High Polycyclic Aromatic Hydrocarbons Research Articles

Polycyclic Aromatic Hydrocarbons (PAHs) in “Yerba Mate” (Ilex paraguariensis) Fractions

The aim of this study was to evaluate polycyclic aromatic hydrocarbons (PAHs) contamination, distribution, and toxicity in “yerba mate” fractions, and to propose actions to reduce its pollution. Sixteen PAHs were quantified using a recently developed methodology by HPLC-DAD/FLD, obtaining recoveries higher than 84.5% and relative standard deviation of individual compounds from 0.2% to 9.6%. The PAHs distribution was not normal. The Inverse Gaussian, Birnbaum-Saunders, Lognormal, Gamma, and Weibull were the models that best described benzo(a)pyrene and PAH4 distribution. The fraction that was significantly less contaminated was stem. Also, there was significant difference between leaf and powder fractions, the latter being the one that presented higher PAHs concentration. This may be due to the products generated in the pyrolysis of wood, used in the drying process of “yerba mate.” If powder were removed, a reduction of ∼3.5% of ∑PAHs and 6.5% of TEQ would be achieved. Although eliminating powder could be a strategy to reduce PAHs contamination, this would not be enough to diminish PAHs levels below the regulatory limits.

Presence and distributions of POPS in soil, atmospheric deposition, and bioindicator samples in an industrial-agricultural area in Turkey.

In this study, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) were detected in the soil, lichen pine needle, and total deposition samples in the Meriç-Ergene Basin, which is one of the most important regions in terms of industrial and agricultural activities in Turkey. POP concentrations were measured in 192 samples selected to represent four seasons over a 1-year period across four different regions: an intensive industrial area, an industrial + residential area, an agricultural area, and a background area. Total PAH concentrations are found in the range of 69.6-887.6ng/g, 74.6-1277.7ng/g, 113.4-588.9ng/g, and 0.00-937.8ng/m2-day; total PCB concentrations are 9.98-62.9ng/g, 6.8-68.1ng/g, 11.3-32.7ng/g, and 0.00-144.4ng/m2-day; total OCPs concentrations are 5.9-83.2ng/g, 7.3-85.6ng/g, 9.9-97.1ng/g, and 0.00-137.6ng/m2-day respectively for soil, lichen, pine needles, and bulk samples. The data were evaluated according to pollutant groups and spatial and temporal changes. The highest PAH and PCB values were detected in lichen samples from industrial areas. The highest OCP values were detected for total deposition and soil samples and in the agricultural area. The results showed that two- to three-ring PAHs, hepta-PCBs, and cyclodienes were the most widespread pollutant groups. Statistical analyses were performed to evaluate the accumulation and indication properties of the matrices in the study for 0.05 significance level. The pollutant group in which matrices are most similar is PAHs. Total deposition samples showed the most different pattern in terms of indications, especially for PCBs. For OCP results, the concentration values obtained in soil samples were different from all other matrices. It was determined that the indication properties of the matrices identified as pollutant indicators differ markedly from the pollutant type, and this difference is at the lowest level for PAH pollutants. Graphical abstract ᅟ.

Bioaccessibility of polycyclic aromatic hydrocarbons in central air conditioner filter dust and its occupational exposure to shopping mall employees

The assessment of the human health risk of dust exposure to polycyclic aromatic hydrocarbons (PAHs) has been hampered by a lack of data on the bioaccessibility. The purpose of this study was to apply in vitro methods using simulated lungs with artificial lysosomal fluid (ALF) and Gamble's solution and digestive fluid to assess the bioaccessibility of 8 high molecular weight PAH (PAH8) in central air conditioner (AC) filter dust from a shopping mall in northeast China. Overall, the bioaccessible PAH8 concentration (μg/g) in AC filter dust samples after ALF and Gamble's solution extraction for 24 h were notable, with a mean of 1.71 ± 0.6 and 1.92 ± 0.5 in the sales areas, and a mean of 1.61 ± 0.2 and 1.85 ± 0.2 in the office areas. AC filter dust exposed to simulated digestive fluid had a mean bioaccessible PAH8 concentration (μg/g) of 1.60 ± 0.4 in the sales areas and 1.15 ± 0.2 in the office areas. Benzo[b]fluoranthene (BbF) made the most significant contribution to the total and bioaccessible PAH8 concentrations in all of the AC filter dust after simulated digestive fluid extraction, while the bioaccessibility was driven by chrysene (Chr, sales areas) and indeno[1,2,3-c,d]pyrene (Ind, office areas). Both the bioaccessibility and concentration of PAH8 in simulated lung fluid were mainly driven by benzo[a]pyrene (BaP). This study highlights the need to conduct bioaccessibility experiments for an adequate exposure assessment of health risk.

