Model-based evaluation of the use of polycyclic aromatic hydrocarbons molecular diagnostic ratios as a source identification tool

Spatiotemporal distributions and ecological risk of polycyclic aromatic hydrocarbons in the surface seawater of Laizhou Bay, China

The spatial-temporal distribution, source, and potential ecological risk of polycyclic aromatic hydrocarbons (PAHs) in surface seawater from Laizhou Bay were investigated. The total PAH (ΣPAH) concentrations ranged from 277 to 4393 ng/L with an average of 1178 ng/L, thereby suggesting a relatively moderate to high PAH exposure level in Laizhou Bay in comparison to other bays in the world. The composition patterns and source apportionment results revealed that the coal, biomass burning, diesel emissions, and petroleum combustion as well as the combination of these processes were the dominant sources of PAHs in the surface water, which were closely associated with sail process and sewage effluents. The ecological risk assessment indicated that benzo(a)pyrene (BaP), phenanthrene (Phe), luoranthene (Flua), and naphthalene (Nap) would exist ecological risks in most of surface seawater sites, but the probabilistic risk assessment (PRA) results showed that the current level of risk is not as severe as the risk quotient (RQ) results revealed.

The seasonal change of PAHs in Svalbard surface snow

The Arctic region is threatened by contamination deriving from both long-range pollution and local human activities. Polycyclic Aromatic Hydrocarbons (PAHs) are environmental tracers of emission, transport and deposition processes. A first campaign has been conducted at Ny-Ålesund, Svalbard, from October 2018 to May 2019, monitoring weekly concentrations of PAHs in Arctic surface snow. The trend of the 16 high priority PAH compounds showed that long-range inputs occurred mainly in the winter, with concentrations ranging from 0.8 ng L-1 to 37 ng L-1. In contrast to this, the most abundant analyte retene, showed an opposite seasonal trend with highest values in autumn and late spring (up to 97 ng L-1), while in winter this compound remained below 3 ng L-1. This is most likely due to local contributions from outcropping coal deposits and stockpiles. Our results show a general agreement with the atmospheric signal, although significant skews can be attributed to post-depositional processes, wind erosion, melting episodes and redistribution.

Polycyclic aromatic hydrocarbon record in an urban secondary carbonate deposit over the last three centuries (Paris, France)

Preserving water resources and limiting pollution are central environmental issues in the current context of intense anthropization. Among organic pollutants, polycyclic aromatic hydrocarbons (PAHs) are commonly analysed as part of water quality assessments. After being emitted into the atmosphere, these persistent organic pollutants are deposited on the continental surface, where they are transported to the aquatic environment by run-off and infiltration waters. Mainly due to anthropogenic emissions, PAHs can therefore be considered as a proxy for human activities. Urban secondary carbonate deposits (USCDs), similar to cave speleothems, have recently been studied for their potential as natural archives of water quality. However, USCDs have never been used to trace water organic pollution and only a few studies on PAHs in speleothems are available. This study focuses on a well-dated USCD covering the last 300 years from the Great Aqueduct of Belleville (north-east of Paris, France). The aim is to determine the nature and variation of trapped organic compounds over time and to discuss their origin, transport, and link with changes in soil occupation due to human activities. To do so, high-resolution solid-phase UV fluorescence imaging analyses were combined with chemical analyses of PAHs and organic carbon carried out on low-weight samples. The results show that PAHs have been present in urban surface water for 300 years. Over the last few decades, a 7-fold increase is observed, accompanied by a change in the pollution source, enriched in high-molecular-weight PAHs, probably linked to urban dust. This study also reveals modes of transport directly influenced by changes in the soil occupation that are very different from those usually encountered in natural environments. This work thus paves the way for a better long-term understanding of the impact of human activity on the transfer of pollutants to sub-surface waters.

Use of molecular composition and compound-specific isotope analysis for source appointment of PAHs in sediments of a highly industrialized area

This study utilized both conventional molecular analysis and compound-specific isotopic techniques to identify the sources of polycyclic aromatic hydrocarbons (PAHs) in sediments of Ulsan Bay, South Korea. The concentrations of 15 traditional and 11 emerging PAHs were determined in sediments from 21 source sites and 26 bay sites. The concentrations and compositions of traditional and emerging PAHs varied significantly, even at sites close to the source areas. The results obtained from diagnostic ratios and the positive matrix factorization model for source identification were inconsistent in adjacent source areas. The δ13C profiles of PAHs, such as phenanthrene (Phe), fluoranthene (Fl), pyrene (Py), and benz[a]anthracene (BaA) in the sediments showed distinct features depending on the surrounding sources. In urban sediments, lighter δ13CPhe values were observed (mean: -25.1‰), whereas relatively heavier values of δ13CPy were found in petroleum industry areas (mean: -23.4‰). The Bayesian isotope mixing model indicates that the predominant source of PAHs in Ulsan Bay sediments was the petroleum industry (45%), followed by the non-ferrous metals industry (30%), automobile industry (18%), and urban areas (6.3%). These results demonstrated the utility of stable isotopes in assessing the sources and contributions of PAHs in small-scale regions. However, there are still limitations in compound-specific isotope analysis of PAHs, including insufficient end-members for each source, difficulty in analysis, and the influence of non-point sources; thus, further study is needed to expand its application.

Air pollution prevention in central China: Effects on particulate-bound PAHs from 2010 to 2018

Long-term trends in particulate-bound polycyclic aromatic hydrocarbon (PAH) concentrations in air in Zhengzhou (a severely polluted city in central China) between 2010 and 2018 were studied to assess the effectiveness of an air pollution prevention and control action plan (APPCAP) implemented in 2013. The PM2.5, sum of 16 PAHs (Σ16 PAHs), benzo[a]pyrene (BaP), and BaP toxic equivalent concentrations were high before 2013 but 41%, 77%, 77%, and 78% lower, respectively, after the APPCAP. The maximum daily Σ16 PAHs concentration between 2014 and 2018 was 338 ng/m3, 65% lower than the maximum of 961 ng/m3 between 2010 and 2013. The ratio between the Σ16 PAHs concentrations in winter and summer decreased over time and was 8.0 in 2011 and 1.5 in 2017. The most abundant PAH was benzo[b]fluoranthene, for which the 9-year mean concentration was 14 ± 21 ng/m3 (15% of the Σ16 PAHs concentration). The mean benzo[b]fluoranthene concentration decreased from 28 ± 27 ng/m3 before to 5 ± 4 ng/m3 after the APPCAP (an 83% decrease). The mean daily BaP concentrations were 0.1-62.8 ng/m3, and >56% exceeded the daily standard limit of 2.5 ng/m3 for air. The BaP concentration decreased from 10 ± 8 ng/m3 before to 2 ± 2 ng/m3 after the APPCAP (a 77% decrease). Diagnostic ratios and positive matrix factorization model results indicated that coal combustion and vehicle exhausts were important sources of PAHs throughout the study period, contributing >70% of the Σ16 PAHs concentrations. The APPCAP increased the relative contribution of vehicle exhausts from 29% to 35% but decreased the Σ16 PAHs concentration attributed to vehicle exhausts from 48 to 12 ng/m3. The PAH concentration attributed to vehicle exhausts decreased by 79% even though vehicle numbers strongly increased, indicating that pollution caused by vehicles was controlled well. The relative contribution of coal combustion remained stable but the PAH concentration attributed to coal combustion decreased from 68 ng/m3 before to 13 ng/m3 after the APPCAP. Vehicles made dominant contributions to the incremental lifetime cancer risk (ILCRs) before and after the APPCAP even though the APPCAP decreased the ILCRs by 78%. Coal combustion was the dominant source of PAHs but contributed only 12-15% of the ILCRs. The APPCAP decreased PAH emissions and changed the contributions of different sources of PAHs, and thus strongly affected the overall toxicity of PAHs to humans.

Spatiotemporal distribution, sources apportionment and ecological risks of PAHs: a study in the Wuhan section of the Yangtze River

This study investigated the sources, contamination and ecological risks of polycyclic aromatic hydrocarbons (PAHs) based on their spatiotemporal distribution in aquatic environment in the Wuhan section of the Yangtze River (WYR). The fugacity ratio evaluation indicated that sediment was secondary release sources of two- and three-ring PAHs and sinks of four- and five-ring PAHs. The total concentrations of PAHs (Σ16PAHs) ranged from 2.51 to 102.5 ng/L in water with the dominant contribution of 47.8% by two-ring PAHs. Σ16PAHs in sediments varied from 5.90 to 2926 ng/g with the contribution of 35.4% by four-ring PAHs. The higher levels of PAHs occurred around developed industrial areas during the wet season, which was related to local industrial emissions and influenced by rainfall/runoff. Annual flux of Σ16PAHs was estimated of 28.77 t. The PMF model analysis revealed that petroleum and industrial emissions were the dominant sources in water accounting for 58.5% of the total pollution, although traffic emission was the main source for sediment accounting for 44.6%. Risk assessments showed that PAHs in water were at low risks, whereas about 44% of the sediments were identified as medium risks. Therefore, energy structure adjustment and further implement of regulation and monitoring are necessary to reduce PAH emissions.

