【作者】 范国兰；

【导师】 崔兆杰；

【作者基本信息】 山东大学 ， 环境工程， 2008， 博士

【摘要】 多氯联苯（PCBs）是持久性有机污染物（POPs）的一类,具持久性、半挥发性、生物蓄积性、高毒性等特点,是《关于持久性有机污染物的斯德哥尔摩公约》中规定的首批控制消除的12类污染物之一。类二噁英类多氯联苯（DL-PCBs）是指邻位上没有或只有一个氯原子取代基的PCBs,具有12种同系物,是PCBs中毒性最强的一类。虽然DL-PCBs在环境和生物样品中的含量较低,但毒性贡献值却比较高,因此在生物体中PCBs的研究,DL-PCBs更为重要,是目前国内外研究的热点领域。本研究在详细查阅和系统分析国内外相关研究的基础上,建立了植物中DL-PCBs的分析方法,进一步分析了黄河三角洲地区植物中DL-PCBs的含量和污染情况,对污染物来源进行了识别,探讨了DL-PCBs在不同植物中的积累特点和差异,得出了DL-PCBs在植物体不同部分中的分布规律。（1）植物中痕量DL-PCBs分析方法的研究与建立植物中PCBs分析存在杂质干扰多、目标污染物含量低等问题,目前针对植物样品中痕量DL-PCBs的研究很少,迫切需要建立简便快速的专属性分析方法。因此,本研究从样品的前处理技术开始,通过优化改进实验条件和参数,建立了简便快速的植物中DL-PCBs的分析方法,可以实现植物样品中痕量DL-PCBs的定性定量分析。具体条件及结果如下:样品前处理。通过对索氏提取条件参数的优化研究,得出最佳条件:利用200mL正己烷/丙酮（1:1V/V）混合溶剂,回流速度4次/h索氏提取20-30g（干重）植物样品24h。提取后的萃取液用浓硫酸/高锰酸钾进行处理,然后用Florisil柱净化。样品中DL-PCBs分析。采用弱极性和中极性双毛细管柱色谱互补分离技术结合GC/MS分析样品中的DL-PCBs,该方法可以很好的将DL-PCBs同其它PCBs异构体和有机氯农残的干扰组分彼此分开,能够有效的分析植物样品中的DL-PCBs。研究结果表明,12种DL-PCBs的加标回收率在75.56%-87.42%之间,植物样品平行测量的相对标准偏差在3.60%-14.53%,符合美国EPA标准中回收率（70%-140%）及环境样品精密度相对标准偏差（＜20%）的要求。（2）黄河三角洲地区典型植物中DL-PCBs的含量及来源为了研究黄河三角洲地区植物中DL-PCBs的含量和来源,于2006年10月对黄河三角洲地区白茅（Imperata cylindrical var.major）、芦苇（Phragmitesaustralis（Cav.）Trin.ex Steud）、碱蓬（Suaeda Heteroptera）、柽柳（Tamarixchinensis Lout.）、柳树（Salix matsudana Koidz.）五种典型植物及对应土壤中DL-PCBs含量进行了测定。其中,植物中DL-PCBs总量的含量范围为575.48-819.23ng/kg,DL-PCBs各同系物的含量范围为2.32-237.36ng/kg;植物所对应土壤中DL-PCBs总量的含量范围为147.75-505.58ng/kg,DL-PCBs各同系物的含量范围为2.48-403.58ng/kg。DL-PCBs在黄河三角洲地区植物和土壤中的含量不论从总量还是同系物水平上均比文献报道中的其它地区低。通过对土壤和植物中DL-PCBs各同系物浓度的相关分析,得出植物中DL-PCBs的浓度与土壤不显著相关,这说明黄河三角洲植物中的DL-PCBs主要来源不是土壤,根据DL-PCBs的辛醇-空气分配系数(k_oa)和辛醇-水分配系数(K_ow)的数值范围,结合其它同类研究的结果,可以判断大气是其主要来源。（3）黄河三角洲地区典型植物对DL-PCBs的积累特点通过对DL-PCBs在黄河三角洲地区三种一年生植物（白茅、芦苇、碱蓬）和两种多年生植物（柽柳、柳树）体内及相应土壤中浓度的分析比较,研究了DL-PCBs在不同种类植物中的总量和成分差异性,从DL-PCBs的辛醇-空气分配系数、同系物种类、植物的分类和生长时间等方面阐明了造成这种差异的原因。主要研究结果如下:①不同种类植物中积累的DL-PCBs的总量和成分差异性白茅中DL-PCBs总量（575.48ng/kg）在五种植物中最低,其它四种植物间无显著差异;12种DL-PCBs在所有植物样品中均有检出,其中只有PCB126在各植物间的积累水平相同,另外,PCB77、PCB81、PCB114、PCB123和PCB156在三种以上植物中存在显著差异,差异最大的PCB81在柽柳中的含量是白茅中含量的72倍。②植物中DL-PCBs积累的影响因素DL-PCBs的K_oa对植物积累量的影响。通过对log K_oa与C植物/C白茅（芦苇、碱蓬、柽柳、柳树四种植物中DL-PCBs含量与白茅中DL-PCBs含量比值）之间的关系分析,当logK_oa为8.46时,C植物/C白茅的数值为2.0-72.3,当logK_oa为11.25时,C植物/C白茅为0.7-1.5。由此可见,植物积累DL-PCBs的种间差异程度随着辛醇-空气分配系数的增大而减少,K_oa是DL-PCBs在不同植物间积累量产生差异的重要影响因素。植物类型对植物积累DL-PCBs量的影响。通过对五种植物中12种DL-PCBs浓度的聚类分析知,五种植物中,白茅和芦苇的积累方式最为相似,因为它们属于同一个科—禾本科,所以相对于其它植物而言,白茅和芦苇对DL-PCBs的积累最相似。植物组织的不同生长时间对积累DL-PCBs特性的影响。通过对植物中的DL-PCBs浓度与log K_oa的相关分析发现,碱蓬、芦苇、白茅三种一年生植物中二者相关（p＜0.05）,相关系数分别为0.354,0.464,0.390,而多年生植物中二者相关性不显著。由此可以看出多年生植物和一年生植物对DL-PCBs的积累特点不同,这是由于多年生植物中不同生长时间的组织对DL-PCBs的积累存在差异,一年生组织的生物量在整株中所占的比例较小,因此多年生植物中的DL-PCBs浓度与log K_oa没有体现出显著的相关性。（4）黄河三角洲地区典型植物不同组织中DL-PCBs的分布规律选取一年生植物碱蓬、多年生植物柳树两种植物于2007年11月进行研究,通过对碱蓬的地上、地下部分和柳树的叶、根及不同生长时间的枝条中DL-PCBs浓度的测定,探讨不同植物组织中DL-PCBs的分布规律。①碱蓬不同部分中DL-PCBs的分布规律实验结果表明,碱蓬地上部分的DL-PCBs含量显著高于地下部分,总浓度分别为1263.33ng/kg和889.47ng/kg。从DL-PCBs同系物的组分在碱蓬不同部位的分析结果看,PCB81、77、123、118、114在碱蓬地上部分的积累浓度显著高于在地下部分中的积累浓度,而其它7种DL-PCBs同系物间差异不显著,低氯代的DL-PCBs更容易在碱蓬的地上部分积累。②柳树不同组织中DL-PCBs的积累分布规律通过对柳树各组织中DL-PCBs含量的测定,得出叶中总含量为3054.64ng/kg,根中总含量为704.28ng/kg,一二三四级枝条中总含量分别为538.58、770.75、714.65、552.59ng/kg。以上结果可见,在柳树的六种组织中,叶中DL-PCBs总含量最高;枝条中DL-PCBs总含量从高到低依次为:二级枝条＞三级枝条＞四级枝条＞一级枝条;根中的DL-PCBs总含量与三级枝条相似,与其它组织差异显著。根据柳树各部分中DL-PCBs同系物含量的测定结果知,叶片中12种DL-PCBs同系物浓度均高于其它各部分,各级枝条和根中的各DL-PCBs同系物并未表现出明显的差异性。③DL-PCBs在两种植物不同组织中分布规律的影响因素通过对碱蓬和柳树中DL-PCBs总含量与植物中粗脂肪含量的相关分析知,二者不显著相关。将碱蓬和柳树各部分中的DL-PCBs总含量与植物中的总有机碳含量进行相关分析研究发现,碱蓬和柳树各部分中的DL-PCBs总含量与总有机碳含量的关系都呈显著负相关,相关系数为-0.661,-0.854（p＜0.05）。这是因为,DL-PCBs的积累没有总有机碳的积累快,生长稀释的作用造成了总有机碳含量高的部位DL-PCBs含量反而少的趋势。更多还原

