Anthropogenic Polycyclic Aromatic Hydrocarbons Research Articles

Sedimentary records of polycyclic aromatic hydrocarbons and organochlorine pesticides to reconstruct anthropogenic activities in Lake Issyk-Kul region (Kyrgyzstan), and their effects on the lake environment

Vertical distributions of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in a sediment core from Lake Issyk-Kul are powerful tools for reconstructing historical anthropogenic activities over the past 350 years. Four periods were identified according to the variations in these environmental proxies. Period Ⅰ (1670s–1800s) corresponds to a phase of limited anthropogenic activity reflected by the lowest ΣPAH16 concentrations, mainly from biomass combustion and petrogenic processes. Along with pronounced deforestation due to wildfires documented in the pollen record, a similar decrease in PAHs suggests that PAHs were most likely generated by natural sources around Lake Issyk-Kul during this period. Period Ⅱ (1800s–1930s) reflects increasing agricultural activities with fluctuations in various PAH concentrations. Anthropogenic biomass-derived PAH inputs from agricultural activities gradually replaced natural inputs to Lake Issyk-Kul, coinciding with several historical events. However, natural factors still mainly controlled changing lake levels before the 1930s. Period Ⅲ (1930s–1970s) corresponds to rapid development of agricultural activities, inferred by slight increases in ΣPAH16 concentrations dominated by coal-derived PAHs and a considerable increase in ΣOCP18 concentrations. Concentrated agricultural activities around Lake Issyk-Kul significantly influenced environmental changes in grain size and water level in the lake. Period Ⅳ (post-1970 s) corresponds to intensive industrial and urban activities, including a 10-year economic depression (1990s–2000s), characterized by the highest ΣPAH16 concentrations mainly from petroleum combustion followed by a sharp drop after the 1990s as the dissolution of the Soviet Union. Industrialization and urbanization in study area have changed the trophic state of Lake Issyk-Kul, particularly in recent years. Climate change has also induced “lateral remobilization” of contaminants, increasing pollution levels in this mountain lake.

Dosage concentration and pulsing frequency affect the degradation efficiency in simulated bacterial polycyclic aromatic hydrocarbon-degrading cultures

A major source of anthropogenic polycyclic aromatic hydrocarbon (PAH) inputs into marine environments are diffuse emissions which result in low PAH concentrations in the ocean water, posing a potential threat for the affected ecosystems. However, the remediation of low-dosage PAH contaminations through microbial processes remains largely unknown. Here, we developed a process-based numerical model to simulate batch cultures receiving repeated low-dosage naphthalene pulses compared to the conventionally used one-time high-dosage. Pulsing frequency as well as dosage concentration had a large impact on the degradation efficiency. After 10 days, 99.7%, 97.2%, 86.6%, or 83.5% of the 145 mg L−1 naphthalene was degraded when given as a one-time high-dosage or in 2, 5, or 10 repeated low-concentration dosages equally spaced throughout the experiment, respectively. If the simulation was altered, giving the system that received 10 pulses time to recover to 99.7%, pulsing patterns affected the degradation of naphthalene. When pulsing 10 days at once per day, naphthalene accumulated following each pulse and if the degradation was allowed to continue until the recovered state was reached, the incubation time was prolonged to 17 days with a generation time of 3.81 days. If a full recovery was conditional before the next pulse was added, the scenario elongated to 55 days and generation time increased to 14.15 days. This indicates that dissolution kinetics dominate biodegradation kinetics, and the biomass concentration of PAH-degrading bacteria alone is not a sufficient indicator for quantifying active biodegradation. Applying those findings to the environment, a one-time input of a high dosage is potentially degraded faster than repeated low-dosage PAH pollution and repeated low-dosage input could lead to PAH accumulation in vulnerable pristine environments. Further research on the overlooked field of chronic low-dosage PAH contamination is necessary.

Global trade drives transboundary transfer of the health impacts of polycyclic aromatic hydrocarbon emissions

International trade leads to a redistribution of pollutant emissions related to the production of goods and services and subsequently affects their severe health impacts. Here, we present a framework of emissions inventories, input-output model, numerical atmospheric chemistry model, and estimates of the global burden of disease. Specifically, we assess emissions and health impacts of polycyclic aromatic hydrocarbons (PAH), a carcinogenic byproduct of production activities, and consider income, production, final sale, and consumption stages of the global supply chain between 2012 and 2015. We find that in 2015, global anthropogenic PAH emissions were 304 Gg (95% CI: 213~421 Gg) and estimated related lifetime lung cancer deaths were 6.9 × 104 (95% CI: 1.8 × 104~1.5 × 105 deaths). The role of trade in driving the PAH-related health risks was greater than that in driving the emissions. Our findings indicate that international cooperation is needed to optimise the global supply chains and mitigate PAH emissions and health impacts.