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.

Source apportionment and human health risk of PAHs accumulated in edible marine organisms: A perspective of "source-organism-human"

Most PAHs produced by human activities can be absorbed and accumulated by edible organisms and pose a potential hazard to human health. However, the source apportionment and human health risk of PAHs accumulated in edible organisms remains largely unknown. Therefore, we conducted source analysis and health risk assessment based on the PAH concentrations in ten marine fish from coastal areas of Guangdong, China. Results showed that the pollution of PAHs in fish organisms was at "Minimally polluted" level, and that all marine fish had the ability to accumulate PAHs. Risk assessment indicated Carcinogenic risk of PAHs in four populations was at a "Cautionary risk" level, with urban children suffered the highest risk. Petroleum pollution, Coal and biomass combustion, and Marine transport emissions were identified as the main anthropogenic sources for PAHs in organisms, and Marine transport emissions accounted for the highest Carcinogenic risk. The Acceptable daily intake for all populations were far below their actual daily intake without causing "Cautionary risk". Our findings provide new insights into the source apportionment and health risk of PAHs from a "source-organism-human" perspective, and suggested that joint management of three anthropogenic sources would be an effective way to prevent the health risks of PAHs.

A critical insight into occurrence and fate of polycyclic aromatic hydrocarbons and their green remediation approaches

Over the last century, the tremendous growth in industrial activities particularly in the sectors of pharmaceuticals, petrochemicals and the reckless application of fertilizers and insecticides has raised the contamination of polyaromatic hydrocarbons (PAHs) tremendously. For more than a decade, the main focus of environmental experts is to come up with management approaches for the clean-up of sites polluted with PAHs. These are ubiquitous in nature i.e., widely distributed in ecosystem ranging from soil, air and marine water. Most of the PAHs possess immunotoxicity, carcinogenicity and genotoxicity. Being highly soluble in lipids, they are readily absorbed into the mammalian gastro intestinal tract. They are widely distributed with marked tendency of getting localized into body fat in varied tissues. Several remediation technologies have been tested for the removal of these environmental contaminants, particularly bioremediation has turned out to be a hope as the safest and cost-effective option. Therefore, this review first discusses various sources of PAHs, their effect on human health and interactions of PAHs with soils and sediments. In this review, a holistic insight of current scenario of existing remediation technologies and how they can be improvised along with the hindrances in the path of these technologies are properly addressed.

A novel biomass pyrogenic index and its application coupled with black carbon for improving polycyclic aromatic hydrocarbon source identification

To accurately subdivide the sources of polycyclic aromatic hydrocarbons (PAHs), the composition characteristics of 36 total polycyclic hydrocarbons (T-PAHs; 16 parent PAHs and 20 alkylated PAHs [A-PAHs]) in biomass-residue samples were analyzed. A novel biomass pyrogenic index (BPI) was defined based on A-PAH-fingerprinting differences between biomass-combustion and petroleum sources of PAHs and the sum of the concentrations of pyrene, fluoranthene, benzo[a]anthracene, and alkylated homologs) divided by the ∑value of EPA PAHs with 2-3 rings. BPIs of < 0.5 and > 0.5 indicated that the PAHs originated mainly from biomass combustion and petroleum, respectively. And the ∑targeted A-PAH pairs influencing the BPI/black carbon (BC) ratio was used to identify PAH sources in surface-sediment samples, using 0.5 as the threshold to distinguish between different sources across the strait. The columnar sediments were used to verify the accuracy of two source-identification methods. The results revealed that the main PAH sources changed since 2005, which is highly consistent with those obtained using positive matrix factors and a changing trend in the main types of local energy use. These results highlight the significance of A-PAHs in accurately identifying PAH sources and suggest that applying compositional differences in BC from different sources for PAH-source identification merits further study.

Characterization of Polycyclic Aromatic Hydrocarbons (PAHs) associated with fine aerosols in ambient atmosphere of high-altitude urban environment in Sikkim Himalaya

Polycyclic Aromatic Hydrocarbons (PAHs) compounds are ubiquitous in ambient air due to their persistence, carcinogenicity, and mutagenicity. Gangtok being one of the cleanest cities in India located in Eastern Himalayan region, witnesses high developmental activities with enhanced urbanization affecting the ambient air quality. The present study aims to measure PM_2.5 and PAHs in the ambient atmosphere of the Sikkim Himalaya to understand the influence of natural and anthropogenic activities on aerosol loading and their chemical characteristics. The PM_2.5 samples were collected and analysed for the duration from Jan 2020 to Feb 2021.The seasonal mean concentrations of PM_2.5 and PAHs were observed to be high during autumn and low during summer season. Overall, the annual mean concentration of PM_2.5 was found higher than the prescribed limit of World Health Organization and National Ambient Air Quality Standards. The concentration of the 16 individual PAHs were found to be highest during autumn season (55.26 ± 37.15 ng/m³). Among the different PAHs, the annual mean concentration of fluorene (3.29 ± 4.07 ng/m³) and naphthalene (1.15 ± 3.76 ng/m³) were found to be the highest and lowest, respectively. The Molecular Diagnostic Ratio (MDR) test reveals higher contribution from heavy traffic activities throughout the winter and autumn seasons. The other possible sources identified over the region are fossil fuel combustion, and biomass burning. The multivariate statistical analysis (Multifactor Principal Component Analysis) also indicates a strong association between PM_2.5 /PAHs and meteorological variables across the region in different seasons. The precipitation and wind pattern during the study period suggests that major contribution of the PM_2.5 and PAHs were from local sources, with minimal contribution from long-range transport. The findings are important for comprehending the trends of PAH accumulation over a high-altitude urban area, and for developing sustainable air quality control methods in the Himalayan region.

Application of a hybrid GEM-CMB model for source apportionment of PAHs in soil of complex industrial zone

Accurate source apportionment is essential for preventing the contamination of pervasive industrial zones. However, a limitation of traditional receptor models is their negligence of transmission loss, which consequently reduces their accuracy. Herein, chemical mass balance (CMB) and generic environmental model (GEM) was fused into a new method, which was employed to determine the traceability of polycyclic aromatic hydrocarbons (PAHs) in a complex zone containing three coking plants, two steel plants, and one energy plant. Five categories of fingerprints comprising various compounds were established for the six plant sources where seven PAHs with low-high rings were screened as the best. Considering volatilization, dry deposition, and advective and dispersive transport, the GEM model generated 232 "compartments" in multimedia to capture subtle variations of PAHs during transmission. More than 90 % of the transmission of the seven PAHs varied between 0.4 % and 6.0 %. Over pure CMB model, acceptable results and best-fit results improved by 1.6-44.4 % and 0.3-80.8 % in the GEM-CMB model. Additionally, the coking, steel, and energy industries accounted for 36.4-56.1 %, 25.6-41.7 %, and 18.3-23.6 % of PAHs sources at four receptor points, respectively. Furthermore, quantifying contaminant loss rendered the traceability results more realistic, judged by distances and discharge capacities. Accordingly, these outcomes can help in precisely determining soil contamination.

Occurrence, sources, and spatial variation of POPs in a mountainous tropical drinking water supply basin by passive sampling

Persistent organic pollutants (POPs) are widely distributed along the world and their levels in surface waters may pose a risk to human health due to consumption of contaminated water or fish long-term exposure to contaminated water. The occurrence of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in the Piedras river (Colombia) is a problem of serious concern since freshwater is conducted to a drinking water supply system that provides more than 3 million users. In this research, we deployed silicone rubber membranes as passive samplers in two sampling campaigns at seven sampling stations selected along the river, to assess sources and spatial variation of POPs. The measurements confirmed freely dissolved concentration of the EPA prioritized PAHs (excluding naphthalene), PCBs, heptachlor isomers, dieldrin, endosulfan isomers, among other POPs at trace levels in the water source. The Risk Quotient (RQ) method was applied to prioritize POPs with the highest potential toxicity over aquatic ecosystems. The OCP Heptachlor overcome RQ, while Dieldrin and Endosulfan, and some PAHs congeners such as Perylene, Pyrene, Benzo[a]pyrene, and Fluoranthene displayed medium-risk RQ. Significant differences between sampling stations assessed by One-way ANOVA suggested that the main PAHs and PCBs sources to the river were the punctual discharge from the WWTP and a leachate discharge form a landfill located in the study area. Additionally, nonpoint sources of OCPs were identified. Our results showed that the origin of PAHs and PCBs are associated with urban activities, while the contribution of OCPs is related to the presence of legacy pesticides from past usage in agricultural activities in the basin.

