Development of analytical methods for polycyclic aromatic hydrocarbons (PAHs) in airborne particulates: A review

In the present work, the different sample collection, pretreatment and analytical methods for polycyclic aromatic hydrocarbons （PAHs） in airborne particulates is systematacially reviewed, and the applications of these pretreatment and analytical methods for PAHs are compared in detail. Some comments on the future expectation are also presented.

Highly Efficient Photocatalytic Remediation of Simulated Polycyclic Aromatic Hydrocarbons （PAHs） Contaminated Wastewater under Visible Light Irradiation by Graphene Oxide Enwrapped Ag3PO4 Composite

Effective removal of polycyclic aromatic hydrocarbons （PAHs） from wastewater before their discharge into the environment is an ever pressing requirement. In this study, for the first time, simulated PAHs contaminated wastewater was photocatalytically remediated with graphene oxide （GO） enwrapped silver phosphate as visible light-driven photocatalysts. The GO/Ag3PO4 photocatalysts exhibited superior photocatalytic activity and stability compared with pure Ag3PO4, g-C3N4 and TiO2 （P25）. The degradation efficiency of naphthalene, phenanthrene and pyrene could reach 49.7%, 100.0% and 77.9%, rspectively within 5 min irradiation. The apparent rate constants of photocatalytic degradation of 3 wt% GO/Ag3PO4 composRe photocatalyst were 0.14, 1.21 and 2.46 rain^-1 for naphthalene, phenanthrene and pyrene, respectively. They were about 1.8, 1.5 and 2.0 times higher than that of pure Ag3PO4, and much higher than that of g-C3N4 and TiO2. Meanwhile, the efficiencies of 44.6%, 95.2% and 83.8% were achieved for naphthalene, phenanthrene and pyrene degradation even after 5 times of recycling in the GO/Ag3POa-PAHs photocatalysis system. Reactive species of O2^- and h^＋ were considered as the main partici- pants for oxidizing naphthalene, phenanthrene and pyrene.

Preliminary Study on PAHs Distribution in High-grade Oil Shale and Its Spontaneous Combustion Product in Fushun,Liaoning Province

Spontaneous combustion of oil shale is very common as a result of long-time exposure to the air in the Fushun West Open-Pit Mine and West Dump. The PAHs in the high-grade off shale and its spontaneous combustion product were analyzed semiquantitatively by GC-MS in order to investigate their distribution in different states and their potential negative effects on the environment. Totally 57 and 60 PAHs and their alkyl homologues were identified in the two analyzed samples, among which the alkyl derivatives were predominant, taking up to about 65% in the total PAHs. Those low-molecular mass PAHs （3- or 4-ring） were the main compounds in the two samples. Ten of sixteen USEPA priority pollutant PAHs were detected in two samples, of which phenanthrene was the richest whose contents were 6.93% and 15.03%. Based on comparison of analysis results, the amount and contents of PAHs, except for triaromatic steroid group, were higher in the burning oil shale. So it can be determined that the effects caused by spontaneous combustion of oil shale would be more serious and that the effects of the Fushun oil shale and its spontaneous combustion on the environment should not be ignored in the future work.

PAH-biodegradation potential of indigenous microorganisms: evidence from the respiratory activity of surfacesediments in the Quanzhou Bay in China

Seven stations were established in the Quanzhou Bay （24.73°-24.96°N, 118.50°-118.70°E） in China on three cruises to determine the concentrations of polycyclic aromatic hydrocarbons （PAHs） and the numbers of PAH-degrading bacteria in surface sediments. Assessing the biodegradation potential of indigenous microorganisms by measuring the respiratory intensity with the addition of PAHs in sediment samples was also one of the aims of this study. The results show that the total PAH concentrations of the sediments were 99.23-345.53 ng/g dry weight （d.w.）, and the PAHs composition pattern in the sediments was dominated by phenanthrene, fluoranthene and pyrene. The numbers of phenanthrene, fluoranthene and pyrene-degrading bacteria during three cruises were 1.42×10^3-8.93×10^4 CFU/g d.w., 8.29×10^3 9.43×10^4 CFU/g d.w. and 7.05×10^3-9.43×10^4 CFU/g d.w., respectively. The addition of three model PAH compounds （phenanthrene, fluoranthene and pyrene） showed a great influence on the increasing of the microbial activity in the sediments. And there was a significant correlation among the change of respiratory activity, PAH concentration and the number of PAH-degrading bacteria. The change in respiratory activity under PAHs selective pressure could, to a certain extent, indicate the potential degradative activity of the PAH-degrading microbial community.

