表面活性剂洗脱污染土壤中多氯联苯(PCBs)的研究与应用

多氯联苯(PCBs)为一类在环境中广泛分布且难以降解的持久性有机污染物。利用表面活性剂亲油和亲水的两亲特性．将多氯联苯从土壤中洗脱出来，从而修复受污染土壤是当前环境研究的热点之一。文章综述了近年来国内外使用表面活性剂溶液修复多氯联苯污染土壤的研究进展。表面活性剂对土壤中多氯联苯的洗脱作用主要是：(1)表面活性剂通过减小液一固之间的表面张力，将阻塞在土壤孔隙中的多氯联苯分散到溶液中来；(2)表面活性剂通过形成胶束，促使多氯联苯从土壤中重新分配到疏水的胶束核中。洗脱效果与表面活性剂种类、性质、质量浓度及土壤成份有关，通常非离子型表面活性剂效果较好，对多氯联苯的洗脱可达86％。含多氯联苯洗脱液可利用生物降解、紫外光照射及焚烧等方法进行后续处理。     

生物表面活性剂鼠李糖脂对PCBs污染土壤的修复作用研究

利用生物表面活性鼠李糖脂（RL）洗脱土壤,再通过紫外光预照射与生物降解协同去除洗脱液中的PCBs的组合方法对多氯联苯（PCBs）污染土壤进行修复,旨在研究RL在修复PCBs污染土壤中的作用及其机理。结果表明,RL对PCBs的洗脱具有显著的促进作用,PCBs的总洗脱率与RL的质量浓度呈正相关。当洗脱液中加入2 000 mg.L-1的RL,在3次批洗脱后,人工污染土样和陈化土样的PCBs总洗脱率分别达到了90.1%和47.1%。PCBs降解菌P.LB400在以RL或联苯为碳源的驯化培养基中均能够快速生长。当土壤洗脱液中的PCBs被P.LB400的生长细胞菌液降解时,RL对PCBs的生物降解具有显著的促进作用;而在P.LB400的休眠细胞降解体系中,RL对PCBs的生物降解有一定的抑制作用。紫外光预照射对土壤洗脱液中PCBs的生物降解有一定的促进作用。紫外光预照射和生物降解的耦合有利于提高PCBs的降解速率。     

生物与化学表面活性剂对多氯联苯的协同增溶作用

采用室内序批试验比较研究了单一的生物/非离子化学表面活性剂(SAA)与生物-非离子混合表面活性剂对商业用多氯联苯(PCBs)Aroclor1242的增溶作用.结果表明,生物表面活性剂鼠李糖脂(RL)对Aroclor1242的增溶作用要高于三种非离子SAA,三种非离子SAA对Aroclor1242的增溶作用顺序为POE(6)＞POE(10)＞Brij35,与其亲水亲油平衡值(HLB)呈负相关;鼠李糖脂与非离子SAA对Aroclor1242的增溶存在协同效应,混合表面活性剂溶液中Aroclor1242的摩尔增溶比(MSR)、胶束相/水相间的分配系数(Kmc)均大于对应的单一表面活性剂,其协同增溶作用顺序为RL-Brij35＞RL-POE(10)＞RL-POE(6),协同增溶作用的大小与其中的非离子表面活性剂的HLB值呈正相关.     

多氯联苯复合污染土壤的微生物群落结构多样性变化

土壤微生物群落结构多样性是指示土壤生态系统稳定性及其功能的重要传感器。采用磷脂脂肪酸(Phospholipid fatty acids,PLFAs)方法,对长江三角洲地区某POPs高风险区PCBs长期复合污染土壤的微生物群落结构多样性进行了初步研究。结果表明,PCBs重度污染土壤中格兰氏阴性菌(16:1w9、cy17:0等)和厌氧微生物(18:1w7)的PLFAs组分含量较多,而格兰氏阳性菌(如i15:0、i17:0等)、放线菌(16:0(10Me))及真菌(18:2ω6,9)和好氧性微生物的PLFAs含量较低,表明PCBs污染土壤中微生物群落结构与组成发生了明显变化。这一结果为PCBs降解微生物资源的定向筛选提供了科学依据。     