Gas-particle partitioning of polycyclic aromatic hydrocarbons from oil combustion involving condensate, diesel and heavy oil

This study focuses on the gas-particle (G-P) partitioning of 16 polycyclic aromatic hydrocarbons (PAHs) from oil combustion, which is one of the important contributors of anthropogenic PAHs but has been rarely studied. The combustions of different types of oils involving ultra-light to heavy oils were investigated, and the PAH partitioning mechanism was determined by the widely used Junge-Pankow adsorption model, Koa absorption model, and dual sorption model, respectively. The results show that the source-specific diagnostic ratios of Ant/(Ant+Phe) are between 0.09 and 0.24, the estimated regression slopes of G-P partition coefficients (KP) of the total PAHs on their sub-cooled liquid vapor pressures (PLO) are in the range of − 0.34 to − 0.25, and the predicted fractions of PAHs in the particle phase (φ) by Koa absorption model are close to the measured values, while the log KPvalues of the LMW PAHs from the combustions of diesel and heavy oil are better represented by the dual sorption model. Our findings indicate that PAHs are derived from mixed sources that include the unburned original oil and combustion products, and the PAH partitioning mechanism is governed by the process of absorption into organic matter because of the unburned oil, but both adsorption and absorption exist simultaneously in the lighter PAHs from the combustions of heavier oils (i.e., diesel and heavy oil). Based on these findings, the understanding of the fate and transport of PAH emissions and the optimization of the emergency responses to accidents such as marine oil spills would be potentially improved.

Source apportionment and health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in the coastal ecosystem of the Brunei Bay, Brunei

Pollution characteristics and associated ecological risks of PAHs in sediments from Brunei Bay, Brunei were investigated. The concentrations of ∑16 PAHs ranged from 826.7 to 2955.3 μg kg−1, indicating moderate to high level of pollution. Source apportionment of PAHs by molecular isomeric ratios and positive matrix factorization model indicated impact of potential anthropogenic PAH sources including combustion of biomass and fossil fuels. The data indicated relatively no significant ecotoxicological risk for most of PAH compounds. To estimate the individual c-PAH toxicity, the toxic equivalent quantity (c-TEQ) was calculated. Results of the TEQ analysis showed that BaP followed by DBA and BaA are the most carcinogenic of PAHs examined in the study area. The evaluation of human health risk of PAHs revealed that the cancer risk of PAHs for adults and children was higher than the USEPA threshold (<1E−06) and lower than 1E-3, implying low to moderate risk.

Historical deposition of PAHs in mud depocenters from the Southwestern Atlantic continental shelf: The influence of socio-economic development and coal consumption in the last century

Polycyclic aromatic hydrocarbon (PAH) concentrations were determined in four dated sediment cores collected in mud depocenters of the southern Brazilian continental shelf. Core dating results covered the interval between 1925 and 2017. The total PAH concentrations (ΣPAHs) ranged from 44.69 ng g−1 to 305.43 ng g−1 and were similar between the analysed cores. Fine-grained sediments and total organic carbon (TOC) results did not correlate with the ΣPAHs, indicating that the variations in PAH concentrations are mostly related to variations in sources and emissions. PAH source appointment indicated a high input of a natural compound (perylene) and the predominance of anthropogenic PAHs from coal, biomass, and fuel combustion. Alkylated PAHs presented high contributions throughout all cores. The historical deposition of PAHs was associated with different periods of the socio-economic and industrial development of near coastal cities and reflected very well the history of coal production and consumption in the southern region of Brazil. The low levels of ΣPAHs before 1945 in all analysed cores may be related to the beginning of the industrialization process and the lower urbanization degree in the region. Between 1945 and 1965, the gradual ΣPAHs increase reflects the establishment and enlargement of the southern Brazilian industrial sector. The interval between 1965 and 1990 corresponded to the highest ΣPAHs in three of the four analysed cores. After 1990, a relative decrease in the ΣPAHs was observed in most cores and may be related the multiple cuts of incentives to the industrial usage of coal, as well as to Brazil's efforts in environmental regulation for coal extraction and consumption.