Multivariate optimization of an extraction procedure based on magnetic molecular imprinted polymer for the determination of polycyclic aromatic hydrocarbons in sea water

The present work deals with the optimization of a magnetic solid phase extraction of polycyclic aromatic hydrocarbons (PAHs) from sea water, based on molecular imprinted microparticles, for subsequent GC–MS analysis. The extraction efficiency of the magnetic molecular imprinted polymer (MIP) was compared with that of the corresponding non-imprinted polymer; only small differences in the recovery of the extraction procedure were shown, but higher repeatability was observed using MIP. An experimental design (Plackett-Burman) allowed a fast optimization identifying the only significant factor influencing the extraction recovery, namely the ratio between the amount of microparticles and the sample volume. Two optimal ratios, based on the PAHs molecular weight, were selected for 20 mL of sea water samples: 5 mg or 20 mg of microparticles for compounds ranging from 128 to 228 and from 252 to 278 Da, respectively. The recoveries ranges were 76–104% for the low molecular weight PAHs and 95–101% for the high molecular weight PAHs. The analytical method showed satisfactory figures of merit, with detection limits ranging from 30 to 375 ng L−1 and relative standard deviations on replicate extractions from 3.7 to 12.2%. The developed method, which is fast, easy and requires very small volumes of organic solvent, was applied for the determination of PAHs in selected sea water samples.

Response of the fungal community to chronic petrogenic contamination in surface and subsurface soils

The contamination of soil with petrogenic hydrocarbons represents a significant human health concern as a result of the carcinogenic and mutagenic properties of a number of compounds commonly found in petroleum products such as polycyclic aromatic hydrocarbons (PAHs). Although it is known that soil fungal communities play an important role in the degradation of highly branched petroleum hydrocarbons and high molecular weight PAHs, little information is available regarding the impact of petrogenic contamination on the structure and diversity of the fungal community and the impact of soil type on the fungal community response. Here, the aim of this study was to evaluate the impact of petrogenic contamination on fungal communities in two soil types. In sandy soils, the most contaminated test pit had the highest fungal diversity. Fungal profiles were dominated by species from the class Eurotiomycetes and included the well-known hydrocarbon-degrading species of Aspergillus and Eurotiales. The dominance of these species did not change with contamination concentration, suggesting a level of adaptability to multiple carbon sources. There appeared to be no correlation between fungal species diversity and contaminant concentration in the clayey soil. Similar dominant fungal species were identified in the clay and sandy soils, all of which were part of the phylum Ascomycota. The clayey soils had a higher species diversity and range-weighted richness compared to sandy soils, which may be a result of the pore connectivity theory i.e. as a result of low water connectivity in soils the formation of diverse communities is promoted through creation of microhabitats.

Women’s occupational exposure to polycyclic aromatic hydrocarbons and risk of breast cancer

ObjectiveTo estimate the association between occupational polycyclic aromatic hydrocarbon (PAH) exposure and female breast cancer.MethodsLifetime work histories for 1130 cases and 1169 controls from British Columbia and Ontario (Canada) were...

