High Concentrations Of Polycyclic Aromatic Hydrocarbons Research Articles

Pah levels in the soil-litter-vegetation-atmosphere system of Atlantic Forest remnants in Southeast Brazil.

Although the Brazilian Atlantic Forest is a hotspot for biodiversity conservation, it is one of the most fragmented biomes in Brazil and also affected by air pollutants such as polycyclic aromatic hydrocarbons (PAHs). The study aimed at measuring the PAH levels in leaf trees, litter, soil, and atmosphere of two Atlantic Forest remnants impacted by air pollutants during summer and winter periods; identifying emission sources; and investigating the relationship among the PAH concentrations in the soil, litter, leaves, and atmosphere. Site 1 is situated in the largest South American city, with rainy summers and dry winters, and characterized by intense urbanization. Site 2 is situated in a large forest continuum and is characterized by wet climate with no defined dry seasons. It is more distant from the anthropogenic urban sources than site 1, but closer to an industrial complex. No differences were detected for PAH amounts (summer + winter) in the particles and wet deposition fluxes between sites. In site 1, the highest concentrations of PAHs in the particles were measured during the winter while in the leaf trees were measured during the summer. PMF model showed that sites 1 and 2 receive PAHs mainly from vehicle emissions and industrial activities, respectively. The accumulation of heavier compounds in soil and leaves via wet deposition was more evident in site 2. PAHs were mainly stored in the soil of site 1, contrasting with site 2, where they were retained in litter, which were attributed to disturbances of decomposer community and reduced decomposition rates.

Distribution, risk assessment, and source apportionment of polycyclic aromatic hydrocarbons (PAHs) using positive matrix factorization (PMF) in urban soils of East India.

This study investigated 16 United States environmental protection agency priority PAHs profiles and their sources in 40 urban soils collected from two industrialised cities, Jamshedpur and Bokaro, in east India and assessed their health risk to humans. The results showed the predominance of high molecular weight (HMW) PAHs (4-5 rings). The total PAHs concentration in surface soils ranged from 2223 to 11,266ng/g and 729 to 5359ng/g (dw), respectively, for Jamshedpur and Bokaro. Higher concentrations of PAHs were recorded at the selected industrial areas and heavy traffic zones of both cities. In JSR city 4-ring PAHs contributed 43% of total PAHs trailed by 5-ring PAHs 27.2%. Similarly, in BKR city 4-ring PAHs contributed 34% of the total PAHs, followed by 3-ring PAHs 28.9% and 5-ring PAHs 22.9%. Total organic carbon in surface soils exhibited moderate correlation with the low molecular weight (ΣLMW) PAHs (R2 = 0.69) and a comparatively strong correlation with the ΣHMW PAHs (R2 = 0.89), suggesting strong adsorption of HMW PAHs to urban soils. The Diagnostic and PMF modelling analysis indicated that the major sources of PAHs contamination in soils were petroleum combustion, vehicular emissions, biomass, and coal combustion. The health risk assessment shows that the cumulative probability of carcinogenic risks was under the acceptable limits of 10-4 to 10-6. At some sampling areas in both cities, the maximum value of total exposure cancer risk slightly exceeded the acceptable limits indicating some carcinogenic risk for adults.

Distribution, source and ecological risk assessment of polycyclic aromatic hydrocarbons in groundwater in a coal mining area, China

The impact of exposure to polycyclic aromatic hydrocarbons (PAHs) on the ecological environment has aroused widespread concern in coal mining areas. Coal mining and solid waste accumulation are among the main reasons for the widespread occurrence of PAHs in groundwater in mining areas. In this study, the PAH content in groundwater in a coal mining area in northern Anhui, China, was determined via gas chromatography–mass spectrometry (GC–MS). The seasonal variation, composition, spatial distribution and sources of PAHs were analyzed, and their potential ecological risks were evaluated. The concentration of ∑PAHs in groundwater ranged from 15.04 to 449.13 ng/L, mainly including 2- and 3-ring PAHs. There were obvious differences in the PAH distribution in groundwater, and higher PAH concentrations were detected in groundwater near industrial parks and solid waste dumping areas. Diagnostic ratio analysis indicated that the PAHs mainly originate from the combustion of coal, biomass and petroleum. The positive matrix factorization (PMF) results revealed that coal and biomass combustion, traffic emissions, coking emissions and oil leakage contributed 46.59%, 20.06%, 18.70% and 14.65%, respectively, to the detected PAHs. The ecological risk assessment results indicated that this area experienced a moderate ecological risk, and the mean ecological risk values during the wet season were lower than those during the dry season.

