An innovative classification system for ranking the biological effects of marine aromatic hydrocarbons based on fish embryotoxicity

Petroleum hydrocarbon pollution is a global concern,particularly in coastal environments.Polycyclic aromatic hydrocarbons(PAHs) are regarded as the most toxic components of petroleum hydrocarbons.In this study,the biomonitoring and ranking effects of petroleum hydrocarbons and PAHs on the marine fish model Oryzias melastigma embryos were determined in the Jiulong River Estuary(JRE) and its adjacent waters in China.The results showed that the levels of petroleum hydrocarbons from almost all sites met the primary standard for marine seawater quality,and the concentrations of the 16 priority PAHs in the surface seawater were lower compared with those in other coastal areas worldwide.A new fish expert system based on the embryotoxicity of O.melastigma(OME-FES) was developed and applied in the field to evaluate the biological effects of petroleum hydrocarbons and PAHs.The selected physiological index and molecular indicators in OME-FES were appropriate biomarkers for indicating the harmful effects of petroleum hydrocarbons and PAHs.The outcome of OME-FES revealed that the biological effect levels of the sampling sites ranged from level Ⅰ(no stress) to level Ⅲ(medium stress),which is further corroborated by the findings of nested analysis of variance(ANOVA) models.Our results suggest that the OME-FES is an effective tool for evaluating and ranking the biological effects of marine petroleum hydrocarbons and PAHs.This method may also be applied to evaluate other marine pollutants based on its framework.

Changes in the Non-targeted Metabolomic Profile of Three-year-old Toddlers with Elevated Exposure to Polycyclic Aromatic Hydrocarbons

Objective To investigate changes in the urinary metabolite profiles of children exposed to polycyclic aromatic hydrocarbons(PAHs)during critical brain development and explore their potential link with the intestinal microbiota.Methods Liquid chromatography-tandem mass spectrometry was used to determine ten hydroxyl metabolites of PAHs(OH-PAHs)in 36-month-old children.Subsequently,37 children were categorized into low-and high-exposure groups based on the sum of the ten OH-PAHs.Ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry was used to identify non-targeted metabolites in the urine samples.Furthermore,fecal flora abundance was assessed by 16S rRNA gene sequencing using Illumina MiSeq.Results The concentrations of 21 metabolites were significantly higher in the high exposure group than in the low exposure group(variable importance for projection>1,P<0.05).Most of these metabolites were positively correlated with the hydroxyl metabolites of naphthalene,fluorine,and phenanthrene(r=0.336–0.531).The identified differential metabolites primarily belonged to pathways associated with inflammation or proinflammatory states,including amino acid,lipid,and nucleotide metabolism.Additionally,these distinct metabolites were significantly associated with specific intestinal flora abundances(r=0.34–0.55),which were mainly involved in neurodevelopment.Conclusion Higher PAH exposure in young children affected metabolic homeostasis,particularly that of certain gut microbiota-derived metabolites.Further investigation is needed to explore the potential influence of PAHs on the gut microbiota and their possible association with neurodevelopmental outcomes.

Mitigation of polycyclic aromatic hydrocarbons(PAHs)in roasted beef patties by cold plasma treatment and products quality evaluation

The cold plasma(CP)technique was applied to alleviate the contamination of polycyclic aromatic hydrocarbon(PAH)in this investigation.Two different CP treatments methods were implemented in the production of beef patties,to investigate their inhibition and degradation capacity on PAHs.With 5 different cooking oils and fats addition,the inhibition mechanism of in-package cold plasma(ICP)pretreatment was explored from the aspect of raw patties fatty acids composition variation.The results of principal component analysis showed that the first two principal components accounted for more than 80%of the total variation in the original data,indicating that the content of saturated fatty acids was significantly positively correlated with the formation of PAHs.ICP pretreatment inhibited the formation of PAHs by changing the composition of fatty acids,which showed that the total amount of polyunsaturated fatty acids decreased and the total amount of monounsaturated fatty acids increased.Sensory discrimination tests demonstrated there were discernable differences between 2 CP treated samples and the controls,utilization of the ICP pretreatment in meat products processing was expected to achieve satisfying eating quality.In conclusion,CP treatment degraded PAHs through stepwise ring-opening oxidation in 2 reported pathways,the toxicity of PAHs contaminated products was alleviated after CP treatment.