Spatial distribution, driving factors and health risks of fine particle-bound polycyclic aromatic hydrocarbons (PAHs) from indoors and outdoors in Hefei, China

Atmospheric particulate matter, especially in urban and industrial environments, can act as a source of different organic pollutants that can pose significant health impacts to residents. However, the pollution status and transport mechanisms of fine particle-bound polycyclic aromatic hydrocarbons (PAHs) in indoor and outdoor environments are uncertain. This study aimed to determine the spatial distribution and morphological characteristics of fine particle-bound PAHs and analyze the factors (source contributions and backward trajectories) that influence their concentrations. The results showed that mean concentrations of 16 PAHs were higher in indoor dust as compared to outdoor dust. In addition, the lowest concentrations of the 16 PAHs were found on the 11-20th floor, with smoking households > nonsmoking households (except Nap, Acy, and Ace). The 2-3 ring PAHs were more prominent in households with cooking activities. The particle size distribution showed that most of the particles were <62 μm in diameter, indicating that the indoor particles were smaller in size. Furthermore, the range of δ13C values in the outdoor dust (-30.17 ~ -28.63 ‰) samples was significantly lower than in indoor dust (-28.29 ~ -22.53 ‰). The results based on diagnostic ratios, positive matrix factorization (PMF) analysis and backward trajectory model analysis suggested that the sources of PAHs in indoor and outdoor dust were mixed, originated both locally and from neighboring provinces transported over long distances, especially concentrated in the Yangtze River Delta area. Finally, carcinogenic risk values for indoor dust were greater than those for outdoor dust. Therefore, it is recommended that local governments and industries with high PAH emissions should implement proper protocols to monitor and minimize the pollution levels of PAHs in the urban industrial environment in order to mitigate their health risks.

Polycyclic aromatic hydrocarbons in soils of Central Plains Urban Agglomeration, China: The bidirectional effects of urbanization and anthropogenic activities

To investigate the variations in environmental behavior (levels, distribution, sources, and soil toxicity) of polycyclic aromatic hydrocarbons (PAHs) under the impact of anthropogenic activities during the urbanization process, we collected soil samples from 195 sites in the Central Plains Urban Agglomeration (CPUA), North China, and analyzed 16 U.S. Environmental Protection Agency (EPA) PAH priority pollutants. We divided the sampling sites into three groups (urban area, industrial area, and farmland) and collected soil samples (0-20 cm surface layer). ∑₁₆PAHs concentrations in the soils of the urban area, industrial area, and farmland ranged from 24.2 to 4400 ng/g, 12.3-8780 ng/g, and 20.9-852 ng/g (the average value of 349, 634, and 186 ng/g), respectively. The 4 to 5 ring PAHs were dominant compounds in three soil types, accounting for 65-80% of the ∑₁₆PAHs. The results of the source analysis showed that the PAHs in the soils of CPUA were mainly from energy consumption. PAH levels in urban and industrial soils had a potential low cancer risk. The impact of urbanization on PAHs in the soil was bidirectional. On the one hand, the level of PAHs in the farmland soil might increase due to burning coal and agricultural machinery, which releases diesel or petrol fumes. On the other hand, in the urbanization process, the PAH content in urban soil and industrial soil showed a downward trend due to the implementation of environmental protection policies in China, which have reduced the atmospheric input of PAHs into the soil.

Distribution and Relationships of Polycyclic Aromatic Hydrocarbons (PAHs) in Soils and Plants near Major Lakes in Eastern China

The distributions and correlations among polycyclic aromatic hydrocarbons (PAHs) in soils and plants were analyzed. In this study, 9 soil samples and 44 plant samples were collected near major lakes (Hongze Lake, Luoma Lake, Chaohu, Changhu, Danjiangkou Reservoir, Wuhan East Lake, Longgan Lake, Qiandao Lake and Liangzi Lake) in eastern China. The following results were obtained: The total contents of PAHs in soil varied from 99.17 to 552.10 ng/g with an average of 190.35 ng/g, and the total contents of PAHs in plants varied from 122.93 to 743.44 ng/g, with an average of 274.66 ng/g. The PAHs in soil were dominated by medium- and low-molecular-weight PAHs, while the PAHs in plants were dominated by low-molecular-weight PAHs. The proportion of high-molecular-weight PAHs was the lowest in both soil and plants. Diagnostic ratios and principal component analysis (PCA) identified combustion as the main source of PAHs in soil and plants. The plant PAH monomer content was negatively correlated with Koa. Acenaphthylene, anthracene, benzo[k]fluoranthene, benzo[b]fluoranthene and dibenzo[a,h]anthracene were significantly correlated in plants and soil. In addition, no significant correlation between the total contents of the 16 PAHs and the content of high-, medium-, and low-molecular-weight PAHs in plants and soil was found. Bidens pilosa L. and Gaillardia pulchella Foug in the Compositae family and cron in the Poaceae family showed relatively stronger accumulation of PAHs, indicating their potential for phytoremediation.

Molecular signatures of organic particulates as tracers of emission sources

Chemical signature of airborne particulates and deposition dusts is subject of study since decades. Usually, three complementary composition markers are investigated, namely, (i) specific organic compounds; (ii) concentration ratios between congeners, and (iii) percent distributions of homologs. Due to its intrinsic limits (e.g., variability depending on decomposition and gas/particle equilibrium), the identification of pollution sources based on molecular signatures results overall restricted to qualitative purposes. Nevertheless, chemical fingerprints allow drawing preliminary information, suitable for successfully approaching multivariate analysis and valuing the relative importance of sources. Here, the state-of-the-art is presented about the molecular fingerprints of non-polar aliphatic, polyaromatic (PAHs, nitro-PAHs), and polar (fatty acids, organic halides, polysaccharides) compounds in emissions. Special concern was addressed to alkenes and alkanes with carbon numbers ranging from 12 to 23 and ≥ 24, which displayed distinct relative abundances in petrol-derived spills and exhausts, emissions from microorganisms, high vegetation, and sediments. Long-chain alkanes associated with tobacco smoke were characterized by a peculiar iso/anteiso/normal homolog fingerprint and by n-hentriacontane percentages higher than elsewhere. Several concentration ratios of PAHs were identified as diagnostic of the type of emission, and the sources of uncertainty were elucidated. Despite extensive investigations conducted so far, the origin of uncommon molecular fingerprints, e.g., alkane/alkene relationships in deposition dusts and airborne particles, remains quite unclear. Polar organics resulted scarcely investigated for pollution apportioning purposes, though they looked as indicative of the nature of sources. Finally, the role of humans and living organisms as actual emitters of chemicals seems to need concern in the future.

Comparison of atmospheric polycyclic aromatic hydrocarbons (PAHs) over six years at a CAWNET background site in central China: Changes of seasonal variations and potential sources

Total suspended particles (TSP) and gaseous samples were collected by using a high-volume sampler from March 2012 to March 2013 and January 2018 to January 2019 at a background site (Jinsha, JSH) in central China to study the chemical characteristics, seasonal variations, and potential sources of polycyclic aromatic hydrocarbons (PAHs). The average concentrations of ∑₁₅PAHs were 24.55 ± 9.19 ng m^-3 in 2012/2013 and 20.98 ± 9.77 ng m^-3 in 2018/2019. Low-ring PAHs were more concentrated in gas phase while high-ring PAHs were prone into particle phase. The concentrations of PAHs in the two sampling years were high in winter but low in summer and autumn. The relationships between the gas concentrations of PAHs and temperature indicated that most PAHs were influenced by long-range atmospheric transport (LRAT) in 2012/2013 and in 2018/2019, excluding anthracene (Ant) and pyrene (Pyr) were partially affected by air-surface re-volatilization in 2012/2013. The source of atmospheric PAHs at JSH was similar in 2012/2013 and 2018/2019,which was mainly due to the LRAT of PAHs emitted from biomass/fossil fuel combustion in the northern area of JSH. From 2012/2013 to 2018/2019, there was no significant difference between the concentrations of PAHs in spring and winter, whereas the concentrations of PAHs decreased from 2012/2013 to 2018/2019 in summer. In all, the control of PAHs at the source region was partially effective from 2012/2013 to 2018/2019.

