Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in surface sediment and bivalve from the Changjiang Estuary, China

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.

Polychlorinated dibenzo-p-dioxins and dibenzofurans in flue gas emissions from municipal solid waste incinerators in China

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.

Surface Electrostatic Potentials of Polychlorinated Dibenzofurans and Their Applications in Quantitative Structure-toxicity Relationships

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.

EXAMINATION OF POLYCHLORINATED DIBENZO-P-DIOXINS AND POLYCHLORINATED DIBENZOFURANS INTO PROCESS WATER OF KRAFT PULP BLEACHING MILL FROM ASPECT OF ENVIRONMENTAL WATER QUALITY

Process water of a pulp mill with kraft cooking, oxygen delignification and chlorine bleaching or chlorine dioxide (ECF) bleaching was examined from an aspect of a new level for environmental water quality in Japan. According to the new level, a concentration of dioxins consisting of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (PCBs) in environmental water is restricted to less than 1 pg- TEQ/L. We clarified that the 2,3,7,8-tetrachlorodibenzofuran (TCDF) concentrations were 0.5 pg/L or less. In addition, a main source of 1,3,6,8- and 1,3,7,9-tetrachlorodibenzo-p-dioxins in the process water seemed to be an agrochemical in water supplied from a river.

Polychlorinated Dibenzofurans and Dibenzo-p-Dioxin in Tree Bark from an Industrialized Area: What the 2,3,7,8-Cl Substituted Congeners Tell Us, and What Is Missing

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.

电性拓扑态指数预测PCDFs光解半衰期

以电性拓扑态指数(E-state indices)为参数,应用偏最小二乘法(PLS)对48种多氯代二苯并呋喃(PCDFs)在云杉(Picea abies)针叶和飞灰表面的光解半衰期(t1/2)进行模拟分析,分别获得5变量和4变量定量结构-性质相关(QSPR)模型.模型交叉验证相关系数(Qc2um)分别为0.758和0.701,标准偏差(SD)分别为0.047和0.049,模型具有较高的预测能力和可靠性.随着氯原子取代数目的增多,PCDFs与活性氢供体接触的“位阻效应”增大,PCDFs分子中苯环的静电荷密度随之降低,以致高氯代PCDFs较难发生光解作用.

六六六热解废渣中2,3,7,8-取代PCDDs和PCDFs的测定

采用HPLC和GC/MS法对六六六热解废渣中的PCDDs和PCDFs进行了测定.使用此种方法,于废渣中检出了所有2,3,7,8-取代的同系物.此外,还根据各CDDs、CDFs的毒性当量因子TEFs,计算了废渣的毒性当量TEQs,约为612一924μg/g.分析表明,OCDD是含量最丰富的异构体,而 1,2,3,4,6,7,8-HpCDD,1.2,3,4,6,7,8-HpCDF和1,2,3,4.7.8-HXCDF则是最重要的成份,它们构成废渣TEQs的绝大部分.

PCDFs的Ah受体结合能力的定量结构效应关系

应用单苯环氯取代方法取G1～G10 10个分子结构描述符,通过正向逐步线性回归方法构建对于Ah受体结合能力的定量结构-性质相关(QSAR)模型.与有关文献相比,此模型能更好地预测多氯代二苯并呋喃(PCDFs)竞争结合Ah受体logEC50值,各自变量间不存在共线性.模型可以较好地反映PCDFs分子Ah受体结合能力与其分子氯取代位点之间的关系.

应用分子电性距离矢量预测二噁英类化合物PCDFs的正辛醇水分配系数

应用分子电性距离矢量对 13 5种二英类化合物多氯代二苯并呋喃 (PCDFs)的结构进行了表征 ,通过多元线性回归方法建立了PCDFs的正辛醇 水分配系数与分子电性距离矢量之间的定量关系模型 ,与有关文献报道的模型相比 ,该模型具有显著的相关性 (n =51,R =0 .92 7,Sd =0 . 193 62 ,F =44.8697) .另外采用逐步回归的方法 (SMR)从原模型参数中选取了 2个参数建立了一新模型 ,其模型相关系数为R =0 . 92 4;继以留一法进行交互检验 ,其相关系数与之接近 ,R =0 .910 。

Determination of the Most Toxic Polychlorodibenzofurans in Fresh Milk from Southwest Iran

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.

