全氟化合物典型异构体特异性环境行为及其生物富集研究
文献类型：学位论文
| 作者 | 史亚利 |
| 学位类别 | 博士 |
| 答辩日期 | 2015-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 蔡亚岐 |
| 关键词 | 全氟化合物 异构体 环境行为 内脏分布 生物富集，PFASs PFASs isomers environmental behavior tissue distribution bioaccumulation |
| 其他题名 | PFASs isomers specific environmental behavior and bioaccumulation in aquatic environment |
| 学位专业 | 环境科学 |
| 中文摘要 | 经过二十多年的发展，全氟和多氟化合物（Per- and polyfluoroalkyl substances，PFASs）相关研究已取得了长足的进展，研究已经表明许多PFASs是具有持久性、累积性和明显毒性效应的全球性的新型污染物， 并且其同系物因碳链长度、所带官能团的不同，可表现出不同的环境行为、生物累积性和毒性效应。随着研究的深入，许多新的科学问题逐渐显现，如长距离传输和 人体暴露研究中的溯源问题，环境行为和毒性效应的异构体差异问题等，而对PFASs在各环境和生物过程中的异构体分馏现象的科学认识恰恰是深入理解这些问 题的理论和技术关键。另外，随着POPs公约的逐步实施，对PFOS的替代行动逐步展开，各种新型PFASs被越来越多地生产使用并通过各种不同途径进入 到各环境介质，参与不同的环境和生物过程，但目前科学界对它们的环境行为和毒性效应等还缺乏足够的认识。针对以上情况，本论文将在建立可靠的常见 PFASs典型异构体分析方法的基础上，开展异构体和生物组织器官特异性的环境行为和生物累积研究，并对作为PFOS替代物而大量使用的新型多氟化合物 F-53B的环境行为和生物累积进行探索，论文主要包括以下研究内容： 1、对比了不同填料色谱柱对PFOS和PFOA典型异构体的分离及分析性能，选定了五氟苯基色谱分离柱，确定了流动相组成、质谱参数、进样体积等分离和检 测条件，优化了不同环境和生物样品的萃取和净化方法，建立了固相萃取-液相色谱-串联质谱联用（SPE-HPLC-MS/MS）技术分析PFOS和 PFOA典型异构体的分析方法。该方法对各种环境和生物介质中PFOA和PFOS异构体的定量限分别在0.014-0.36 ng/L（水）、0.003-0.13 μg/kg dw（底泥）、0.004-0.108 μg/kg ww（肌肉）、0.006-0.152 μg/kg ww（血液）和0.014-0.36 μg/kg ww（肝脏）之间，对实际样品的加标回收率在70.1-119.7%之间，相对标准偏差（RSD）小于15%。该方法可用于各种环境和生物样品的检测，满 足环境科学研究的需求。 2、以山东省小清河为研究区域，开展了水环境中PFASs的空间分布和异构体分馏研究。结果发现在该区域河水中存在PFASs的严重污染，其中PFOA为 最主要的PFAS，浓度高达366 μg/L，其它短链全氟羧酸（C4-C7）也有较高浓度的存在，其最高值在8.9-37.1 μg/L之间；从短链全氟羧酸和PFOA的空间分布可以推断位于小清河某支流附近的氟聚合物生产厂是小清河PFASs污染的重要来源；尽管在从河水、底泥 到鱼体的环境过程中，观察到了明显的直链PFOA异构体富集分馏现象，但是位于该支流下游河水中的PFOA异构体组成（L-PFOA所占比例平均 值：77.23%）却与传统的电化学氟化法生产的产品异构体组成（L-PFOA：78%）高度相似，该结果进一步支持了小清河河水中PFOA的污染主要来 自于使用电化学合成工艺的该氟聚合物生产厂废物排放的结论，并同时证明短链PFAS同系物和PFOA等异构体组成可以作为地表水样品中全氟烷基羧酸类污染 来源研究的有力工具；对PFOA各异构体的泥水分配系数（Kd）和生物富集因子（BAF）的计算表明，相比于支链异构体，PFOA直链异构体更易在底泥和 鱼体内分配或富集，但各支链异构体之间没有显著性差异；排放通量估算表明该氟聚合物生产厂的排放对该区域乃至环渤海地区PFOA等污染总量具有显著贡献。 首次对F-53B的生物累积进行的野外实验观察研究表明，F-53B具有类似或者稍强于PFOS的生物累积性。 3、开展了高污染区域鲫鱼体内PFASs异构体特异性的器官分布研究。结果表明PFOA、PFOS和FOSA在鲫鱼各个器官内均以直链异构体为主，其比例 分别为84.16-89.87%（L-PFOA），65.00-90.83%（L-PFOS）和64.48-81.78%（L-FOSA）。通过对比各异 构体在各组织和血液中浓度的比值（tissue/blood，TBR）发现，PFOS和PFOA直链异构体的TBRs值均显著高于支链异构体 （Kruskal Wallis Test，P<0.05），该结果可能意味着与支链异构体相比，直链异构体更倾向于在一些深度储藏性的器官（肌肉，心脏，脑，肝脏，肾脏 等）中累积。通过计算胆汁和肝脏浓度的比值（BLR）的方法评价了各异构体通过胆汁排泄的潜能，结果证实PFOS和PFOA支链异构体更易通过此途径被排 出体外；血液中较低的br-FOSA/br-PFOS比值预示血液中丰富的酶的存在促进了FOSA向PFOS的转化，但这种转化对本研究中鱼体内PFOS 浓度的贡献不大。另外，我们还对多氟醚磺酸F-53B和PFOS的组织器官分布进行了对比研究，发现二者不仅浓度相似，而且器官分布顺序也相似，均以血液 浓度最高，肌肉浓度最低，这表明二者在鱼体不同组织器官或体液中具有相似的生物累积性；与PFOS相比（BLR平均值：1.696），F-53B具有较低 的BLR值（平均值：0.750）说明F-53B可能更难通过胆汁排泄，该结果进一步支持了上一章中关于F-53B具有比PFOS更高或相似累积性的结 论。 4、选择具有多种PFASs高污染的武汉汤逊湖为暴露场所，采用野外自然围养方式，以鲫鱼为模型动物开展了PFASs在鲫鱼体内各器官的累积动力学研究。 在暴露期间（60天）鲫鱼体内各器官中PFASs均有显著的累积趋势，尤其是水中浓度最高的PFBA、PFBS和PFOA、PFOS的累积趋势最为明显， 但它们又具有各自不同的变化趋势。PFBA在整个暴露期间呈现波动式小幅增长趋势，在暴露终点（D60）浓度达到最高（0.95-5.66 μg/kg ww），但仅为暴露前浓度的10倍左右。PFBS在不同器官中的浓度在暴露25天或60天达到峰值，最高值在7.33-69.99 μg/kg ww之间，是暴露前浓度的1.5-132倍，并以肝脏、胆汁浓度增长最快。PFOA变化趋势与PFBA相似，暴露期间各器官最高浓度在0.20-8.34 μg/kg ww之间，但均在最低浓度的16倍以下。PFOS在各器官的累积趋势最为明显，其在所有器官中浓度均在第60天达到最高（23.93-293 μg/kg ww），为暴露前浓度的40倍以上，最高达到162倍。以上结果说明了PFASs在生物体内的累积具有明显的碳链长度和官能团依赖性，也具有一定的暴露浓 度依赖性。 |