Occurrence, origin and potential ecological risk of dissolved polycyclic aromatic hydrocarbons and organochlorines in surface waters of the Gulf of Gabès (Tunisia, Southern Mediterranean Sea)

We investigated the occurrence, origin, and potential ecological risk of dissolved polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCBs) and organochlorine pesticides (OCPs) in 27 surface water samples collected from a highly anthropized and industrialized area in the Gulf of Gabès (Tunisia, Southern Mediterranean Sea) in October-November 2017. The results demonstrated a wide range of concentrations (ng L^-1) with the following decreasing order: Ʃ16 PAHs (17.6-71.2) > Ʃ20 PCBs (2.9-33.7) > Ʃ6 DDTs (1.1-12.1) > Ʃ4 HCHs (1.1-14.8). Selected diagnostic ratios indicated a mixture of both pyrolytic and petrogenic sources of PAHs, with a predominance of petrogenic sources. PCB compositions showed distinct contamination signatures for tetra- to hepta-chlorinated PCBs, characteristic of contamination by commercial (Aroclor) PCB mixtures. The dominant OCP congeners were γ-HCH, 2,4'-DDD and 2,4'-DDE, reflecting past use of Lindane and DDTs in the study area. Agricultural, industrial and domestic activities, as well as atmospheric transport are identified as potential sources of PAHs, PCBs and OCPs in surface waters of the Gulf of Gabès. Toxic equivalents (TEQs) suggested a low carcinogenic potential for PAHs in seawater samples (mean of 0.14 ng TEQ L^-1). Evaluation of risk coefficients revealed low risk for PAHs and PCBs, and moderate to severe risk for OCPs.

Seasonal distribution of PM2.5-bound polycyclic aromatic hydrocarbons as a critical indicator of air quality and health impact in a coastal-urban region of Poland

This study focuses on the inter-seasonal distribution and variability of thirteen native PAHs adsorbed onto respirable PM_2.5 fraction collected in a coastal-urban region of northern Poland, in 2019. The backward trajectory analysis and several diagnostic ratios were applied to determine seasonal profiles of PAH congeners and their major sources in airborne samples. The annual cumulative mean value of total PAHs in PM_2.5 was 6.92 ± 10.1 ng m^-3, varying in the following range: 0.32 ng m^-3 (May) - 68.57 ng m^-3 (January). Seasonal mass concentrations of total particulate PAHs were ranked as follows: summer (1.27 ng m^-3) < spring (4.83 ng m^-3) < autumn (6.16 ng m^-3) < winter (18.5 ng m^-3). Clear seasonal differences in PAH concentrations can be explained by direct impact of local and regional urban/industrial activities, with priority winter contribution of coal combustion in residential and commercial sectors. In addition, for summer measurements the diagnostic ratios indicated that high molecular weight PAHs were mainly derived from vehicle emission and petrochemical industry, while relatively low mass contribution of 4-ring congeners to the total sum of PAHs was attributed to photochemical processing. The analysis of meteorological parameters (temperature, relative humidity) and gaseous precursors (SO₂, NO₂, NO_x, O₃ and CO) exhibits their statistically significant correlations with PAHs, indicating local/regional primary emission. The incremental lifetime cancer risk was 1.23 × 10^-5, suggesting potential toxicity and carcinogenicity for adult females and males. This study highlights the importance of the implementation of health risk assessment model in urbanized coastal zones.

Occurrence of polycyclic aromatic hydrocarbons (PAHs) in the seafood from an important fishing area in the East China Sea and a comparison between seafood from different origins

Polycyclic aromatic hydrocarbons (PAHs) were analyzed in a variety of coastal marine seafood from the Wentai fishing area, which is in proximity to highly urbanized areas and provides a significant portion of the marine aquatic products in Eastern China. Specifically, total PAHs ranged from 320 to 2500 ng/g d.w., whereas carcinogenic PAHs ranged from 21 to 92 ng/g d.w. According to the source diagnosis, the PAHs in the seafood were generally from sources highly related to fossil fuel. Thus, it is necessary to control the unintentional use of fossil fuels and optimize the energy structure in the terrestrial area nearby. Moreover, the food chain structure and the environmental behavior of PAHs through the food chain, which are relevant to dietary risk, were assessed. The δ¹⁵N values fell in a narrow range, which indicates a relatively short food chain, which is due to overfishing in this area. Furthermore, in this shortened food chain, the trophic magnification factors (TMFs) ranged from 0.23 to 6.6, which were generally higher than those in more complex food chains. The cancer risk (ILCR) ranged from 2.2 × 10^-8 to 2.2 × 10^-6. It is noted that the carcinogenic risk of consuming yellow croaker, which is one of the most popular seafood among people on the east coast of China, was the highest. In conclusion, trophic magnification implied a possible elevated risk through this marine food chain, and overfishing may have increased the uncertainty associated with TMF estimations.

Indexes of tobacco smoke contribution to environmental particulates based on molecular fingerprints of alkanes

Tobacco smoke (TS) is the source of a number of toxicants affecting the atmosphere and poses a threat to smokers and the whole community. Chemical, physical, and toxicological features of smoking products (vapors as well as mainstream, side stream, and third-hand smoke) have been investigated extensively. Special attention is paid to organic compounds (individually or in combination giving rise to peculiar molecular fingerprints), potentially able to act as "chemical signature" of TS. In this regard, the percent distribution of long-chainnormal, iso, and anteiso alkanes was ascertained as typical of TS. Nevertheless, until now no indexes have been identified as suitable for assessing the global TS contribution to environmental pollution, e.g., the TS percentage in carbonaceous aerosol and in deposited dusts, the only exception consisting in the use of nicotelline as tracer. This paper describes the results of an extensive study aimed at chemically characterizing the nonpolar lipid fraction associated to suspended particulates (PMs) and deposition dusts (DDs) collected at indoor and outdoor locations. Based on the iso, anteiso, and normal C₂₉-C₃₄ alkane profile in the samples as well in tobacco smoke- and no-TS-related emissions (literature data), various parameters describing the distribution of compounds were investigated. Finally, a cumulative variable was identified as the tobacco smoke impact index (TS%) suitable for estimating the TS percentage occurring in the particulate matter. The TS% rates were plotted vs. the exceedance of normal C₃₁ alkane with respect to the average of C₂₉ and C₃₃ homologs, which results higher in TS than in most other emissions, revealing a link in the case of suspended particulates but not of deposited dusts. According to back analysis carried out on all particulate matter sets, it was found that traces of TS affect even remote areas, while inside the smokers' homes the contributions of TS to PM could account for up to ~61% and ~10%, respectively, in PM and DD. This confirms the need of valuing the health risk posed by TS to humans, by means of tools easy to apply in extensive investigations.

Change in diagnostic ratios in expelled oils and residual extracts during semi-open pyrolysis experiments of an organic-rich shale

In order to investigate the effectiveness of diagnostic ratios in polycyclic aromatic hydrocarbon (PAH) source discrimination, semi-open pyrolysis experiments have been performed on an organic-rich, immature shale from the Winnipegosis Formation in southeastern Saskatchewan, Western Canada Sedimentary Basin. The concentrations and distributions of PAHs in expelled oils and residual extracts change drastically with increasing pyrolysis temperatures. The difficulty and inconsistency commonly encountered by using diagnostic ratios for PAH source identification in environmental samples seem to be rooted in the great variation of the diagnostic ratios themselves under different formation temperatures. No single diagnostic ratio allows a simple segregation of PAHs into petrogenic or pyrogenic sources. Some diagnostic ratios such as anthracene/phenanthrene and benz[a]anthracene/chrysene compound pairs are mostly effective for low-temperature pyrolysis, whereas indeno[1,2,3-cd]pyrene/benzo[ghi]perylene, aromatic hydrocarbon ring number distribution and degree of alkylation are mainly valid for high-temperature pyrolysis. The diagnostic ratios based on fluoranthene/pyrene, benzo[bk]fluoranthene/benz[a]pyrene compound pairs enjoy limited validity over a narrow pyrolysis range, whereas parameters derived from aromatic hydrocarbon ring number distribution, degree of alkylation and 1,7-/(2,6- + 1,7-dimentylphenanthrene) may be undistinguishable between petrogenesis and low-temperature pyrolysis. The apparent temperature-related variability must be taken into account when using the diagnostic ratios for source identification purposes. Multiple molecular markers need to be carefully selected to confirm the results obtained with PAH diagnostic ratios. Mechanical use of diagnostic ratios most likely leads to misinterpretation of environmental samples.