Detection of polychlorinated biphenyls employing chemical dechlorination followed by biphenyl whole cell sensing system

Polychlorinated biphenyls (PCBs) are a mixture of 209 individual chlorinated compounds commonly known as PCB congeners. These compounds are hydrophobic and are persistent in the environment. Their use was banned in the US a few decades ago because of harmful health effects. Therefore, detection of PCBs in environmental samples is increasingly important. To that end, we have developed a two-step simple and sensitive method for the detection of total PCBs. Specifically, our method involves dechlorination of PCBs to biphenyl followed by detection of biphenyl using a whole cell sensing system as the detection system. The whole cell sensing system consists of cells of the strain Pseudomonas pseudoalcaligenes KF707 harboring plasmid pSD7000. Plasmid pSD7000 contains the gene of lacZ, a reporter protein under the control of the bph operon. The detection is achieved through the emission of light afforded by the expression of reporter protein triggered by the presence of biphenyl. Due to the fact that this operon is activated only by few PCB congeners, a chemical dechlorination method was employed to convert all PCBs to biphenyl, and thus all the PCBs present in a given sample are able to be detected. The results showed that PCB congeners were rapidly (30?min) and efficiently (>98.5%) dechlorinated to biphenyl using a Mg/K₂PdCl₆ catalyst, and the biphenyl could be subsequently quantified using the whole cell sensing system. This hybrid analytical method that combines classical dechlorination with novel biosensing methods may find applications in the on-site monitoring of PCBs contamination levels.     

Distribution patterns of polychlorinated biphenyls in soils collected from Zhejiang province, east China

Polychlorinated biphenyls (PCBs) were determined in surface soil samples from Zhejiang Province, east China. Concentrations of total PCBs ranged widely from 7.50 to 263 ng kg⁻¹ with a mean value of 45.4 ng kg⁻¹ (dry matter basis). In general, concentrations in soil samples from the southern part of the test area and especially from some sites near hills tended to be higher than those from other sites. The prevailing winds may have been the main factor influencing the spatial distribution of PCBs in soils. Other factors may have included the distribution of residential areas and land use variables. In this paper we also discuss the relationships between OCPs and PCBs in soils and relationships between these and land use variables as revealed by correlation analysis.     

电子垃圾拆解区土壤中典型手性PCBs分布及对映体特征

龙塘镇位于广东省清远市,是国内最大的进口电子垃圾集中处理处置地之一.通过对龙塘镇土壤中7种手性PCBs对映体浓度和对映体百分数(enantiomer fractions,EF)值的测定,发现龙塘镇土壤样品除PCB45和PCB174外,其余5种手性PCBs在土壤中均有不同程度的检出.土壤中5种目标手性PCBs(PCB91...     

Contamination and source assessment of metals,polychlorinated biphenyls,and polycyclic aromatic hydrocarbons in urban soils from Addis Ababa,Ethiopia

Urban areas in developing countries are facing vast environmental problems as a result of rapid urbanization and industrialization. Of major concern is the contamination of soils which are increasingly becoming sinks for environmental pollutants. However, to date only little is known about the pollution in the megalopolises of developing countries. The aim of this study was to assess the contamination and potential sources of metals, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in the urban environment of Addis Ababa, the capital of Ethiopia. The investigation revealed the presence of most of the analyzed pollutants in soil and sediment samples with total concentrations (dry wt) of PAHs ranging from 186 to 3150?µg?kg^?1, PCBs from 0.4 to 19?µg?kg^?1, Cu from 14 to 173?mg?kg^?1, Zn from 36 to 440?mg?kg^?1, Pb from 9 to 700?mg?kg^?1, and Ni from 16 to 72?mg?kg^?1. In addition, polyaromatic sulfur heterocycles, typical for oil and petrol residues, were detected in several soil samples. Source identification approaches revealed that Pb, Zn, and Cu are most likely derived from pyrolytic sources, with elevated values in samples related to waste combustion and traffic emissions. Ni is most probably of geogenic origin. For PCBs it is indicated that they are derived from a single source. However, correlations with technical PCB mixtures were inconsistent. PAHs originate from the combustion of biomass, vehicular exhausts, and petrogenic sources.     