非道路用柴油机半挥发性有机物排放特性

在一台国Ⅱ标准的非道路用柴油机上对半挥发性有机物(SVOCs)进行采样研究发现,非道路用柴油机排放气相SVOCs高于颗粒固相SVOCs,且在两相中的排放量均呈现随负荷增加而增加的趋势.在气相和颗粒固相SVOCs中检出以烷烃为主,其次为多环芳烃类物质,包括2,3-二氢茚、四氢化萘、联苯、萘、芴、蒽、菲、芘等及其同系物.同时在对SVOCs中PAHs的研究中发现,柴油机排放的PAHs以气相为主,含量明显高于颗粒固相中PAHs;对比气固两相的浓度分布发现,气相PAHs中萘、苊烯、二氢苊、芴、菲、蒽为主,占气相PAHs质量比高达95%,而颗粒固相中PAHs则以菲、芘、荧蒽、屈、苯并(a)蒽等为主,其中苯并(a)蒽与屈在不同工况下质量比达80%以上;气相中PAHs环数以3环和2环为主,而大部分工况下颗粒固相中PAHs环数以4环为主,其次为3环.

高效液相色谱法测定蓝绿藻中微囊藻毒素

以铜绿微囊藻为研究对象,考察了不同溶剂、不同超声波震荡时间和不同固相萃取(SPE)洗脱液浓度对藻毒素提取效率的影响,以及梯度淋洗HPLC分离藻毒素条件的优化。藻毒素浓度在1~100 mg·L-1范围内,峰面积与藻毒素进样量呈线性关系,相关系数为0.999 5,检出限为0.12 ng。方法可靠、灵敏度较高,用于实际藻样中藻毒素的测定,回收率为96.5%~98.0%。

Polycyclic aromatic hydrocarbons in soils of Beijing and Tianjin region: Vertical distribution, correlation with TOC and transport mechanism

The contents and distribution of 20 polycyclic aromatic hydrocarbons （PAHs） and heterocyclic aromatic hydrocarbons （HAHs） were investigated in 16 soil profiles of Beijing and Tianjin region. Transport of high molecular weight PAHs （HMWPAHs） and the correlation between total organic carbon （TOC） and their concentrations were also discussed. The results indicated that highly contaminated sites were located at urban or wastewater irrigation areas and pollutants mainly accumulated in topsoil （〈 40 cm）, with a sharp content decrease at the vertical boundary of 30-40 cm. Total PAHs/HAHs concentrations in soils from Tianjin were markedly greater than those from Beijing. Even the contents at bottoms of soil profiles in Tianjin were higher than those in topsoils of Beijing soil profile. HMWPAHs dominated the PAH profiles, exhibiting a uniform distribution of pyrogenic origin between topsoils and deep layers. Furthermore, the percentages of HMWPAHs remained relative constant with the depth of soil profiles, which were consistent with the distribution of particulate matter-associated PAHs in the local atmospheric environments. Therefore, HMWPAHs transport with particulates might be the predominant source found in soil profiles.