Dilution of concentrations of PAHs from atmospheric particles, bulk deposition to soil: a review.

Polycyclic aromatic hydrocarbons (PAHs) are emitted to the atmosphere by various anthropogenic activities as well as natural sources, they undergo long-range transport, are degraded (e.g., by photolysis) and finally they are deposited onto the surface and potentially accumulate in topsoil. The dry deposition of particle-bound PAHs dominates the accumulation of PAHs in soil and their further fate in soil is governed by sorption/desorption from these airborne particles. This paper offers an overview on concentrations of particle-bound PAHs, the dry deposition fluxes and finally concentrations of PAHs in soil. In addition, spatial and temporal variations of PAHs are considered. The results show that concentrations of particle-bound PAHs typically range from 1mgg-1 up to 10mgg-1 in cities with coal-based heating in winter and in countries with coal-based industry incl. electrical power production. These values are very high and exceed the legal limits set in soils by orders of magnitude. Atmospheric deposition rates typically reach several mgm-2a-1, but in winter, especially in countries with heating, deposition rates are up to 10 times higher. PAHs concentrations in soils show a very wide variation from less than 1µgg-1 in rural areas up to 10µgg-1 in urban space, which is about 1000 times lower than the concentration of PAHs on particles in the atmosphere. This demonstrates the relevance of high concentrations of PAHs on airborne particles deposited on soils, which also highlights the importance of considering incremental lifetime cancer risk models for both air and soil and assessing the total health risk of PAHs to humans.

Plant contribution to the remediation of PAH-contaminated soil of Dagang Oilfield by Fire Phoenix.

Pot experiments were conducted to evaluate plant contribution during remediation of the polycyclic aromatic hydrocarbons (PAH)-contaminated soil of Dagang Oilfield by Fire Phoenix (a mixture of Festuca L.). The results showed that Fire Phoenix could grow in soil contaminated by high and low concentrations of PAHs. After being planted for 150days, the total removal rate of six PAHs in the high and low PAH concentrations was 80.36% and 79.79%, significantly higher than the 58.79% and 53.29% of the unplanted control group, respectively. Thus, Fire Phoenix can effectively repair the soil contaminated by different concentrations of PAHs. In high concentrations of PAHs, the results indicated a positive linear relationship between PAH absorption in tissues of Fire Phoenix and the growth time in the early stage. In contrast, the contents of PAHs were just slightly increased in the late period of plant growth. The main factor for the dissipation of PAHs was plant-promoted biodegradation (99.04%-99.93%), suggesting a low contribution of PAH uptake and transformation (0.07%-0.96%). The results revealed that Fire Phoenix did not remove the PAHs in the soil by accumulation but promoted PAH dissipation in the soil by stimulating the microbial metabolism in the rhizosphere.

Non-equilibrium influence on G/P partitioning of PAHs: Evidence from the diurnal and nocturnal variation