【Abstract】 Polychlorinated biphenyls（PCBs） are a group of persistent organic pollutants （POPs）.Being persistent,semivolatile,bioaccumulted and high toxic,PCBs are listed in the 12 primary group pollutants in "Stockholm Convention on Persistent Organic Pollutants".Dioxin-like PCBs（DL-PCBs） are referred to the non-ortho and mono-ortho PCBs,including 12 congeners.DL-PCBs are the most toxic group of compounds in the PCBs.Though the concentrations of DL-PCBs in the environmental and biological matrices are low,they contribute much to the total toxic value of pollutants.Therefore,DL-PCBs are more important than the other PCB congeners for the study of PCBs in biological matrices,and are becoming a research hotspot in the world.In this study,firstly the analysis method of dioxin-like PCBs（DL-PCBs） was set up based on the review of related literature,secondly the pollution conditions and sources of DL-PCBs in the typical plants from Yellow River delta were studied, thirdly the accumulation characteristics of DL-PCBs in plants were explored,finally, DL-PCBs the distribution patterns of DL-PCBs in plants were given out.（1） Research on the analysis method of trace DL-PCBs in plantsThe analytical difficulties in the analysis of PCBs in plants are due to the complex components of plants,trace concentration of DL-PCBs in plants,etc. Current studies about analysis of trace DL-PCBs in plants are seldom reported,so convenient and rapid methods to determine the trace DL-PCBs in plants are required. By study of pretreatment technology and experimental parameters improvement,a rapid and accurate analysis method of trace DL-PCBs in plants were developed in this study.Samples pretreatment.The parameters of Soxhlet extraction was studied,the results are as follows:200mL mixed solvents hexane/acetone（1:1,V/V） were used to extract 20-30g dry weight of plant samples,Soxhlet time was 24h,the reflux speed was 4 circles/h.The extraction was then concentrated and treated with concentrated sulfuric acid and potassium permanganate solution,and the Florisil column was used for purification.DL-PCBs analysis.Dual-column system with low and intermediate polarities combined with GC/MS was used analyze DL-PCBs in plant samples.The method can separate 12 DL-PCBs from the bulk PCBs and organochlorine pesticides,and effectively analyze DL-PCB congeners in the plant samples.The results found the spiked recovery of this method was in the range of 75.56%-87.42%,the relative standard deviation（RSD） of repeated plant samples was in the range of 3.60%-14.53%,meeting the US EPA standard of recoveries（70%-140%） and RSD of repeated samples（＜20%）.