Tissue distribution provides important information regarding the pharmacokinetic behavior of pollutants and is invaluable when analyzing the risk posed to avian species by the exposure to such kind of pollutants. In t...Tissue distribution provides important information regarding the pharmacokinetic behavior of pollutants and is invaluable when analyzing the risk posed to avian species by the exposure to such kind of pollutants. In this study, concentrations of polychlorinated dibenzo-p-dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs） were determined in muscle, liver, spleen, kidney, stomach, gall bladder, skin, heart, pancreas, intestine and lung tissue extracts of cormorants collected from Dongting Lake, China. Tissue distribution results showed preferential accumulation of PCDD/Fs in both liver and skin. The total concentration of PCDD/Fs ranged from 421 to 5696 pg/g lipid weight. Octachlorinated dibenzo-p-dioxin （OCDD） was the predominant congener in all tissues and contributed between 31% and 82% to all 17 PCDD/Fs in different tissues. The liver/muscle ratios progressively increased with the degree of chlorination of PCDDs, except for OCDD. The relative toxic potential of PCDDs and PCDFs in tissues were calculated using the World Health Organization （WHO） Toxic Equivalency Factors （TEFs） for birds. The concentrations of WHO-toxic equivalent in different tissues ranged between 14.8 and 2021 pg/g lipid weight. These results indicated PCDD/Fs may have been bio-accumulated in cormorant via food-web. Furthermore, when compared with studies reported in the literatures, the PCDD/Fs levels in the cormorant collected from Dongting Lake were still relatively high.展开更多
Polychlorinated dibenzo-p-dioxins and furans （PCDD/Fs） emissions in flue gas from two types of municipal solid waste incinerators （MSWIs） most commonly used in China were investigated in this study. The selected i...Polychlorinated dibenzo-p-dioxins and furans （PCDD/Fs） emissions in flue gas from two types of municipal solid waste incinerators （MSWIs） most commonly used in China were investigated in this study. The selected incinerators include two grate-type MSWIs： MSWI-A （350 t/d） and MSWI-B 050 t/d）, and two fluidized bed MSWIs： MSWI-C （400 t/d） and MSWI-D （400 t/d）, which are all equipped with semi-dry lime scrubber and bag filter except MSWI-D equipped with cyclone and wet scrubber （WS） as air pollutant control device （APCD）. Results indicated that the emission concentration and the international toxic equivalents （I-TEQs） of the PCDD/Fs from the stacks were in the range of 1.210-10.273 ng/Nm^3 and 0.019-0.201 ng I-TEQ/Nm^3, respectively. They were greatly lower than the emission regulation standard of PCDD/Fs in China （1.0 ng I-TEQ/Nm^3）. However, only the PCDD/Fs emission level from MSWI-C was below 0.1 ng I-TEQ/Nm^3. Although the homologue profiles were distinct, the contributions of the 2,3,7,8-subsituted congeners to the total I-TEQ were similar among all the investigated MSWIs. Two major 2,3,7,8-substituted congeners, 2,3,4,7,8-PeCDF and 1,2,3,7,8-PeCDD, account for 47% and 9% （average values） of the total I-TEQ values, respectively. The correlation between PCDD/Fs levels and composition of flue gas was also discussed.展开更多
Surface sediments and bivalves were collected from the Changjiang Estuary in December 2003 and November 2004, respectively. Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in these samples were mea...Surface sediments and bivalves were collected from the Changjiang Estuary in December 2003 and November 2004, respectively. Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in these samples were measured with high-resolution chromatography (HRGC)/High Resolution Mass Spectrometer (HRMS). The concentrations of total PCDD/Fs and toxic equivalent (TEQ) were 169.83±119.63 and 0.81±0.36 pg/g dry weight (dw) in sediments, and 580.33±240.17 and 7.24±3.65 pg/g dw in bivalves. The homolog compositions of PCDD/Fs were similar among samples, the most abundant congener was octa-chlorinated dibenzo-p-dioxin (OCDD) and then octa-chlorinated dibenzofuran (OCDF) and 1,2,3,4,6,7,8-hepta-chlorinated dibenzo-p-dioxin (HpCDD). The herbicide pentachlorophenol (PCP) and sodium pentachlorophenol (Na-PCP) were proved the main source of PCDD/Fs in this area.展开更多
The distribution and geochemical significance of dibenzofurans,phenyldibenzofurans and benzo[b]naptho-furans in source rocks from Niger Delta basin,Nigeria,were investigated by Rock-Eval pyrolysis and gas chro-matogra...The distribution and geochemical significance of dibenzofurans,phenyldibenzofurans and benzo[b]naptho-furans in source rocks from Niger Delta basin,Nigeria,were investigated by Rock-Eval pyrolysis and gas chro-matography--mass spectrometry(GC--MS).The data obtained from the source rocks evaluation showed that the rock samples contained type 1/III kerogen capable of generating oil and gas and were within immature to early mature stage.The relative abundance of the Cor,C1-and C2-dibenzofurans range from 1.75%to 29.82%,27.60%to 40.52%and 29.66%to 6889%,respectively.The diben-zofurans were dominated by C-dibenzofurans.Among the C1-dibenzofurans,2-+3-methyldibenzofuran was the most abundant in the rock samples while 1-methy ldibenzofuran appeared to be the least.The relative abundance of benzo[b]naphtho[1,2-d]furan(1,2]BNF),benzo[b]naph-tha[2,1-d]furan(2.1]BNF)and benzo[b]naphtha[2,3-d]fu-ran([2.3]BNF)in the rock extracts range from 12.01%to 52.58%,32.61%to 75.219%and 10.27%to 52.43%.The wide range of values recorded for the three isomers of benzo[b lnapthofurans in the samples suggest source rocks formed from mixed organic matter.Among the pheny ldibenzofuran isomers,4-pheny ldibenzofuran was the most abundant while 1-phenyldibenzofuran was the least.Phenyldibenzofuran ratio-1(PhFR-1)and pheny ldibenzofuran ratio-2(PhFR-2)values range from 0.13 to 1.20 and 0.11 to 2.11,respectively.The resuls showed that the relative abundance of PhFR-1 and PhFR-2 increase gradually with increasing burial depth and maturity(VRo≤0.77%,MPI-1≤0.62.Tmax s 443℃),and have a good correlations with calculated vitrinite reflectance.MPI-I and maximum Temperature(Tmax)-This range of values suggested immature to early mature source rocks.The source rocks were found to have shale and coul lithologics and deposited in a lacustrine/fuvial deltaic settings within immature to early mature stages based on the distribution of dibenzofurans,pheny ldiben-zofurans and benzo[b]naphthofurans in the source rocks.This study showed that dibenzof urans,phenyldibenzofu-rans and benzo[b]naphthofurans were ffcive in deter-mining the origin,depositional environment and thermal maturity of source rocks in Niger Delta basin,Nigeria.展开更多
