclic aromatic hydrocarbons (PAHs) over the fifth largest Chinese lake: residual levels, source apportionment, and correlations with suspended particulate matter (SPM)-bound PAHs in water

Residual levels and temporal-spatial distribution characteristics of polycyclic aromatic hydrocarbons (PAHs) in dustfall were studied at the seasonal scale between June 2010 and May 2011 in the fifth largest shallow lake in China. PAHs flux of atmospheric deposition and the impact on the PAHs in the lake water column were estimated. The major sources of PAHs were identified by multiple methods. We found that (1) the seasonal residual levels of 16 priority controlled PAHs (PAH₁₆) were spring (8.89 ± 3.93 μg g^-1) > summer (6.68 ± 4.31 μg g^-1) > winter (6.06 ± 2.95 μg g^-1) > autumn (3.55 ± 2.21 μg g^-1). (2) Significant positive correlations were found between the PAH levels in the dustfall and the suspended particle material (SPM) content, as well as between the deposition flux and the PAH content in the water in all four seasons. (3) Vehicle emissions, coal combustion, biomass combustion, and coke ovens were the four major sources in Lake Chaohu, accounting for 12.7%, 40.9%, 14.5%, and 31.9% of the total PAHs, respectively. (4) Compared to long-distance trajectories, short-distance trajectories played a more important role in the external sources of atmospheric PAHs in the region of Lake Chaohu.

Multi-Media Exposure to Polycyclic Aromatic Hydrocarbons at Lake Chaohu, the Fifth Largest Fresh Water Lake in China: Residual Levels, Sources and Carcinogenic Risk

The residual levels of 16 priority polycyclic aromatic hydrocarbons (PAHs) in environment media and freshwater fish were collected and measured from Lake Chaohu by using Gas chromatography-mass spectrometry. Potential atmospheric sources were identified by molecular diagnostic ratios and the positive matrix factorization (PMF) method. PAH exposure doses through inhalation, intake of water and freshwater fish ingestion were estimated by the assessment model recommended by US EPA. The carcinogenic risks of PAH exposure were evaluated by probabilistic risk assessment and Monte Carlo simulation. The following results were obtained: (1) The PAH16 levels in gaseous, particulate phase, water and fish muscles were 59.4 ng·m−3, 14.2 ng·m−3, 170 ng·L−1 and 114 ng·g−1, respectively. No significant urban-rural difference was found between two sampling sites except gaseous BaPeq. The relationship between gaseous PAHs and PAH in water was detected by the application of Spearman correlation analysis. (2) Three potential sources were identified by the PMF model. The sources from biomass combustions, coal combustion and vehicle emission accounted for 43.6%, 30.6% and 25.8% of the total PAHs, respectively. (3) Fish intake has the highest lifetime average daily dose (LADD) of 3.01 × 10−6 mg·kg−1·d−1, followed by the particle inhalation with LADD of 2.94 × 10−6 mg·kg−1·d−1. (4) As a result of probabilistic cancer risk assessment, the median ILCRs were 3.1 × 10−5 to 3.3 × 10−5 in urban and rural residents, which were lower than the suggested serious level but higher than the acceptable level. In summary, the result suggests that potential carcinogenic risk exists among residents around Lake Chaohu. Fish ingestion and inhalation are two major PAH exposure pathways.

Polycyclic aromatic compounds in the Canadian Environment: Aquatic and terrestrial environments

Polycyclic aromatic compounds (PACs) are ubiquitous across environmental media in Canada, including surface water, soil, sediment and snowpack. Information is presented according to pan-Canadian sources, and key geographical areas including the Great Lakes, the Alberta Oil Sands Region (AOSR) and the Canadian Arctic. Significant PAC releases result from exploitation of fossil fuels containing naturally-derived PACs, with anthropogenic sources related to production, upgrading and transport which also release alkylated PACs. Continued expansion of the oil and gas industry indicates contamination by PACs may increase. Monitoring networks should be expanded, and include petrogenic PACs in their analytical schema, particularly near fuel transportation routes. National-scale roll-ups of emission budgets may not expose important details for localized areas, and on local scales emissions can be substantial without significantly contributing to total Canadian emissions. Burning organic matter produces mainly parent or pyrogenic PACs, with forest fires and coal combustion to produce iron and steel being major sources of pyrogenic PACs in Canada. Another major source is the use of carbon electrodes at aluminum smelters in British Columbia and Quebec. Temporal trends in PAC levels across the Great Lakes basin have remained relatively consistent over the past four decades. Management actions to reduce PAC loadings have been countered by increased urbanization, vehicular emissions and areas of impervious surfaces. Major cities within the Great Lakes watershed act as diffuse sources of PACs, and result in coronas of contamination emanating from urban centres, highlighting the need for non-point source controls to reduce loadings.