Selenium alleviates phytotoxicity of phenanthrene and pyrene in Alternanthera Philoxeroides

To investigate if selenium can alleviate phytotoxicity of phenanthrene and pyrene, two high molecular weight (HMW) PAHs (polycyclic aromatic hydrocarbons) in Alternanthera philoxeroides are considered. A 60-day pot-culture experiment was carried out to assess the effects of selenium (0.5 mg Se·kg−1 soil) on A. philoxeroides exposed to two PAH pollutants, pyrene (PYR) and phenanthrene (PHE), at levels of 10, 100, and 1000 mg·kg−1. The test index included growth, chlorophyl, gas exchange and chlorophyl fluorescence parameters, and indicators of oxidative stress (H2O2 and malondialdehyde MDA). The response of plants to PAH exposure was concentration dependent; indicators of plant health declined, while indicators of plant stress rose. The maximum values of H2O2 and MDA were recorded at 1000 mg·kg−1 PYR, followed by 1000 mg·kg−1 PHE. However, application of Se (0.5 mg·kg−1) to the soil significantly decreased the phytotoxic response to PAH exposure. This study demonstrated that Se increases the tolerance of A. philoxeroides to PYR and PHE, improving the feasibility of phytoremediating high level PAH contamination and expediting ecological restoration.

Accumulation of metals and polycyclic aromatic hydrocarbons in agricultural soil after additions of street sediment in southern Ontario

Prior to 2012 street sediment from the Greater Toronto Area was being managed by a local authority and provided to rural landowners under the assumption it was clean fill. The aim of this study was to characterise the chemical and physical composition of that street sediment applied to an agricultural field in southwestern Ontario, Canada and determine if contaminants had migrated to native soil. Soil was sampled from an impact and a background location during the fall of 2016 at four soil depths (0–10, 10–20, 20–30 and 30–40 cm below the surface) to characterise texture, pH, organic content, recoverable metals and total polycyclic aromatic hydrocarbons (PAHs). Textural analysis revealed street sediment was dominated by very coarse and coarse sand which differed from the native silty clay loam and extended to 30 cm below the surface. Some PAHs, including benzo(a)pyrene (1.29 μg g−1) exceeded the typical regional background concentrations. A distinct pattern of high molecular mass PAHs in the native soil below street sediments suggests that PAHs have migrated to native soil. To our knowledge this is the first study to report PAH concentrations in street sediment in Ontario and to show their potential movement and introduction to native soil. Future studies should focus on transport mechanisms and understanding movement of PAHs in native coarse textured soil.

Occurrence, composition profiles and risk assessment of polycyclic aromatic hydrocarbons in municipal sewage sludge in China

A nationwide survey, including 75 sludge samples and 18 wastewater samples taken from different wastewater treatment plants (WWTPs) from 23 cities, was carried out to investigate the occurrence and composition profiles of polycyclic aromatic hydrocarbons (PAHs) in China. In total, the concentrations of ∑16PAHs in sludge ranged from 565 to 280,000 ng/g (mean: 9340 ng/g) which was at a moderate level in the world. The composition profiles of PAHs were characterized by 3- and 4-ring PAHs in textile dyeing sludge and 4- and 5-ring PAHs in domestic sludge. Significant variations in regional distribution of PAHs were observed. Both the principal components analysis and diagnostic ratios revealed that vehicle exhaust, coal and natural gas combustion were the main sources of PAHs in China. The estimated concentrations of PAHs were 3820 ng/L and 1120 ng/L in influents and effluents of the WWTPs, respectively. The high toxic equivalent quantity (TEQ) values of PAHs are ascribed to the high PAH levels. Risk quotient values (RQs) in sludge indicated that there was low potential risk to soil ecosystem after sludge had been applied one year except for indeno [1,2,3-cd]pyrene (IcdP) detected in Huaibei, Anhui province.

Degradation of fluorene and phenanthrene in PAHs-contaminated soil using Pseudomonas and Bacillus strains isolated from oil spill sites