Binding characteristics of perylene, phenanthrene and anthracene to different DOM fractions from lake water

Six hydrophobic and hydrophilic fractions were isolated using XAD-8 and XAD-4 resins, and were extensively characterized. Partition coefficients of perylene, pbenanthrene and anthracene binding to the six fractions were determined by fluorescence quenching titration. The Kdo~ values obtained for the polycyclic aromatic hydrocarbons （PAHs） binding to the hydrophobic fractions were larger than those to the hydrophilic fractions. Nonlinear Stem-Volmer plots were observed when binding phenanthrene and anthracene to some hydrophilic fraction samples, suggesting saturation of polar interaction binding sites. A significant correlation of logKdo~ values with molecular weights and molar absorptivities at 280 nm was observed, while atomic ratio of C/t-I was found to be a poor indicator for aromaticity. Other structural descriptors such as paraffinic carbon and polarity influenced the DOM-fraction ability to bind PAHs. Different interaction mechanisms underlying binding of the different fractions to the PAHs were also discussed.

Emission characteristics of dioxins,furans and polycyclic aromatic hydrocarbons during fluidized-bed combustion of sewage sludge

Pre-dried sewage sludge with high sulfur content was combusted in an electrically heated lab-scale fluidized-bed incinerator. The emission characteristics of polychlorinated dibenzo-p-dioxins （PCDDs）, polychlorinated dibenzofurans （PCDFs） and polycyclic aromatic hydrocarbons （PAHs） were studied. Coal and calcium oxide （CaO） were added during the sewage sludge combustion tests to optimize combustion conditions and control SO2 emission. The results indicated that the flue gases emitted during mono-combustion of sewage sludge were characterized by relatively high concentrations of SO2, NOx and organic pollutants, due to the high sulfur, nitrogen, and volatile matter content of sewage sludge. The total 16 USEPA priority PAHs and 2,3,7,8-substituted PCDD/Fs produced from sewage sludge combustion were found to be 106.14 μg/m^3 and 8955.93 pg/m^3 in the flue gas, respectively. In the case of cocombustion with coal （msludge/mcoal =1：1）, the 16 PAHs and 2,3,7,8-substituted PCDD/Fs concentrations were markedly lower than those found during mono-combustion of sewage sludge. During co-combustion, a suppressant effect of CaO on PCDD/Fs formation was observed.

Polycyclic aromatic hydrocarbon biodegradation and extracellular enzyme secretion in agitated and stationary cultures of Phanerochaete chrysosporium

The extracellular enzyme secretion and biodegradation of polycyclic aromatic hydrocarbons （PAHs） were studied in agitated and shallow stationary liquid cultures of Phanerochaete chrysosporium. Veratryl alcohol and Tween80 were added to cultures as lignin peroxidase （LIP） and manganese peroxidase （MnP） inducer, respectively. Shallow stationary cultures were suitable for the production of enzyme, whereas agitated cultures enhanced overall biodegradation by facilitating interphase mass transfer of PAHs into aqueous phases. The use of a LiP stimulator, veratryl alcohol, did not increase PAH degradation but significantly enhanced LiP activity. In contrast, Tween80 increased both MnP secretion and PAH degradation in shallow stationary cultures. On the other hand, high PAH degradation was observed in agitated cultures in the absence of detectable LiP and MnP activities. The results suggested that extracellular peroxidase activities are not directly related to the PAH degradation, and the increased solubility rather than enzyme activity may be more important in the promotion of PAH degradation.

热处理对致密岩石物理性质的影响

致密气藏低孔低渗和超低含水饱和度等特征使其潜在水相圈闭损害严重,致密天然气产出表现为多尺度特征.选取泥页岩、致密砂岩和致密碳酸盐岩岩心,开展了100-600℃高温处理对岩心渗透率、孔隙度、重量、长度、直径和声速的影响实验.实验结果表明,碳酸盐岩、致密砂岩和泥页岩的热开裂阈值分别在300-400℃、300-500℃和500-600℃;高温处理后,岩心重量和密度降低,体积增加,泥页岩岩心孔隙度和渗透率提高幅度最显著,600℃处理后声波时差比常温时岩心声波时差提高了1.3倍.热处理消除了水相圈闭和粘土矿物膨胀损害,提高岩石孔隙度和渗透率,恢复或改善致密储层多尺度传质,有利于致密天然气资源开发,但同时高温使岩石破裂,扩展天然裂缝或产生新裂缝,导致工作液漏失,因此,热致裂给勘探开发致密天然气提出了机遇与挑战.