Spatial distribution, sources and quantitative human health risk assessments of polycyclic aromatic hydrocarbons in urban and suburban soils of Chile

This work investigated the concentrations and health risks of polycyclic aromatic hydrocarbons (PAHs) found in Chilean soils for the first time. The urban and suburban soils were collected from 28 sampling sites in three regions of Chile: Magallanes (in Punta Arenas commune), Valparaíso and the Santiago metropolitan area. The PAH concentrations, fractions and their potential sources were studied. Statistical analyses using t tests (p < 0.01) showed that (a) PAH concentrations in the urban sites were higher than those in the suburban sites; (b) the presence of anthracene and chrysene was significantly greater in the urban sites than the suburban sites; and (c) the fraction of four-ring PAHs to total PAHs was larger in the urban sites than the suburban sites. The primary PAH source in urban soils was determined to be the combustion of gasoline, grass, wood and coal. In contrast, PAHs in suburban soils were possibly derived from pyrogenic sources (e.g. incomplete combustions). The total cancer risks (TCRs) and the total hazard index (HI) were quantified from 12 PAHs in both urban and suburban soils in terms of cancer and non-cancer risks, respectively. The average TCR of all sites was within an acceptable level (TCR < 10^-6), and none of the HIs from any locations were deemed harmful (HI < 1).

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.

Characterization, source apportionment, air/plant partitioning and cancer risk assessment of atmospheric PAHs measured with tree components and passive air sampler

In this study, ambient air and olive tree components (leaf and branch) were simultaneously collected and analyzed for polycyclic aromatic hydrocarbons (PAHs) to investigate their levels and accumulations, temporal variations, possible sources, air-plant partitioning and cancer risks for 12 months. During the sampling period, total of 14 PAH (∑₁₄PAH) concentrations measured in the olive leaves (dissolved and particle phase) and braches (1- and 2-year-old) were 593 ± 472, 81 ± 67, 558 ± 273 and 316 ± 213 ng/g dry weight (DW), respectively. Similarly, the average ∑₁₄PAH concentrations measured in the ambient air was found to be 15 ± 16 ng/m³. Generally, 4-, 5- and 6- ring PAHs were the dominant groups for all tree components, while 2- and 3-ring PAHs were predominant in the air samples. Ring distributions and molecular diagnosis ratios were employed to determine PAH sources in the sampling site. Petroleum and combustion-related sources were found to be important. The Pearson correlation coefficient was allowed to figure out the affinity between PAH levels in the sampling materials and meteorological factors. Temperature and mixing layer height were found to be effective factors on the concentrations. Atmospheric PAH levels were also predicted to employ a bark-air exchange model for determining the PAH movement direction. The predicted/measured ratios were above 1.0. This was probably due to utilizing the branch values rather than bark values in the model. Finally, the risk of cancer has been evaluated. The calculated cancer risks via inhalation were at low levels for adults and children.

Uptake, translocation, and risk assessment of PAHs in contaminated soil-air-vegetable systems based on a field simulation experiment