Spatial and seasonal variations of PAHs in soil, air, and atmospheric bulk deposition along the plain to mountain transect in Hubei province, central China: Air-soil exchange and long-range atmospheric transport

Polycyclic aromatic hydrocarbons (PAHs) are a long-term environmental problem faced by human society. The sources of involuntary PAHs are complex, moreover, secondary emissions of fixed PAHs in the environment occur due to global change and disturbance of human activities. Samples of three environmental media including soil, air, and atmospheric bulk deposition were collected to observe the spatial distribution and seasonal variation, to discuss the source or sink of PAHs and their association with the air mass transport along the plain (Jianghan Plain, JHP) to mountain transect, and explore the geographic scope of the atmospheric transport influence. The results obtained showed that 16 individual PAHs generally existed in all environmental multimedia being studied, and the PAHs concentration in air, soil and deposition flux of atmospheric bulk was higher in JPH than in "Western Hubei Mountains" (WHMs). Considerably high PAHs concentrations were obtained from the soil, air and atmospheric bulk deposition in winter, summer, and both summer and winter, respectively. The air-soil fugacity fraction of PAHs indicated that the soil of Dajiuhu (DJH) is likely to be a sink. Backward air trajectory simulation confirmed that most of the air mass passes over the JHP before reaching DJH, combined with the (transport and persistence level III) TaPL3 model results JHP are acting as sources. However, seasonal changes lead to a shift in the roles of soil sources and sinks. The TaPL3 model calculated that PAHs are transported through water for a wider range of effects and a longer persistence, even up to 10 years.

Polycyclic Aromatic Hydrocarbons (PAHs) in the intertidal sediments of Pearl River Estuary: Characterization, source diagnostics, and ecological risk assessment

The surface intertidal sediments in the Pearl River Estuary of China were analyzed from multiple perspectives, including the distribution characteristics, potential sources, and biological risks of polycyclic aromatic hydrocarbons (PAHs). The average concentration of PAHs, ranging from 73.68 ng/g to 933.25 ng/g, was 346.78 ng/g. PAHs are mainly composed of the 2- and 3-ring PAHs, with naphthalene (Nap), phenanthrene (Phe), pyrene (Pyr), benzo(g,h, i) perylene (Dib), fluoranthene (Flua), and indeno (1,2,3-c,d) pyrene (Ind) as the dominant constituents. The principal component analysis combined with multiple linear regression showed that petroleum combustion and biomass/coal combustion have contributed 52.78% and 40.53%, respectively, to the PAHs in intertidal sediments of Pearl River Estuary. The occurrence of adverse biological effects as a result of PAH contamination in the intertidal sediments of Pearl River Estuary has increased by 8% based on the mean value of the probable effect quotient.

Organic pollutants in protected plain areas: The occurrence of PAHs, musks, UV-filters, flame retardants and hydrocarbons in woodland soils

Protected woodlands are rare and small portions of the plain territory of northern Italy, where agricultural, industrial and urban activities strongly dominate the landscape. Such natural areas are frequently set on river floodplains and are therefore potentially conditioned by the contamination brought by the surface waters. We investigated the occurrence of multiple categories of organic pollutants, including Polycyclic Aromatic Hydrocarbons (PAHs), Musk fragrances, UV-filters, organophosphorus and novel brominated Flame Retardants (FRs) and Total Petroleum Hydrocarbons (TPH) in woodland soils of eight different protected areas. The samples collected in the floodplains of the Po, Adige and Fratta rivers resulted more contaminated, with levels of PAHs up to 633 ng g^-1. Moreover, these samples for the first time revealed the presence of personal care products, primarily 2-ethylhexyl-4-methoxycinnamate (EHMC) and tonalide (AHTN), in soils of protected woodlands, reaching respectively 3.4 ng g^-1 and 5.0 ng g^-1, together with the occurrence of both organophosphorus and brominated FRs, with total concentrations up to 15 ng g^-1. Higher concentrations of hydrocarbons, with TPH in the range 5-65 μg g^-1, were instead reflecting the inputs of long chain n-alkanes from epicuticular waxes more than petrogenic contamination.

Seasonal variations of polycyclic aromatic hydrocarbons in coastal sediments of a marine resource hot spot: the case of pars special economic energy zone, Iran

Polycyclic aromatic hydrocarbons (PAHs) are an important group of compounds of major environmental concern, which are in the class of persistent organic pollutants. Therefore, the key purpose of this research was to analyze seasonal fluctuations and to determine the probability of polycyclic aromatic hydrocarbons in coastal sediments of the Iranian Marine Resource Center based on the evaluation of 16 US-EPA important PAH compounds. These compounds have been collected from intertidal sediments located in the marine resources of southern Iran in different seasons. These samples of the surficial sediment were collected at the PSEEZ area using a stainless steel grab sampler in four seasons, from depths between 0.5 and 30 m. Surface sediment samples were removed by spoons and carefully placed in an aluminum foil; they were taken to the laboratory on ice and held at 20° C until their study. After extraction, by using a rotary evaporator apparatus, samples were condensed. The assay was added to roughly 2 g of activated copper flasks in the refrigerator for 36 h for desulfurization. Among different seasons, the highest concentration was observed in winter, with a mean of 281.3 ng g^-1. According to ecological risk assessment (concentrations of possible effects, low effect range, degree of threshold effects, and median effect range), PAH risks in surface sediments of PSEEZ were lower than the threshold results levels (TEL), possible effects levels (PEL), low range of effects (ERL), and median range of effects (ERM), indicating that a biological effect would rarely occur. The dry weight scale of the concentration of ∑PAHs ranges from 145.7 to 348.42 ng g^-1 with a mean quantity of 260.52 ng g^-1. Therefore, according to the amount of ∑PAH concentration, the sediments in the PSEEZ area indicated moderate to heavy pollutions. In this way, the sedimentary surface ecosystems of the Persian Gulf were considered as moderately polluted compared with other ecosystems worldwide. Our study highlighted some of the research gaps in PAH contamination studies and the level of PAH contamination. Therefore, this study will provide a scientific background, planning, and policies for PAH pollution control and environmental protection in Iran and similar regions around the world.

Tracing human footprint and the fate of atmospheric polycyclic aromatic hydrocarbons over the Pearl River Estuary, China: Importance of particle size

Few studies have focus on size-segregated particulate polycyclic aromatic hydrocarbons (PAHs) in the oceanic atmosphere. To better understand the impacts of anthropogenic activities on atmospheric PAHs, a heavily human-impacted estuary, the Pearl River Estuary (PRE), was chosen as a case study. We collected gaseous and size-segregated particulate samples of ambient air at two sites in the PRE, as well as from the exhaust emissions of the cruise ship used in the sampling campaign. In addition, surface seawater samples were collected. Size distribution patterns of high molecular-weight (HMW) particulate PAHs were bimodal at one site and unimodal at the other, suggesting PAHs at the former site were derived not only from long-range atmospheric transport but also from local sources. Gas-particle partition coefficients of HMW PAHs in size-segregated particles varied with particle sizes, mostly higher in fine particles (<1.8 μm). Dry deposition flux of Σ₂₃PAHs (defined as the sum of 23 PAHs) was contributed mainly from coarse particles (>1.8 μm), and HMW PAHs with lower dry deposition velocities could be transported farther away. With respect to air-water exchange, lower MW PAHs tended to have net volatilization, whereas higher MW PAHs were likely to have net deposition. This study sheds new lights on the origins and fate of atmospheric PAHs over the PRE, and suggests the emissions of maritime traffics should be regulated. Collected near the metropolitan regions, atmospheric PAHs over the PRE were highly affected by anthropogenic activities, especially for HMW PAHs, which could pose a long-lasting impact to the oceanic atmosphere and marine organisms.

Using diagnostic ratios to characterize sources of polycyclic aromatic hydrocarbons in the Great Lakes atmosphere

The present study characterized source profiles of polycyclic aromatic hydrocarbons (PAHs) for the Great Lakes atmosphere using nine PAH diagnostic ratios (DRs). The samples were collected from six sites in the Great Lakes basin during 1996-2018 within the Integrated Atmospheric Deposition Network (IADN). In general, pyrogenic sources, including coal combustion and vehicular emissions, were the most important contributors to atmospheric profiles, in particular at the urban sites. Diesel emissions accounted for a larger portion of the traffic-originated PAHs than gasoline emissions at all sites, but this compositional pattern was less obvious at the urban sites. Temporal analyses for DRs revealed that the relative contribution of petrogenic sources and volatilization from surfaces has been increasing gradually, and that the gaps in PAH emissions between diesel- and gasoline-engines appeared to be further amplified in recent years. Coal combustion and non-pyrogenic emissions were the main PAH sources for winter and summer air, respectively, but none of the DRs responded to these changes. DRs were generally different between vapor and particle phases. Our findings shed light on spatial and temporal trends of PAH DRs and PAH source characterization in the Great Lakes basin. Additionally, this study confirmed the usefulness of DRs, especially when combined with the PMF analysis, while also highlighting the limitation of multiple DRs.

Occurrence and source apportionment of organic pollutants in deep sediment cores of the Venice Lagoon

In this study, recent and aged inputs of five classes of organic contaminants (i.e. PCBs, OCPs, PCDD/Fs, PAHs, and n-Alkanes) were evaluated in eight deep sediment cores of the Venice Lagoon, collected along the path of a new waterway whose excavation is under evaluation by local authorities, to assess the environmental quality status of the area. Diagnostic indices were calculated for identifying pollutant distribution patterns and their major emission sources, whose relative contribution was quantified by a Positive Matrix Factorization source apportionment model. Sedimentary depth profiles highlighted higher contamination in the top layer, mainly related to ship traffic combustion and vehicular/industrial emissions from the mainland. Nevertheless, a significant level of pollution has been detected also in the deeper layers, probably due to the transport of particulate matter through the aquifers underlying the lagoon seabed. The results underlined the threat posed by the possible resuspension of pollutants in the water column during contaminated sediment dredging.