Distribution and Source Apportionment of Polycyclic Aromatic Hydrocarbons from Atmospheric Particulate Matter PM2.5 in Beijing

A total of 11 PM2.5 samples were collected from October 2003 to October 2004 at 8 sampling sites in Beijing city. The PM2.5 concentrations are all above the PM2.5 pollution standard （65 μg m^-3） established by Environmental Protection Agency, USA （USEPA） in 1997 except for the Ming Tombs site. PM2.5 concentrations in winter are much higher than in summer. The 16 Polycyclic aromatic hydrocarbons （PAHs） listed as priority pollutants by USEPA in PM2.5 were completely identified and quantified by high performance liquid chromatography （HPLC） with variable wavelength detector （VWD） and fluorescence detector （FLD） employed. The PM2.5 concentrations indicate that the pollution situation is still serious in Beijing. The sum of 16 PAHs concentrations ranged from 22.17 to 5366 ng m^-3. The concentrations of the heavier molecular weight PAHs have a different pollution trend from the lower PAHs. Seasonal variations were mainly attributed to the difference in coal combustion emission and meteorological conditions. The source apportionment analysis suggests that PAHs from PM2.5 in Beijing city mainly come from coal combustion and vehicle exhaust emission. New measures about restricting coal combustion and vehicle exhaust must be established as soon as possible to improve the air pollution situation in Beijing city.

Effect of organic wastes on the plant-microbe remediation for removal of aged PAHs in soils

The effectiveness of in-situ bioremediation of polycyclic aromatic hydrocarbons （PAHs） may be inhibited by low nutrients and organic carbon. To evaluate the effect of organic wastes on the PAHs removal efficiency of a plant-microbe remediation system, contaminated agricultural soils were amended with different dosages of sewage sludge （SS） and cattle manure （CM） in the presence of alfalfa （Medicago sativa L.） and PAHs-degraders （Bacillus sp. and Flavobacterium sp.）. The results indicated that the alfalfa mean biomasses varied from 0.56 to 2.23 g/pot in root dry weight and from 1.80 to 4.88 g/pot in shoot dry weight. Low dose amendments, with rates of SS at 0.1% and CM at 1%, had prominent effects on plant growth and soil PAHs degradation. After 60-day incubation, compared with about 5.6% in the control, 25.8% PAHs removal was observed for treatments in the presence of alfalfa and PAHs-degraders; furthermore, when amended with different dosages of SS and CM, the removed PAHs from soils increased by 35.5%--44.9% and 25.5%-42.3%, respectively. In particular, the degradation of high-molecular-weight PAHs was up to 42.4%. Dehydrogenase activities （DH） ranged between 0.41 and 1.83 ~tg triphenylformazan/（g dry soil.hr） and the numbers of PAHs-degrading microbes （PDM） ranged from 1.14x106 to 16.6x106 most-probable-number/g dry soil. Further investigation of the underlying microbial mechanism revealed that both DH and PDM were stimulated by the addition of organic wastes and significantly correlated with the removal ratio of PAHs. In conclusion, the effect of organic waste application on soil PAHs removal to a great extent is dependent on the interactional effect of nutrients and dissolved organic matter in organic waste and soil microorganisms.