某生活垃圾焚烧厂排放废气、飞灰、环境空气和土壤中各二噁英类单体分布特征

以某生活垃圾焚烧企业为研究对象,研究其烟道气废气、焚烧飞灰、企业周边环境空气和土壤中二噁英的水平和各二噁英类单体指纹分布特征,研究结果表明,废气中的二噁英呈现出冬季稍高于夏季的排放特征,呋喃对总∑TEQ的贡献率范围为72%-90%.飞灰作为垃圾焚烧中二噁英的主要捕集途径,TEQ浓度季度变化比废气更加明显,呋喃对总∑TEQ的贡献率范围为74%-81%.环境空气和土壤中二噁英的季度分布特征与废气、飞灰的分布特征一致,且主导风向土壤中二噁英的TEQ浓度明显高于次主导风向.环境空气单体指标中呋喃对总∑TEQ的贡献率与废气和飞灰规律一致,说明该区域环境空气中的二噁英与企业排放废气中的二噁英具有同源性.与废气、飞灰和环境空气相比,土壤中呋喃与二噁英的比值和呋喃对总∑TEQ的贡献率存在差异,说明土壤中的二噁英并非单一来源于企业排放废气.废气、飞灰、企业周边环境空气和土壤中的17种PCDD/Fs单体中含量最丰富的是O8CDD,PCDDs的浓度随着取代氯原子个数的增加而增大.17种PCDD/Fs单体中对毒性当量贡献最大的单体是2,3,4,7,8-P5CDF.2,3,7,8-T4CDD是引起废气中二噁英排放呈现出冬季稍高于夏季的特征污染因子,需要重点关注.

Polychlorinated dibenzo-p-dioxins and dibenzofurans in different tissues of the cormorants (Phalacrocorax carbo) from Dongting Lake,China

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.

A novel molecular distance edge vector as applied to chemical modeling of quantitative structure-retention relationships:Various gas chromatographic retention behaviors of polychlorinated dibenzofurans on different polarity-varying stationary phases

Based on the identical group as a pseudo atom instead of a typical atom, a novel modified molecular dis-tance-edge (MDE) vector μ was developed in our laboratory to characterize chemical structure of polychlorinated diben-zofurans (PCDFs) congeners and/or isomers. Quantitative structure-retention relationships (QSRRs) between the new VMDE parameters and gas chromatographic (GC) retention behavior of PCDFs were then generated by multiple linear regression (MLR) method for non-polar, moderately polar, and polar stationary phases. Four excellent models with high correlation coefficients, R=0.984-0.995, were proposed for non-polar columns (DB-5, SE-54, OV-101). For the moder-ately polar columns (OV-1701), the correlation coefficient of the developed good model is only 0.958. For the polar col-umns (SP-2300), the QSRR model is poor with R=0.884. Then cross validation with leave-one out of procedure (CV) is performed in high correlation with the non-polar (Rcv=992-0.974) and weakly polar (Rcv=921) columns and in little cor-relation (Rcv=0.834) with the polar columns. These results show that the new μ vector is suitable for describing the re-tention behaviors of PCDFs on non-polar and moderately polar stationary phases and not for the various gas chroma-tographic retention behaviors of PCDFs on the different po-larity-varying stationary phases.

Estimation of n-Octanol/water Partition Coeffi-cients(lgK_(ow)) and the Aqueous Solubility(-lg_(Sw)) of all PCDF Congeners by Density Functional Theory

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.

Aspects of formation and degradation of polychlorinated dibenzo-p-dioxins and dibenzofurans

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.

Quantitative structure-retention relationship for polychlorinated dibenzofurans based on molecular interaction field analysis

A new quantitative structure-retention relationship (QSRR) model is developed for polychlorinated dibenzofurans (PCDFs) based on molecular interaction field (MIF) analysis. The MIF of all 135 PCDFs is calculated using DRY, C1= and C3 probe, characterizing the hydrophobic and steric interaction between PCDFs and different groups of stationary phase. Then QSRR model is constructed by multiblock partial least squares (MBPLS), and the significance of each block is evaluated by the block importance in the prediction (BIP) method. The model used for prediction is statistically significant, with calibration and cross-validation correlation coefficients 0.9990 and 0.9980 respectively, and relative error less than 1.0%. The results of MBPLS and BIP show that the steric properties have dominant influence on the retention behavior of PCDFs, and then the hydrophobic effects.