Gas/particle (G/P) partitioning is an important behavior for the atmospheric transport of polycyclic aromatic hydrocarbons (PAHs). In this study, paired daytime and nighttime air samples were collected for one year in order to study the diurnal and nocturnal variations of concentration and G/P partitioning of PAHs. Higher PAHs concentrations in total phase were observed in nighttime. The geomean (GM) concentrations of Σ15PAHs in total phase were 69.6 and 52.8 ng/m3 in nighttime and daytime, respectively. More obviously diurnal and nocturnal variations were observed in non-heating season, with the GM ratios of Σ15PAHs in nighttime to daytime of 1.65 and 1.06 in non-heating season and heating season, respectively. The results could be attributed to emission sources and meteorological conditions. The values of particulate phase fraction (ϕP) and G/P partitioning quotient (log KP) were used to quantify the phase distribution of PAHs. For most high molecular weight PAHs, the values of ϕP and log KP in nighttime were higher than those in daytime, which could be mainly attributed to the lower temperature in nighttime. However, for the three light molecular weight PAHs (Acy, Ace and Flu), higher values of ϕP and log KP were observed in daytime. The regression of log KP against log KOA for the three PAHs in daytime differed from those in nighttime. The chemical losses of PAHs in different phases might be responsible for the result. These findings suggested that the chemical loss of PAHs in gas phase should be considered for the G/P partitioning process.

Community-based assessment of marine resources contamination after a large-scale oil spill.

As of August 2019, several oil slicks reached the Brazilian coast, compromising local ecosystems and the economy of coastal communities. In this context, this study aimed to assess seafood quality at the Canavieiras Extractive Reserve (RESEX), located in the state of Bahia, Northeastern Brazil, by determining polycyclic aromatic hydrocarbons (PAHs) concentrations in local biota following the oil spill. It was designed and carried out in a participatory manner, involving RESEX fishers, shellfish and crab gatherers and managers, as well as university researchers. A total of 72 biota samples were analyzed, and the sum of the 16 priority USEPA PAHs ranged from less than the limit of detection to 30.81 ng g-1 (w.w.). When also considering alkylated compounds, concentrations ranged from 3.53 to 360.75 ng g-1 (w.w.). No sample contained PAHs concentrations suggestive of human consumption risks. No difference in PAHs concentrations between the six studied areas and regarding different biota feeding habits were observed. Higher PAHs concentrations were generally noted in molluscs, as these organisms do not have enzyme systems capable of metabolizing these compounds. This initiative demonstrated the feasibility of participatory construction resulting in a study concerning valued species to local communities, ensuring a contribution to local fishing and marketing activities.

ASSESSMENT OF THE DEGREE AND SOURCE OF POLYOLEFIN RECYCLATES CONTAMINATION

This study has the aim of analysing the degree of contamination of recycled polyolefin purchased from the market by focusing on the content of polycyclic aromatic hydrocarbons (PAHs). Additionally, the impact of the mechanical recycling process on the polyolefin chemical quality was investigated. Results indicated that recycled polyethylene (PE) had higher PAHs concentrations by 10 to 20 folds in comparison to the pristine PE. Similarly, recycled polypropylene (PP) indicated higher PAHs concentrations in comparison to the virgin polypropylene, yet with lower degree of difference. Analysing the 8 indicators assigned by the Regulation EU 1272/2013 amending REACH Annex XVII, all recycled specimens showed concentrations lower than the limit of 0.5 mg kg-1, which indicates that there is no restriction in material’s utilisation. This study functioned as a preliminary assessment to check the suitability of recycled plastics for their further utilisation. Additionally, the study indicates that polyolefin can experience quality deterioration when uncontrolled recycling conditions are applied.

Kontaminace příbřežních sedimentárních těles řeky Odry u Bohumína organickými polutanty