Biodegradation of 3-ring and 4-ring polycyclic aromatic hydrocarbons (PAHs) model (fluorene, phenanthrene, fluoranthene and pyrene) were investigated. Twenty-seven bacterial strains were isolated from contaminated-site by oil spills. PAHs-degrading bacteria were screened to select high tolerant species for ensuring an efficient bioremediation. Each of the isolated bacterial strains was grown under different PAHs concentrations (250, 500, 1000 and 1500 mg/L). Among the 27 strains, 8 resulted to be resistant to high concentration level of PAHs (1500 mg/L) and thereof can use PAHs as sole source of carbon and energy. The most tolerant strains were molecularly identified using mass spectrometer MALDI-TOF VITEK MS and 16S rDNA sequencing approaches. The identified bacterial strains Pseudomonas stutzeri (P. stutzeri), Bacillus simplex (B. simplex) and Bacillus pumilus (B. pumilus) were used for the bioremediation experiment of soils contaminated by PAHs. The studies were conducted under controlled conditions using soil spiked with a mixture of the target PAHs and the three microcosm strains. The results revealed that only fluorene and phenanthrene, which are low molecular weight PAHs, were degraded efficiently within 72 days of test organism incubation. These degradations were about 65–86% and 86–95% for fluorene and phenanthrene, respectively. At the same time and conversely to fluorene and phenanthrene, the high molecular weight PAHs, pyrene and fluoranthene were recalcitrant to these selected microbial strains. The biodegradation kinetics of both fluorene and phenanthrene were fit a first order rate with R2 values ranging from 0.88 to 0.92. The half-lives of phenanthrene (2.4–2.7 days) and those of fluorene (3.5–4.6 days) were all less than 10 days, delineating therefore acclimatization with the strains.

Health risk assessment and source apportionment of polycyclic aromatic hydrocarbons associated with PM10 and road deposited dust in Ahvaz metropolis of Iran.

The objective of this study was to compare the characteristics of polycyclic aromatic hydrocarbons (PAHs) in PM10 and road dust samples, as well as to identify and quantify the contributions of each source profile using the positive matrix factorization (PMF) receptor model. Health risk assessment was carried out using toxic equivalency factors and incremental lifetime cancer risk (ILCR), which quantitatively estimate the exposure risk for age-specific groups. PM10 samples were collected on PTFE filters in the metropolitan area of Ahvaz. Road dust samples were also collected from all over the urban areas with different land uses. Total PAH concentrations in PM10 and road dust samples were 0.5-25.5ng/m3 and 49.3-16,645µg/kg, respectively. Pyrene was the highest PAH in the PM10 profile, whereas fluoranthene became the highest PAH in the road dust. Abundance of benzo[ghi]perylene at PM10 and road dust samples suggested a source indicator for traffic emissions. The results demonstrate that in 36.5% of samples, PM10 concentrations exceed the maximum concentration level recommended by EPA. A multiple linear regression model was used to estimate the influence of meteorological parameters (temperature, wind speed, and relative humidity) on buildup of PAHs. All of PAH species show higher concentrations during the cold and typical days rather than the dust event days and warm periods. PMF analysis showed that vehicular emissions (50.6%) and industrial activities (especially steel industries) (30.4%) were first two sources of PAHs bounded with PM10, followed by diesel emissions (11.6%) and air-soil exchange (7.4%). For road dust samples, three common sources were also identified: vehicular traffic (48%), industrial activities (42.3%), and petrogenic sources (9.7%), in line with that of diagnostic molecular ratios results. According to the results of health risk assessment model, the ILCR of exposure to PAHs associated with PM10 and road-deposited dust was higher than the guidelines of USEPA, indicating high carcinogenic risk.

Maternal urinary metabolites of PAHs and its association with adverse birth outcomes in an intensive e-waste recycling area