Organochlorine pesticides and polycyclic aromatic hydrocarbons in water and sediment of the Bosten Lake,Northwest China

We evaluated organic pollution in Bosten Lake, Xinjiang, China, by measuring the concentrations and distributions of organochlorine pesticides （OCPs） and polycyclic aromatic hydrocarbons （PAHs）. Water and sediment samples were collected from 19 sites 031-1319） in the lake for analysis. Our analytical results show that the concentrations of total OCPs in water ranges from 30.3 to 91.6 ng/L and the concentrations of PAHs ranges from undetectable （ND） to 368.7 ng/L. The concentrations of total OCPs in surface （i.e., lake bottom） sediment ranges from 6.9 to 16.7 ng/g and the concentrations of PAHs ranges from 25.2 to 491.0 ng/g. Hexachlorocyclohexanes （HCHs） and dichlorodiphenyltrichloroethanes （DDTs） account for large proportions of the OCPs. Low α- to γ-HCH ratios in both water and sediment samples indicate possible contributions from both industrial products and lindane. DDTs in water are probably from historical input, whereas DDTs in sediments are from both historical and recent inputs. Moreover, DDT products in both water and sediments were from multiple sources in the northwestern part of the lake（B11, B12, B13, and B14）. Fugacity ratios for DDT isomers （p,p＇-DDE and p,p＇-DDT） at these sites were generally higher than equilibrium values. These results suggest that the input from the Kaidu River and diffusion of DDTs from the sediment to the water are responsible for DDT pollution in the water. Lower-molecular-weight PAHs, which originate primarily from wood and coal combustion and petroleum sources, represent the major fraction of the PAHs in both water and sediment samples. Our findings indicate that OCPs and PAHs in Bosten Lake can be attributed primarily to human activities. A risk assessment of OCPs and PAHs in water and sediment from Bosten Lake, however, suggests that concentrations are not yet high enough to cause adverse biological effects on the aquatic ecosystem.

Uptake and accumulation of phenanthrene and pyrene in spiked soils by Ryegrass(Lolium perenne L.)

Phytoremediation has long been recognized as a cost-effective method for the removal of polycyclic aromatic hydrocarbons （PAHs） from soil. A study was conducted to investigate the uptake and accumulation of PAHs in root and shoot of Lolium perenne L. Pot experiments were conducted with series of concentrations of 3.31-378.37 mg/kg for phenanthrene and those of 4.22-365.38 mg/kg for pyrene in a greenhouse. The results showed that both ryegrass roots and shoots did take up PAHs from spiked soils, and generally increased with increasing concentrations of PAH in soil. Bioconcentration factors（BCFs） of phenanthrene by shoots and roots were 0.24- 4.25 and 0.17-2.12 for the same treatment. BCFs of pyrene by shoots were 0.20-1.5, except for 4.06 in 4.32 mg/kg treatment, much lower than BCFs of pyrene by roots （0.58-2.28）. BCFs of phenanthrene and pyrene tended to decrease with increasing concentrations of phenanthrene and pyrene in soil. Direct uptake and accumulation of these compounds by Lolium perenne L. was very low compared with the other loss pathways, which meant that plant-promoted microbial biodegradation might be the main contribution to plant-enhanced removal of phenanthrene and pyrene in soil. However, the presence of Lolium perenne L. significantly enhanced the removal of phenanthrene and pyrene in spiked soil. At the end of 60 d experiment, the extractable concentrations of phenanthrene and pyrene were lower in planted soil than in non-planted soil, about 83.24%-91.98% of phenanthrene and 68.53%-84.10% of pyrene were removed from soils, respectively. The results indicated that the removal of PAHs in contaminated soils was a feasible approach by using Lolium perenne L.

Toxic effects of fluoranthene and copper on marine diatom Phaeodactylum tricornutum

To investigate the effects of polycyclic aromatic hydrocarbons (PAHs) and metals on the population reproduction,antioxidative defense system and cell ultrastructure of the marine diatom,fluoranthene and Cu2+ were selected to test their toxicity to Phaeodactylum tricorntum,in the laboratory.The results indicated that both fluoranthene and Cu2+ inhibited population reproduction of P.tricorntum.When the algal cells were exposed to fluoranthene or Cu2+ for 72 h,ultrastructure damage in the cells was observed un...