Background: Today’s presence of polychlorinated dibenzofurans (PCDFs) in foodstuff, such as milk and milk products, is considered to be the major concern for human health. This study was aimed to determine the concen...Background: Today’s presence of polychlorinated dibenzofurans (PCDFs) in foodstuff, such as milk and milk products, is considered to be the major concern for human health. This study was aimed to determine the concentrations of the most toxic congeners of furans in pasteurized milk samples produced in southwest Iran. Material and method: 15 composite samples of pasteurized milk were collected from 3 major dairy factories in Khuzestan Province (southwest of Iran) in summer, autumn and winter from July 2011 to March 2012. After precipitation of the proteins, fat phase was reduced and extracted with hexane and ether. After dehydration, furans existed in fat percolated with hexane through a column chromatography that contained respectively silica gel/silver nitrate, silica gel, silica gel/sulphuric acid and with percolating output through another column that contained activated charcoal and silica gel and washed the lower column with a mixture of dichloromethane-hexane and toluene, concentrated and dissolved in mobile phase and analyzed using HPLC: 150 mm × 4.6 mm ID, 5 μm cosmosil 5 NPE column equipped with a UV detector at 254 and 235 nm, mobile phase: methanol/water (80:20, v/v) at flow rate of 1 ml/min. Results: All samples were found to be contaminated with furans. The average concentration of 2,3,7,8 TCDF and 2,3,4,7,8 PCDF were 1.91 pg/g and 1.77 pg/g in lipid content ranging from 2% to 3% respectively. The mean total content of furans in milk fat was 0.36 TEQ (Toxic Equivalency) pg/g which was below the recommended EU (European Union) threshold value 3 pg (WHO-PCDFs-TEQ/g fat). Also, result showed that there were statistically significant differences between each factory during 3 seasons.展开更多
2-nitrobenzofuran is studied as dienophile in polar thermal Diels-Alder reactions with normal electron demand using several structurally different dienes. A very strong electron-acceptor group, such as nitro group, en...2-nitrobenzofuran is studied as dienophile in polar thermal Diels-Alder reactions with normal electron demand using several structurally different dienes. A very strong electron-acceptor group, such as nitro group, enhances the dienophilic character of these heterocyclic compounds and owing to the fact that this substituent is easily extruded under thermal conditions this reaction sequence becomes a simple method of organic compound＇s families with heteroatom rings preparation. Part of this work is specifically concerned with theoretical studies. The global and local electrophilicity and nucleophilicity indexes were calculated for the dienophile and dienes used in this work. A concise synthesis of dibenzofurans has been development via cycloaddition reactions.展开更多
We analyzed polychlorinated dibenzofurans (PCDF) and dibenzo-p-dioxins (PCDD) in 27 tree bark samples from the industrialized area near Sauget, Illinois, USA. The trees were located within 4 km of the W. G. Krummrich ...We analyzed polychlorinated dibenzofurans (PCDF) and dibenzo-p-dioxins (PCDD) in 27 tree bark samples from the industrialized area near Sauget, Illinois, USA. The trees were located within 4 km of the W. G. Krummrich (WGK) plant, the oldest and largest chemical plant in Sauget, with 24 of 27 samples collected from residential areas. The percent of total PCDF or PCDD profiles of ten 2,3,7,8- Cl substituted PCDF and seven PCDD congeners is homogeneous: 90% of the variance among the samples is explained by 3 eigenvalues in a principal components analysis. The homogeneity of the data suggests that samples were affected by similar types of sources which may have been influenced by electric power generation, chemical waste incineration, and large-scale thermal production of chlorinated chemicals. Quantitatively, the 2,3,7,8-Cl substituted congener analysis does not account for 90% of the concentration of tetra- and penta-Cl homologues and 80% of hexa-Cl and 50% of hepta-Cl homologues. The World Health Organization stated during establishment of toxic equivalence factors (TEF, 2005 version) that calculation of toxic equivalents (TEQs) is not suitable for abiotic matrices, such as tree bark, which are not involved in human exposures. Our results show that the non-2,3,7,8-Cl substituted congeners have high concentrations and should be included in analysis.展开更多
Two new dibenzofurans, 7,8-dimethoxy-4-methyldibenzofuran-1-carboxaldehyde, named ligumedial (1) and 7,8-dimethoxy-4-methyldibenzofuran-1-carboxylic acid, named ligumediaoic acid (2), have been isolated from the under...Two new dibenzofurans, 7,8-dimethoxy-4-methyldibenzofuran-1-carboxaldehyde, named ligumedial (1) and 7,8-dimethoxy-4-methyldibenzofuran-1-carboxylic acid, named ligumediaoic acid (2), have been isolated from the underground parts of Ligularia intermedia. Their structures were elucidated by spectroscopic methods.展开更多