Vegetable consumption is a potential toxin exposure pathway for humans. Studies have recognized that vegetables can uptake organic contaminants via roots and translocate pollutants to their aerial parts. However, the aerial parts might also directly uptake polycyclic aromatic hydrocarbons (PAHs) from contaminated soils. This has not been extensively studied. The aim of this study was to explore the uptake and translocation of PAHs in contaminated soil-air-vegetable systems. Sixteen individual PAHs in contaminated soils, vegetable roots, and leaves were identified using GC-MS. The results showed that the average PAH concentrations both in roots and leaves from the reference soil, the moderately contaminated soil, and the heavily polluted soil increased as expected. PAHs with log K_OW < 5 accumulated more easily in roots and leaves. Using a Pearson correlation analysis, isomer ratios, and a principal component analysis (PCA), it was found that the contaminated soil not only caused PAH accumulation in roots, but also increased the PAH concentration in leaves. Quantitatively, the absorption of PAHs in roots in the moderately contaminated soil (70.3 ng m^-3) was approximately twice that of the reference soil (40.8 ng m^-3). The PAHs absorbed by vegetable roots in the heavily polluted soil (74.7 ng m^-3) was only slightly higher than that of the moderately polluted soil. In addition, the PAH dose volatilized into the air from the reference soil, the moderately contaminated soil, and the heavily polluted soil also showed an increasing trend. The incremental lifetime cancer risk (ILCR) indicated that adult females had a higher cancer risk via vegetable consumption than other groups. Although vegetable consumption had a slight effect on cancer risk for some groups in the present study, the cancer risk of PAHs caused by eating vegetables grown in heavily contaminated soil still requires attention.

Characteristics and source apportionment of polycyclic aromatic hydrocarbons of groundwater in Hutuo River alluvial-pluvial fan, China, based on PMF model

PAH contamination in water environment has become an important water quality problem in China. In this study, groundwater PAHs were monitored in September 2019 at 48 groundwater sites, and statistical analysis and positive matrix factorization (PMF) model were used to analyze the characteristic of PAHs in groundwater and to identify the pollution sources of PAHs in the Hutuo River Basin, Hebei Province, China. The results showed that the concentration of the PAHs in groundwater was low and the total PAHs (∑PAHs) ranged from below detection limit to 260.6 ng/L and with a mean value of 17.7 ng/L. The concentration of PAHs in groundwater was obviously affected by the land use. Based on molecular ratio method, the main source of PAHs in groundwater is the biomass combustion, while the results of PMF source analysis were more accurate and the results showed that the primary sources and contribution rate of PAHs in groundwater were wood, coal, and gasoline sources (41.4%), followed by oil and diesel sources (39.4%), and natural gas combustion (19.2%). There was obvious spatial variation in the contribution of pollution sources to PAHs at the sites of different land uses in this region. The highest contribution of nature gas combustion, oil and diesel sources, and wood, coal, and gasoline combustion to PAHs was found in the urban area (0.617 ng/L), industrial area (0.380 ng/L), and village area (0.379 ng/L), respectively. The results can provide scientific basis for the prevention and control of PAH contamination in groundwater in this area.

The PM2.5-bound polycyclic aromatic hydrocarbon behavior in indoor and outdoor environments, part I: Emission sources

The previous research, aimed at exploring the relationships between the indoor and outdoor air quality, has evidenced that outdoor PM_2.5-bound polycyclic aromatic hydrocarbons (PAH) levels exhibit significant daily and seasonal variations which does not necessary corresponds with PAH indoor dynamics. For the purpose of this study, a three-month measurement campaign was performed simultaneously at indoor and outdoor sampling sites of a university building in an urban area of Belgrade (Serbia), during which the concentrations of O₃, CO, SO₂, NO_x, radon, PM_2.5 and particle constituents including trace metals (As, Cd, Cr, Mn, Ni and Pb), ions (Cl^-, Na⁺, Mg²⁺, Ca²⁺, K⁺, NO₃^-, SO₄^2- and NH₄⁺) and 16 US EPA priority PAHs were determined. Additionally, the analysis included 31 meteorological parameters, out of which 24 were obtained from Global Data Assimilation System (GDAS1) database. The Unmix and PAH diagnostic ratios analysis resolved the source profiles for both indoor and outdoor environment, which are comparable in terms of their apportionments and pollutant shares, although it should be emphasized that ratio-implied solutions should be taken with caution since these values do not reflect emission sources only. The highest contributions to air quality were attributed to sources identified as coal combustion and related pyrogenic processes. Noticeable correlations were observed between 5- and 6-ring high molecular weight PAHs, but, except for CO, no significant linear dependencies with other investigated variables were identified. The PAH level predictions in the indoor and outdoor environment was performed by using machine learning XGBoost method.