Sources and diffusive air–water exchange of polycyclic aromatic hydrocarbons in an oligotrophic North–Patagonian lake

Polycyclic aromatic hydrocarbons (PAHs) are semivolatile organic compounds of environmental concern. This study aims to investigate the influence of local sources of anthropogenic PAHs and their air–water exchange fluxes in an oligotrophic North–Patagonian lake in Chile. The monitoring was carried out in Panguipulli Lake during a six-month period during the autumn and winter seasons (March to August 2017) using a high–volume air sampler and a pump system for water samples. We detected and quantified fifteen PAHs in the gas phase (mean ∑15PAHs = 11.6 ng m−3) and dissolved water phase (mean ∑15PAHs = 961.8 pg L−1). Methylphenanthrenes and pyrene dominated the concentrations of PAHs in the studied phases. To determine sources of PAHs we used the PAH ratios of Light Molecular Weight/Heavy Molecular Weight (∑LMW/∑HMW) and Phenanthrene/Anthracene (Phe/Ant). The PAH ratio results revealed a pyrogenic source. We estimated the air–water diffusive exchange fluxes and fugacity ratios for the studied compounds. In general, air–water diffusive exchanges of PAHs showed a net volatilization for the less hydrophobic (log KOW < 4) and lighter PAHs (MW ≤ 170 g mol−1), and a net deposition trend for the more hydrophobic (log KOW 4–7) and higher molecular weight PAHs (MW ≥ 178 g mol−1). We found a significant correlation between log water/air fugacity ratios and log KOW of PAHs. Therefore, it is suggested that this oligotrophic lake acts as a sink by accumulating hydrophobic and mid-high molecular weight PAHs derived mainly from pyrogenic sources. This study is the first attempt to understand the sources and behavior of PAHs in oligotrophic lakes in the Southern Chile where information is scarce regarding the occurrence of PAHs.

Isolating different natural and anthropogenic PAHs in the sediments from the northern Bering-Chukchi margin: Implications for transport processes in a warming Arctic

Polycyclic aromatic hydrocarbons (PAHs) have become the dominating burden in the Arctic ecosystems, but their transport pathways and relative importance of different sources in the Arctic remained unclear, and this would be further complicated by climate change. Here we interpreted 27 PAHs in 34 surface sediments from the northern Bering-Chukchi margin. We integrated source apportionment methods (including diagnostic ratios, principal component analysis, hierarchical analysis, and positive matrix factorization (PMF) model) together with geochemistry parameters, which reveal a gradually clear picture of the spatial patterns of different sources. The total PAH concentrations (50.4 to 896.0 ng/g dw) exhibited a “hilly” shape with the increase of latitude, showing the highest level of PAHs in the northeast Chukchi Sea. The total BaP toxic equivalent quotient (TEQ) for carcinogenic compounds was from 1.06 to 33.3 ng TEQ/g. Most PAHs showed positive correlations with silt content, total organic carbon, stable carbon isotopes and black carbon (p < 0.01 or 0.05). Generally, source apportionment methods revealed an increasing petrogenic source of PAHs with latitudes. The PMF model further differentiated two petrogenic (36.7%), two pyrogenic (softwood and fossil fuel combustion, 35.5%) and one in-situ biogenic source (Perylene, 27.8%). An extremely high petrogenic signal was captured in the Canada Basin margin, possibly originating from the Mackenzie River via ice drifting with Beaufort Gyre, while another petrogenic source may come from coal deposit erosion by deglaciation. Softwood combustion (characterized by Retene) exhibited exclusively higher contribution in the northeast Chukchi Sea and might result from the increasing wildfire in Alaska due to climate change, whereas fossil fuel combustion exhibited similar contributions across different latitudes. Our results revealed natural PAHs as important “inside sources” in the Arctic, which are highly sensitive to global warming and deserves more attention.