Polychlorinated dibenzofurans (PCDFs) represent an important kind of serious pollutant. They are highly toxic and persistent in environment. In this paper, geometrical optimizations and subsequent calculations o...Polychlorinated dibenzofurans (PCDFs) represent an important kind of serious pollutant. They are highly toxic and persistent in environment. In this paper, geometrical optimizations and subsequent calculations of electrostatic potentials (ESPs) on molecular surface have been performed for all 135 PCDF congeners at the HF/6-31G* level. The effects of substitution value and variation of substitution position upon the surface ESPs have been discussed. A series of statistic-based structural descriptors derived from the surface ESPs have been calculated. For some PCDF congeners, linear relationships between aryl hydrocarbon receptor (AhR) biding affinity and aryl hydrocarbon hydroxylase (AHH) induction potency as well as theoretical descriptors have been established by multiple linear regression method. It appears that the quantities derived from the surface ESPs, Vs,min, Vs , VS +, σ+ and Nvmin, 2 together with the molecular surface area and the energy gap between HOMO and LUMO can be well used to express the quantitative structure-toxicity relationships of PCDFs.展开更多
The thermodynamic properties of dibenzofurans （DFs）, xanthones （XTs） and an-thraquinones （AQs） with one and two positions substituted with hydroxyls in the ideal gas state at 298.15 K and 1.013×10^5 pa were...The thermodynamic properties of dibenzofurans （DFs）, xanthones （XTs） and an-thraquinones （AQs） with one and two positions substituted with hydroxyls in the ideal gas state at 298.15 K and 1.013×10^5 pa were calculated at the B3LYP/6-311G^＊ level using Gaussian 03 program. The isodesmic reactions were designed to calculate the standard free energy of formation （△fG^θ）. Three types of hydrogen bonds exist in the three kinds of chemicals and their bond energies were ascertained as 7-15, 15-23 and 49-58 kJ·mo1^-1 respectively by comparing the △fG^θ values. Electronic density topology analysis was applied to validate the strength of bond.展开更多
The research progress on the mechanisms of formation and degradation of polychlorinated dibenzo-p-dioxins ( PCDDs ) and dibenzofurans ( PCDFs ) is reviewed. The primary sources of PCDD/Fs are chemical, thermal, photoc...The research progress on the mechanisms of formation and degradation of polychlorinated dibenzo-p-dioxins ( PCDDs ) and dibenzofurans ( PCDFs ) is reviewed. The primary sources of PCDD/Fs are chemical, thermal, photochemical and enzymatic reactions. Most of the thermal sources result in emissions into air. The studies on the photodegradation and biodegradation offer promise for destruction of PCDD/Fs in environment.展开更多
Labeled polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs)were extracted by three different methods,i.e.,soxhlet extraction,hot extraction and accelerated solvent extraction(ASE).The PCDD/Fs were detected by...Labeled polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs)were extracted by three different methods,i.e.,soxhlet extraction,hot extraction and accelerated solvent extraction(ASE).The PCDD/Fs were detected by high resolution gas chromatography-high resolution mass spectrometry.Comparisons of the three methods were carried out by recovery of PCDD/Fs,solvent consumption and extraction time.The results showed that all of the method could extract labeled PCDD/Fs efficiently.ASE was a time saving procedure with lowest consumption of solvents compared with the other two methods.展开更多
A rapid pretreatment method of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in soil and analysis by high resolution gas chromatograph-high resolution mass spectrometry was present.The extraction and a...A rapid pretreatment method of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in soil and analysis by high resolution gas chromatograph-high resolution mass spectrometry was present.The extraction and alumina clean up of PCDD/Fs in soil was achieved by accelerated solvent extractor.Then the multi-layer silica-gel column was used for further clean up.The whole method has been evaluated on certified reference soil and farm soil.Accuracy and precision of this method was tested with satisfactory results.展开更多
Based on the Industrial Source Complex Short-Term Version 3 （ISCST3） model, a simplified modeling approach was developed to predict concentrations of congeners of polychlorinated-p-dioxins and dibenzofurans （PCDD/F...Based on the Industrial Source Complex Short-Term Version 3 （ISCST3） model, a simplified modeling approach was developed to predict concentrations of congeners of polychlorinated-p-dioxins and dibenzofurans （PCDD/Fs） of agricultural soil, within a radius of 3 kin from a municipal solid waste incinerator （MSWI） plant after its 4-year operation in Hangzhou, China. Comparisons were made between the measured and estimated congener-specific concentrations and the international-toxic equivalent （I-TEQ） values of soil samples with respect to distance from the stack. The results indicate that the predictions of soil PCDD/F concentrations and K-TEQ values were generally lower than their observations, and that the higher the degree of underestimation seems, the greater the further downwind one gets. Nevertheless, most of the predictions were in good agreement with the trend of measured ones and were within a factor of ten for samples located within 1 kin of the plant. Besides, analysis of contributions of various deposition pathways confirms that in addition to wet particle deposition, the dry gaseous deposition is essential for realistic prediction of PCDD/F depositions to soil, especially for tetra- and penta-chlorinated dioxins.展开更多