Distribution of polychlorinated biphenyls and polybrominated diphenyl ethers in soils of a previous E-waste processing center

Surface soil samples were taken from a previous electronic waste (E-waste) recycling centerin Taizhou area, Zhejiang province, China. Concentrations, profiles, and possible sources of 19 polychlorinated biphenyls and 7 poly-brominated diphenyl ethers were analyzed to assess their current state in the soil after phase out of massive dismantling of E-wastes. The concentrations of the 7 polybrominated diphenyl ethers ranged from 11 to 128 µg kg^?1 with an average of 41 ± 10 µg kg^?1 (dw), with 2,2′,4,4′-tetrabromdiphenyl ether being the most abundant. These values were substantially lower than the levels in 2006. The concentrations of the 19 polychlorinated biphenyls ranged from 36 to 760 µg kg^?1, with an average of 181 ± 68 µgkg^?1 (dw) which was also lower than the levels in 1995 or 2006. However, the concentrations of some tetra-, penta- and hexa-chlorobiphenyls were comparable or even higher than before. Furthermore, the average concentration of 7 indicator polychlorinated biphenyls was 108 ± 41 µg kg^?1(dw) which exceeded the New Dutch List target value of 20 µgkg^?1. Principal component analysis indicated that polychlorinated biphenyls were mainly distributed into three groups in accordance with the number of chlorine atoms and anthropogenic source. Therefore, the impact of the historical dismantling of E-wastes is still significant.     

Uptake of polychlorinated biphenyls from sea water by Gammarus oceanicus

The uptake of a polychlorinated biphenyl preparation containing 5 to 7 chlorine atoms/molecule, solubilized in a nonionic surfactant in sea water, by Gammarus oceanicus was measured spectrophotometrically. Uptake occurred in living animals across the general integument. It is suggested that uptake rates are dependent upon the total surface area of the integument, although no accurate method of determining this is known. The rate of uptake decreased after 4 to 6 hours exposure and uptake was dependent upon concentration of polychlorinated biphenyls in sea water. The stage of the intermoult of G. oceanicus did not affect uptake rates.     

金属及其氧化物催化降解多氯联苯的研究进展

催化降解因其高的反应速率和降解彻底性,在氯代有机物的削减中得到广泛应用.目前研究较多的催化剂为零价态和氧化态的碱金属和碱土金属、过渡金属及贵金属,包括单金属和双金属两种.这类催化剂表面活性位点多样,在氯代有机物的降解中显示出优异的活性.多氯联苯(Polychlorinated Biphenyls,简称PCBs)是一类有毒难降解的持久性有机污染物.本文阐述了不同价态的单金属和双金属催化剂催化降解PCBs的反应机理,并介绍了影响反应速率和产物选择性的因素.并对金属及其氧化物催化降解PCBs的应用现状做了评述,对该技术的发展进行展望.     

不同水源灌溉的农田表层土壤中多氯联苯和多溴联苯醚的浓度分布特征

本工作主要关注北京郊区污水河、地下水及混合水源灌溉的3块农田的表层土壤中,26种多氯联苯(PCBs)和14种多溴联苯醚(PBDEs)的浓度分布特征,并对目标污染物各单体浓度之间的相关性进行了统计学分析.结果显示,所有供试表层土壤样品中共检出26种PCBs(∑26PCBs),浓度水平范围为130—1.93×103ng.kg-1干重.检出的PCBs种类包括12种共平面多氯联苯异构体(15.6—433 ng.kg-1干重),6种指示型多氯联苯异构体(50.7—452 ng.kg-1干重)和其它8种多氯联苯同系物(52.1—1.15×103ng.kg-1干重).同时还检出14种多溴联苯醚同系物(∑14PBDEs),浓度水平范围为1.81—14.4μg.kg-1干重,其中十溴联苯醚(BDE-209)为最主要的组分,约占总组分94%以上.污水河河水和地下水混合灌溉的农田中PCBs和PBDEs的浓度大于地下水灌溉农田中的含量.此外,在所有样品中发现高氯代的多氯联苯同系物(氯原子数≥4)浓度之间存在显著的相关性,可能与灌溉水源和土壤对高氯代联苯的强保留等因素有关.     