Effect of northern boreal forest fires on PAH fluctuations across the arctic

Polycyclic aromatic hydrocarbons (PAHs) are formed by the incomplete combustion of fossil fuels and forest or biomass burning. PAHs undergo long-range atmospheric transport, as evidenced by in situ observations across the Arctic. However, monitored atmospheric concentrations of PAHs indicate that ambient PAH levels in the Arctic do not follow the declining trend of worldwide anthropogenic PAH emissions since the 2000s, suggesting missing sources of PAHs in the Arctic or other places across the Northern Hemisphere. To trace origins and causes for the increasing trend of PAHs in the Arctic, the present study reconstructed PAH emissions from forest fires in the northern boreal forest derived by combining forest carbon stocks and MODIS burned area. We examined the statistical relationships of forest biomass, MODIS burned area, emission factors, and combustion efficiency with different PAH congeners. These relationships were then employed to construct PAH emission inventories from forest biomass burning. We show that for some PAH congeners, for example, benzo[a]pyrene (BaP)—the forest-fire-induced air emissions are almost one order of magnitude higher than previous emission inventories in the Arctic. A global-scale atmospheric chemistry model, GEOS-Chem, was used to simulate air concentrations of BaP, a representative PAH congener primarily emitted from biomass burning, and to quantify the response of BaP to wildfires in the northern boreal forest. The results showed that BaP emissions from wildfires across the northern boreal forest region played a significant role in the contamination and interannual fluctuations of BaP in Arctic air. A source-tagging technique was applied in tracking the origins of BaP pollution from different northern boreal forest regions. We also show that the response of BaP pollution at different Arctic monitoring sites depends on the intensity of human activities.

Hepatobiliary Analyses Suggest Chronic PAH Exposure in Hakes (Urophycis spp.) Following the Deepwater Horizon Oil Spill

Prior to the Deepwater Horizon oil spill, we lacked a comprehensive baseline of oil contamination in the Gulf of Mexico's sediments, water column, and biota. Gaps in prespill knowledge limit our ability to determine the aftereffects of the Deepwater Horizon blowout or prepare to mitigate similar impacts during future oil spill disasters. We examined spatiotemporal differences in exposure to and metabolism of polycyclic aromatic hydrocarbons (PAHs) in 2 hake species (Urophycis spp.) to establish a current baseline for these ecologically important, abundant, and at‐risk demersal fishes. Gulf hake (Urophycis cirrata) and southern hake (Urophycis floridana) were collected throughout the Gulf of Mexico during extensive longline surveys from 2012 to 2015. Analyses of biliary PAH metabolites and liver PAH concentrations provided evidence of exposures to di‐ and tricyclic compounds, with the highest concentrations measured in the northern Gulf of Mexico. Species‐specific differences were not detected, but temporal trends observed in biliary PAHs suggest a decrease in acute exposures, whereas increasing liver PAHs suggest chronic exposures marked by greater assimilation than metabolism rates. To our knowledge, the present study provides the first multitissue contaminant analyses, as well as the most exhaustive biometric analyses, for both gulf and southern hakes. Though sources of exposure are complex because of multiple natural and anthropogenic PAH inputs, these results will facilitate the development of much needed health metrics for Gulf of Mexico benthos. Environ Toxicol Chem 2019;38:2740–2749. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Significance of Perylene for Source Allocation of Terrigenous Organic Matter in Aquatic Sediments.

Perylene is a frequently abundant, and sometimes the only polycyclic aromatic hydrocarbon (PAH) in aquatic sediments, but its origin has been subject of a longstanding debate in geochemical research and pollutant forensics because its historical record differs markedly from typical anthropogenic PAHs. Here we investigate whether perylene serves as a source-specific molecular marker of fungal activity in forest soils. We use a well-characterized sedimentary record (1735-1999) from the anoxic-bottom waters of the Pettaquamscutt River basin, RI to examine mass accumulation rates and isotope records of perylene, and compare them with total organic carbon and the anthropogenic PAH fluoranthene. We support our arguments with radiocarbon (14C) data of higher plant leaf-wax n-alkanoic acids. Isotope-mass balance-calculations of perylene and n-alkanoic acids indicate that ∼40% of sedimentary organic matter is of terrestrial origin. Further, both terrestrial markers are pre-aged on millennial time-scales prior to burial in sediments andareinsensitive to elevated 14C concentrations following nuclear weapons testing in the mid-20th Century. Instead, changes coincide with enhanced erosional flux during urban sprawl. These findings suggest that perylene is definitely a product of soil-derived fungi, and a powerful chemical tracer to study thespatial and temporal connectivity between terrestrial and aquatic environments.