Pentachlorphenol (PCP) was widely used as a biocide and insecticide for wood preservation. Chlorinated dioxins and furans (2,3,7,8-substituted PCDD and PCDF congeners) were inadvertent byproducts of PCP production. As...Pentachlorphenol (PCP) was widely used as a biocide and insecticide for wood preservation. Chlorinated dioxins and furans (2,3,7,8-substituted PCDD and PCDF congeners) were inadvertent byproducts of PCP production. As such, it is an important source of PCDD/F contamination in treated wood and in soil/ sediment near sites that produced or used PCP. It has been noted in the literature, that PCP congener profiles are similar to some combustion profiles, as well as sewage sludge and particulate deposition. In a very broad sense, this is true. OCDD and 1,2,3,4,6,7,8-HpCDD are typically the dominant constituents in these source categories. There is however, a distinct, consistent and repeatable feature in the lower chlorinated tetra, penta and hexa PCDD/F range of PCP related samples: an order of magnitude increase in concentration as a function of degree of chlorination. Because lower chlorinated furans concentrations make up less than 1% of the total PCDD/F in PCP, it is difficult to differentiate PCP from other OCDD dominated source profiles on bargraphs that use a linear-scale y axis. Using a log-scale y axis, however, PCP impacted profiles are obvious, and are not easily confused with congener profiles from other sources.展开更多
Optimized calculation of dibenzofuran （DF） and 135 polychlorinated dibenzofurans （PCDFs） was carried out at the B3LYP/6-31G＊ level in GAUSSIAN 98 program. Based on the theoretical linear solvation energy relation...Optimized calculation of dibenzofuran （DF） and 135 polychlorinated dibenzofurans （PCDFs） was carried out at the B3LYP/6-31G＊ level in GAUSSIAN 98 program. Based on the theoretical linear solvation energy relationship （TLSER） model, the obtained structural parameters were taken as theoretical descriptors to establish the novel quantitative structureproperty relationship （QSPR） model for predicting n-octanol/water partition coefficients （lgKow） of PCDFs. The new model of lgKow achieved in this work contains three variables： energy of the highest occupied molecular orbital （EHOMO）, the most negative atomic partial charge （q^-） and average molecular polarizability （a）, of which R^2= 0.9011 and SD = 0,17 with larger t values. In addition, the variation inflation factors （VIF） of variables in the present model are all less than 5.5, suggesting high accuracy of the lgKow model. And the results of cross-validation test （q^2 = 0.8688） and method validation also show this model exhibits optimum stability and better predictive power than semi-empirical method. At the same time, it is found that the aqueous solubility （-lgSw） has high relative correlation with constant volume molar heat capacity （Cv^0）, of which R^2 = 0.9777 and SD = 0.22. Moreover, lgKow and -lgSw values of all PCDF congeners were predicted respectively.展开更多
The adsorption of dibenzofuran on three commercial granular activated carbons (ACs) was investigated by dynamic experiment to correlate the adsorption equilibrium and kinetics with the structure of activated carbons.P...The adsorption of dibenzofuran on three commercial granular activated carbons (ACs) was investigated by dynamic experiment to correlate the adsorption equilibrium and kinetics with the structure of activated carbons.Physical properties including surface area, average pore diameter, micropore area and micropore volume of the activated carbons were characterized by N2 adsorption experiment on ASAP2010. To calculate the adsorption parameters, adsorption isotherm data were fitted to the Langmuir equation, and adsorption kinetic data were fitted to the linear driving force (LDF) diffusion model. From the correlation results, it is concluded that the adsorption equilibrium and diffusion coefficient of dibenzofuran on activated carbon are controlled respectively by the total adsorbent surface area and the adsorbent pore diameter.展开更多
A field study and theoretical calculations were performed to clarify the levels, profiles, and distributions of polybrominated dibenzo-p-dioxins and dibenzofurans(PBDD/Fs) in a cement kiln co-processing solid waste, w...A field study and theoretical calculations were performed to clarify the levels, profiles, and distributions of polybrominated dibenzo-p-dioxins and dibenzofurans(PBDD/Fs) in a cement kiln co-processing solid waste, with a focus on the PBDF formation mechanism.The raw materials contributed greatly to input of PBDD/Fs into the cement kiln. The PBDD/F concentrations in the raw materials were much higher than those in particle samples from different process stages in the cement kiln. The PBDD/F concentrations in the clinkers were1.40% of the concentrations in the raw materials, which indicated that the high destruction efficiencies for PBDD/Fs by cement kiln. PBDD/F distribution patterns in particle samples collected from different process stages indicated the cement kiln backend was a major site for PBDD/F formation. PBDFs with high levels of halogenation, such as heptabrominated furans(Hp BDF), were the dominant contributors to the total PBDD/F concentrations and accounted for 42%–73% of the total PBDD/F concentrations in the particle samples. Our results showed that co-processing of municipal solid waste in a cement kiln may influence the congener profile of PBDD/Fs, especially for the higher halogenated PBDD fraction. In addition, there were significant correlations between the decabromodiphenyl ether and heptabrominated furan concentrations, which is an indicator of transformation from polybrominated diphenyl ethers to PBDD/Fs. Theoretical calculations were performed and demonstrated that elimination of HBr and Br_2 from polybrominated diphenyl ethers were the dominant formation pathways for PBDD/Fs. These pathways differed from that for polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs).展开更多
Catalytic hydrodeoxygenation(HDO)is one of the most effective methods to upgrade the oxygen-containing compounds derived from coal tar to valuable hydrocarbons.Herein,an efficient bimetallic catalyst Pt_(1)Ni_(4)/MgO ...Catalytic hydrodeoxygenation(HDO)is one of the most effective methods to upgrade the oxygen-containing compounds derived from coal tar to valuable hydrocarbons.Herein,an efficient bimetallic catalyst Pt_(1)Ni_(4)/MgO was prepared and applied in the HDO of dibenzofuran(DBF).High yield(95%)of the desired product bicyclohexane(BCH)was achieved at 240℃and 1.2 MPa of H_(2).Superior catalytic performance could be ascribed to the"relay catalysis"of Pt sites and Ni sites,and the reaction pathway is proposed as well.Scale-up experiment and recyclability test were also performed,which demonstrated the recyclability and promising potential application of Pt_(1)Ni_(4)/MgO.展开更多