生活垃圾焚烧厂周边住宅小区内二噁英类物质的暴露特征及健康风险评估

以长江中下游地区某生活垃圾焚烧处理厂为监测对象,研究其主导上、下风向住宅小区内的环境空气、土壤和室内积尘等各环境介质中二噁英的浓度水平和分布特征。研究结果表明,该生活垃圾焚烧厂排放废气中的二噁英毒性当量浓度为0.007~0.064 ng·m^(-3),满足《生活垃圾焚烧污染控制标准》(GB 18485—2014)中规定的二噁英毒性当量限值0.1 ng·m^(-3)。4个住宅小区内环境空气、土壤和室内积尘中二噁英毒性当量浓度分别是0.12~0.19 pg·m^(-3)、1.1~4.8 ng·kg^(-1)和1.1~5.3 ng·kg^(-1),均处于较低水平。住宅小区内环境空气中二噁英的浓度呈现出秋冬季稍高于春夏季的现象,与废气中二噁英排放特征一致,下风向小区C和小区D环境介质中二噁英的浓度明显高于其他点位,说明本研究区域内的二噁英主要来源于该生活垃圾焚烧厂,在秋冬季要加强焚烧企业的管控力度。通过比较同一住宅小区、同一监测时段室内积尘和土壤监测数据发现,室内积尘对人体的暴露风险要大于土壤暴露风险。通过人群健康风险评估发现,儿童的呼吸暴露量是成人的4倍,儿童经口摄入土壤或室内积尘的日均暴露量是成人的10倍,儿童的暴露应该得到更高的重视。

气相色谱/高分辨质谱联用测定环境样品中的二噁英和类二噁英多氯联苯

样品采用索氏抽提,抽提液依次经酸性硅胶床、多段混合硅胶柱和凝胶渗透色谱柱(GPC)净化后,用Florisil硅藻土柱分离出样品中的二噁英(PCDD/Fs)和类二噁英多氯联苯(dioxin-like PCBs),采用同位素稀释法和气相色谱/高分辨质谱联用仪(GC/HRMS)测定了其中的17个2,3,7,8-氯取代二噁英类化合物和12个类二噁英多氯联苯。结果表明,用该法分析二噁英和多氯联苯标准溶液,平行4次的分析结果为:RSD(PCDD/Fs)<8.9%,RSD(PCBs)<11.4%;回收率可达60%-105%。PCDD/Fs和PCBs的检出限分别为0.1-0.8 pg/g和0.05-0.6 pg/g。应用本方法成功测定了沉积物、淤泥、土壤和飞灰中的二噁英和类二噁英多氯联苯,并计算出它们的毒性当量。

“永固紫”染料和四氯苯醌中多氯代二苯并二噁/呋喃的分析

采用浓硫酸对5种不同来源的四氯苯醌和“永固紫”染料样品进行溶解分散,用甲苯提取和多层色谱柱纯化,利用同位素稀释法及高分辨气相色谱质谱(HRGCHRMS)联用技术,测定了其中的多氯代二苯并二口恶口英呋喃(PCDDF)的质量比。结果表明“永固紫”染料及其原料中PCDDF的质量比异常高,八氯代二苯并二口恶口英呋喃(OCDDF)已达到μgg级甚至100μgg级,七氯代二苯并二口恶口英呋喃(HpCDDF)和六氯代二苯并二口恶口英呋喃(HxCDDF)质量比也达到ngg级。所有样品的毒性当量浓度(TEQ)均已超过10pgg的危险水平,是纺织品中PCDDF的一类重要污染源。并进一步探讨了PCDDF的来源。

模拟烟气中痕量有机污染物生成的在线实时监测

多环芳烃和二恶英是两类剧毒的持久性有机污染物,为了研究其生成和排放过程,需要开发一种能用于烟气的实时检测方法。该文采用高分辨力的真空紫外光电离/微型正交加速型电离飞行时间质谱仪(VUV-TOF-MS),对由聚氯乙烯(PVC)在氮气流中热解形成的模拟烟气中多环芳烃和二恶英的前驱物进行了实时在线检测。然后和离线方法的分析结果进行对比,给出了烟气中多环芳烃和二恶英前驱物的实时浓度曲线。再根据三氯苯和二恶英的转化率,估算出二恶英的在线浓度范围。同时根据对烟气中多环芳烃和二恶英前驱物的时间行为特征的研究,讨论了PVC热解时多环芳烃和二恶英前驱物的发生机理和成长途径。