烷基化多环芳烃的细菌降解研究进展

烷基化多环芳烃（alkylated polycyclic aromatic hydrocarbons, A-PAHs）是以多环芳烃（PAHs）为母环,具有烷基侧链的稠环芳香烃,是一类在环境中广泛存在的持久性有机污染物.微生物降解是其在环境中降解去除的主要途径,与真菌、藻类等相比,细菌降解A-PAHs得到更多的关注.本文对APAHs的污染现状及生态毒性,细菌降解甲基萘、甲基菲的研究进展进行了概述,以PAHs的降解酶和降解基因作为参考,总结了A-PAHs可能涉及的降解酶及降解基因.本文有助于了解环境中A-PAHs的生物降解研究现状,为寻找高效的A-PAHs降解方法及减轻其生态风险提供理论依据.     

红树林生态系统多环芳烃的污染研究进展

多环芳烃（PAHs）是一类广泛存在于天然环境中的持久性有机污染物,对生态环境和人类健康造成严重的潜在威胁。文章介绍了红树林生态系统PAHs污染的研究现状;总结了红树林生态系统PAHs的污染分布及其来源,以及PAHs污染胁迫对红树植物生长的影响;评述了红树植物对PAHs的直接吸收、红树林湿地微生物对PAHs的降解等研究;最后,对红树林生态系统PAHs污染的研究趋势进行了分析和展望,提出了今后可能的研究方向,主要包括：（1）综合应用多学科交叉研究典型PAHs在红树林生态系统中的环境行为;（2）结合双光子激光共焦扫描显微技术等原位研究手段,开展红树植物对典型PAHs的吸收、存赋形态、转运等相关研究;（3）结合激光诱导时间分辨荧光光谱测定系统,实现对现场红树林生态系统中PAHs等有机污染物的原位检测。     

微生物修复土壤多环芳烃污染的研究进展

多环芳烃是一类具有致癌、致畸、致突变性质的持久性有机污染物,主要来源于煤、石油等燃料的不完全燃烧,易吸附于固体颗粒表面和有机腐殖质,化学结构稳定,能长期存在于自然环境,给人类健康和生态环境带来很大的危害。中国土壤多环芳烃污染严重,因此急需寻求有效的修复方法进行治理。在众多的多环芳烃污染修复方法中,微生物修复因其低成本、高效、污染少等优点成为研究热点。科学家们从自然界中分离出了多种细菌、真菌等具有降解多环芳烃能力的微生物,并对多环芳烃的降解机理进行了探索,结果表明,微生物在代谢活动过程中能够产生酶来实现对土壤中多环芳烃的降解。细菌主要通过产生双加氧酶来催化多环芳烃的加氧反应,而真菌可以通过分泌木质素降解酶系或单加氧酶来氧化多环芳烃。两种途径均是首先通过降低多环芳烃的稳定性,使之容易被进一步降解。目前,微生物修复技术正逐步应用于PAHs污染土壤的实地修复,且已取得一定成效。文章简要介绍了降解多环芳烃的微生物,对多环芳烃的微生物降解机制进行了综述,讨论了影响微生物修复过程的因素,列举了常见的微生物修复相关技术,展望了今后的研究趋势。     

海洋环境中多环芳烃的微生物降解研究进展

多环芳烃 (PAHs)是一类广泛分布于海洋环境中的含有两个苯环以上的有毒有害污染物 ,主要来源于人类活动和能源利用过程 ,如石油、煤、木材等的燃烧过程 ,石油及石油化工产品的生产过程 ,海上通过地面径流、污水排放及机动车辆等燃料不完全燃烧后的废气随大气颗粒的沉降进入海洋环境中 .由于多环芳烃的潜在毒性、致癌性及致畸诱变作用[1,2 ] ,通过生物累积及食物链的传递作用 ,给海洋生物、生态环境和人体健康带来极大危害 ,已引起各国环境科学家的极大重视 .美国环保局在上世纪 80年代把 16种未带分支的多环芳烃确定为环境中的优先污染物[…     

液相色谱法测定大气样品中多环芳烃的方法优化

优化了液相色谱法测定大气样品中多环芳烃(PAHs)的前处理净化手段,相较于弗洛里土柱,硅胶能有效去除仪器分析中目标物定性和定量分析的背景干扰.通过控制样品溶剂转换时浓缩体积,提高了低环数多环芳烃的回收率,各目标物的空白加标回收率在53%—128%之间(RSD20%).使用高效液相色谱(HPLC)二极管阵列/荧光检测器联用测定大气中的PAHs,当以100 L·min~(-1)采样24 h时,16种PAHs的方法检出限为0.08—0.29 ng·m~(-3),定量下限为0.32—1.16 ng·m~(-3).通过对实际样品的测定,验证了方法的可行性.     