Sedimentary archive of Polycyclic Aromatic Hydrocarbons and perylene sources in the northern part of Taihu Lake, China

In the present work, we analyzed the concentration patterns of 20 Polycyclic Aromatic Hydrocarbons (PAHs) in 25 surface sediments and 11 sediment cores from the northern part of Taihu Lake, China. Three of the cores were dated based on 137Cs activity for the deposition age of the sediment. The spatial distributions of the PAH concentrations show that the inflow rivers into Zhushan Bay and Meiliang Bay were the main pathway for PAHs and sediment input to the northern part of the lake. This results in substantially higher PAH concentrations (up to 5000 ng/g) and sedimentation rates (higher than the average of 3–4 mm/a) in the area close to the river outlets. In addition, results also show that PAH concentrations in the sediments considerably increased from the early 1960s, but the decreasing concentrations in the upper layers of the sediment could be attributed to the introduction of measures on environmental improvement from ca. 2000. There were both anthropogenic and biogenic origins of perylene in the lake sediments, which were distinguished based on spatial distribution patterns and also the concentration proportions of perylene to the sum of the 20 PAHs. In the cores collected close to river outlets, the concentration proportions of perylene typically range from 0.02 to 0.18 and there are significant positive linear correlations between the concentration of perylene and three anthropogenic PAHs (Benzo[a]pyrene, Benzo[e]pyrene, Pyrene), suggesting that perylene was dominated by anthropogenic input. However, the cores collected further away from the river outlets show the concentration proportions between 0.13 and 0.96, and present significant negative correlations or no correlations between perylene and the three PAHs, suggesting that perylene was mainly formed by biogenic activities. Furthermore, the different perylene sources accompanied with the location distributions imply that anthropogenic activities could inhibit its biogenic formation.

Sedimentary polycyclic aromatic hydrocarbons record recent anthropogenic activities near high-elevation Lake Sayram, northwest China

Mountain lakes are sensitive to natural perturbations and human activities. Profiles of anthropogenic polycyclic aromatic hydrocarbons (PAHs) in lake sediments serve as a natural archive from which human impacts on lakes can be reconstructed. Two parallel sediment cores (34 cm long) were extracted from Lake Sayram in the Tianshan Mountains of arid northwest China and dated using 210Pb and 137Cs. PAHs in the sediments were used to infer the past ∼150 years of anthropogenic impact on the lake. Results showed that PAH concentrations in the lake sediments were generally low, but nevertheless reflect some human activity. Benzo(ghi)perylene (BghiP) and indeno(1, 2, 3-cd)pyrene (IcdP) are typical markers of vehicular traffic, so significant correlations between PAH (especially BghiP and IcdP) and metal concentrations suggest that PAHs in sediments are effective proxies for anthropogenic activities. Furthermore, constrained cluster analysis revealed that the vertical profile of PAHs was characterized by three periods that correspond to changes in human activities. Prior to the 1960s, low PAH concentrations in the sediments generally indicate that the lake was virtually unaffected by human impact. BghiP and IcdP concentrations, however, displayed a minor peak in the 1950s, possibly reflecting transport from a remote polluted region via prevailing westerly winds. From the 1960s through the 1990s, relatively high values of PAHs, especially high molecular weight (HMW) PAHs BghiP and IcdP, and heavy metal enrichment factors (EFs), were related to increasing anthropogenic activities. After the 1990s, maxima of PAHs, HMW PAHs, BghiP, IcdP, EFs, together with highest total phosphorus (TP) and total organic carbon (TOC) values, reflect intensive human-related impact on the lake. The coincidence of limnological changes and local socio-economic development suggest that sedimentary PAHs record recent anthropogenic impact on Lake Sayram.

Presence of polycyclic aromatic hydrocarbons in sediments and surface water from Shadegan wetland – Iran: A focus on source apportionment, human and ecological risk assessment and Sediment-Water Exchange