（2） Loadings and sources of DL-PCBs in typical plants from Yellow River deltaTo investigate the loadings and sources of DL-PCBs in plants from Yellow River delta,five typical plant species were chosen to determine the DL-PCBs concentrations in October,2006,including Imperata cylindrical var.major, Phragmites australis（Cav.） Trin.ex Steud,Suaeda Heteroptera,Tamarix chinensis Lout.,Salix matsudana Koidz.The total concentrations of DL-PCBs in plants were 575.48-819.23 ng/kg, DL-PCBs congener concentrations measured in plants were 2.32-237.36 ng/kg;the total concentrations of DL-PCBs in the associated soils were 147.75-505.58 ng/kg, and DL-PCBs congener concentrations in the associated soils were 2.48-403.58 ng/kg.The total concentrations or congener concentrations of DL-PCBs in plants and associated soils from Yellow River delta were far lower than those about other area in the published reports.To identify the sources of DL-PCBs in plants,correlation analysis of congener concentration of DL-PCBs in plants and those in the corresponding soils were carried out.The results show the concentrations of DL-PCBs in the plants were not significantly related to those in the corresponding soils.This indicates that the source of DL-PCBs in plants from Yellow River delta was not from soil.Combined with the related studies,considering the octanol-air coefficients(K_oa) and octanol-water coefficients(K_ow) of DL-PCBs,it can be concluded that air was the main source of pollutants.（3） Characteristics of DL-PCBs accumulation in plants from Yellow River deltaThe DL-PCBs concentrations in three annual plants（I.cylindrical,P.australis, S.Heteroptera） and two perennial plants（T.chinensis,S.matsudana） were compared to explore the interspecies variance of DL-PCBs accumulation in plants. Octanol-air coefficients,plant taxonomy and growth time were studied as factors resulted in the variance of pollutants accumulated in plants of different species.①Total concentrations and congener concentrations of DL-PCBs in different plant speciesThe total concentration of DL-PCBs in I.Cylindrical was the lowest among the five species（575.48 ng/kg）,and the other four species was not significantly different from each other.All the 12 DL-PCB congeners were detected in each plant sample, only PCB126 did not show different accumulation among species.PCB77,PCB81, PCB114,PCB123 and PCB156 concentrations were found be significant different among at least three species.The congener with largest variance was PCB 81,whose concentration in T.chinensis was 72 times higher than that in I.Cylindrical.②Influence factors of DL-PCBs accumulation in plantsInfluence of DL-PCBs K_oa on pollutant accumulation in plants.Relations of log K_oa and CP/CI（DL-PCB concentrations in P.australis,S.Heteroptera,T.chinensis, S.matsudana versus that in I.cylindrical） was investigated.When log K_oa was 8.46, CP/CI was 2.0-72.3,When log K_oa was 11.25,CP/CI was 0.7-1.5。Thus,the interspecies variance of plants decreased with increasing log K_oa of DL-PCBs.K_oa was an important factors resulted in DL-PCBs accumulation variance in different plant species.Influence of plant types on DL-PCBs accumulation in plants.Hierarchical cluster analysis of the five plant species labeled by the concentrations of DL-PCBs congeners was conducted.The results show that I.cylindrical and P.australis, which belong to the same family--Gramineae,had the most similar patterns of DL-PCBs accumulation among the five species.This is because only I.cylindrical and P.australis belong to the same family in this study,leading to the smallest variance of their accumulation patterns among the five species.Influence of growth