气相色谱-质谱联用测定土壤及底泥样品中的多环芳烃和硝基多环芳烃

采用气相色谱-质谱联用法测定了某化工厂火灾后周边土壤和底泥中的多环芳烃(PAHs)和硝基多环芳烃(Nitro-PAHs).结果表明,距离爆炸地点最近的几个采样点PAHs的含量均在16.61μg·g-1以上,其中厂东北采样点的PAHs总含量甚至高达417.4μg·g-1,污染最为严重;部分样品中检测到三环以下的硝基多环芳烃,三环以上的几乎均未检出.说明在燃烧爆炸过程中产生了多环芳烃,但没有显著产生高致癌性、致突变性的硝基多环芳烃.     

土壤和地下水中多环芳烃生物降解研究进展

多环芳烃是一类普遍存在于环境中的难降解的危险性"三致"有机污染物。受污染的土壤和地下水中的多环芳烃,生物降解是其归宿的主要途径。研究表明,对于土壤中低分子量多环芳烃类化合物,微生物一般以唯一碳源方式代谢;而大多数细菌和真菌对四环或四环以上的多环芳烃的降解作用一般以共代谢方式开始。文章重点论述了多环芳烃的来源、降解多环芳烃的微生物、生物降解机理、影响生物降解的因素以及生物修复方法。认为今后的研究方向是高分子量多环芳烃的降解机理与降解途径,基因工程技术在多环芳烃生物降解方面的应用,以及生物表面活性剂产生的机理及其在实际处理中的应用等。     

土壤多环芳烃污染根际修复研究进展

多环芳烃(polycyclicaromatichydrocarbons,PAHs)是环境中普遍存在的具有代表性的一类重要持久性有机污染物,具“三致性”、难降解性,在土壤环境中不断积累,严重危害着土壤的生产和生态功能、农产品质量和人类健康。修复土壤多环芳烃污染已成为研究的焦点。根际修复是利用植物-微生物和根际环境降解有机污染物的复合生物修复技术,是目前最具潜力的土壤生物修复技术之一。对国内外学者近年来在土壤多环芳烃污染根际修复的效果、根际修复机理和根际修复的影响因素方面的研究进展作了较系统的综述,并分别分析了单作体系、混作体系、多进程根际修复系统和接种植物生长促进菌根际修复系统对土壤多环芳烃的修复效果。指出根际环境对PAHs的修复主要有3种机制:根系直接吸收和代谢PAHs;植物根系释放酶和分泌物去除PAHs,增加根际微生物数量,提高其活性,强化微生物群体降解PAHs。并讨论了影响根际修复PAHs的环境因素如植物、土壤类型、PAHs理化性质、菌根真菌以及表面活性剂等。植物-表面活性剂结合的根际修复技术、PAHs胁迫下根际的动态调节过程、运用分子生物学技术并结合植物根分泌物的特异性筛选高效修复植物以及植物富集的PAHs代谢产物进行跟踪与风险评价将成为未来研究的主流。     

氯代多环芳烃的污染现状及毒性研究进展

氯代多环芳烃(chlorinated polycyclic aromatic hydrocarbons,Cl-PAHs)是一种多环芳烃的氯代衍生物,具有与二噁英相似的毒性效应,并且在各种环境介质中广泛存在。Cl-PAHs已成为一种新型有机污染物,对生态环境和人体健康造成潜在的威胁。本文从Cl-PAHs的来源、污染现状、毒性效应与人体健康风险评价等几个方面对国内外有关Cl-PAHs的研究现状和最新进展进行了系统综述。     