Polycyclic aromatic hydrocarbons (PAHs) contamination in aquatic system is of concern since it may constitute a sink of these contaminants for wetland ecosystem. We investigated pollution characteristics and ecological risks of PAHs by sampling contaminated sediments and water from the Shadegan wetland in Khuzestan province, south-west Iran. Concentrations of total PAHs in water and sediment samples varied from 42 ± 2.3–136 ± 7.5ng/L and 10 ± 0.5–317 ± 14.3µg/kg, respectively. Source apportionment of PAHs by both approaches (Principal component analysis-multiple linear regression (PCA-MLR) and molecular isomeric ratios of specific PAHs), indicated impact of potential anthropogenic PAH sources including oil spill and incomplete combustion, bulrush combustion, vehicular exhaust and fishing boat emissions. Comparing the PAHs concentration with sediments quality guidelines based on the effect range low values/effects range-median values (ERL/ERM) and the threshold effect levels/probable effect levels (TEL/PEL). Also, a risk quotient (RQ) was elaborated for evaluation of potential toxic effects on aquatic ecosystem. Our data showed relatively insignificant adverse impact for most individual compounds. The toxic equivalent quantity (TEQ) was also calculated to estimation the PAHs toxicity. TEQ value of PAHs (1.9µg/kg) was lower than the safe level (600µg/kg). The fugacity fraction approach was applied to explain the trend of the selected PAHs for water–sediment exchange, which showed that the fluxes for most priority PAHs were from water to sediment suggesting no secondary source impact.

Chronic polycyclic aromatic hydrocarbon exposure causes DNA damage and genomic instability in lung epithelial cells.

Cell exposure to atmospheric polycyclic aromatic hydrocarbons (PAHs) is closely associated with DNA damage and genomic instability. We assessed the mechanisms of chronic and acute PAH exposure-induced genotoxicity in two human lung epithelial cell lines, A549 and NC-H1975. We sampled atmospheric PAHs at the Xixi Campus, Zhejiang University in Hangzhou, China during August (non-haze episode) and November (haze episode) 2015. We identified vehicle emissions as a dominant anthropogenic PAH source in our study. PAHs were extracted according to the United States Environmental Protection Agency Method TO-13A. We found that chronic PAH exposure saturated lung cell xenobiotic metabolic pathways, promoting intercellular reactive oxygen species production and accumulation. Chronic alteration of the cellular redox status resulted in DNA damage and genomic instability. Chronic PAH exposure also perturbed the cellular DNA damage response, inducing S phase arrest and inhibiting apoptosis. Dysregulation of PAH metabolism and the DNA damage response altered cellular homeostasis and increased cell susceptibility to subsequent PAH exposures, thereby enhancing the likelihood of genomic mutation and instability.

Polycyclic aromatic hydrocarbons (PAHs) in Chinese forest soils: profile composition, spatial variations and source apportionment

Previous studies reported that forest ecosystems can play a vital role in scavenging anthropogenic polycyclic aromatic hydrocarbons (PAHs) and act as primary reservoirs of these environmental pollutants. The present study aimed to investigate the occurrence, spatial pattern and source apportionment of PAHs across Chinese background forest soils (O- & A-horizons). The 143 soils collected from 30 mountains showed significantly (p < 0.05) higher levels of ∑15PAHs (ng g−1 dw) in O-horizon (222 ± 182) than A-horizon (168 ± 161). A progressive increase in the levels of lighter PAHs was observed along altitudinal gradient, however heavier PAHs did not show any variations. Carbon contents (TOC & BC) of forest soils were found weakly correlated (p < 0.01) with low molecular weight (LMW)-PAHs but showed no relation with high molecular weight (HMW)-PAHs. Source apportionment results using PMF and PCA revealed that PAHs in forest soils mainly come from local biomass burning and/or coal combustion and attributed that forest soils may become a potential sink for PAHs in the region.

Historical record of anthropogenic polycyclic aromatic hydrocarbons in a lake sediment from the southern Tibetan Plateau.

High-altitude lake sediments can be used as natural archives to reconstruct the history of pollutants. In this work, the temporal distribution of polycyclic aromatic hydrocarbons (PAHs) was determined in a sediment core collected from the southern Tibetan Plateau (TP), which was dated by using the 210Pb dating method and validated with the 137Cs fallout peak. The concentrations of the anthropogenic PAHs (Σ8PAH) in the sediment core ranged from 0.83 to 12ng/g dw, and the fluxes of the Σ8PAH were in the range of 2.1-27g/cm2/year. The temporal variations in the concentration and input flux of anthropogenic PAHs were low with little variability before the 1950s, and then gradually increased from the 1950s to the 1980s, and an accelerated increase was observed after the early 1980s. The content of total organic carbon played an insignificant role in affecting the time trends of PAHs in the sediment core. Diagnostic concentration fractions of PAH components indicate PAHs in the lake sediment of the southern TP which are mainly from biomass burning and/or from long-range atmospheric transport.