time on DL-PCBs accumulation in plants.Correlation analysis of log K_oa and DL-PCBs concentrations in the five plant species was carried out.A positive correlation between log K_oa and DL-PCBs concentrations of three annual species（I.cylindrical,P.australis and S.Heteroptera） was found,with Pearson correlation coefficients of 0.390,0.464 and 0.354（p＜0.05） respectively.But in the perennial species（T.chinensis and S.matsudana）,the correlation between log K_oa and DL-PCBs concentrations was not significant.The results indicate different uptake mechanism of PCBs by annual and perennial plants.This can be explained by the various DL-PCBs accumulation properties of annual and perennial tissues in perennial species,and annual tissues occupied low proportions of the biomass of whole perennial plants,therefore,correlation between log K_oa and DL-PCBs concentrations in the perennial species was not significant.（4） The DL-PCBs distribution in the plant tissues from Yellow River delta and influence factorsAn annual plant（S.Heteroptera） and a perennial plant（S.matsudana） were collected in November,2007.The above-ground and under-ground parts of S. Heteroptera,the leaves,roots and branches of different growth time were determined for the DL-PCBs concentrations,exploring the distribution patterns of DL-PCBs in plants.①DL-PCBs distribution in different parts of S.HeteropteraThe total amount of DL-PCBs concentrations in the above-ground parts （1263.33 ng/kg） of S.Heteroptera was higher than that in the under-ground parts （833.47 ng/kg）.On the congener level,PCB 81,77,123,118,114 were more accumulated in the above-ground parts of S.Heteroptera than that in the under-ground parts,which indicated that the low-chlorinated PCBs are more likely to be absorbed by the above-ground parts of S.Heteroptera.②DL-PCBs distribution in different parts of S.matsudanaThe total DL-PCBs concentrations in the leaves,roots,four kinds（primary, secondary,three-level and four-level） of S.Heteroptera were determined,which were 3054.64 ng/kg in the leaves,704.28 ng/kg in the roots,538.58、770.75、714.65、552.59 ng/kg in the four kinds of branches.The results indicate that total DL-PCBs concentrations were the highest in the leaves,which in the branches were secondary＞three-level＞four-level＞primary,and the total DL-PCBs concentrations in the roots are similar to that in the third-level branches and differed significantly from the other tissues.On the congener level,DL-PCBs concentrations in the leaves were significantly higher than that of other tissues,but no significant difference was found in the rest tissues.③Influence factors of DL-PCBs distribution in plantsCorrelation Analysis of total values of DL-PCBs concentrations of S. Heteroptera and S.matsudana and lipid concentration in different plant tissues was conducted,and no significant correlation was found.The DL-PCBs concentrations of S.Heteroptera and S.matsudana in different plant tissues were found to be significantly negatively related to total organic carbon concentration.This can be explained that accumulation of DL-PCBs was not as fast as that of the total organic carbon,the growth dilution effect resulted in the phenomenon that the organs with high carbon concentration have less DL-PCBs.更多还原