Backward modeling of urinary test reliability for assessing PAH health risks: An approximation solution for naphthalene

Urine sample tests are one of the most common methods of estimating human exposure to polycyclic aromatic hydrocarbons (PAHs) and assessing population health risks. To evaluate the reliability of the urine test and the impact of other PAH elimination routes on the health risk estimated by this test, we proposed a backward modeling framework integrating other common elimination routes of PAH metabolites to calculate the overall intake rate of the parent PAH based on the levels of corresponding main metabolites in urine. Due to limited biotransformation data, we selected naphthalene as an example to evaluate model performance and collected urine samples from 234 random adults in Shenzhen. The overall intake rates of naphthalene were then simulated and compared to current literature data. The simulated intake rates of naphthalene ranged from 3.70 × 10-3 mg d-1 to 1.95 mg d-1 and followed a lognormal distribution with a median value of 6.51 × 10-2 mg d-1. The results indicated that, if naphthalene exposure occurred only via food for the population of Shenzhen, the literature data fell within the most frequent interval [3.70 × 10-3, 4.45 × 10-2] but were lower than the simulated median value. However, if other exposure routes were considered, the allocation factor-adjusted literature data were close to the simulated median values. In addition, under normal physiological conditions, the simulated results were more sensitive to 1-hydroxynaphthalene (1-OHN) and 2-hydroxynaphthalene (2-OHN) levels in urine than other biometric variables, which is due to the limited load of 1-OHN and 2-OHN in human elimination routes. Furthermore, the suggested safety levels of 1-OHN and 2-OHN in urine to protect 99% of the general population of Shenzhen were 6.40 × 10-6 and 3.75 × 10-5 mg L-1, which could be used as regulatory indicators based on the high reliability of the model.

Polycyclic aromatic hydrocarbon status in post-hurricane Harvey sediments: Considerations for environmental sampling in the Galveston Bay/Houston Ship Channel region

Hurricane Harvey led to a broad redistribution of sediment throughout Galveston Bay and the Houston Ship Channel (GB/HSC), but the resulting changes in chemical contaminant distributions have yet to be characterized. To address this question, we collected and analyzed post-Harvey sediment for concentrations of the EPA 16 Priority Pollutant polycyclic aromatic hydrocarbon (PAHs), determining the extent to which the spatial distribution and sourcing of contaminants may have changed in contrast to historical surface sediment data (<5 cm) from the National Oceanic Atmospheric Administration (NOAA) available for the years 1996-2011. We found a small, but detectable increase from pre- to post-Harvey in PAH concentrations, with PAH diagnostic sourcing indicating combustion origins. Of the detected PAHs, none exceeded Sediment Quality Guideline values. Overall, we have added to the understanding of PAH spatial trends within the GB/HSC region, and developed a reference PAH baseline to inform future studies.

Human health and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in sediment of Woji creek in the Niger Delta region of Nigeria

Human health risk was determined by assessing risk due to dermal contact with the sediment and Benzo [a] pyrene -equivalent concentrations (BaP-TEQ- carcinogenic equivalents and BaP-MEQ- mutagenic equivalents). Ecological risk of PAHs in the sediment was determined by comparing PAHs concentrations to effect range low (ERL) and effect range median (ERM); to estimate the risk associated with the combined effects of PAHs, mean ERM quotient (mERMq) was calculated. Results revealed that hazard index (HI) due to dermal contact of the sediment for adults are 596 and 73.84 for children. Similarly, cancer risk for adults was all >10^-1 and was within 10^-3 ≤ 10^-1 for children, for every compound; the sum of cancer risk for adults and children were 8.26 and 1.022 respectively.

Risk assessment of PAHs and N-PAH analogues in sediment cores from the Niger Delta