Three kinds of commercial activated carbons, such as Norit RB1, Monolith and Chemviron activated carbons, were used as adsorbents for adsorption of dibenzofuran. The average pore size and specific surface area of thes...Three kinds of commercial activated carbons, such as Norit RB1, Monolith and Chemviron activated carbons, were used as adsorbents for adsorption of dibenzofuran. The average pore size and specific surface area of these activated carbons were measured. Temperature Programmed Desorption (TPD) experiments were conducted to measure the TPD curves of dibenzofuran on the activated carbons, and then the activation energy for desorption of dibenzofuran on the activated carbons was estimated. The results showed that the Chemviron and the Norit RB1 activated carbon maintained higher specific surface area and larger micropore pore volume in comparison with the Monolith activated carbon, and the activation energy for the desorption of dibenzofuran on these two activated carbons was higher than that on the Monolith activated carbon. The smaller the pore of the activated carbon was, the higher the activated energy of dibenzofuran desorption was.展开更多
基金supported by the National Key Technologies R&D Program of Ministry of Science and Technology of China (No. 2007BAC27B01)the National Science and Technology Infrastructure Program of Ministry of Science and Technology of China (No. 2008FY2101000)
文摘Tissue distribution provides important information regarding the pharmacokinetic behavior of pollutants and is invaluable when analyzing the risk posed to avian species by the exposure to such kind of pollutants. In this study, concentrations of polychlorinated dibenzo-p-dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs） were determined in muscle, liver, spleen, kidney, stomach, gall bladder, skin, heart, pancreas, intestine and lung tissue extracts of cormorants collected from Dongting Lake, China. Tissue distribution results showed preferential accumulation of PCDD/Fs in both liver and skin. The total concentration of PCDD/Fs ranged from 421 to 5696 pg/g lipid weight. Octachlorinated dibenzo-p-dioxin （OCDD） was the predominant congener in all tissues and contributed between 31% and 82% to all 17 PCDD/Fs in different tissues. The liver/muscle ratios progressively increased with the degree of chlorination of PCDDs, except for OCDD. The relative toxic potential of PCDDs and PCDFs in tissues were calculated using the World Health Organization （WHO） Toxic Equivalency Factors （TEFs） for birds. The concentrations of WHO-toxic equivalent in different tissues ranged between 14.8 and 2021 pg/g lipid weight. These results indicated PCDD/Fs may have been bio-accumulated in cormorant via food-web. Furthermore, when compared with studies reported in the literatures, the PCDD/Fs levels in the cormorant collected from Dongting Lake were still relatively high.
基金the Natural Science Foundation of Zhejiang Province (No. X206955)Zhejiang Medical and Health Research Fund (No. 2007A047)the Education Bureau of Zhejiang Prov-ince (No. N20080181), China
文摘Polychlorinated dibenzo-p-dioxins and furans （PCDD/Fs） emissions in flue gas from two types of municipal solid waste incinerators （MSWIs） most commonly used in China were investigated in this study. The selected incinerators include two grate-type MSWIs： MSWI-A （350 t/d） and MSWI-B 050 t/d）, and two fluidized bed MSWIs： MSWI-C （400 t/d） and MSWI-D （400 t/d）, which are all equipped with semi-dry lime scrubber and bag filter except MSWI-D equipped with cyclone and wet scrubber （WS） as air pollutant control device （APCD）. Results indicated that the emission concentration and the international toxic equivalents （I-TEQs） of the PCDD/Fs from the stacks were in the range of 1.210-10.273 ng/Nm^3 and 0.019-0.201 ng I-TEQ/Nm^3, respectively. They were greatly lower than the emission regulation standard of PCDD/Fs in China （1.0 ng I-TEQ/Nm^3）. However, only the PCDD/Fs emission level from MSWI-C was below 0.1 ng I-TEQ/Nm^3. Although the homologue profiles were distinct, the contributions of the 2,3,7,8-subsituted congeners to the total I-TEQ were similar among all the investigated MSWIs. Two major 2,3,7,8-substituted congeners, 2,3,4,7,8-PeCDF and 1,2,3,7,8-PeCDD, account for 47% and 9% （average values） of the total I-TEQ values, respectively. The correlation between PCDD/Fs levels and composition of flue gas was also discussed.
基金supported by National Research Program (No. 2003CB415005)"Youth Chen-Guang Project" of Wuhan Bureau of Science and Technology (No. 200750731259).
文摘Surface sediments and bivalves were collected from the Changjiang Estuary in December 2003 and November 2004, respectively. Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in these samples were measured with high-resolution chromatography (HRGC)/High Resolution Mass Spectrometer (HRMS). The concentrations of total PCDD/Fs and toxic equivalent (TEQ) were 169.83±119.63 and 0.81±0.36 pg/g dry weight (dw) in sediments, and 580.33±240.17 and 7.24±3.65 pg/g dw in bivalves. The homolog compositions of PCDD/Fs were similar among samples, the most abundant congener was octa-chlorinated dibenzo-p-dioxin (OCDD) and then octa-chlorinated dibenzofuran (OCDF) and 1,2,3,4,6,7,8-hepta-chlorinated dibenzo-p-dioxin (HpCDD). The herbicide pentachlorophenol (PCP) and sodium pentachlorophenol (Na-PCP) were proved the main source of PCDD/Fs in this area.
基金The authors gratefully acknowledge the State Key Laboratory of Petroleum Resources and Prospecting,College of Geoscience,China University of Petroleum,Beijing,China for granting A.B.Ogbesejana an international visiting research fellowship towards this research work.