Spatio-temporal variation and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in surface dust of Qom metropolis, Iran

The objective of this research was to determine seasonal variation, distribution, potential health risk, and source identification of 16 polycyclic aromatic hydrocarbons (PAHs) in the surface dust of eight urban areas of Qom. The total levels of 16 PAHs ranged from 364.83 to 739.26 ng g^-1, with an average of 478.27 ng g^-1. Sites 1 and 8 showed the highest (491.33 ng g^-1) and lowest (465.08 ng g^-1) concentrations of PAHs, respectively. The PAHs demonstrated the highest and the lowest levels in autumn (553.41 ng g^-1) and summer (402.30 ng g^-1), respectively. Naphthalene (Nap) showed the highest amounts in all of the areas (75.57 ng g^-1). Source apportionment indicated that vehicular emissions and combustion of fossil fuels (liquid fossil fuel, crude oil, and gas) are the main sources of the PAHs. Toxic equivalency quantities (TEQs) index exhibited a mean concentration of 47.41 ng g^-1, and benzo[a]pyrene (BaP) and dibenzo[a,h]anthracene (DBA) together contributed more than 80% of TEQ, indicating high risk potential of these compounds. Total incremental lifetime cancer risk (ILCR) presented higher value (2.62 × 10^-7) for children than for adults (2.53 × 10^-7), one-fold lower than the threshold (10^-6). The spatial ILCR for the study areas and seasons showed the highest cancer risk in site 2 and winter. Taken together, the carcinogenic risk of PAHs to children and adults, respectively, through direct ingestion and dermal contact pathways illustrated values close to the baseline, suggesting that more attention should be paid to the issue in the study area.

The risk assessment of inorganic and organic pollutant levels in an urban area affected by intensive industry

The city of Litvínov (North Bohemia, Czech Republic) is seriously affected by coal mining, coal processing, and intensive industrial activities. Within the urban area, the potential environmental hazard of risk elements (in soil and vegetation) and polycyclic aromatic hydrocarbons (PAHs, in soils) was estimated using selected environmental and human health hazard indices. In total, 24 sites were sampled, including the city center, residential areas, industrialized zone, and areas close to operating and/or abandoned coal mines. The results showed elevated values of As, Cd, Cu, Ni, Pb, and Zn in soils (the maximum levels of individual pollution indices varied between 3 and 5 for As, Pb, and Zn); the risk assessment code (RAC) values indicated high bioaccessibility of Cd and Zn. The high mobility of Cd was confirmed by their bioaccumulation factors (BAF) in the aboveground biomass of Taraxacum sect. Ruderalia and Polygonum aviculare, reaching up to 1.9 and 2.9, respectively. The Cd content in plants presents a substantial health hazard for herbivores such as Oryctolagus cuniculus living within the urban area. The PAH levels in the soils also showed elevated values; the contents of benzo(a)pyrene exceeded more than 2-fold the indicative values for potential health risk for biota, especially near the abandoned coal mines. The incremental lifetime cancer risks (ILCR) for ingestion of the contaminated soil showed only low or negligible cancerogenic risk, varying between 6.7 × 10^-7 and 1.6 × 10^-5 for children, and between 9.9 × 10^-7 and 2.7 × 10^-6 for adults. However, the potential health impact of the inhalation of the contaminated particulate matter should be included in the further research. Although the contamination level in the investigated area does not represent an imminent environmental and health risk, the potential remediation measures should be considered in the future.

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.

Spatiotemporal distribution, risk assessment and source appointment of metal(loid)s in water and sediments of Danjiangkou Reservoir, China

Danjiangkou Reservoir is the biggest artificial reservoir in China. But spatiotemporal distribution and risks of metal(loid)s in it were still unclear after the operation of Middle Route of South-to-North Water Diversion Project. In this study, distribution pattern of fifteen metal(loid)s in the Danjiangkou Reservoir was investigated. It was shown that metal(loid)s concentrations in the water were much lower than the drinking water quality standards in China, while Sb, Co, Cd and Cr were identified as the major pollutants in the sediments. Environment-metal(loid)s correlation analysis revealed total organic carbon, sulfate, temperature, dissolved oxygen and total phosphorus markedly controlled metal(loid)s distribution in the water, while organic carbon, total phosphorus and ammonia nitrogen shaped their distribution in the sediments. Results of risk assessment further revealed that the sediments of Danjiangkou Reservoir were minor to moderate polluted, and Sb, Cd exhibited the highest potential ecological risk. Additionally, source identification showed agricultural activities (25.3%), industrial and mining activities (17.5%) and natural processes (57.2%) were the dominant sources of metal(loid)s burden in the sediments. Overall, the results are of significance to understanding the ecological risk and pollution sources in the Danjiangkou Reservoir, which is essential for the effective management of metal(loid)s pollution.

Contamination and human health risks of polycyclic aromatic hydrocarbons in surface soils from Tianjin coastal new region, China

Polycyclic aromatic hydrocarbons (PAHs) in urban soils are of increasing concern because of their potential toxicity and persistence. However, there is limited information about PAHs in Tianjin coastal new region, although it is an important economic and industrial center in Northern China. Here we determined the concentrations of PAHs in 210 surface soil samples collected from this region according to administrative divisions covering Han'gu district, Tanggu district, and Dagang district, to evaluate their contamination and potential cancer risks. The concentrations of 16 PAHs ranged from 58.2 to 9160 ng g^-1, and the highest concentration was found in Han'gu district. According to the incremental lifetime cancer risk (ILCR) model, the soils from Han'gu district and Dagang district posed a moderate carcinogenic risk to residents, and dermal contact was the main exposure pathway. Besides, ILCRs for children through ingestion were comparable to those for adults but apparently higher than adolescents, while ILCRs of dermal contact for adults were higher than children and adolescents. Comparisons between the layout of industrial zones and the distributions of PAHs as well as ILCRs indicate that PAHs accumulating in soils and then incurring risk areas is partly controlled by the economic and industrial structure.

Elucidating the distribution and sources of street dust bound PAHs in Durgapur, India: A probabilistic health risk assessment study by Monte-Carlo simulation

Spatial and seasonal distribution of PAHs, source identification, and their associated carcinogenic health risk was investigated in street dust of Durgapur, India. Street dust is an important indicator to detect the quality of the environment as well as the sources of pollutants. The obtained results showed fluctuation in PAHs concentrations from 2317 ± 402 ng/g to 5491 ± 2379 ng/g along with the sampling sites. Seasonal variation revealed higher PAHs concentrations in the winter season (5401 ± 993 ng/g) with the maximum presence of 4-ring PAHs. Two-way analysis of variance (ANOVA) exposed that the sites, seasons and site-season interactions were vividly affected by dissimilar PAHs. The PAHs source identification was investigated by principal component analysis (PCA), positive matrix factorization (PMF), diagnostic ratios, and they revealed pyrogenic, diesel, gasoline, wood and coal combustion to be the key sources of the PAHs in street dust. Obtained results from incremental lifetime cancer risk (ILCR) model exhibited the carcinogenic risk for children ranged from 2.4E-06 to 3.8E-06 while 2.1E-06 to 3.4E-06 for adults which were above the baseline value 1.0E-06. The Monte Carlo simulation model identified cumulative cancer risk of sixteen PAHs in 50th percentile were 2.8 and 1.7 times more while in 95th percentile, the values were 8.8 and 7.8 times higher than the acceptable value of 1E-06 for child and adult respectively.

Polycyclic aromatic hydrocarbons in the Baltic Sea - Pre-industrial and industrial developments as well as current status

We report on Baltic Sea polycyclic aromatic hydrocarbon (PAH) pressure based on the U.S. EPA PAHs in view of millennial and decadal developments utilizing data from sediment deposits and seawater. Pre-industrial PAH contents ranged from 500 to 4500 ng/g TOC. Maximum PAH contents were up to 100,000 ng/g TOC and date back to the 1960s to 1970s with maximum pollutant inputs. Contemporary sediment PAH contents with 10,000 to 35,000 ng/g TOC and seawater concentrations with about 1 to 16 ng/l show spatial variability due to different local inputs and sediment characteristics. Pre-industrial compositional change from low molecular weight to high molecular weight (HMW) PAH indicates changing sources from mostly petroleum to combustion. Application of diagnostic ratios reveals petroleum and combustion as contemporary PAH sources and that traffic emissions continuously contribute to the Baltic PAH profile. Medium to high toxicological risk to the marine community might arise from current HMW PAH contents.