东莞市夏季大气颗粒物中的多环芳烃及硝基多环芳烃

以东莞市2011年夏季不同区域的大气颗粒物为研究对象,定性定量分析了其中多环芳烃(PAHs)及硝基多环芳烃(NPAHs)的浓度、组成.采用特征比值法分析了PAHs及NPAHs的来源,并通过PEFs毒性评价法评价了颗粒物中多环芳烃及硝基多环芳烃的BaP等效毒性,估算出个体致癌指数.结果表明东莞市颗粒物上16种多环芳烃总含量在12.60—193.95 ng·m-3范围内,6种硝基多环芳烃的总含量在5.88—62.79 ng·m-3,隧道环境中多环芳烃及硝基多环芳烃的浓度最高.除隧道环境中颗粒物的等效毒性及个体致癌指数超标外,东莞市颗粒物上PAHs及NPAHs对人体均不构成严重威胁.     

Toxic equivalency factor approach for risk assessment of polycyclic aromatic hydrocarbons

The toxic equivalency factor (TEF) method has been developed to evaluate structurally related compounds, sharing a common mechanism of action. Because certain polycyclic aromatic hydrocarbons (PAHs) appear to fit this requirement and are ubiquitous environmental contaminants, these compounds are TEF candidates. Toxicity is often expressed relative to benzo[a]pyrene (BaP), the reference standard (e.g., TEF = EC50_BaP/EC50_PAH). BaP‐like toxicity or toxic equivalents (TEQs) can then be calculated: TEQ = S(PAH _i × TEF _i ), where PAH _i and TEF _i are the concentration and TEF, respectively, for individual PAH congeners. Representative TEFs for PAHs were compiled from studies measuring carcinogenic potency and surrogate biomarkers. This review examines the application of TEFs to PAHs with established criteria (i.e., demonstrated need, defined chemical grouping, broad toxicological database, endpoint consistency, additivity, common mechanism of action, consensus). Although all criteria are not satisfied (e.g., endpoint inconsistency, nonadditivity) and more rigorous validation studies are needed, the TEF method is useful when limitations are recognized. Refinements of the method might include incorporation of pharmacokinetic factors and segregation of TEFs derived from mammalian vs. nonmammalian systems to increase endopoint consistency. Probabilistic analysis may also prove useful to assess the range of TEF values reported both within and between human health and ecological risk assessments.     

Urban fractionation of polycyclic aromatic hydrocarbons from Dalian soils

This report evidences the fractionation of polycyclic aromatic hydrocarbons (PAHs) from urban to rural areas, and a higher contribution of coal and wood combustion in rural areas. PAHs are persistent semi-volatile organic pollutants in the environment. PAHs originate from the incompleted combustion of fossil fuel and biomass. Cities are usually considered as primary sources of PAHs. Due to different types and loads of fuel consumption in various functional areas of a city, the levels and composition profiles of PAHs are expected to be different. We, therefore, studied the mechanisms ruling PAH distributions in soils from a major Chinese city. Seventeen soil samples were collected in urban traffic areas, residential and park areas, suburban areas and rural areas of Dalian, northeastern China. PAHs were analyzed using a high-performance liquid chromatography. The composition profiles and seasonal variation of PAHs were investigated. Results show that the proportions of low-weight molecular PAHs to total PAHs increased with urban-suburban-rural gradient. This trend is explained by the “urban fractionation” of PAHs. Furthermore, the spring/autumn ratios of PAH concentrations were higher than 1. Specifically, the spring/autumn ratio was 1.79 for two ring PAHs, 1.42 for three ring PAHs, and lower than 1.20 for five and six ring PAHs. The spring/autumn ratios of phenanthrene were higher than 1 and increased with increasing distance from the urban areas. The results imply that the contribution of coal and wood combustion PAHs increases with the urban-suburban-rural gradient.     

Sampling of airborne polycyclic aromatic hydrocarbons with semipermeable membrane devices

Semipermeable membrane devices (SPMDs) are nowadays used as passive samplers of organic pollutants. The knowledge of the sampling rate values (R_S) of each substance trapped on membranes is necessary to calculate their average concentration. Here we calculate R_S values for 16 polycyclic aromatic hydrocarbons using the comparison of active sampling method results and the amounts sequestered by SPMDs at varying exposure times.Selected article from the Regional Symposium on Chemistry and Environment, Krusevac, Serbia, June 2003, organized by Dr. Branimir Jovancicevic.     