Chemical-surveys of sediments are source of information about historical-pollution in aquatic-ecosystems, because ecological/human-health risks may arise from polycyclic-aromatic-hydrocarbons (PAHs) and nitrogen-PAHs presence in aquatic-environments, particularly sediments, where they partition. Despite this, sediment-PAHs/N-PAHs have not been reported in the Niger Delta. This study investigated vertical-profiles of PAHs/N-PAHs in 2 cm-intervals-segments from Bonny Estuary, Niger Delta. Analysis showed that ƩPAHs/ƩN-PAHs in segments ranged from 8699 to 22,528 μg/kg and 503 to 2020 μg/kg, respectively. Abundant-PAH/N-PAH are 2,6-dimethyl-naphthalene and benzo[a]acridine. PAHs/N-PAHs in the samples appeared to be from petrogenic and pyrogenic-sources. Petrogenic-PAHs/N-PAHs were predominated by 2-, 3-rings, alkylated-substituents, while, pyrogenic-PAHs/N-PAHs were dominated by 4-, 5-, 6-rings. Surface-sediments were dominated by petrogenic-PAHs/N-PAHs while, deeper-cores were heavily-contaminated with pyrogenic-PAHs/N-PAHs. ƩPAHs exceeded the ISQGs and PELs of CSQGs. Ʃ-quinoline/Ʃ-acridine exceeded the guidelines for protection of aquatic-life. Furthermore, there are concerns over toxic-ratios >70% in the estuary. Such surveys may be helpful in future sediment-management-decisions for contaminated-systems and long-term-monitoring of sediments to assess remediation/recovery. CAPSULE: Distinct sources of PAHs and N-PAHs exist in the Niger Delta ecosystem and, there are concerns over toxic ratios >70% in the oil rich region and the potential for adverse biological effects.

A high-efficiency phenanthrene-degrading Diaphorobacter sp. isolated from PAH-contaminated river sediment

Polycyclic aromatic hydrocarbons (PAHs) are typical persistent organic pollutants that accumulate in the environment, mainly from anthropogenic activities. Microbial degradation is the main pathway of PAHs degradation in the natural environment. Therefore, the widen of the available bank of microbial resources and exploration of the molecular degradation mechanisms of PAHs are crucial to the proper management of PAHs-polluted sites. In this work, a bacterial strain, YM-6, which has a high ability to utilize phenanthrene (PHE) as its sole source of carbon and energy, was isolated from sediment contaminated with PAHs. The strain YM-6 was found to degrade 96.3% of 100 mg/L of PHE in liquid cultures within 52 h. The strain was identified as Diaphorobacter sp. by 16S rDNA sequencing. The optimum growth conditions of the YM-6 strain were studied, and the results indicated that the optimum growth temperature of the strain was 30 °C, and the optimum growth pH was 7. The stain is well-suited for high-temperature stress (40 °C), and it could withstand 400 mg/L of PHE. The strain's PHE metabolism was assayed using GC-MS analyses. The results revealed that the YM-6 strain metabolized PHE via the phthalic acid pathway because the intermediates, such as phthalic acid, diethyl ester and phthalaldehydic acid, methyl ester, were detected. The use of this strain may be an attractive alternative for the bioremediation of polycyclic aromatic hydrocarbons in an aquatic environment.

Spatial and vertical distribution, composition profiles, sources, and ecological risk assessment of polycyclic aromatic hydrocarbon residues in the sediments of an urban tributary: A case study of the Songgang River, Shenzhen, China

In this study, the Songgang River (SR) was selected as a typical tributary that is heavily polluted by rapid urbanization and industrialization. The polycyclic aromatic hydrocarbon (PAH) distribution at five representative sampling sites from different urban functional areas was studied. The chemical and physical properties and spatial and vertical distribution of PAHs in sediments were investigated. PAH source identification and the ecological risks of the sediments were evaluated. The results suggested that the industrial zone and dense residential and commercial areas were the most contaminated areas of the SR, as the chemical and physical properties of total organic carbon content in sediments was the highest at the dense residential and commercial areas (0.1-4.5%); however, the acid volatile sulfide, total nitrogen, and total phosphorus contents were the highest in the industrial zone, with ranges of 700.0-1618.4 mg/kg dw, 22.4-3543.9 mg/kg dw, and 82.3-4550.7 mg/kg dw, respectively. The spatial distribution of residual PAHs in the sediment cores showed a wide variation among different urban functional areas, and the vertical characterization (0-300 cm) depicted a significant decreasing trend with depth and with an abrupt increase at 180 cm. The concentration of ∑16 PAHs ranged from 208.7 to 7709.8 ng/g dw, with the highest concentrations obtained in the industrial zone. The low molecular weight-PAHs (153-6720 ng/g dw) were predominant in the sediments. Furthermore, there were combined sources (biomass burning: 40.3%; fossil fuel combustion: 25.5%; mixed source: 21.5%; oil pollution: 12.7%) and a long term accumulation effect, with anthropogenic activities and industrial pollution as the major contributing sources. The concentrations of Nap, Acy, Ace, Flu, and Ant exceeded the lower limit of the sediment quality criteria, and higher toxic equivalent concentration values of the total carcinogenic PAHs were observed nearby the midstream of the SR, which may cause adverse biological effects and implies a need for regular monitoring.