Spatial distribution and source identification together with environmental health risk assessment of PAHs along the coastal zones of the USA

Identification of polycyclic aromatic hydrocarbons (PAHs) sources and hot spot areas are the primary driving forces for their control in the environment. This study was performed in the US coastal areas to identify the major sources of PAHs and investigate the spatial distribution associated with carcinogenic PAHs (CPAHs) using a novel spatial forecasting method for the first time in environmental sciences. Diagnostic ratios of PAHs demonstrated the predominance of pyrogenic sources compared to petrogenic sources within the area of study. Five factors were extracted using positive matrix factorization method with respect to 16 priority PAHs, indicating the dominance of pyrogenic versus petrogenic sources mainly as a result of combustion products in the environment. The total toxic benzo[a]pyrene equivalency (TEQ) for all CPAHs ranged from 0.03 to 10,456 ng/g containing a mean of 199 ng/g. The contribution of each CPAH to the total TEQ varied according to the following order: benzo[a]pyrene (65.4%), dibenzo[a,h]anthracene (12%), benzo[b]fluoranthene (10%), benzo[a]anthracene (6%), indeno[1,2,3-c,d]pyrene (6%), benzo[k]fluoranthene (0.5%) and chrysene (0.1%). The spatial analysis by fixed rank kriging (FRK) highlighted a similar pattern associated with all of the CPAHs with higher values in the northern part of New Jersey State. In particular, Passaic River, Upper New York/New Jersey Harbor, Mullica River, Schuylkill River, Newark Bay and Christina River were the most contaminated stations regarding the observed values of CPAHs.

Controlling factors for the distribution of typical organic pollutants in the surface sediment of a macrotidal bay

Marine sediment is the final sink of polycyclic aromatic hydrocarbons (PAHs) from river input and atmospheric deposition. Such kind of pollutant cycles in the marine environment is usually controlled by hydrodynamic conditions. Many previous studies have explored how ocean currents influence pollutant distribution, but very few studies have focused on the relationships between the distribution patterns of pollutant and residual currents or sediment transport. In this study, 16 monomers of PAHs from 135 surface sediment samples collected in the Hangzhou Bay, a typical macrotidal bay, were systematically identified and their sources were analyzed. The sediment characteristics and distribution pattern were also comprehensively analyzed. The results showed the seabed sediments were moderately polluted by PAHs with a level of 38.58-1371.06 ng/g (median 186.70 ng/g). Most of the PAHs are composed of three to five rings, originated from combustion of coal and firewood. The combustion of oil also contributes to PAHs in seabed sediments for some areas. The PAHs are found to be concentrated within the estuary and the offshore areas, as well in coastal ocean. Fine-grained sediment transport is controlled by residual currents, which leads to PAH accumulation in the bay and the offshore areas, forming a high-value distribution pattern. Hence, we conclude that residual current is the main factors that control the long-term distribution of PAHs in the seabed sediments of the macrotidal bay. Temporal and spatial varying models of PAHs were needed in a further study to explore further the mechanisms how PAHs are transported in coastal areas.

Improved comprehensive ecological risk assessment method and sensitivity analysis of polycyclic aromatic hydrocarbons (PAHs)

Based on the existing comprehensive ecological risk assessment methods of PAHs, this paper proposed an improved hierarchical Archimedean copula integral assessment (HACIA) model with the optimization in the model selection mechanism and accelerating the calculation speed, and according to which performed the sensitivity analysis of the integrated risk relative to the underlying grouped risk probability. Taihu Lake in China and the Bay of Santander in Spain were taken as study areas, whose samples were obtained and extracted concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs). After briefly analyzing their concentration characteristics and source, their comprehensive ecological risks were evaluated by the improve HACIA model and their sensitivity was also analyzed. The results proved that, for Taihu Lake, pyrogenic sources occupied the dominance, especially grass, coal and wood combustion, while the risk proportion of 5-rings PAHs was the lowest indeed based on the improved HAICA model. For the Bay of Santander, source apportionment indicated both petrogenic and pyrogenic sources, mainly from vehicle emissions including gasoline and diesel engines, and 4-ring PAHs were urgently needed to be managed. However, the sensitivity analysis results of two study areas showed that the most effective control target for reducing integral risk has no obvious relationship with the maximum grouped risk. And a clear linear relationship between the maximum sensitivity range and the logarithm of the initial overall risk only presented in one of study areas, which required further research to clarify. In brief, the improved HACIA model is helpful to evaluate the comprehensive ecological risk of 16 PAHs, and formulate risk management strategies based on grouped risk assessment and sensitivity analysis, with the former points out the admonitory risk and the latter helps to find the most effective mitigation measures.

Spatiotemporal toxicity assessment of suspended particulate matter (SPM)-bound polycyclic aromatic hydrocarbons (PAHs) in Lake Chaohu, China: Application of a source-based quantitative method

The spatiotemporal associations between the emissions and environmental toxicities of polycyclic aromatic hydrocarbons (PAHs) in lake still remain an issue. Here, we focused on the suspended particulate matter (SPM)-bound PAHs in Lake Chaohu, China to quantitatively estimate their spatiotemporal toxicities from different sources. A source-based quantitative method, positive matrix factorization (PMF)-benzo[a]pyrene-based toxic equivalency (TEQ_BaP) model, was applied. Firstly, we investigated the spatiotemporal characteristics of SPM-bound PAHs. The concentrations of Σ₂₁ PAHs ranged from 1646 to 19267 ng·g^-1. Low-ring PAHs were found to have the highest fractions. T-distributed stochastic neighbor embedding (t-SNE)-partitioning around medoid (PAM) technic revealed significantly spatiotemporal variation characteristics of SPM-bound PAHs in Lake Chaohu. Season, location (west or east lake zone), and sample classification (estuary or lake) together governed the patterns. Then, their potential sources were apportioned. Our results found that diagnostic ratios did not work perfectly. However, 3 factors were separated by PMF model. Unburned petroleum (F1), biomass, coal and gasoline combustion (F2), and diesel, straw combustion (F3) were the main sources of PAHs, accounting for 36.16%, 48.96% and 14.88%, respectively. The patterns of the source profiles were season-dependent. Finally, the toxicity of SPM-bound PAHs from different sources were predicted by PMF-TEQ_BaP model, and the model predictions were satisfactorily acceptable. Overall, predicted Σ₁₉ TEQ_BaP of SPM-bound PAHs in Lake Chaohu ranged from 20.8 to 947.9 ng·g^-1. Benzo[e]pyrene (BeP), benzo[a]pyrene (BaP) and benzo[b]fluoranthene (BbF) were the main toxic species. Temporally, PAH toxicity posed significantly seasonal differences. F3 had primary contributions to Σ₁₉ TEQ_BaP. Cutting the diesel consumption and using cleaner energy substitutes were suggested to reduce the PAH toxicity in Lake Chaohu. Overall, we expected this study could give new insights into the spatiotemporal associations between the sources and toxicities of SPM-bound PAHs in lake ecosystem.

Post relocation of industrial sites for decades: Ascertain sources and human risk assessment of soil polycyclic aromatic hydrocarbons

As a persistent organic pollutant, polycyclic aromatic hydrocarbons (PAHs) may still residually pollute industrial sites after relocation. This study investigated the contamination status of PAHs in the topsoils of three industrial legacy sites (the Shougang industrial ruins, the original Beijing coking plant area, and an abandoned gas station) that relocated more than 10 years ago from downtown Beijing. The sources of PAHs in the soil were qualitatively and quantitatively analyzed, and health risks were evaluated for different groups of people. The total concentration of 16 PAHs in the study area ranged from 371.1 ng g^-1 to 4073.9 ng g^-1. The pollution levels of the three study areas were abandoned gas station > Beijing coking plant > Shougang ruins. In terms of composition, low-ring aromatics accounted for the majority of the detected PAHs, and in the dry season, low-ring aromatics accounted for a higher proportion in the three areas than in the wet season. The comparison of the PAH diagnostic ratio and PMF model verification showed that the sources of PAHs in the Shougang ruins and the Beijing coking plant area were mainly those of biomass and coal combustion, accounting for 66.3% and 56.1% of the total detected PAHs, respectively; the PAH sources of the abandoned gas station storage tank area were largely that of petrol (33.9%) and diesel combustion (23.8%). Since these industrial sites were located in urban centers, this study also conducted a health risk assessment of the topsoil. The total carcinogenic risk range of the three contaminated sites was 1.41E-06 to 2.47E-05. Abandoned industrial sites have potential carcinogenic risks to human health. The government needs to conduct comprehensive risk assessments and remedial measures on soils of industrial legacy sites to achieve land reuse.