Eco-toxicity and health risk assessment of polycyclic aromatic hydrocarbons in surface sediments of Burullus Lake in Egypt

Polycyclic aromatic hydrocarbons(PAHs)are ubiquitous environmental contaminants of growing concern due to their potential ecological and human health risks.This study presents a comprehensive assessment of PAHs contamination in the surface sediments of Burullus Lake,a vital and second largest delta lake in Egypt.The aim was to evaluate the eco-toxicity and potential health risks associated with the presence of these compounds.Surface seven sediment samples were collected from various drains in the southern part of Burullus Lake.Soxhlet extraction method was employed to extract PAHs(16PAHs)from the sediment sample.Analytically,target compounds were located using HPLC.The results showed that samples contained PAHs levels ranging from 0.038×10^(-6)to 0.459×10^(-6),which is considered heavily polluted by the European standard for PAHs pollution.Additionally,there was no apparent source of PAHs in the ElKhashah drain or the Brinbal Canal,as HPLC found none of the compounds.The most prevalent compound in sediment samples along the study area was fluoranthene.The diagnostic indices in the present study indicated that the hydrocarbons in the region originated from pyrolytic and man-made sources along the drains of Burullus Lake.The principal component analysis(PCA)and diagnostic ratios revealed that coal combustion and pyrolytic sources were responsible for the PAHs contamination in the surface sediments.The non-carcinogenic risk(HI),which is the product of the HQs for the adult and child populations,respectively,was calculated.HI values under 1,therefore,demonstrated that they had no carcinogenic effects on human health.TEQs and MEQs in the sediments of Burullus Lake do not have a cancer-causing impact on people.For the safety of nearby wildlife,aquatic life,and people,all activities that raise petroleum hydrocarbon levels in Burullus Lake must be adequately regulated and controlled.According to the ecological risk assessment,there is little chance that PAHs will be found in the sediments of Burullus Lake.This study underscores the urgent need for effective pollution control measures and regular monitoring of PAHs levels in Burullus Lake sediments to protect the aquatic ecosystem and public health.It also highlights the importance of considering eco-toxicity and human health risks in integrated risk assessments of PAHs-contaminated environments.

Study on Adsorption Removal of Polycyclic Aromatic Hydrocarbons by Modified Mussel Shells

Polycyclic aromatic hydrocarbons(PAHs)are typical persistent organic pollutants(POPs)that are commonly found in the environment.They are carcinogenic,teratogenic,mutagenic and biodegradable obviously.In this paper,the modified mussel shells were used to adsorb and remove anthracene.The results show that the adsorption removal rate of the mussel shells was higher after calcination at 600℃.5%H_(3)PO_(4) solution was more suitable for shell treatment than 3 mol/L ZnCl_(2) solution.As the dosage of the modified shells was 0.5 g/L,the adsorption reached a stable state,and the removal rate of PAHs was about 69.44%;the adsorption efficiency rose with the increase of time.It can be seen that as a new and cheap biological adsorbent,the modified shells can be used to remove PAHs from wastewater.

Extraction of the Residual Polycyclic Aromatic Hydrocarbons in the Long-term Contaminated Soil in the Field

[Objective] The aim of this study was to find a better method to exactly quantify the residual polycyclic aromatic hydrocarbons（PAHs）in the long-term contaminated soil in the field so as to provide basis for the remediation for PAHs contaminated soil.[Method]The comparisons of soxhlet extraction,ultrasonic extraction and shaking extraction were studied in the agricultural soil irrigated with oil sewage over a long period of time.[Result]The total PAHs extracted by soxhlet extraction were the highest（6 873.7 μg/kg）,followed by shaking extraction（6 698.8 μg/kg）and ultrasonic extraction（5 737.6 μg/kg）.Among these methods,the highest extracted 4 and 6 rings PAHs were in the soxhlet extraction,the highest extracted 2 and 5 rings PAHs were in the shaking extraction,and the highest extracted 3 rings PAHs were in the ultrasonic extraction.[Conclusion]This study had provided basis for the selection of the assessment method of residual PAHs in the field soil.