文摘The distribution and geochemical significance of dibenzofurans,phenyldibenzofurans and benzo[b]naptho-furans in source rocks from Niger Delta basin,Nigeria,were investigated by Rock-Eval pyrolysis and gas chro-matography--mass spectrometry(GC--MS).The data obtained from the source rocks evaluation showed that the rock samples contained type 1/III kerogen capable of generating oil and gas and were within immature to early mature stage.The relative abundance of the Cor,C1-and C2-dibenzofurans range from 1.75%to 29.82%,27.60%to 40.52%and 29.66%to 6889%,respectively.The diben-zofurans were dominated by C-dibenzofurans.Among the C1-dibenzofurans,2-+3-methyldibenzofuran was the most abundant in the rock samples while 1-methy ldibenzofuran appeared to be the least.The relative abundance of benzo[b]naphtho[1,2-d]furan(1,2]BNF),benzo[b]naph-tha[2,1-d]furan(2.1]BNF)and benzo[b]naphtha[2,3-d]fu-ran([2.3]BNF)in the rock extracts range from 12.01%to 52.58%,32.61%to 75.219%and 10.27%to 52.43%.The wide range of values recorded for the three isomers of benzo[b lnapthofurans in the samples suggest source rocks formed from mixed organic matter.Among the pheny ldibenzofuran isomers,4-pheny ldibenzofuran was the most abundant while 1-phenyldibenzofuran was the least.Phenyldibenzofuran ratio-1(PhFR-1)and pheny ldibenzofuran ratio-2(PhFR-2)values range from 0.13 to 1.20 and 0.11 to 2.11,respectively.The resuls showed that the relative abundance of PhFR-1 and PhFR-2 increase gradually with increasing burial depth and maturity(VRo≤0.77%,MPI-1≤0.62.Tmax s 443℃),and have a good correlations with calculated vitrinite reflectance.MPI-I and maximum Temperature(Tmax)-This range of values suggested immature to early mature source rocks.The source rocks were found to have shale and coul lithologics and deposited in a lacustrine/fuvial deltaic settings within immature to early mature stages based on the distribution of dibenzofurans,pheny ldiben-zofurans and benzo[b]naphthofurans in the source rocks.This study showed that dibenzof urans,phenyldibenzofu-rans and benzo[b]naphthofurans were ffcive in deter-mining the origin,depositional environment and thermal maturity of source rocks in Niger Delta basin,Nigeria.
文摘Background: Today’s presence of polychlorinated dibenzofurans (PCDFs) in foodstuff, such as milk and milk products, is considered to be the major concern for human health. This study was aimed to determine the concentrations of the most toxic congeners of furans in pasteurized milk samples produced in southwest Iran. Material and method: 15 composite samples of pasteurized milk were collected from 3 major dairy factories in Khuzestan Province (southwest of Iran) in summer, autumn and winter from July 2011 to March 2012. After precipitation of the proteins, fat phase was reduced and extracted with hexane and ether. After dehydration, furans existed in fat percolated with hexane through a column chromatography that contained respectively silica gel/silver nitrate, silica gel, silica gel/sulphuric acid and with percolating output through another column that contained activated charcoal and silica gel and washed the lower column with a mixture of dichloromethane-hexane and toluene, concentrated and dissolved in mobile phase and analyzed using HPLC: 150 mm × 4.6 mm ID, 5 μm cosmosil 5 NPE column equipped with a UV detector at 254 and 235 nm, mobile phase: methanol/water (80:20, v/v) at flow rate of 1 ml/min. Results: All samples were found to be contaminated with furans. The average concentration of 2,3,7,8 TCDF and 2,3,4,7,8 PCDF were 1.91 pg/g and 1.77 pg/g in lipid content ranging from 2% to 3% respectively. The mean total content of furans in milk fat was 0.36 TEQ (Toxic Equivalency) pg/g which was below the recommended EU (European Union) threshold value 3 pg (WHO-PCDFs-TEQ/g fat). Also, result showed that there were statistically significant differences between each factory during 3 seasons.
文摘2-nitrobenzofuran is studied as dienophile in polar thermal Diels-Alder reactions with normal electron demand using several structurally different dienes. A very strong electron-acceptor group, such as nitro group, enhances the dienophilic character of these heterocyclic compounds and owing to the fact that this substituent is easily extruded under thermal conditions this reaction sequence becomes a simple method of organic compound＇s families with heteroatom rings preparation. Part of this work is specifically concerned with theoretical studies. The global and local electrophilicity and nucleophilicity indexes were calculated for the dienophile and dienes used in this work. A concise synthesis of dibenzofurans has been development via cycloaddition reactions.
文摘We analyzed polychlorinated dibenzofurans (PCDF) and dibenzo-p-dioxins (PCDD) in 27 tree bark samples from the industrialized area near Sauget, Illinois, USA. The trees were located within 4 km of the W. G. Krummrich (WGK) plant, the oldest and largest chemical plant in Sauget, with 24 of 27 samples collected from residential areas. The percent of total PCDF or PCDD profiles of ten 2,3,7,8- Cl substituted PCDF and seven PCDD congeners is homogeneous: 90% of the variance among the samples is explained by 3 eigenvalues in a principal components analysis. The homogeneity of the data suggests that samples were affected by similar types of sources which may have been influenced by electric power generation, chemical waste incineration, and large-scale thermal production of chlorinated chemicals. Quantitatively, the 2,3,7,8-Cl substituted congener analysis does not account for 90% of the concentration of tetra- and penta-Cl homologues and 80% of hexa-Cl and 50% of hepta-Cl homologues. The World Health Organization stated during establishment of toxic equivalence factors (TEF, 2005 version) that calculation of toxic equivalents (TEQs) is not suitable for abiotic matrices, such as tree bark, which are not involved in human exposures. Our results show that the non-2,3,7,8-Cl substituted congeners have high concentrations and should be included in analysis.