The aim of this study is to investigate present-day contamination levels of selected organic pollutants (POPs) in channel side bars and identify their sources. The studied area is located on the Odra River in the north-eastern part of the Czech Republic (at the border between the Czech Republic and Poland), between the city Bohumín and Odra´s confluence with Olše River. Sediment samples were taken directly from the channel side bars and subsequently measured for grain size analysis, concentrations of total organic carbon (TOC), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and specific biomarkers (terpenoids). Three main facies were recognized in channel side bars. Grain-size analysis showed the predominance of silt fraction, followed by variable sand contents, whereas the contents of clay fraction were almost stable. No statistically significant correlation was found between grain size and the concentrations of POPs except a weak correlation between PAHs, PCBs and sand fraction. POPs including PAHs, PCBs and OCPs showed high variability. In all samples, the sum of PAHs (maximumvalue of 78.1 mg kg-1) greatly exceeded the Czech preventive limit for dry soil. The sources of PAHs were analysed by employing diagnostic ratios and plots of specific PAH compounds. The results showed a high degree of correspondence suggesting a petrogenic origin associated with direct input into the river system. Relatively high concentrations of PAHs are a consequence of the vicinity of the pollution source and location in natural river reach enabling sedimentation of polluted sediments. Concentrations of PCB, hexachlorobenzene and DDT metabolites were almost insignificant in most of the samples, except for several samples having higher PCB values (maximum value of 47.6 μg kg-1). Specific biomarker compounds were used as an indicator of the presence of fossil matter, and H29 17α(H),21β(H) hopane showed the highest concentrations. The homohopane index indicated petroleum and vehicle exhausts origin. TOC revealed a positive correlation with specific biomarkers (homo hopanes and 16 α(H)- phyllocladane, hexachlorbenzene and PCB.

Size-fractionated PM-bound PAHs in urban and rural atmospheres of northern Thailand for respiratory health risk assessment

Size-fractionated particulate matters (SPMs) in a range of 9.0 to 0.43 μm, classified based on aerodynamic diameter (dae) as fine PMs (0.43 μm ≤ dae < 2.1 μm) and coarse PMs (2.1 μm ≤ dae < 9.0 μm) were collected by cascade impactors (7 fractions) during smoke haze (SH) and non-smoke haze (NSH) seasons in urban and rural areas of Chiang Mai, Thailand. Their polycyclic aromatic hydrocarbons (PAHs) compositions were determined for respiratory health risk assessment. During SH episode, concentrations of SPMs and PAHs in the rural area were approximately two times higher than in the urban area and about 62–68% of the SPMs were fine particles. Conversely, during NSH season the concentrations in the urban area were higher due to traffic emission. The finest particle sizes (0.65–0.43 μm) contained the highest PAHs concentrations among the other PM sizes. Benzo[b]fluoranthene was a main PAH component found during SH season suggesting biomass burning is a major pollutant source. High molecular weight (5–6 rings) PAHs with high carcinogenicity were likely to concentrate in fine particles. Distribution patterns of SPMs and PAHs during SH season were bimodal with the highest peak at a fine size range (0.65–0.43 μm) and a small peak at a coarse size range (5.8–4.7 μm). Respiratory health risk was estimated based on toxicity equivalent concentrations of PAHs bound-SPMs and inhalation cancer risk (ICR). Relatively high ICR values (1.14 × 10−4 (rural) and 6.80 × 10−5 (urban)) were found during SH season in both areas, in which fine particles played an important role. It revealed that high concentration of fine particles in ambient air is related to high respiratory health risk due to high content of carcinogenic substances.

Optimization of a Low Volume Extraction Method to Determine Polycyclic Aromatic Hydrocarbons in Aerosol Samples

This work describes the optimization of an extraction method for the determination of polycyclic aromatic hydrocarbons (PAHs) and their nitro- and oxy-PAH derivatives in atmospheric particulate matter (PM) samples, and demonstrates that this method is also effective for the determination of levoglucosan. The optimization of the extraction solvents was performed using a three-component mixture design with the solvents dichloromethane, methanol, and acetonitrile. The number of extractions, volume of solvent, and duration of extraction in an ultrasonic bath were optimized using a full factorial design followed by a central composite design. The analyses were performed by gas chromatography coupled with mass spectrometry. The optimized conditions of the method were three extractions using 4.0 ml of acetonitrile, with ultrasonication for 34 min. The proposed method presented good linearity (r &amp;gt; 0.990) and acceptable precision for low (100 ng ml−1, RSD: 1–16%), medium (300 ng ml−1, RSD: 1–19%), and high (500 ng ml−1, RSD: 2–16%) concentrations of PAHs. The limits of quantification for different PAHs ranged from 10 to 50 ng ml−1, which were suitable for atmospheric PM. Assessment of the method using sample matrix spiking/recovery assays, as well as use of a reference method, showed good recoveries for levoglucosan and for most of the PAHs and their derivatives, except for the most volatile compounds, which were lost during the evaporation of the solvent. The results for PM samples extracted by the optimized method and the reference method were in good agreement. The proposed method required 97% less solvent than the reference method, shortened the analysis time by 85%, and proved to be accurate and precise for the determination of at least 27 PAHs and their derivatives present in PM samples collected with a low-volume sampler.

