Mineralization of aqueous pentachlorophenolate by anodic contact glow discharge electrolysis

Exhaustive mineralization of pentachlorophenolate ion (PCP) in phosphate buffer was carried out using anodic contact glow discharge electrolysis (CGDE), in which plasma was sustained between the electrolyte and anode. During CGDE, PCP degraded smoothly. The amount of total organic carbon decreased significantly, indicating the eventual conversion of the carbon atoms of benzene nucleus to inorganic carbons. Furthermore, chlorine atoms in PCP were liberated as chloride ions. As a primary intermediate product, 2,3,5,6- tetrachloro-1,4-benzoquinone was detected, and oxalate and formate as byproducts were also found. It was revealed that disappearance of PCP obeyed first-order kinetics. The reaction rate was generally unaffected by both O2 and inert gases in the cell, although it decreased by raising initial pH of solution. In addition, a plausible reaction pathway involving hydroxyl radical was proposed.     

二氧化锰氧化降解五氯酚

以二氧化锰为氧化剂,研究了pH 4.12的水溶液中五氯酚氧化降解的反应动力学,并讨论了反应溶液的pH对反应动力学的影响.结果表明,五氯酚对二氧化锰的氧化作用具有较强的反应感受性.在pH一定和二氧化锰充分过量的条件下,随着反应的进行,五氯酚的降解速度变慢,遵循的不是简单的准一级反应动力学而是复合的反应动力学.此外,随溶液pH由3.5升高6.6,五氯酚的降解速度发生显著地下降.运用溶剂萃取和气质联用仪的分析方法,检测到2个主产物和1个次产物.其中,次产物是由四氯-1,4-氢醌与四氯儿茶酚组成的混合物;2个主产物是由五氯酚氧自由基偶合而成的二聚体,且是同分异构体.在观测到的表面反应动力学和降解产物的基础上,提出了五氯酚被二氧化锰氧化降解的反应流程图.     

稀有鮈鲫HMGR基因全长克隆及雄鱼经五氯酚暴露基因表达的分析

3-羟基-3-甲基戊二酰辅酶A还原酶(3-hydroxy-3-methylglutaryl coenzyme A reductase,HMGR)是甲羟戊酸(mevalonic acid,MVA)途径中的第一个关键限速酶.克隆稀有鮈鲫HMGR基因全长,分析该基因在不同组织及雄鱼经不同浓度五氯酚(pentachlorophenol,PCP)暴露的表达差异,探索PCP对类固醇激素前体(胆固醇)合成水平基因转录调控的内分泌干扰机制.采用同源克隆策略及cDNA末端快速扩增技术(rapid-amplification of cDNA ends,RACE),从稀有鮈鲫肝脏中首次克隆得到3 101碱基(bp)的HMGR基因cDNA全长,基因命名为GrHMGR(GenBank accession No:KF885724).GrHMGR编码884个氨基酸,系统发育树分析表明,GrHMGR编码的蛋白与其他鱼类来源的HMGR氨基酸序列同源性较高.Real-time PCR分析表明GrHMGR的表达有组织特异性,在大脑,性腺和肝脏中均有表达,性腺中表达量最高.稀有鮈鲫雄鱼经不同浓度PCP暴露后,GrHMGR在大脑和性腺的表达随PCP浓度的增加显著下降,然而在肝脏组织中表达趋势有所不同.HMGR的表达下降会减少胆固醇的合成.说明PCP暴露会通过干扰稀有鮈鲫的胆固醇合成途径,进而对内分泌系统产生影响.     