Polycyclic aromatic hydrocarbons (PAHs) are well-known carcinogenic and endocrine disrupting chemicals that have been concerned over the past few decades. We aimed to determine the hydroxylated PAH (OHPAH) metabolite concentrations in maternal urine collected from the e-waste-contaminated area of Guiyu and the reference area of Haojiang, China, and to evaluate their health effects on birth outcomes. The median ƩOHPAH concentration was 6.87 μg/g creatinine from Guiyu, and 3.90 μg/g creatinine from Haojiang. 2-OHNap and 1-OHPyr were the predominant metabolites. Residence in Guiyu and recycling in houses were associated with elevated 2-OHNap and 1-OHPyr. Standardized mean difference revealed that compared to low PAH metabolite levels in the first quartile, high PAH metabolite levels in the fourth quartile especially for 1-OHPyr, ƩOHPAHs and sometimes hydroxylphenanthrene compounds, presented a reduced size in birth outcomes (overall SMD: −0.09; 95% CI: −0.15, −0.03), including head circumference, BMI and Apgar 1 score, and increased size in height. After adjusting for confounders in regression models, an interquartile increase in ΣOHPAHs was associated with a decrease of 234.56 g in weight (95% CI: −452.00, −17.13), 1.72 cm in head circumference (95% CI: −2.96, −0.48), 1.06 kg/m2 in BMI (95% CI: −1.82, −0.31) and 0.42 in Apgar 1 score (95% CI: −0.66, −0.18), respectively. These findings suggest high exposure to PAHs during pregnancy in e-waste areas, posing a potential threat to neonatal development, which likely can be attributed to direct e-waste recycling activities. Ongoing studies should be continued to monitor human exposure and health, in particular for vulnerable individuals in e-waste-polluted areas.

Growth and Phytoremediation Efficiency of Winged Bean in Fluorene- and Pyrene-Contaminated Soil.

Winged bean is a tropical legume that has been reported to enhance polycyclic aromatic hydrocarbon (PAH) biodegradation in soil. However, there is insufficient information about the susceptibility of winged bean to PAH toxicity in long term study. In this study, winged bean was planted in soil contaminated with either fluorene (124.5mg/kg) or pyrene (98.4mg/kg) for 90days. Plant growth parameters and PAH disappearances from soil were measured every 30days. Neither fluorene nor pyrene led to decreased shoot and root length of winged bean and all the winged bean plants flowered on day 90. However, the chlorophyll b content in the leaves decreased since day 60 and further decreased significantly by day 90 when winged bean was grown in the presence of fluorene or pyrene. The presence of fluorene and pyrene led to reduced root nodule formation at 30 and 60days. Despite the reduced chlorophyll b content and decreased number of root nodules, winged bean could enhance pyrene removal significantly on day 30 compared to unplanted soil. Subsequently, pyrene degradation in the unplanted soil caught up and there was no statistically significant difference between the two treatments at 60 or 90 days. Negligible amounts of PAHs were accumulated in the shoot and root tissues of winged bean. These results showed that winged bean can speed up the removal of high MW PAHs from contaminated soil and we conclude that this plant is suitable for PAH phytoremediation.

Characterization of polycyclic aromatic hydrocarbons (PAHs) in small craft harbour (SCH) sediments in Nova Scotia, Canada

Polycyclic aromatic hydrocarbons (PAHs) have been widely studied in sediments due to their ubiquity and persistence in aquatic environments and potential for impairment to biota. Small craft harbour (SCH) sediments in Nova Scotia (NS), Canada, have yet to be studied comprehensively. SCHs are essential to the fishing industry, which is important for the Canadian economy. This spatiotemporal characterization study evaluated thirty-one SCHs across NS between 2001 and 2017 by analyzing sediment reports (secondary data). Sediment PAH concentrations varied widely across all SCHs. Few SCHs exhibited sediment PAH concentrations likely to impair biota based on comparison to sediment quality guidelines. Sediments in the Gulf region of NS were least impacted by PAHs, while the Southwest region was most impacted. Distribution of individual PAHs in sediments follows global trends, with high molecular weight PAHs dominating samples.

Efficiency of Polycyclic Aromatic Hydrocarbons (PAHs) Degrading Consortium in Resisting Heavy Metals During PAHs Degradation