Analysis of polycyclic aromatic hydrocarbons (PAHs) content in singed edible ruminant hides and skins of animals from North-western Nigeria

ABSTRACT PAHs are hazardous chemicals associated to cancer and other health concerns that endanger food safety. This study aimed at Assessment of PAHs content in singed ruminant hides and skins sold in retail outlets within seven major abattoirs of North-western Nigeria. Concentration of PAHs was investigated on 96 singed and unsigned hides and skins samples using Gas-Chromatograph Mass-Spectrometer-detector (GC-MSD). The cattle and camel hides had higher frequency of PAH occurrence. Acenaphthene ng/kg (5.07 ± 4.44) and (3.80 ± 4.73) exhibited the highest PAHs concentrations and was detected in singed camel hides. Chrysene (0.02 ± 0.00 ng/kg) is the only PAH found in unsigned (control) samples and was seen in cattle hide. Additionally, Naphthalene, Indeno [1,2,3.c.d] pyrene and Chrysene linked to cancer were detected. However, all singed PAHs did not exceed EU maximum permissible limit (12 µg/kg) 12,000 ng/kg. Singeing significantly elevated (P < 0.05) PAHs concentration in ruminant hides and skins. Hence, singed ruminant hides and skins from North-western Nigeria are to a large extend safe for consumption. However, perpetual patronage of singed ruminant hides and skins needs to be discouraged to abate public health concerns in the long run.

Environmental Risk Assessment of Vehicle Exhaust Particles on Aquatic Organisms of Different Trophic Levels.

Vehicle emission particles (VEPs) represent a significant part of air pollution in urban areas. However, the toxicity of this category of particles in different aquatic organisms is still unexplored. This work aimed to extend the understanding of the toxicity of the vehicle exhaust particles in two species of marine diatomic microalgae, the planktonic crustacean Artemia salina, and the sea urchin Strongylocentrotus intermedius. These aquatic species were applied for the first time in the risk assessment of VEPs. Our results demonstrated that the samples obtained from diesel-powered vehicles completely prevented egg fertilization of the sea urchin S. intermedius and caused pronounced membrane depolarization in the cells of both tested microalgae species at concentrations between 10 and 100 mg/L. The sample with the highest proportion of submicron particles and the highest content of polycyclic aromatic hydrocarbons (PAHs) had the highest growth rate inhibition in both microalgae species and caused high toxicity to the crustacean. The toxicity level of the other samples varied among the species. We can conclude that metal content and the difference in the concentrations of PAHs by itself did not directly reflect the toxic level of VEPs, but the combination of both a high number of submicron particles and high PAH concentrations had the highest toxic effect on all the tested species.

Environmental occurrence, spatial distribution, and source identification of PAHs in surface and groundwater samples of Abou Ali River-North Lebanon

This paper assesses the concentrations, spatial distribution, compositional patterns, and sources of polycyclic aromatic hydrocarbons (PAHs) in the dissolved aqueous phase along the Abou Ali River course. The 16 priority PAHs, listed by the USEPA, were investigated in surface- and groundwater samples for 2years starting August 2015 and ending in March 2017. Statistical analysis was done by using the ANOVA test at p < 0.05. The spatial distribution analysis and illustration were done using the ARC GIS software. The total PAHs concentration in surface and groundwater samples varied between not detected to 15.162ngmL-1 and not detected to 0.635ngmL-1, respectively. The highest concentration of PAHs in surface water was observed at site S16, downstream of the river. However, the absence of PAHs was noticed at sites S1 and S2 of the upstream. The contamination levels of PAHs were found to be high in surface water samples, and low in groundwater samples. The 5- and 6-ring PAHs were the most abundant species among others in surface water samples, whereas the 3-ring PAHs were the most abundant in groundwater. Pyrogenic inputs deriving from fuel combustion, incineration, and miscellaneous burning were found to be the main PAH sources in surface and groundwater without ignoring the contribution of petrogenic inputs in some areas.