Polychlorinated dibenzo‐p‐dioxins and dibenzofurans (PCDD/Fs) in dated environmental samples,and their connection to known sources

This article investigates available environmental data from measurements of the everywhere present contaminants polychlorinated dibenzo‐p‐dioxins and dibenzofurans (PCDD/F) in dated trends in sediment, soil and herbage from locales in Europe and North America. The PCDD/F data are examined in relation to potential major PCDD/F sources based on volume: wood and coal, example of natural combustion; pentachlorophenol (PnCP), example of chlorinated aro‐matics; and polyvinyl chloride (PVC) pyrolysis, example of chlorinated aliphatic. Collected PCDD/F data of congener sums and 2, 3, 7, 8‐substituted congener (PCDD/F profiles) have been investigated with multivariate methods: principal component analysis (PCA) and partial least squares projection to latent structures model (PLS). The results show that PCDD/F data from 12 locales can be separated in one to three independent profiles. Normally one profile is related to the PCDD/F found in PnCP and another to combustion. A subtype of the ‘PnCP’ and ‘combustion’ profiles indicates PCDD/F contributions from PVC‐related combustions. The environmental profiles exhibit some differences from the suggested sources. The relatively unprotected PCDD/F related to PnCP is suggested to have passed photolytic and/or thermal dechlorinations. Lower‐chlorinated congeners in environmental profiles related to combustion appear to have been influenced by environmental distribution processes. PCDD/F data before industrial production of chlorinated organics have only limited similarity to PCDD/F in technical PnCP profiles; an average 4.6% of the PCDD/F is related to PnCP. This suggests that PnCP similarity in recent deposition profiles cannot be a result of environmental transformation. The average proportion of PnCP‐related PCDD/F profile in recent depositions is 35% with North America high (average 57%) and Europe low (average 24%).     

Uptake and toxicity of some pesticides on three freshwater fishes (Oreochromis niloticus,Clarias gariepinus and Chrysicthys nigrodigitatus)

Studies were carried out to determine the toxicity of some selected pesticides on fresh water fish in a tropical environment. The uptake of the pesticides lindane, pentachlorophenol (PCP), and propoxur, which are frequently used by farmers and industrialists were studied in concrete ponds at the University of Cape Coast, in Ghana. The fishes used for the study were Oreochromis niloticus, Clarias gariepinus, and Chrysicthys nigrodigitatus, and were obtained from cultured ponds in the Cape Coast District and Mankessim in the Central Region and Weija Dam, in the Greater Accra region of Ghana. Single high lethal concentration (SD) or acute treatment and cumulative/chronic (or multiple minor) lethal concentration (CD) treatment were employed in administering the pesticides to the fishes via water. Gas chromatograph (GC) Electron Capture Detector (ECD) analysis was done on the dead fishes to see the extent of ingestion. The LC₅₀ values obtained for lindane on the three fish samples were as follows: Chrysicthys?–?0.38?mg?L^?1; Oreochromis?–?0.42?mg?L^?1, and Clarias?–?1.2?mg?L^?1. Mortalities occurred in fish within 3–5 days of application. For the PCP on Chrysicthys, Oreochromis, and Clarias species the LC₅₀ values were 0.42, 0.32 and 0.64?mg?L^?1, respectively for over a 2–3 day period. For a three-time influx period of propoxur the LC₅₀ for Chrysicthys, Oreochromis, and Clarias, were 22.0, 30.40, and 45.04 (all in mg?L^?1), respectively. The results obtained indicated that the pesticides had adverse effects on the general growth and reproduction of fishes. Gonadosomatic indices also showed that the pesticides affected the development of the body, the gonads, and their reproduction.     

生物炭对水中五氯酚的吸附性能研究

利用小麦秸秆和花生壳在300,400,600℃条件下制备生物炭,运用元素分析仪、扫描电镜和比表面积仪对生物炭的理化性质进行表征,同时探讨其对水中五氯酚(PCP)的吸附特性.结果表明,随炭化温度升高,生物炭芳香性增加,极性降低.花生壳生物炭对水中PCP的吸附效果优于小麦秸秆生物炭,3种温度制备的生物炭对PCP吸附量表现为400℃>600℃>300℃.随着生物炭添加量增大,水中PCP去除能力由81.79%提高至89.02%,生物炭的吸附量由30.32减小至5.54mg/g.生物炭对PCP的吸附动力学更符合准二级动力学方程,吸附等温线符合Freundlich方程.吸附过程主要受快速反应控制,降低反应温度有利于生物炭对水中PCP的吸附.     