半透膜被动采样装置(SPMDs)对PAHs 和壬基酚类的静态富集

半透膜采样装置(SPMDs)是一种被动采样装置,它能模拟有机污染物穿过生物膜从水相到生物有机相的分配平衡过程,使得结果能显示出污染物的生物可利用性。它能对环境中有机污染物进行长时间连续监测,所得的是污染物被SPMD富集后的时间权重浓度。本实验测定了温度为18℃时标准SPMD对7种PAHs和3种NPnEO(n=0～2)的静态富集过程,通过测定污染物达到平衡时在SPMD内的浓度和在水相中浓度的比值,求解了各自的SPMD/水分配平衡常数KSPMD。表明了有机污染物在SPMD和水相之间达到分配平衡所需要的时间是随着其Kow值的增高而逐渐增长的,还与其各自的分子极性有关,并且几种达到富集平衡的PAHs在SPMD内的浓度也是随着其Kow值的增高而逐渐变大。比较KSPMD的理论值和实测值可以发现,对于PAHs而言,其实测值都高于理论值,而NPnEO都是实测值低于其理论值。但是KSPMD实测值和理论值随污染物Kow值变化的趋势相同。     

环境中的氧化多环芳烃综述

氧化多环芳烃(OPAHs)是芳环上具有至少一个羰基氧(C=O)的PAH衍生物,广泛存在于环境中.氧化多环芳烃主要通过含碳燃料的燃烧和PAHs的转化释放到环境中,且其较稳定难降解,因此OPAHs被称为生物和化学降解的"末端产物".目前,在多种动物组织样本中都可检测出OPAHs,并发现OPAHs可能比亲代PAHs具有更强的毒性.本文阐述了OPAHs的理化性质、来源、测定方法、环境分布、转运和转化、(生态)毒理学效应及其毒性作用机制,并对今后的研究方向进行了展望,进而为该类化合物的环境污染及生态风险评估提供相应参考.     

Analysis of polycyclic aromatic hydrocarbons by sensitized room temperature phosphorescence

Direct and selective simultaneous determination of several polycyclic aromatic hydrocarbons by sensitized room temperature phosphorescence in sodium dodecylsulphate micellar solutions was studied. This approach improved, for example, the selectivity factor in determining pyrene in the presence of fluoranthene by a factor of 350, and determined benz[a]anthracene and anthracene in the presence of pyrene with the selectivity factors as high as 200–220. Triphaflavine and acridine orange as triplet energy donors, thallium (I) nitrate as a heavy atom, and sodium sulphite were used as scavengers of oxygen. A comparative study of linear concentration ranges, detection limits and selectivity factors is presented here for pyrene, benz[a]anthracene and anthracene determination by fluorescence, phosphorescence and sensitized phosphorescence. Electronic Publication     

Phylogenetic analysis of hyperaccumulator plant species for heavy metals and polycyclic aromatic hydrocarbons

Increasing concentration of heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) in the soil may impose a serious threat to living organisms due to their toxicity and the ability to accumulate in plant tissues. The present review focuses on the phylogenetic relationships, sources, biotransformation and accumulation potential of hyperaccumulators for the priority HMs and PAHs. This review provides an opportunity to reveal the role of hyperaccumulators in removal of HMs and PAHs from soils, to understand the relationships between pollutants and their influence on the environment and to find potential plant species for soil remediation. The phylogenetic analysis results showed that the hyperaccumulators of some chemicals (Co, Cu, Mn, Ni, Zn, Cd) are clustered on the evolutionary tree and that the ability to hyperaccumulate different pollutants can be correlated either positively (Cd–Zn, Pb–Zn, Co–Cu, Cd–Pb) or negatively (Cu–PAHs, Co–Cd, Co–PAHs, Ni–PAHs, Cu–Ni, Mn–PAHs). Further research needs to be extended on the focus of commercializing the techniques including the native hyperaccumulators to remediate the highly contaminated soils.