Sixteen priority polycyclic aromatic hydrocarbons in roadside soils at traffic light intersections (Bratislava, Slovakia): concentrations, sources and influencing factors.

Combustion of fossil fuels is the most important source of polycyclic aromatic hydrocarbons (PAHs) in the environment. Cities are typical of many human activities which are dependent on fossil fuels (road and railway transport, heat generation, waste incineration and industry) on a small area, leading to high concentrations of PAHs in urban air, dust and soil. The aim of this study was to determine the possible influence of urban traffic on the accumulation of sixteen priority PAHs in soils (n = 132 at two soil depths of 0-10cm and 10-20cm) taken at intersections (n = 37) with different traffic volumes and road ages. Variable concentrations of the sum of PAHs (∑16PAH) ranging from 188 to 21,950μg/kg with a mean and median of 3021μg/kg and 1930μg/kg were recorded, respectively. Concentrations of PAHs positively correlated with soil organic carbon content (TOC) (rSpearman = 0.518; p <0.001). Statistically significant positive correlations between ∑16PAH concentrations and traffic volume/road age were found in this study (rSpearman = 0.689/0.619; p <0.001), while ∑16PAH concentration decreased with increasing distance from the road edge and was statistically lower at a soil depth of 10-20cm than at 0-10cm (p <0.05). Multivariate statistical methods (principal component analysis and cluster analysis) applied to log-ratio transformed data (clr) to decrease the constant sum constraint coupled with positive matrix factorisation (PMF) modelling pointed to the dominance of pyrogenic emission sources, with 62.1% traffic-related (petrol and diesel emissions, liquid fuel and motor oil spills, and tyre wear) according to PMF results.

Polycyclic aromatic hydrocarbons in sediments and shellfish from Todos os Santos bay, Brazil

The present study evaluated the occurrence of 24 Polycyclic Aromatic Hydrocarbons (PAHs) in sediments and shellfish (Anomalocardia flexuosa, Crassostrea rhizophorae, and Mytella guyanensis) of Todos os Santos bay (BTS, Brazil). Total PAHs levels ranged from 89 to 921 ng g-1 dry weight (d.w.) in sediments, and from 66 to 505 ng g-1 d.w. in shellfish, signalizing that BTS was moderately contaminated by PAHs, mostly from pyrogenic activities. The bioaccumulation factor (BAF) of total PAHs ranged from 0.20 to 2.9 and did not show a clear trend among the studied species. BAFs of high molecular weight compounds were higher for A. flexuosa (specie found buried in fine sediment), while those of low molecular weight compounds were higher for C. rhizophorae (specie found in the roots of mangrove trees). High concentrations of PAHs, especially benzo[a]pyrene and dibenzo[a,h]anthracene, suggest that contamination compromises shellfish quality and raise concern about seafood consumption safety.

Assessment of polycyclic aromatic hydrocarbons from industrial stack emissions in a Brazilian urban area

ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) were analysed in gas and particulate phase emitted by industrial stacks in the urban area of Divinópolis, Minas Gerais, Brazil. Higher concentrations of PAHs were found in the gas phase than the particulate phase. The carcinogenic potency of PAHs relative to benzo(a)pyrene was estimated for samples. Benzo(a)pyrene equivalents ranged from 0.01 to 1061.66 ng m−3. The estimated risk of lifetime lung cancer was 8.1 × 10−3. PAH emission sources were evaluated by diagnostic ratio and principal component analysis (PCA). Diagnostic ratios of PAHs indicated the use of coal/biomass and oil combustion in the evaluated industries. The PCA suggested that the industries are using a fuel mix, contrary to the information provided by the industries.