Distribution and Risk Assessment of Polycyclic Aromatic Hydrocarbons in Mussels from the Middle and Lower Main Stream of Huaihe River

[ Object] The aim was to discuss the pollution status of polycyclic aromatic hydrocarbons （PAHs） in mussels from the middle and lower main stream of Huaihe River, which will provide a scientific basis for dietary safety of mussels. [ Method] Suspended matter, sediment, and mussel samples were collected from Wuxiaojie and Fushanji in middle and lower reaches of Huaihe River. All samples were extracted with Soxhlet, separated through Silica GeI-Al2O3 column, and determined by GC-MS, and then 16 typical PAHs contents in the prior table listed by American EPA were obtained. [ Result] The results indicated that total PAHs concentrations in suspended matters and sediments of Wuxiaojie were significantly higher than those in Fushanji respectively. However, PAHs concentrations in mussels of the two samplings showed little difference; as for single PAH component, low-ring PAHs were more advantaged in suspended matters of two sampling sites, while high-ring PAHs were more advantaged in mussels. PAHs in sediments of Wuxiaojie assumed low-ring aspect, though PAHs in sediments of Fushanji assumed high-ring aspect. [ Conclusion] In spite of that sediments and mussels were not yet contaminated according to the ecological risk assessment of PAHs, its potential hazards couldn＇t be ignored any more.

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.

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.

Geochemical characterization of aromatic hydrocarbons in crude oils from the Tarim,Qaidam and Turpan Basins,NW China

Based on the systematic study of aromatic hydrocarbons in over 100 crude oil samples collected from the Tabei and Tazhong uplifts in the Tarim Basin,the western depression area in the Qaidam Basin and the Tabei depression in the Turpan Basin,the geochemical characteristics of the marine（Tarim Basin）,saline lacustrine（Qaidam Basin）,and swamp（Turpan Basin） oils were investigated.The marine oils from the Tarim basin are characterized by relatively low abundance of diaromatic hydrocarbons such as biphenyl and naphthalene,and relatively high abundance of triaromatic hydrocarbons including phenanthrene,dibenzothiophene and fluorene.In contrast,the swamp oils from the Turpan Basin are dominated by the highest relative abundance of diaromatic hydrocarbons and the lowest relative abundance of triaromatic hydrocarbons in all the oil samples in this study.The relative abundance of diaromatic and triaromatic hydrocarbons in the saline lacustrine oils from Qaidam Basin is between that in Tarim oils and Turpan oils.Aromatic parameters based on the isomer distributions of dimethylnaphthalenes（DMN）,trimethylnaphthalenes（TMN）,tetramethylnaphthalenes（TeMN） and methylphenanthrenes（MP）,i.e.,1,2,5-trimethylnaphthalene（TMN）/1,3,6-TMN ratio,1,2,7-TMN/1,3,7TMN ratio,（2,6-＋2,7-）-dimethylnaphthalenes（DMN）/1,6-DMN ratio,1,3,7-TMN/（1,2,5-＋1,3,7-）TMN,1,3,6,7-TeMN/（1,3,6,7-＋1,2,5,6-＋1,2,3,5-）-TeMN ratio and MP index,may reflect the diversity of organic source input,thermal maturity and depositional environments.In addition,the dibenzothiophenes（DBTs）/fluorenes（Fs） and dibenzofurans（DBFs）/Fs ratios were found to the very useful and effective in determining genetic types of crude oils for the marine,saline lacustrine,and swamp depositional environments,and for oil-oil correlations.

Distribution and deposition of polycyclic aromatic hydrocarbons in precipitation in Guangzhou, South China

Polycyclic aromatic hydrocarbons （PAHs） were measured in precipitation from March to August 2005 in Guangzhou, South China. Fourteen PAHs were studied, and their total concentrations varied from 616.6 to 3486.7 ng/L in dissolved phase and from 403.8 to 3125.5 ng/L in particulate phase. The estimated deposition loading of PAHs was 3568 ug/m^2 during the monitoring period. The deposition of PAHs was a potential source for Pearl River comparing with the contents of surface water. In addition, the high concentration in precipitation here implied that PAHs pollution was a potential environmental problem in Guangzhou. Most precipitation concentrations of PAHs in March （the last month in winter in Guangzhou） were higher than in the other months （in rainy season）. PAHs inclined to be adsorbed to particulate phase with the increase of molecular weight in rainwater. Combustion of fossil fuel and biomass might be the major source of PAHs, while the direct leakage or volatilization from petroleum products might be insignificant.

