好氧生物泥浆法降解土壤中三氯代多氯联苯的影响因素分析

采用好氧生物泥浆法处理多氯联苯（PCBs）污染土壤,基于五因素三水平正交试验探究葡萄糖、联苯、任意甲基化-β-环糊精（RAMEB）、土水比和降解菌剂5个因素对PCBs降解效率的影响.结果表明：在好氧生物泥浆体系中,仅三氯代PCBs含量显著下降（最高降解率为42.1%）,而四氯~七氯代PCBs含量无显著变化.以三氯代PCBs的降解率为试验指标,对正交试验结果进行极差分析,可知影响三氯代PCBs好氧降解率的主次因素依次为：土水比、RAMEB、葡萄糖、降解菌剂、联苯.其中,葡萄糖和联苯对三氯代PCBs的降解有抑制作用,而土水比、RAMEB及降解菌剂对三氯代PCBs的降解有促进作用.因此,通过提升泥浆体系传质水平、提高PCBs生物有效性及增加降解菌数量,有望进一步提高好氧生物泥浆法降解PCBs的效率.     

Potential and Limitations of Microbial Reductive Dechlorination for Bioremediation Applications

Current knowledge and recent advances in the area of microbial reductive dechlorination of polychlorinated organic compounds are summarized. Factors which may limit the efficacy of the dechlorination process for the in situ bioremediation of contaminated soil and sediment systems are identified. Results of recent studies on the anaerobic biotransformation of soil-sorbed chlorinated ethenes and sediment-sorbed chlorinated benzenes are provided to illustrate how low contaminant bioavailability may control the rate and extent of dechlorination in subsurface systems, especially those with long-term contamination. Use of nonionic, polysorbate surfactants as the sole electron donors of a mixed, methanogenic culture supported the microbial sequential reductive dechlorination of either free or sediment-bound hexachlorobenzene (HCB) to primarily 1,3-dichlorobenzene, but did not enhance the bioavailability of sediment-bound HCB as compared to microcosms, which used glucose. Because current knowledge on the interactions of dechlorinating populations with other microbial populations in the presence of alternative terminal electron acceptors (e.g., nitrate, Fe³⁺ , Mn⁴⁺) is limited, such interactions and their effect on the dechlorination process in subsurface systems need to be further explored to improve our understanding of the reductive dechlorination process in complex environmental systems and lead to the development of more efficient in situ bioremediation technologies and strategies.     

Enhanced hepatotoxicity induced by repeated exposure to polychlorinated biphenyls and 2,3,7,8-tetrachlorodibenzo-p-dioxin in combination in male rats

2,3,7,8-Tetrachlorodibenzo-p-dioxin(TCDD) and polychlorinated biphenyls(PCBs) are among persistent polyhalogenated aromatic hydrocarbons that exist as complex mixtures in the environment worldwide.The present study was attempted to investigate the hepatotoxicity following repeated exposure to TCDD and PCBs in combination in male rats,and to reveal the involvement of potential mechanisms.Male Sprague-Dawley rats were exposed to TCDD(10 μg/kg) and Aroclor 1254(10 mg/kg,a representative mixture of PCBs) alone ...     

吉林省公主岭市青少年头发中多氯联苯污染水平的研究

应用气相色谱-质谱（GC-MS）分析了23份采自吉林省公主岭市青少年（12～18岁）头发样品中的30种多氯联苯（PCBs）,并对头发样品中PCBs的构成和来源进行了解析,对其与性别的相关性进行了分析.结果表明,头发样品中PCBs的检出率为100%,PCBs总含量ΣPCBs为（68.85±36.72）ng.g-1,含量范...     

微波诱导金属氧化物去除模拟污染土壤中的PCB77

采用硅藻土模拟实际土壤,选用纳米金属氧化物为催化剂,在密封体系中研究了微波诱导催化反应对PCB77污染土壤的修复效果,考察了微波辐射时间、不同纳米金属氧化物、酸的浓度和类型、MnO2添加量对PCB77去除效果的影响.结果表明,与无微波辐射的对照相比,微波诱导催化反应1 min后PCB77的去除率提高了1倍.仅微波辐射条件下,PCB77的去除率随着辐射时间的增加而提高,10 min趋于平衡.此时,在加入8 mol/L H2SO4体系中PCB77可去除50%;在加入水的体系中,去除率约为20%;而在加入10 mol/L NaOH或无水体系中去除率几乎为0.微波诱导MnO2催化去除PCB77的效果最好,反应1 min去除率高达90%以上,而Fe2O3、CuO和Al2O3的催化去除效果较差.在微波诱导MnO2催化条件下,随着H2SO4溶液浓度从1mol/L增加到8 mol/L,PCB77的去除率从37.0%增加到98.5%,且H2SO4溶液主要是起酸化作用.此外,添加0.01、0.03和0.05g MnO2对PCB77催化去除效果基本相同.     