基金This work was financially supported by the National Natural Science Foundation of China for outstanding young scientists to Z. T. Wang (No. 39825129).
文摘Two new dibenzofurans, 7,8-dimethoxy-4-methyldibenzofuran-1-carboxaldehyde, named ligumedial (1) and 7,8-dimethoxy-4-methyldibenzofuran-1-carboxylic acid, named ligumediaoic acid (2), have been isolated from the underground parts of Ligularia intermedia. Their structures were elucidated by spectroscopic methods.
基金Supported by the Ph.D. Fund of Ningbo (No. 2004A610010)
文摘Polychlorinated dibenzofurans (PCDFs) represent an important kind of serious pollutant. They are highly toxic and persistent in environment. In this paper, geometrical optimizations and subsequent calculations of electrostatic potentials (ESPs) on molecular surface have been performed for all 135 PCDF congeners at the HF/6-31G* level. The effects of substitution value and variation of substitution position upon the surface ESPs have been discussed. A series of statistic-based structural descriptors derived from the surface ESPs have been calculated. For some PCDF congeners, linear relationships between aryl hydrocarbon receptor (AhR) biding affinity and aryl hydrocarbon hydroxylase (AHH) induction potency as well as theoretical descriptors have been established by multiple linear regression method. It appears that the quantities derived from the surface ESPs, Vs,min, Vs , VS +, σ+ and Nvmin, 2 together with the molecular surface area and the energy gap between HOMO and LUMO can be well used to express the quantitative structure-toxicity relationships of PCDFs.
文摘The thermodynamic properties of dibenzofurans （DFs）, xanthones （XTs） and an-thraquinones （AQs） with one and two positions substituted with hydroxyls in the ideal gas state at 298.15 K and 1.013×10^5 pa were calculated at the B3LYP/6-311G^＊ level using Gaussian 03 program. The isodesmic reactions were designed to calculate the standard free energy of formation （△fG^θ）. Three types of hydrogen bonds exist in the three kinds of chemicals and their bond energies were ascertained as 7-15, 15-23 and 49-58 kJ·mo1^-1 respectively by comparing the △fG^θ values. Electronic density topology analysis was applied to validate the strength of bond.
文摘The research progress on the mechanisms of formation and degradation of polychlorinated dibenzo-p-dioxins ( PCDDs ) and dibenzofurans ( PCDFs ) is reviewed. The primary sources of PCDD/Fs are chemical, thermal, photochemical and enzymatic reactions. Most of the thermal sources result in emissions into air. The studies on the photodegradation and biodegradation offer promise for destruction of PCDD/Fs in environment.
文摘Labeled polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs)were extracted by three different methods,i.e.,soxhlet extraction,hot extraction and accelerated solvent extraction(ASE).The PCDD/Fs were detected by high resolution gas chromatography-high resolution mass spectrometry.Comparisons of the three methods were carried out by recovery of PCDD/Fs,solvent consumption and extraction time.The results showed that all of the method could extract labeled PCDD/Fs efficiently.ASE was a time saving procedure with lowest consumption of solvents compared with the other two methods.
文摘A rapid pretreatment method of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in soil and analysis by high resolution gas chromatograph-high resolution mass spectrometry was present.The extraction and alumina clean up of PCDD/Fs in soil was achieved by accelerated solvent extractor.Then the multi-layer silica-gel column was used for further clean up.The whole method has been evaluated on certified reference soil and farm soil.Accuracy and precision of this method was tested with satisfactory results.
基金Project (Nos. X506312 and X206955) supported by the NaturalScience Foundation of Zhejiang Province, China
文摘Based on the Industrial Source Complex Short-Term Version 3 （ISCST3） model, a simplified modeling approach was developed to predict concentrations of congeners of polychlorinated-p-dioxins and dibenzofurans （PCDD/Fs） of agricultural soil, within a radius of 3 kin from a municipal solid waste incinerator （MSWI） plant after its 4-year operation in Hangzhou, China. Comparisons were made between the measured and estimated congener-specific concentrations and the international-toxic equivalent （I-TEQ） values of soil samples with respect to distance from the stack. The results indicate that the predictions of soil PCDD/F concentrations and K-TEQ values were generally lower than their observations, and that the higher the degree of underestimation seems, the greater the further downwind one gets. Nevertheless, most of the predictions were in good agreement with the trend of measured ones and were within a factor of ten for samples located within 1 kin of the plant. Besides, analysis of contributions of various deposition pathways confirms that in addition to wet particle deposition, the dry gaseous deposition is essential for realistic prediction of PCDD/F depositions to soil, especially for tetra- and penta-chlorinated dioxins.
文摘Pentachlorphenol (PCP) was widely used as a biocide and insecticide for wood preservation. Chlorinated dioxins and furans (2,3,7,8-substituted PCDD and PCDF congeners) were inadvertent byproducts of PCP production. As such, it is an important source of PCDD/F contamination in treated wood and in soil/ sediment near sites that produced or used PCP. It has been noted in the literature, that PCP congener profiles are similar to some combustion profiles, as well as sewage sludge and particulate deposition. In a very broad sense, this is true. OCDD and 1,2,3,4,6,7,8-HpCDD are typically the dominant constituents in these source categories. There is however, a distinct, consistent and repeatable feature in the lower chlorinated tetra, penta and hexa PCDD/F range of PCP related samples: an order of magnitude increase in concentration as a function of degree of chlorination. Because lower chlorinated furans concentrations make up less than 1% of the total PCDD/F in PCP, it is difficult to differentiate PCP from other OCDD dominated source profiles on bargraphs that use a linear-scale y axis. Using a log-scale y axis, however, PCP impacted profiles are obvious, and are not easily confused with congener profiles from other sources.