Polycyclic aromatic hydrocarbons (PAHs) comprised of many dangerous organic pollutants which affect human cell. The choice of phenanthrene and pyrene as model substrates was based on their classification among the most hazardous PAHs group by the US EPA where they belonged to low and high molecular weights PAHs respectively. Biodegradation of these PAHs is the best strategy that completely removes such pollutants in an environmentally friendly manner. However, the bacteria involved are challenged degradation difficulties as a result of PAHs inhibitory effects to the organisms. This research is aimed at formulating phenanthrene and pyrene degrading consortium that effectively perform best even in complex mixture with hazardous heavy metals. Different bacteria consortia were formulated using the compatibility testing and mathematical permutation approach and the best consortium selected. This selected consortium was then subjected to the degradation of both phenanthrene and pyrene separately in a combined mixture with the selected heavy metals from the inductively coupled plasma optical emission spectrophotometer (ICP-OES) analysis. Consortium composition of C. sakazakii MM045 (2%, v/v) and Enterobacter sp. MM087 (2%, v/v) were found to be much effective during phenanthrene (500 mg/L) and pyrene (250 mg/L) degradation. This consortium also resisted more than 6 mg/L each of Nickel (Ni), Cadmium (Cd), Vanadium (V) and Lead (Pb) in such complex degradation which was found to be more than the concentration in the natural habitat the consortium exists prior to isolation. Such performance makes the selected consortium to be an extremely efficient tool for the PAHs degradation application as many biodegradation agents were reported to be less effective when significant concentration of Ni, Cd, V and Pb are present.

Transport of polycyclic aromatic hydrocarbons in a highly vulnerable karst underground river system of southwest China.

The concentration and fluxes of polycyclic aromatic hydrocarbons (PAHs) were investigated in a karst underground river system in southwest China. Groundwater, particles, and sediments from underground river, topsoil, and surface water were monitored, allowing establishment of a conceptual model of PAH transport at the watershed scale. The results showed that PAHs could be transported from the surface to the subsurface through two migration pathways, which were slow-flowing water in the karst fissure and fast-flowing water in conduits. During rainfall events, increasing PAH levels (concentrations and fluxes) at the underground river exit indicated that hydrodynamic force could facilitate PAH transport. The PAHs in water were dominated by dissolved PAHs, accounting for 58.7% of total, especially in the freely dissolved phase, in which SPM-associated PAHs accounted for 41.3% of the total PAHs. Low molecular weight PAHs dominated transport and were mainly transported in dissolved form, whereas high molecular weight PAHs were dominated by SPM-associated transport during the rainfall events. A significantly positive correlation was observed between two-ring and three-ring freely dissolved PAHs and dissolved organic carbon (p < 0.01), respectively. Moreover, PAHs with four to five rings were relatively more abundant in the dissolved organic matter (DOM) associated phase than in the freely dissolved phase, suggesting a major role of DOM in their transport during rainfall events. The trend of PAH fluxes suggested that particle-facilitated transport was another dominant cause of PAH mobilization.

Effect of biodiesel on PAH, OPAH, and NPAH emissions from a direct injection diesel engine.

Polycyclic aromatic hydrocarbon (PAH), oxy- and nitro-derivate PAH (OPAH and NPAH) emissions from a direct injection diesel engine fueled with conventional fossil diesel (D), waste cooking oil biodiesel (B100), and their two blends (B20 and B50) were compared. The results show that B100 can reduce low molecular weight PAHs such as naphthalene, acenaphthylene, and fluorene as much as 90% compared with diesel. However, the emissions of high molecular weight PAHs including benzo[b]fluoranthene, benzo[k]fluoranthene, and benzo[a]pyrene decrease slightly when using B100. The emission levels for PAHs and OPAHs present comparable, while NPAH emission levels are five to ten times lower than those of PAHs and OPAHs. Compared with diesel, PAH and NPAH emissions significantly decrease. On the contrary, an increase trend of OPAH emission has been observed with adding biodiesel. For the specific parent PAHs and its oxygenated and nitrated derivatives, the fractions of parent PAHs gradually decrease with increasing biodiesel content in the blends, while the corresponding oxygenated and nitrated derivative fractions observably increase, especially for the high molecular weight compounds. Considering the increase of OPAH and NPAH fractions in total particle-phase PAHs when using biodiesel, in-depth biodiesel cytotoxicity assessment should be conducted.

The Developmental Neurotoxicity of Tobacco Smoke Can Be Mimicked by a Combination of Nicotine and Benzo[a]Pyrene: Effects on Cholinergic and Serotonergic Systems.