Fate of PM2.5-bound PAHs in Xiangyang, central China during 2018 Chinese spring festival: Influence of fireworks burning and air-mass transport

Variations of levels, possible source and air mass transmission were investigated for 16 USEPA priority-controlled PAHs in PM_2.5 during 2018 Chinese Spring Festival (CSF) in Xiangyang City, central China which is the North-South pollutant airmass transport channel of China. Totally 37 samples were collected. Mass concentrations of Σ₁₆PAHs for the Pre-CSF day (Pre-CSFD), during the CSF day (CSFD) and after the CSF day (Af-CSFD) are 33.78 ± 17.68 ng/m³, 22.98 ± 6.49 ng/m³, and 8.99 ± 4.44 ng/m³, respectively. High resolution samples showed that Σ₁₆PAHs are higher in the morning (06:00-11:00) or afternoon (11:30-16:30), than those in the evening (17:00-22:00) and at night (22:30-05:30), whereas the result is reversed during the CSFD. Fireworks burning can obviously increase the mass concentration of PAHs. Air mass trajectory indicated that Xiangyang is a sink area of pollutants for northwest and southeast, and the sources of the northeast and southwest. The air mass only can be transmitted out through northeast and southwest. It is effective for improvement of air quality in Wuhan and Hunan to control fireworks emission in Henan and local areas. Fireworks burning was an important source for PAHs during CSFD, biomass, coal combustion, and traffic emission were the main sources of PAHs for Pre-CSFD and Af-CSFD periods. The health risk on the CSFD was higher than the acceptable levels, especially during the intensive fireworks burning, the risk value far exceed 1.0 × 10^-4, controlling burning fireworks is required.

Biomonitoring of polycyclic aromatic hydrocarbons (PAHs) from Manila clam Ruditapes philippinarum in Laizhou, Rushan and Jiaozhou, bays of China, and investigation of its relationship with human carcinogenic risk

This study examined the marine environment and seafood safety using chemical monitoring and multiple biomarkers. Samples were collected from three bays on the Shandong Peninsula in China, Laizhou, Rushan and Jiaozhou, in March, May, August, and October of 2018 and 2019. The polycyclic aromatic hydrocarbon (PAH) concentrations in sediments and tissue samples from the clam Ruditapes philippinarum and multiple biomarkers were measured. All the sampling sites were found to be medium-PAH-contaminated areas (100-1000 ng/g d.w.). According to the correlation analysis, ethoxyresorufin-o-deethylase (EROD) and superoxide dismutase (SOD) activity in the clam's digestive gland were sensitive to PAHs (p < .05), but the incremental lifetime cancer risk (ILCR) was lower than the priority risk level (10^-4) at most sampling sites. EROD, SOD and acetylcholinesterase activity exhibited significant correlations with the ILCR values (p < .01), suggesting that they may serve as good indicators for assessing safe seafood consumption levels for human beings.

Contamination characteristics of polycyclic aromatic hydrocarbons in river and coastal sediments collected from the multi-industrial city of Ulsan, South Korea

River and coastal sediments were collected at 17 stations in Ulsan, the largest industrial city in South Korea, to evaluate the levels, profiles, emission sources, and spatial distribution of polycyclic aromatic hydrocarbons (PAHs). The mean concentration of Σ₁₆ PAHs was 722 ng/g, and fluoranthene was a predominant compound. PAHs with 4-6 rings showed higher proportions than PAHs with 2-3 rings. The stations located near industrial complexes showed elevated levels of indicator compounds for petroleum, coal, coke, and fuel combustion. Therefore, petrochemical industries, coal pier, non-ferrous industries, and vehicles were identified as the emission sources. As industrialization and urbanization progressed, an increase in PAH levels and profile changes were observed as a result of the increasing industrial fuel consumption and the increasing number of vehicles. This is the first study that confirmed the change of PAHs in sediment caused by the change of emission sources over time in Ulsan.