基金This work was supported by the China Postdoctoral Science Foundation (No. 2003033486)
文摘Optimized calculation of dibenzofuran （DF） and 135 polychlorinated dibenzofurans （PCDFs） was carried out at the B3LYP/6-31G＊ level in GAUSSIAN 98 program. Based on the theoretical linear solvation energy relationship （TLSER） model, the obtained structural parameters were taken as theoretical descriptors to establish the novel quantitative structureproperty relationship （QSPR） model for predicting n-octanol/water partition coefficients （lgKow） of PCDFs. The new model of lgKow achieved in this work contains three variables： energy of the highest occupied molecular orbital （EHOMO）, the most negative atomic partial charge （q^-） and average molecular polarizability （a）, of which R^2= 0.9011 and SD = 0,17 with larger t values. In addition, the variation inflation factors （VIF） of variables in the present model are all less than 5.5, suggesting high accuracy of the lgKow model. And the results of cross-validation test （q^2 = 0.8688） and method validation also show this model exhibits optimum stability and better predictive power than semi-empirical method. At the same time, it is found that the aqueous solubility （-lgSw） has high relative correlation with constant volume molar heat capacity （Cv^0）, of which R^2 = 0.9777 and SD = 0.22. Moreover, lgKow and -lgSw values of all PCDF congeners were predicted respectively.
文摘The adsorption of dibenzofuran on three commercial granular activated carbons (ACs) was investigated by dynamic experiment to correlate the adsorption equilibrium and kinetics with the structure of activated carbons.Physical properties including surface area, average pore diameter, micropore area and micropore volume of the activated carbons were characterized by N2 adsorption experiment on ASAP2010. To calculate the adsorption parameters, adsorption isotherm data were fitted to the Langmuir equation, and adsorption kinetic data were fitted to the linear driving force (LDF) diffusion model. From the correlation results, it is concluded that the adsorption equilibrium and diffusion coefficient of dibenzofuran on activated carbon are controlled respectively by the total adsorbent surface area and the adsorbent pore diameter.
基金supported by the National Natural Science Foundation of China(No.21777172)the Collaborative Project supported by Chinese Academy of Sciences and Hebei Academy of Sciences(No.181602)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2016038)
文摘A field study and theoretical calculations were performed to clarify the levels, profiles, and distributions of polybrominated dibenzo-p-dioxins and dibenzofurans(PBDD/Fs) in a cement kiln co-processing solid waste, with a focus on the PBDF formation mechanism.The raw materials contributed greatly to input of PBDD/Fs into the cement kiln. The PBDD/F concentrations in the raw materials were much higher than those in particle samples from different process stages in the cement kiln. The PBDD/F concentrations in the clinkers were1.40% of the concentrations in the raw materials, which indicated that the high destruction efficiencies for PBDD/Fs by cement kiln. PBDD/F distribution patterns in particle samples collected from different process stages indicated the cement kiln backend was a major site for PBDD/F formation. PBDFs with high levels of halogenation, such as heptabrominated furans(Hp BDF), were the dominant contributors to the total PBDD/F concentrations and accounted for 42%–73% of the total PBDD/F concentrations in the particle samples. Our results showed that co-processing of municipal solid waste in a cement kiln may influence the congener profile of PBDD/Fs, especially for the higher halogenated PBDD fraction. In addition, there were significant correlations between the decabromodiphenyl ether and heptabrominated furan concentrations, which is an indicator of transformation from polybrominated diphenyl ethers to PBDD/Fs. Theoretical calculations were performed and demonstrated that elimination of HBr and Br_2 from polybrominated diphenyl ethers were the dominant formation pathways for PBDD/Fs. These pathways differed from that for polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs).
基金Key Laboratory of Biomass Energy and Material,Jiangsu Province(No.JSBEM201912)Chinese Postdoctoral Science Foundation(Nos.2015M571761 and 2016T90465)for financial support+1 种基金funded by the Priority Academic Program Development of Jiangsu Higher Education InstitutionInstrument and Equipment Foundation of Nanjing University of Science&Technology。
文摘Catalytic hydrodeoxygenation(HDO)is one of the most effective methods to upgrade the oxygen-containing compounds derived from coal tar to valuable hydrocarbons.Herein,an efficient bimetallic catalyst Pt_(1)Ni_(4)/MgO was prepared and applied in the HDO of dibenzofuran(DBF).High yield(95%)of the desired product bicyclohexane(BCH)was achieved at 240℃and 1.2 MPa of H_(2).Superior catalytic performance could be ascribed to the"relay catalysis"of Pt sites and Ni sites,and the reaction pathway is proposed as well.Scale-up experiment and recyclability test were also performed,which demonstrated the recyclability and promising potential application of Pt_(1)Ni_(4)/MgO.
基金National Natural Science Foundation of China (No. 20176012) PRA project (E01-01) the Natural Science Foundation of Guangdong Province
文摘Three kinds of commercial activated carbons, such as Norit RB1, Monolith and Chemviron activated carbons, were used as adsorbents for adsorption of dibenzofuran. The average pore size and specific surface area of these activated carbons were measured. Temperature Programmed Desorption (TPD) experiments were conducted to measure the TPD curves of dibenzofuran on the activated carbons, and then the activation energy for desorption of dibenzofuran on the activated carbons was estimated. The results showed that the Chemviron and the Norit RB1 activated carbon maintained higher specific surface area and larger micropore pore volume in comparison with the Monolith activated carbon, and the activation energy for the desorption of dibenzofuran on these two activated carbons was higher than that on the Monolith activated carbon. The smaller the pore of the activated carbon was, the higher the activated energy of dibenzofuran desorption was.