长江三角洲典型地区农田土壤多氯联苯空间分布特征

在面积为27 km² 的长江三角洲某典型污染地区用GPS定位系统布设了191个取样点,采用GC-ECD法测定了表层农田土壤16种多氯联苯组分及含量.统计结果表明,该典型区农田土壤16种多氯联苯总量变化范围是0.01～484.5 ng/g, 平均值是35.52 ng/g,而且以三氯和四氯联苯为主（占55.7%）,同时也含有一定比例的五氯和六氯联苯（占44.3%）.空间分析发现,该区农田土壤中PCBs总量及其各同系物在所研究的尺度上存在较强的空间自相关格局,其PCBs的空间分布模式主要可能受到一些较为分散的人为因素影响,应重点对当地这些人为活动排污行业进行整治,以消除污染来源.     

超声辅助碱解消除沉积物样品多氯联苯检测中有机氯农药的干扰

将超声辅助碱液分解杂质与溶剂萃取相结合,建立了一种快速高效净化、萃取沉积物中多氯联苯(PCBs)的气相色谱分析方法.超声辅助条件下,在2.0 mol.L-1的NaOH甲醇溶液中超声10 min,利用NaOH甲醇溶液的碱解作用即可使有机氯农药(OCPs)完全分解,在利用有机溶剂萃取沉积物中PCBs的同时消除OCPs等干扰.在优化的实验条件下,PCBs各单体的回收率在72.1%—113.7%,相对标准偏差在0.4%—6.3%(n=6)之间.气相色谱图显示,碱解净化后杂质含量显著减少,基线得以明显改善,能满足定性定量检测的要求.利用建立的方法测定了长江口以南海域表层沉积物中PCBs的含量及其分布,24种PCBs的总含量在39.7—493.4 pg.g-1之间,总体上表现为近岸含量较高,同时自长江口沿闽浙沿岸自北向南呈现增高趋势.     

分子电性距离矢量用于多氯代二苯并呋喃光解半衰期的QSPR研究（Molecular Electronegativity Distance Vector（MEDV）Applied to Quantitative Structure-Property Relationship Study on Photolysis Half-Lives of PCDFs）

多氯代二苯并呋喃(PCDFs)是一种典型的持久性有机污染物(POPs),光解是其在环境中转化的主要途径.以分子电性距离矢量(Molecular Electronegativity Distance Vector,MEDV)为参数,应用多元线性回归(Multiple Linear Regression,MLR)和偏最小二乘回归(PLSR)对48种PCDFs在云杉针叶和飞灰表面的光解半衰期(t1/2)进行模拟分析,均获得由2个变量所建的定量结构-性质相关(QSPR)模型.多元线性回归结果:建模相关系数(R)分别为0.860和0.836,标准偏差(SD)分别为0.052和0.053,交互检验复相关系数(Rcv)分别为0.839和0.807,外部检验相关系数(Qex)t分别为0.939和0.853;偏最小二乘回归结果:建模相关系数(R)分别为0.857和0.829,交互检验复相关系数(Rcv)分别为0.849和0.807.结果表明,MEDV能较好地表征该类分子的结构信息,所建QSPR模型具有良好的稳定性和预测能力.     

Hydrothermal treatment of MSWI fly ash for simultaneous dioxins decomposition and heavy metal stabilization

Researches on the hydrothermal treatment of municipal solid waste incineration (MSWI) fly ash were conducted to eliminate dioxins and stabilize heavy metals. In order to enhance decomposing polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzo-furans (PCDFs) during hydrothermal process, a strong reductant carbohydrazide (CHZ) is introduced. A hydrothermal reactor was set up by mixing raw MSWI fly ash or the pre-treated fly ash with water and then heated to a pre-set temperature; CHZ was spiked into solution according to specially defined dosage. Experimental results showed that under the temperatures of 518 K and 533 K, the decomposition rates of PCDDs/PCDFs were over 80% and 90%, respectively, by total concentration. However, their toxic equivalent (TEQ) decreased only slightly or even increased due to the rising in concentration of congeners 2, 3, 7, 8-TCDD/TCDF, which might be resulted from the highly chlorinated congeners losing their chlorine atoms and being degraded during the hydrothermal process. Better results of TEQ reduction were also obtained under the higher tested temperature of 533 K and reactor with addition of 0.1%wt CHZ was corresponded to the best results. Good stabilization of heavy metals was also obtained in the same hydrothermal process especially when ferrous sulphate was added as auxiliary agent.     

强化的零价铁PRB技术对PCBs污染地下水的修复

本实验强化了零价铁可渗透反应墙（Permeable Reactive Barrier,PRB）技术,分别用还原铁粉、还原铁粉＋锌粉、还原铁粉＋活性炭为主要的反应介质,以Arcolor1242为靶污染物,对强化的零价铁PRB技术治理多氯联苯污染的地下水的可行性和有效性进行了模拟研究。实验结果表明：在温度10℃,有效孔隙率为61%~67%,水的渗透速度为0.7~0.8 m.d-1的条件下,3个反应柱稳定期对PCBs的去除率分别达到94%、85%、79%,pH值从6.87升高到8.78、10.2、7.93;氧化还原电位从-48.6 mV降到-135、-107、-86.4 mV;出水铁离子的平均质量浓度为0.241、0.129和0.201 mg.L-1,脱氯率平均值为49.6%、72.6%、58.6%。综合考虑处理效果与成本,用零价铁PRB技术治理PCBs污染的地下水是可行的。