Distribution, source apportionment, and health risk assessment of polycyclic aromatic hydrocarbons in urban soils from Shenyang, China

A total of 74 urban topsoil samples were collected from the central area of Shenyang, China. The concentration, distribution, source, and health risk of 16 polycyclic aromatic hydrocarbons (PAHs) were analyzed. The 16 USEPA priority PAHs were detected in all soil samples. The total concentrations of PAHs ranged from 283 to 21,821 ng/g dry weight (dw), with a mean value of 2370 ng/g and median value of 1427 ng/g. The benzo[a]pyrene toxicity equivalent (BaP_eq) concentrations ranged from 6.03 to 2403 ng/g dw, with a mean value of 308 ng/g and median value of 185 ng/g. High molecular weight PAHs were the predominant components. The spatial distribution revealed that soil PAH concentrations within the Two Ring Road were high, but low in the south of Hun River. Compared with other urban soils, the pollution of PAHs in urban soils of Shenyang was at a moderate level, but increased rapidly compared with previous years, especially fluoranthene. Diagnostic ratios of PAHs and positive matrix factorization model all suggested that PAHs in urban soils of Shenyang were dominantly from pyrogenic origins. The health risk assessment indicated that children had the highest total carcinogenic risk, followed by adolescents and adults. The differences between gender groups for the same age group were insignificant. Ingestion was the dominant exposure pathway, followed by dermal contact and inhalation. The total lifetime carcinogenic risks at all sampling sites were lower than the highest acceptable risk (10^-4), and those of Eastern, Central, and Western Shenyang were higher than those of Northern and Southern Shenyang.

The Great Acceleration of fragrances and PAHs archived in an ice core from Elbrus, Caucasus

The Great Acceleration of the anthropogenic impact on the Earth system is marked by the ubiquitous distribution of anthropogenic materials throughout the global environment, including technofossils, radionuclides and the exponential increases of methane and carbon dioxide concentrations. However, personal care products as direct tracers of human domestic habits are often overlooked. Here, we present the first research combining fragrances, as novel personal care products, and polycyclic aromatic hydrocarbons (PAHs) as combustion and industrial markers, across the onset of the Great Acceleration in the Elbrus, Caucasus, ice core. This archive extends from the 1930s to 2005, spanning the profound changes in the relationship between humans and the environment during the twentieth century. Concentrations of both fragrances and PAHs rose throughout the considered period, reflecting the development of the Anthropocene. However, within this rising trend, remarkable decreases of the tracers track the major socioeconomic crises that occurred in Eastern Europe during the second half of the twentieth century.

Air quality intervention during the Nanjing youth olympic games altered PM sources, chemical composition, and toxicological responses

Ambient particulate matter (PM) is a leading global environmental health risk. Current air quality regulations are based on airborne mass concentration. However, PM from different sources have distinct chemical compositions and varied toxicity. Connections between emission control measures, air quality, PM composition, and toxicity remain insufficiently elucidated. The current study assessed the composition and toxicity of PM collected in Nanjing, China before, during, and after an air quality intervention for the 2014 Youth Olympic Games. A co-culture model that mimics the alveolar epithelium with the associated macrophages was created using A549 and THP-1 cells. These cells were exposed to size-segregated inhalable PM samples. The composition and toxicity of the PM samples were influenced by several factors including seasonal variation, emission sources, and the air quality intervention. For example, we observed a size-dependent shift in particle mass concentrations during the air quality intervention with an emphasized proportion of smaller particles (PM_2.5) present in the air. The roles of industrial and fuel combustion and traffic emissions were magnified during the emission control period. Our analyses revealed that the PM samples demonstrated differential cytotoxic potencies at equal mass concentrations between sampling periods, locations, and time of day, influenced by variations in the predominant emission sources. Coal combustion and industrial emissions were the most important sources affecting the toxicological responses and displayed the least variation in emission contributions between the sampling periods. In conclusion, emission control mitigated cytotoxicity and oxidative stress for particles larger than 0.2 μm, but there was inadequate evidence to determine if it was the key factor reducing the harmful effects of PM_0.2.

Exposure to polycyclic aromatic hydrocarbons (PAHs) in people living in urban and rural areas as revealed by hair analysis

Some polycyclic aromatic hydrocarbons (PAHs) are carcinogenic and mutagenic to humans. However, little is known about PAH exposure to people living in urban and suburban areas through comparative studies. Some studies have indicated that human hair can be used as a noninvasive biomarker of PAH exposure. Therefore, we collected hair samples from 66 volunteers from Nanjing and Ningbo, China, to detect PAH concentrations in this work. The highest levels in the hair samples were found in phenanthrene > anthracene > naphthalene among the parent PAHs. Sixteen parent PAHs showed higher concentrations in the samples from Nanjing than in the samples from Ningbo. Significantly higher levels of some PAHs were observed in male hair than in female hair in Nanjing, and in hair from smokers than in hair from non-smokers in both Nanjing and Ningbo. In addition, there was a significant effect of the age on the concentration of low-molecular-weight PAHs and ∑PAHs in human hair in both Nanjing and Ningbo. Studying the inter-chemical associations between these PAHs indicated similarities and differences between Nanjing and Ningbo.

Current situation of polycyclic aromatic hydrocarbons (PAH) in PM2.5 in a receptor site in Mexico City and estimation of carcinogenic PAH by combining non-real-time and real-time measurement techniques

Air pollution is a public health concern. Polycyclic aromatic hydrocarbons (PAH) are ubiquitous atmospheric pollutants contained in the atmospheric aerosol. PAH in particulate matter with diameters ≤2.5 µm (PM_2.5) represent a human health risk due to their toxic properties. In this study, PAH in PM_2.5 at a receptor site of Mexico City during the dry cold season were determined. The most abundant PAH (median, 10-90th percentile, pg m^-3) were benzo[ghi]perylene (467, 291-697), followed by pyrene (427, 218-642). A decrease around 40% in the carcinogenic PAH onto PM_2.5 was calculated with respect to the same PAH measured a decade ago, at the same receptor site, despite of increase in vehicle fleet. The PAH decrease trend agrees with the decrease trend of CO, NO and NO₂, released into the air by similar emission sources than PAH. Control emissions strategies implemented by local and federal authorities are discussed. PAH analyses were carried out by non-real-time and real-time methods. The PAH non-real-time method involved PM_2.5 sampling, sample treatment and gas chromatography-mass spectrometry analysis. The PAH real-time method involved the use of a photoelectric aerosol sensor (PAS). The PAH determination by non-real time method was selective and efficient, with recoveries between 75 ± 14% and 98 ± 26%. By combining non-real-time and real-time methodologies, multivariate regression models were obtained based on PAS response, NO₂ and wind speed to estimate PAH in PM_2.5 at low-cost (r² = 0.59 to r² = 0.89). Fossil fuel combustion from vehicles was the major source around the sampling site. Diagnostic ratios (DR) based on retene, chrysene, and triphenylene, suggested biomass burning emission sources. Photo-oxidation in sunny months was observed based on benzo[a]pyrene, benzo[ghi]perylene, benz[a]anthracene, indeno[1,2,3-cd]pyrene and black carbon. The correlation analyses suggested transport of PM_2.5, O₃, BC and SO₂ to the sampling site, and local emissions of PAH, NO and CO.

Investigation of polycyclic aromatic hydrocarbons in soils from Caserta provincial territory, southern Italy: Spatial distribution, source apportionment, and risk assessment

The concentrations of polycyclic aromatic hydrocarbons (PAHs) in soils from Caserta provincial territory, southern Italy, were systematically investigated along with their correlations with soil properties and health risk. The concentrations of ∑₁₆PAHs ranged from 10.0 to 4191 ng/g, with a median (1 st quartile, Q1; 3rd quartile, Q3) of 28.5 (17.5-65.0) ng/g; Four-ring PAHs were the most abundant and contributed an average of ∼50.2% of the ∑₁₆PAHs. Significant differences in the spatial distributions of PAHs in soil were observed, with higher levels of PAH contamination found in Caserta city and the surrounding areas. According to the positive matrix factorization (PMF) model, three sources were identified: chemical production and metal smelting, vehicle emissions, and coal/biomass combustion. Soil total organic carbon was significantly correlated with the concentration of total PAHs and the concentrations of PAHs with three-, four-, and five-rings. In contrast, only the concentration of ∑₄DBPs (dibenzo(a,e)pyrene, dibenzo(a,h)pyrene, dibenzo(a,i)pyrene, dibenzo(a,l)pyrene) was well correlated with population density. The soil mass inventory of ∑₁₆PAHs was estimated to be 6.87 metric tons (geometric mean). The ecological risks posed by PAHs in the study are negligible; however, health risks of exposure to soil-borne PAHs were identified based on a probabilistic risk model.