Mechanochemical decomposition of pentachlorophenol by ball milling

The mechanochemical dechlorination of pentachlorophenol (PCP) was studied using CaO and SiO2 powder as additives. The e ects of the milling time and additives on the dechlorination rate were investigated. The resulting product was characterized by X-ray di raction (XRD), Fourier transform infrared spectra (FT-IR), thermogravimetric analysis (TG) and ion chromatography (IC). It is found that grinding operation could dechlorinate PCP, with the formation of inorganic chloride and amorphous carbon. The addition of quartz to the grinding mixture facilitated dechlorination. On the basis of the experimental results, the decomposition mechanism was proposed. Decomposition predominantly proceeds through rupture of C–Cl bond in PCP molecule, followed by the formation of inorganic chlorides.     

利用基因芯片探讨五氯酚发育毒性的作用机制

0hpf斑马鱼胚胎经50μg/L五氯酚(PCP)暴露染毒8 h,提取其总RNA,与Affymetrix公司的斑马鱼基因组芯片杂交.发现与对照组相比,染毒样本中1 149个基因的表达显著增强(Signal log ratio1),501个基因的表达显著减弱(Signal log ratio-1).利用Chipinfo、Genmapp等生物信息学软件对差异表达基因进行了基因本体论功能分类和发育调控通路分析,结果显示,显著差异表达的基因涉及抗氧化、信号传导、翻译调节、转录调节等多个分子功能.五氯酚暴露后斑马鱼胚胎发育重要的调控通路BMP信号、ERK通路、FGF信号、Nodal信号的调控基因smad2、smad5、bmp4、bmp7f、lh、n-ras的表达发生了显著变化,Signal logratio分别为4.6、2.1、1.6、1.0、1.3、1.0.这些结果为进一步阐明五氯酚的发育毒性作用机制提供了标志物.     

五氯酚对HeLa细胞毒性及DNA损伤的研究

以人宫颈癌HeLa细胞为研究对象,运用MTT法检测PCP处理后HeLa细胞的增长抑制率;通过测定细胞培养液中乳酸脱氢酶(LDH)的漏出率和总超氧化物歧化酶(SOD)的活性,评价PCP的细胞毒性作用;彗星实验检测HeLa细胞经不同浓度PCP处理后的DNA损伤.结果表明,PCP对HeLa细胞的半数抑制浓度(IC50)为66.59μmol.L-1;HeLa细胞在12.5、25、50、100和200μmol.L-1 PCP染毒条件下,LDH的漏出率随着染毒时间的增加逐渐增大,具有明显的时间-效应关系,在12.25、17.5和25μmol.L-1 PCP染毒下,细胞培养液中SOD的活性随着染毒时间的增加逐渐下降,存在显著的时间-效应关系,低浓度PCP(25μmol.L-1)显著增加细胞培养液中LDH的漏出率以及PCP(12.25μmol.L-1)显著降低总SOD的活性;PCP(实验浓度为6.25、12.5、25和50μmol.L-1)不会导致HeLa细胞DNA损伤.因此SOD和LDH可作为评价低浓度PCP毒性效应的敏感性生物标志物.     

生活垃圾不同填埋阶段的富里酸对五氯苯酚的降解

采用紫外和红外光谱对不同填埋年限生活垃圾的富里酸(fulvic acid,FA)的结构组成和官能团变化进行分析,并对不同填埋阶段富里酸(FA)的电子转移能力和其对五氯苯酚(pentachlorophenol,PCP)的降解能力进行研究.结果表明,以S.oneidensis MR-1作电子供体,同时添加不同阶段填埋富里酸作电子穿梭体可以显著提高PCP的降解率,降解率能达到80%以上.不同填埋阶段富里酸对PCP的降解有不同的还原转化能力的原因是氧化还原性质存在差异.填埋富里酸具有PCP还原转化能力又归因于其具有电子转移能力,这些功能都利于促进PCP还原脱氯.而填埋富里酸电子转移特性主要源于其结构中含有的电子转移功能基团,其中羟基和羧基是填埋过程富里酸分子中重要的活性官能团,其含量高低将影响PCP还原脱氯效率.