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.

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.

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.

Photoinduced toxicity single and binary mixtures of four polycyclic aromatic hydrocarbons to the marine diatom Skeletonema costatum

Diatom Skeletonema costatum Cleve is one of the main predominant phytoplankton species in the Changjiang Estuary in China. In order to provide some basic information for future assessment of the potential risk on phytoplankton communities in this estuary caused by polycyclic aromatic hydrocarbons（ PAHs）, this alga was selected as a representative to investigate the photoinduced toxicity of PAHs, in single and mixture. Four PAHs including three-ring phenanthrene and anthracene, four-ring fluoranthene and pyrene were tested in the laboratory. The single toxicity of each PAH on this microalga was compared with and without the simulated solar UV radiation. The results showed that this microalga was sensitive to PAH＇ s photoinduced toxicity. Ratios of the 72 h median effect concentration obtained for fluorescent and UV light tests were about 8.4 for phenanthrene, 13.0 for anthracene, 6. 5 for fluoranthene, and 5.7 for pyrene, indicating that UV light enhanced the PAH toxicity to this alga significantly. Under the fluorescent radiation （lacking UV ）, the dose-response curves based on chemical concentrations revealed that the order of toxic strength was fluoranthene greater than pyrene greater than anthracene greater than phenanthrene; while under the UV radiation （476 μW/cm^2 for UVA, 6.5 μW/cm^2 for UVB） it became fluoranthene approximately equaling anthracene greater than pyrene greater than phenanthrene, indicating that the UV light also changed its relative toxicity to this alga. The photoinduced toxicity of PAHs to the marine diatom S. costatum might be a synergistic effect of photosensitization reactions （ e. g. , generation of singlestate oxygen） and photomodification （photooxidation and/or photolysis）. The combined effects of six binary mixtures on the marine diatom S. costatum were investigated using the additive-index method. Four binary-mixtures （ phenanthrene plus anthracene ; phenanthrene plus pyrene ; anthracene plus fluoranthene ; anthracene plus pyrene） were found to be synergistic joint action mode, while two binary-mixtures （phenanthrene plus fluoranthene; fluoranthene plus pyrene） displayed antagonist, revealing a complex pattern of possible interactions. The combined action mode of PAHs might be related to various factors such as the mixture compounds, mixture ratios and test conditions, etc.

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.

Characterization of Hapten-Protein Conjugates for Immunoassay of Polycyclic Aromatic Hydrocarbons(PAHs)

Preparation and characterization of the hapten-protein conjugates are fundamental to developing environmental immunoassays. As a hapten, 1-pyrenebutyric acid（PBA） was conjugated to the carrier protein of bovine serum albumin（BSA） or ovalbumin（OVA） by active ester method. Infrared spectra（IR） showed that PBA-BSA and PBA-OVA conjugates were successfully prepared. The number of the haptens conjugated to the carrier protein was determined by ultraviolet spectra（UV） and matrix-assisted laser desorption ionization time-of-flight mass spectrometry（MALDI-TOF-MS）. The calculated average binding ratios of PBA/BSA and PBA/OVA were 18：1 and 10：1 by UV, and 31：1 and 22：1 by MALDI-TOF-MS, respectively. Although there was a discrepancy between the results determined by the two methods, both of them were useful for the characterization of the hapten-protein conjugates. The antibody was produced against the antigen of PBA-BSA, and the affinity was tested by the double agar diffusion method The conjugates and the antibody could be used for developing a sensitive and selective immunoassay of polycyclic aromatic hydrocarbons（PAHs）.