重金属污染土壤植物修复研究进展

土壤重金属污染是当今世界面临的主要环境问题之一.植物修复定义为利用绿色植物去除环境中的污染物或使其无害化的生物技术.与传统环境修复技术相比,植物修复技术具有治理成本的低廉性,环境美学的兼容性,治理过程的原位性.本文主要对超富集植物的概念和特征、土壤重金属污染植物修复的方法和原理以及土壤重金属植物修复技术的强化措施进行了综述,并对植物修复的近期研究工作进行了展望.     

土壤重金属化学形态的生物可利用性评价

重金属化学形态是近年来土壤化学、植物营养和环境科学研究领域的一个热点和难点,利用重金属的化学形态分布和含量变化来评价重金属的生物可利用性,有利于全面研究重金属的危害性和治理重金属污染土壤。结果表明,水溶态和交换态的重金属易被生物吸收利用,而残留态重金属一般不被生物利用,其它形态如碳酸盐结合态、铁锰氧化物结合态和有机物结合态的生物可利用性主要取决于外界环境的变化。     

北部湾潮间带沉积物中重金属和多氯联苯的分布特征及生态风险评价

选择北部湾9个典型采样点,研究了潮间带沉积物中重金属和多氯联苯(PCBs)的分布特征和生态风险.分析结果表明,Hg、As、Cu、Pb、Zn、Cd、Cr等重金属和总PCBs的平均含量分别为0.100、10.00、19.89、45.97、208.65、0.098、17.86 mg.kg-1和1.48!g.kg-1.重金属和PCBs表现出不同的空间变化规律.相关性分析表明,北部湾潮间带的重金属主要来自人为污染;沉积物的粒度参数和有机质含量等性质特征是影响PCBs分布和迁移的重要因素;重金属和PCBs总量之间不存在明显的相关性.生态风险评价结果表明,PCBs和Cd是北部湾潮间带最主要的生态风险因子,Zn和PCBs是优势污染物;研究区域总体处于中等生态风险等级,表明沿岸港口和临海工业等人为活动已经对北部湾滨海地区造成了一定的环境压力.     

北京市大气中多氯联苯的污染水平和分布特征

利用XAD树脂被动采样技术和同位素稀释高分辨气相色谱/高分辨质谱联用法(HRGC/HRMS)研究了2012年11月至2014年1月北京地区大气中多氯联苯(PCBs)的污染现状、区域分布特征及季节性变化规律.结果表明,北京大气中19种PCBs总浓度为8.42—45.2 pg·m-3(平均值23.1 pg·m-3),各采样点全年平均毒性当量范围为0.33—3.33 fg WHO-TEQ m-3(平均值1.85 fg WHO-TEQ m-3).PCB-11浓度范围为27.9—136pg·m-3,平均值为78.2 pg·m-3.大气中的PCBs以低氯代(2—5氯代)PCBs为主.季节变化规律呈现出夏/秋季节PCBs浓度高于冬/春季节的规律;区域分布特征呈现出人口密集的城区大于背景区、工业区大于城区的规律.     

Monitoring and risk assessment of polychlorinated biphenyls (PCBs) in agricultural soil from two industrialized areas