Tobacco smoke contains polycyclic aromatic hydrocarbons (PAHs) in addition to nicotine. We compared the developmental neurotoxicity of nicotine to that of the PAH archetype, benzo[a]pyrene (BaP), and also evaluated the effects of combined exposure to assess whether PAHs might exacerbate the adverse effects of nicotine. Pregnant rats were treated preconception through the first postnatal week, modeling nicotine concentrations in smokers and a low BaP dose devoid of systemic effects. We conducted evaluations of acetylcholine (ACh) and serotonin (5-hydroxytryptamine, 5HT) systems in brain regions from adolescence through full adulthood. Nicotine or BaP alone impaired indices of ACh presynaptic activity, accompanied by upregulation of nicotinic ACh receptors and 5HT receptors. Combined treatment elicited a greater deficit in ACh presynaptic activity than that seen with either agent alone, and upregulation of nAChRs and 5HT receptors was impaired or absent. The individual effects of nicotine and BaP accounted for only 60% of the combination effects, which thus displayed unique properties. Importantly, the combined nicotine + BaP exposure recapitulated the effects of tobacco smoke, distinct from nicotine. Our results show that the effects of nicotine on development of ACh and 5HT systems are worsened by BaP coexposure, and that combination of the two agents contributes to the greater impact of tobacco smoke on the developing brain. These results have important implications for the relative safety in pregnancy of nicotine-containing products compared with combusted tobacco, both for active maternal smoking and secondhand exposure, and for the effects of such agents in "dirty" environments with high PAH coexposure.

PAHs in urban soils of two Florida cities: Background concentrations, distribution, and sources

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous organic contaminants, which are found in soils throughout the U.S. The objective of this study was to determine the background concentrations, distributions, and sources of 16 USEPA priority PAHs in two urban soils. A total of 114 soil samples were collected from two large cities in Florida: Orlando and Tampa. The results showed that soils were dominated by high molecular weight PAHs in both cities. The average ∑16-PAHs in Orlando and Tampa soils were 3227 and 4562 μg kg−1, respectively. The averages of 7 carcinogenic PAHs based on the benzo[a]pyrene-equivalent (BaP-EQ) concentrations in the two cities were 452 and 802 μg kg−1. BaP-EQ concentrations in 60–62% of samples were higher than the Florida Soil Cleanup Target Level (FSCTL) for residential soils at 100 μg kg−1 and 20–25% of samples were higher than FSCTL for industrial soils at 700 μg kg−1. Based on molecular diagnostic ratios and PMF modeling, major sources of soil PAHs in both cities were similar, mainly from pyrogenic sources including vehicle emissions, and biomass and coal combustion. Based on ArcGIS mapping, PAH concentrations in soils near business districts and high traffic roads were higher. Thus, it is important to consider background PAH concentrations in urban soils when considering soil remediation.

Behavior and Degradation of Polycyclic Aromatic Hydrocarbons (PAHs) in Coking Wastewater of A/O2 and A/O/H/O Processes

Polycyclic aromatic hydrocarbons (PAHs) are typical organic pollutants found in coking wastewater, and their behavior and reduction can be affected by different treatment processes. Based on these considerations, this study investigated the behaviors of PAHs in coking wastewater under A/O2 and A/O/H/O treatment processes, respectively. In order to evaluate variations in PAH removal under two different treatment processes, samples were taken from different treatment units for quantification of PAHs using gas chromatography-mass spectrometry. Results showed that PAHs were barely degraded in anaerobic tanks of either treatment process and accumulated much higher concentrations than in aerobic and hydrolytic tanks. While low molecular weight PAHs (LMW PAHs) in aqueous phase from anaerobic tanks were degraded effectively in aerobic tanks, high molecular weight PAHs (HMW PAHs) mostly accumulated in the sludge phase; these potentially pose a higher environmental risk and therefore need to be treated separately. Moreover, the A/O/H/O process showed higher degradation of PAHs bioavailability and higher removal effectiveness for PAHs with four or more benzene rings than the A/O2 process; this is attributed to the hydrolytic tank's ability to promote hydrolysis of macromolecular organic compounds and therefore improve biodegradability of PAHs. Comprehensive results from the study indicated that the A/O/H/O process is more advantageous for degradation of PAHs than the A/O2 process.