Depolymerization and hydrodeoxygenation of lignin to aromatic hydrocarbons with a Ru catalyst on a variety of Nb-based supports

Efficient conversion of lignin to aromatic hydrocarbons via depolymerization and subsequent hydrodeoxygenation is important.Previously,we found that NbOx species played a key role in the activation and cleavage of C-O bonds in lignin and its model compounds.In this study,commercial niobic acid(HY-340),niobium phosphate(NbPO-CBMM)and lab-made layered niobium oxide(Nb2O5-Layer)were chosen as supports to study the effect of Brosted and Lewis acids on the activation of C-O bonds in lignin conversion.A variety of Ru-loaded,Nb-based catalysts with different Ru particle sizes were prepared and applied to the conversion of p-cresol.The results show that all the Ru/Nb-based catalysts produce high mole yields of C7-C9 hydrocarbons(82.3%-9.1%).What's more,Ru/Nb2O5-Layer affords the best mole yield of C7-C9 hydrocarbons and selectivity for C7-C9 aromatic hydrocarbons,of up to 99.1% and 88.0%,respectively.Moreover,it was found that Lewis acid sites play important roles in the depolymerization of enzymatic lignin into phenolic monomers and the cleavage of the C-O bond of phenols.Additionally,the electronic state and particle size of Ru are significant factors which influence the selectivity for aromatic hydrocarbons.A partial positive charge on the metallic Ru surface and a smaller Ru particle size are beneficial in improving the selectivity for aromatic hydrocarbons.

2D-QSAR Using MLR and 3D-QSAR Using CoMSIA Studies on the Toxicity of Aromatic Hydrocarbons on Larval Sinonvaculina Constricta

Aromatic hydrocarbons,one of the persistent organic pollutants（POPs）,has been usually found in mussels,accumulated for their hard mobility and activities in harbours and estuaries.In this study,based on the 96 hr-LC50 of 12 aromatic hydrocarbons with larval sinonvaculina constricta,three-dimensional quantitative structure-activity relationship（3D-QSAR） technique：comparative molecular similarity indices analysis（CoMSIA） and 2D-QSAR technique：multiple linear regression（MLR） were described to obtain more detailed insight into the structure-activity relationships between the molecular structure and bio-activity.The results show the MLR model based on density functional theory（DFT） calculation carried out at the B3LYP/6-311＊＊ level with Gaussian 03 program yielded a very good correlation with a coefficient squared R2 of 0.716 and a cross-validated Q2 of 0.874.The dipole moment and enthalpy,as the thermodynamic parameters,were two important factors influencing pLC50.Correspondingly,CoMSIA based on the partial least-squares（PLS） methodology with steric,electrostatic,hydrophobic,H-bond donor and acceptor fields contributing simultaneously were employed and the values of R2 and the cross validation with leave-One-Out（LOO） Q2LOO were 0.585 and 0.990,respectively,which reveals the structure features,such as the electronegative substituent（nitro-group）,hydrophobic groups（the benzene ring） and H-bond（nitro-group）,related to the toxicity.The results of 2D-QSAR employing MLR model and 3D-QSAR employing CoMSIA model provide the useful information for predicting the toxicity of other aromatic hydrocarbons by comparing the molecular structures of similar compounds.

Bio-toxicity Effect of Polycyclic Aromatic Hydrocarbons Pyrene on Arabidopsis thaliana

[Objective] The aim was to study the effects of polycyclic aromatic hydrocarbons（PAHs）pyrene on the physiology and biochemistry of plant.[Method] Taking model plant A.thaliana as material,the effects of 4-ring PAHs pyrene stress on A.thaliana growth were studied,as well as the changes of antioxidant enzyme activity and ultrastructure in leaves.[Result] Under pyrene stress,the root growth of A.thaliana was enhanced under low concentration but was inhibited under high concentration.Trichomes of A.thaliana leaves distorted with the increase of pyrene concentration.Under 0.25 mmol/L of pyrene stress for 28 d,the photosynthetic process of A.thaliana was inhibited,and chlorophyll content in A.thaliana leaves decreased significantly.With the increase of pyrene concentration,the activity of peroxidase（POD）,superoxide dismutase（SOD）and ascorbate peroxidase（APX）in A.thaliana leaves increased significantly,while catalase（CAT）activity went up firstly and then went down.In addition,average H2O2 content in A.thaliana leaves under different pyrene concentrations were higher than that of control.Meanwhile,damaged ultrastructures of few chloroplasts in A.thaliana leaves under pyrene stress were observed,and photosynthesis was inhibited significantly.[Conclusion] The study could provide references for the toxic mechanism of PAHs on plant and plant selection in the phytoremediation of PAHs contaminated soil.