Contaminated aquatic sediments

The remediation of contaminated aquatic sediments requires a range of expertise from assessment (investigation, risk evaluations, modeling, and remedy selection) to design and construction. Research in 2019 has added to knowledge on optimizing the use of passive samplers for assessing chemical concentrations in sediment porewater. The porewater and black carbon appear to be better predictors of contaminant bioaccumulation than total organic carbon alone. This has led to better characterization of potential risk at sediment sites. Tools to identify and model sources of chemicals have been developed and used particularly for some metals, polynuclear aromatic hydrocarbons and polychlorinated biphenyls. There is great emphasis on beneficially using dredged sediment, treating it as a resource rather than a waste. Amendments used in sediment caps continue to be refined including the use of activated carbon within the caps and by itself. A technique involving 16S rRNA has been established as a means of identifying microbiological composition that naturally degrade contaminants. © 2020 Water Environment Federation PRACTITIONER POINTS: Sediment capping technology continues to advance Sampling and testing methods continue to be refined Natural processes such as biodegradation are being better understood Beneficial use of dredged sediment continue to be emphasized.

Comparison of receptor models for source identification of organophosphate esters in major inflow rivers to the Bohai Sea, China

A better understanding of the sources of organophosphate esters (OPEs) is a prerequisite for OPE control and the establishment of related environmental policies. Sources of OPEs in 35 major inflow rivers to the Bohai Sea of China were quantitatively analyzed using three effective receptor models (principal component analysis-multiple linear regression (PCA-MLR), positive matrix factorization (PMF), and Unmix) in this paper. The similarities and differences in results from PCA-MLR, PMF, and Unmix were discussed in depth. All three models well predicted the spatial variability of the total concentrations of nine OPEs (triethyl phosphate, tri-n-butyl phosphate, triisobutyl phosphate, tri (2-ethylhexyl) phosphate, tri (2-chloroethyl) phosphate, tris(1-chloro-2-propyl) phosphate, tris(1,3-dichloro-2-propyl) phosphate, triphenyl phosphate, and triphenylphosphine oxide) (∑₉OPEs) (r² = 0.90-0.96, p = 0.000) and explained 98.4%-101.2% of the observed ∑₉OPEs. The predicted ∑₉OPEs values from each pairwise model were significantly correlated (r² = 0.88-0.91, p = 0.000). Three OPE sources were extracted by all three models: rigid and flexible polyurethane foam/coating, cellulosic/acrylic/vinyl polymer/unsaturated polyester, and polyvinyl chloride, contributing 49.9%, 29.7%, and 20.5% by PCA-MLR, 57.9%, 28.6%, and 13.5% by PMF, and 47.9%, 30.8%, and 22.4% by Unmix to the ∑₉OPEs, respectively. PMF was recommended as the preferred receptor model for analyzing OPE sources in water during the monitoring period because of its optimal performance.

Polycyclic aromatic hydrocarbons (PAHs) and esophageal carcinoma in Handan-Xingtai district, North China: a preliminary study based on cancer risk assessment

Extremely high risk of esophageal carcinoma (EC) occurs in Handan-Xingtai district of North China. In spite of various preventive measures and epidemiological investigations that have been conducted for years, incidence and mortality of EC are still in the highest level of China. The etiology of EC remains unclear in the region. Previous studies of our research group proposed that polycyclic aromatic hydrocarbons (PAHs) that derived from numerous coal gangue dumps and atmospheric particulates were major contaminants in these regions. In consideration of mutagenic, teratogenic, and carcinogenic characteristics of PAHs, the authors hypothesized that severe exposure to PAHs could preform as a causative factor for EC. Therefore, four data sets documented in our previous studies were employed in this paper. To quantitatively evaluate the carcinogenic risk imposed by sixteen priority PAHs, incremental lifetime cancer risks (ILCRs) via three exposure pathways were calculated. The results showed that total ILCRs for adult group ranged from 2.08E-05 to 8.63E-02, with an average of 2.00E-02. Total ILCRs for childhood group ranged from 1.09E-05 to 4.48E-02, with an average of 1.04E-02. Total ILCR value of 94% samples exceeded 10^-4, indicating a particularly high carcinogenic risk to local residents. Furthermore, ingestion and dermal contact conducted as principal pathways of exposing to PAHs for each population group, rather than inhalation. It can be speculated that severely exposing to PAHs may be a pathogenesis of EC in Handan-Xingtai district. The rigorous supervise and governance are imperative to avoid severe exposure to PAHs that derived from coal gangue dumps.