Mixed uncertainty analysis of polycyclic aromatic hydrocarbon inhalation and risk assessment in ambient air of Beijing

This article presents the application of an integrated method that estimates the dispersion of polycyclic aromatic hydrocarbons （PAHs） in air, and assesses the human health risk associated with PAHs inhalation. An uncertainty analysis method consisting of three components were applied in this study, where the three components include a bootstrapping method for analyzing the whole process associated uncertainty, an inhalation rate （IR） representation for evaluating the total PAH inhalation risk for human health, and a normally distributed absorption fraction （AF） ranging from 0% to 100% to represent the absorption capability of PAHs in human body. Using this method, an integrated process was employed to assess the health risk of the residents in Beijing, China, from inhaling PAHs in the air. The results indicate that the ambient air PAHs in Beijing is an important contributor to human health impairment, although over 68% of residents seem to be safe from daily PAH carcinogenic inhalation. In general, the accumulated daily inhalation amount is relatively higher for male and children at 10 years old of age than for female and children at 6 years old. In 1997, about 1.73% cancer sufferers in Beijing were more or less related to ambient air PAHs inhalation. At 95% confidence interval, approximately 272-309 individual cancer incidences can be attributed to PAHs pollution in the air. The probability of greater than 500 cancer occurrence is 15.3%. While the inhalation of ambient air PAHs was shown to be an important factor responsible for higher cancer occurrence in Beijing, while the contribution might not be the most significant one.

Influence of rice straw burning on the levels of polycyclic aromatic hydrocarbons in agricultural county of Taiwan

Atmospheric particulate and polycyclic aromatic hydrocarbons （PAHs） size distribution were measured at Jhu-Shan （a rural site） and Sin-Gang （a town site） in central Taiwan during the rice straw burning and non-burning periods. The concentrations of total PAHs accounting for a roughly 58% （34%） increment in the concentrations of total PAHs due to rice-straw burning. Combustion-related PAHs during burning periods were 1.54-2.57 times higher than those during non-burning periods. The mass median diameter （MMD） of 0.88-1.21 μm in the particulate phase suggested that rice-straw burning generated the increase in coarse particle number. Chemical mass balance （CMB） receptor model analyses showed that the primary pollution sources at the two sites were similar. However, ricestraw burning emission was specifically identified as a significant source of PAH during burning periods at the two sites. Open burning of rice straws was estimated to contribute approximately 6.3%-24.6% to total atmospheric PAHs at the two sites.

Biodegradation of polycyclic aromatic hydrocarbons(PAHs)by fungal enzymes:A review

Polycyclic aromatic hydrocarbons（PAHs） are a large group of chemicals.They represent an important concern due to their widespread distribution in the environment,their resistance to biodegradation,their potential to bioaccumulate and their harmful effects.Several pilot treatments have been implemented to prevent economic consequences and deterioration of soil and water quality.As a promising option,fungal enzymes are regarded as a powerful choice for degradation of PAHs.Phanerochaete chrysosporium,Pleurotus ostreatus and Bjerkandera adusta are most commonly used for the degradation of such compounds due to their production of ligninolytic enzymes such as lignin peroxidase,manganese peroxidase and laccase.The rate of biodegradation depends on many culture conditions,such as temperature,oxygen,accessibility of nutrients and agitated or shallow culture.Moreover,the addition of biosurfactants can strongly modify the enzyme activity.The removal of PAHs is dependent on the ionization potential.The study of the kinetics is not completely comprehended,and it becomes more challenging when fungi are applied for bioremediation.Degradation studies in soil are much more complicated than liquid cultures because of the heterogeneity of soil,thus,many factors should be considered when studying soil bioremediation,such as desorption and bioavailability of PAHs.Different degradation pathways can be suggested.The peroxidases are heme-containing enzymes having common catalytic cycles.One molecule of hydrogen peroxide oxidizes the resting enzyme withdrawing two electrons.Subsequently,the peroxidase is reduced back in two steps of one electron oxidation.Laccases are copper-containing oxidases.They reduce molecular oxygen to water and oxidize phenolic compounds.