The effect of gas-phase polycyclic aromatic hydrocarbons on the formation and properties of biogenic secondary organic aerosol particles.

When secondary organic aerosol (SOA) particles are formed by ozonolysis in the presence of gas-phase polycyclic aromatic hydrocarbons (PAHs), their formation and properties are significantly different from SOA particles formed without PAHs. For all SOA precursors and all PAHs, discussed in this study, the presence of the gas-phase PAHs during SOA formation significantly affects particle mass loadings, composition, growth, evaporation kinetics, and viscosity. SOA particles formed in the presence of PAHs have, as part of their compositions, trapped unreacted PAHs and products of heterogeneous reactions between PAHs and ozone. Compared to 'pure' SOA particles, these particles exhibit slower evaporation kinetics, have higher fractions of non-volatile components, like oligomers, and higher viscosities, assuring their longer atmospheric lifetimes. In turn, the increased viscosity and decreased volatility provide a shield that protects PAHs from chemical degradation and evaporation, allowing for the long-range transport of these toxic pollutants. The magnitude of the effect of PAHs on SOA formation is surprisingly large. The presence of PAHs during SOA formation increases mass loadings by factors of two to five, and particle number concentrations, in some cases, by more than a factor of 100. Increases in SOA mass, particle number concentrations, and lifetime have important implications to many atmospheric processes related to climate, weather, visibility, and human health, all of which relate to the interactions between biogenic SOA and anthropogenic PAHs. The synergistic relationship between SOA and PAHs presented here are clearly complex and call for future research to elucidate further the underlying processes and their exact atmospheric implications.

Assessing the relation between anthropogenic pressure and PAH concentrations in surface water in the Seine River basin using multivariate analysis

Understanding the relation between polycyclic aromatic hydrocarbons (PAHs) in freshwater and anthropogenic pressure is fundamental to finding a solution to reduce the presence of PAHs in water, and thus their potential impact on aquatic life. In this paper we propose to gain greater insight into the variability, sources and partitioning of PAHs in labile (or freely dissolved=not associated to the organic matter), dissolved and particulate phases in freshwater. This study was conducted using land use data as a marker of anthropogenic pressure and coupling it with chemical measurements. This study was conducted on 30 sites in the Seine River basin, which is subjected to a strong human impact and exhibits a wide range of land uses. Half of the sites were studied twice. Labile PAHs were measured by semi-permeable membrane devices (SPMDs), and dissolved and particulate phases by grab samples. Partial least squares regressions were performed between chemical measurements and data of anthropogenic pressure. The results indicate different sources for the dissolved phase and particles. Dissolved and labile phases were more related to the population density of the watershed, while particles were more related to a local pressure. Season and land use data are necessary information to correctly interpret and compare PAH concentrations from different sites. Furthermore, the whole data set of the 45 field deployments comprising labile, dissolved, total and particulate PAH concentrations as well as the physico-chemical parameters is available in the supplementary information.

Isotopic Evidence for Oil Sands Petroleum Coke in the Peace-Athabasca Delta.

The continued growth of mining and upgrading activities in Canada's Athabasca oil sands (AOS) region has led to concerns about emissions of contaminants such as polycyclic aromatic hydrocarbons (PAHs). Whereas a recent increase in PAH emissions has been demonstrated within around 50 km of the main center of surface mining and upgrading operations, the exact nature of the predominant source(s) and the geographical extent of the deposition are still under debate. Here, we report a century-long source apportionment of PAHs using dual (δ(2)H, δ(13)C) compound-specific isotope analysis on phenanthrene deposited in a lake from the Athabasca sector of the Peace-Athabasca Delta situated ∼150 km downstream (north) of the main center of mining operations. The isotopic signatures in the core were compared to those of the main potential sources in this region (i.e., unprocessed AOS bitumen, upgrader residual coke, forest fires, coal, gasoline and diesel soot). A significant concurrent increase (∼55.0‰) in δ(2)H and decrease (∼1.5‰) in δ(13)C of phenanthrene over the last three decades pointed to an increasingly greater component of petcoke-derived PAHs. This study is the first to quantify long-range (i.e., >100 km) transport of a previously under-considered anthropogenic PAH source in the AOS region.