For monitoring and risk assessment, levels and distributions of Σ₂₉ PCBs in paddy soil samples collected from Gwangyang (10 sites) and Ulsan (20 sites), heavily industrialized cities in Korea, were investigated using high-resolution gas chromatography/high-resolution mass spectrometry. Overall, total concentrations of Σ₂₉ PCBs in Gwangyang (216.4–978.6 pg g^?1 dw) and Ulsan (273.8–1824.1 pg g^?1 dw) were higher than those (106.6–222.6 pg g^?1 dw) in agricultural soil from Anseong in Korea. The TEQ (toxic equivalency) values from Gwangyang (0.06–0.40 ng TEQ kg^?1 dw) and Ulsan (0.06–0.22 ng TEQ kg^?1 dw) were higher than those (0.04–0.11 ng TEQ kg^?1 dw) in Anseong but lower than the WHO threshold level (20 ng TEQ kg^?1). However, one of the most toxic congeners, PCB 126, gave the highest concentration, possibly posing a risk to the biota. Seven indicator PCB congeners contributed to 50–80% of the total concentration of Σ₂₉ PCBs, indicating the 7 PCBs can be used as valuable indicators for monitoring. The principal component analysis and cluster analysis for the homologue profiles of PCBs indicated that all the samples from both cities had the similar PCB contamination patterns, and the major sources of the PCB contamination were most likely from the usage of Aroclor 1254 than those of Aroclors 1242 and 1260. These PCB technical mixtures were possibly significantly used by various industries including iron and steel industries in Gwangyang and petrochemical and shipbuilding industries in Ulsan.     

污染土壤中菲的修复技术研究进展

菲是多环芳烃中的代表性物质,具有"三致"效应,而且菲的蒸汽压小,辛醇-水分配系数高,生物可利用性低,是一种持久性有机污染物。随着化石燃料的大量使用,受菲污染的土壤越来越多,研究菲的修复技术对污染土壤的再利用具有重要意义。结合目前国内外研究进展,综述了污染土壤中菲的修复方法,包括物理修复、化学修复和生物修复。针对各种修复方法,阐述了其原理、修复条件、实例应用和优缺点,重点论述了植物修复和微生物修复方法的降解机理和应用,分析了微生物性质,包括氧、营养物、温度、土壤理化性质、共存污染物等环境因素对生物降解的影响。由于溶解性的菲有较好的迁移转化能力,因此表面活性剂的助溶作用适用于各种修复方法,选择合适的表面活性剂可以提高修复效果。在各种修复技术中,物理修复是通过物理技术实现菲的解吸与富集,无污染,但是去除率低;化学修复是使用氧化剂将菲氧化分解成无毒易降解的小分子物质或通过添加化学淋洗剂增加菲的溶解性,提高迁移转化能力,用时短,但是引入其他试剂,容易造成二次污染;植物修复是通过植物的提取、降解和固定等过程实现菲的修复,尤其是植物的根际环境为微生物的生长提供有利的条件;微生物修复以菲可作为微生物生长的碳源为基础,在分解酶的作用下实现菲的降解,但是生物修复周期长,可利用的生物少,而且可能生成毒性更高的中间代谢产物。因此,寻找合适的修复物种,采用基因技术提高生物的修复能力或多法联用、取长补短可提高修复效率。最后,在共降解理论的基础上,结合重金属和有机污染物共存时,一种物质的存在对另一种物质的降解有促进作用,提出了协同降解的概念,寻求对多种污染物有协同降解或共降解作用的修复方法是今后发展的主要方向。     

Cement-based solidification/stabilization of contaminated soils by nitrobenzene

The cement-based solidification/stabilization (S/S) of nitrobenzene (NB) contaminated soils, with cement and lime as binders, sodium silicate solution and powder activated carbon (PAC) as additives, was optimized through an orthogonal experiment, and S/S efficiency was estimated by both leaching test and volatilization measurement. The leaching test results showed that the factors affecting S/S efficiency were NB concentration, cement-to-lime ratio and binder-to-soils ratio, in sequence. With increasing curing time, the leaching concentration of NB between different levels of the same factor in the orthogonal experiment decreased, and less than 9% NB leached out from the 28 d cured samples. The volatilization measurement results indicated that 0.5‰ of NB was volatilized during the mixing and curing processes for the samples without PAC in the 28 d cycle, whereas adding 2 wt% and 5 wt% PAC, with respect to the weight of contaminated soils, could reduce NB volatilization to half of its original values either during the mixing or curing process. The optimizing formula, that is, contaminated soils (dry weight):cement:lime= 100:25:25, with 5 wt% additional sodium silicate and 2 wt% additional PAC, was applied to the engineering application of NB contaminated soils. Both the leaching test results of the product and the ambient air quality monitoring results met related regulations during the treating process.