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.

Spatiotemporal occurrence, sources and risk assessment of polycyclic aromatic hydrocarbons in a typical mariculture ecosystem

The spatiotemporal variations, influencing factors and potential sources, as well as the ecological/health risks of polycyclic aromatic hydrocarbons (PAHs) were systematically investigated in seawater, sediment, and fish from Xiangshan Bay, China, one of the most important and oldest domestic marine aquaculture bases. The average concentrations of ΣPAHs in seawater, sediment and fish were 150 ± 70.0 ng/L, 276 ± 271 μg/kg (dry weight, dw), and 434 ± 151 μg/kg (dw), respectively. Naphthalene, phenanthrene, fluoranthene, benzo(b)fluoranthene and pyrene were the dominant contaminants in all samples. The highest PAH concentrations in the seawater and sediment samples occurred in the inner bay where the mariculture and industry are clustered. Seasonal differences were observed in the seawater samples but not in the sediment samples. Among all 15 fish species, large yellow croaker (Larimichthys crocea) (775 μg/kg (dw)), red drum (Sciaenops ocellatus) (749 μg/kg (dw)), and flathead grey mullet (Mugil cephalus) (637 μg/kg (dw)) had relatively high PAH accumulation concentrations in muscle tissue. According to the molecular diagnostic ratio method, the PAHs in seawater mainly originated from a mixed source of petroleum and combustion, whereas biomass/coal combustion sources were identified for sediment. The results obtained from the risk quotient (for seawater), sediment quality guidelines and toxic equivalence quotients (for seawater and sediment) methods showed that the ecological risks posed by PAHs were generally at a low to moderate level. Potentially toxic effects existed from PAH-contaminated fish consumption, and the resulting potential carcinogenic risk was also slightly higher than the recommended guidelines (10−6).

Lethal and sublethal effects of diluted bitumen and conventional oil on fathead minnow (Pimephales promelas) larvae exposed during their early development.

The increasing extraction of bitumen from the oil sands region in Canada is creating a need for transport. Spills from current and projected pipelines represent a significant environmental risk, especially for freshwater ecosystems. The toxicity of diluted bitumen (dilbit) on freshwater fish is largely unknown. This study assessed the toxicity of two dilbits (Clearwater McMurray and Bluesky) and compared their toxicity to a conventional oil (Lloydminster Heavy) on fathead minnow (Pimephales promelas) larvae. Larvae were exposed to various concentrations of the water-accommodated fraction (WAF) of the oils during 7 days from hatching. In the WAF treatments, the concentrations of volatile organic compounds (VOCs), including benzene, toluene, ethylbenzene, xylene (BTEX), hydrocarbons containing 6 to 10 carbon atoms (C6-10), and polycyclic aromatic hydrocarbons (PAHs) and their alkylated forms were measured. Both dilbits contained higher concentrations of light components, while the conventional oil contained the highest concentrations of PAHs and alkylated PAHs. The Clearwater McMurray dilbit induced a higher mortality, with a maximum of 65.3%, while the other oils induced a similar mortality up to 16.5% and 18.6% for Lloydminster and for Bluesky, respectively. All three oils induced an increase in gene expression of the phase I detoxification enzyme (cyp1a) with increasing total hydrocarbon concentrations. All three exposures induced a similar increase in glutathione S-transferase (GST) activity, but no change in gst gene expression. For the Bluesky and Lloydminster exposures, an increase in malondialdehyde concentration was also observed, suggesting a rate limiting capacity of GST and phase II enzymes to perform the biotransformation of the PAH metabolites. Overall, this study brings new insights on the toxicity of dilbits in comparison to conventional oils on early life stages of North American freshwater fish and demonstrated that dilbits can be more toxic than conventional oils, depending on their composition and diluent proportions.