| 英文摘要 | Over the last decades, the global contamination of per- and polyfluoroalkyl substances (PFASs), most of which were proved to be persistent, bioaccumulative and toxic, has attracted significant attention from scientists. The differences in physic-chemical characteristics of PFASs with different carbon or functional group (i.e. –COO- or –SO3-) may lead to their differences in the transport, partitioning and bioaccumulation behavior in the environment. With the deepening of the research, many new scientific problems, such as the source tracking during long-term transport and human exposure, the differences for isomers in the transport, partitioning and toxic effect, have gradually emerged. For understanding these new emerging problems, it is necessary to conduct the study on the isomer fractionation in environmental and biota process. In addition, with the gradual implementation of the POPs Convention, the initiatives to phase out of PFOS have generally been achieved by a substitution to short-chain PFAS homologues and replacements with ether bonds in the perfluoroalkyl chain. Many of these new kinds of PFASs have been or are being entered into various environmental media during the process of production and usage, and accordingly, participate in various environmental process. However, their environmental behavior, bioaccumulation and toxicology effects are rarely available. The main objectives of this dissertation is to develop the analytical methods for the determination of PFOA and PFOS isomers in different environmental and biota samples, to investigate isomers specific environmental behavior and tissue distribution in crucian carp, to explore the environmental behavior and bioaccumulation of F-53B, a substitute for PFOS. It consists of the following five parts: Firstly, the analytical methods were developed for the determination of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) isomers in different environmental and biota samples using high performance liquid chromatography/ electrospray tandem mass spectrometry (HPLC-ESI-MS/MS) by analytical column with PFP stationary phase. The method quantification limits (MQL) for water, sediment, muscle, blood and liver were 0.014-0.36 ng/L, 0.003-0.13 μg/kg dw, 0.004-0.108 μg/kg ww, 0.006-0.152 μg/kg ww, and 0.014-0.36 μg/kg ww, respectively. The recoveries spiked with 10 ng PFOA or PFOS isomers were in the range of 70.1-119.7% with the relative standard deviation (RSD) below 15%. These methods can be used for the determination of PFASs isomers in different environmental and biota samples, and meet the demands for the environmental scientific research. Secondly, the occurrence, spatial trend and isomer fractionation of PFASs were investigated in Xiaoqing River, Shandong province. Perfluoroalkyl carboxylic acids (PFCAs) were detected at very high concentrations in surface water with the highest one of PFOA up to 366 μg/L and PFCAs with short-chain carbon (C4-C7) ranging at 8.9-37.1μg/L. The spatial trend demonstrated that a fluoropolymer manufacturing facility located at the tributary 4 was the dominant source of PFCAs to Xiaoqing River. The composition of PFOA isomers (the mean value of L-PFOA proportions: 77.23%) in surface water downstream of tributary 4 was almost identical to historically produced PFOA using electro chemical fluorination (ECF, 78%). Furthermore, the profiles of branched isomers of C5?C8 PFCAs and strong positive correlations between these homologues in downstream samples suggested a common ECF source for these homologues. Field-based distribution coefficients demonstrated that linear PFOA was significantly enriched in sediment and fish muscle compared to surface water. The bioaccumulation potential of F-53B was observed in the field environment for the first time. Collectively, this study provides valuable insights for quantitative emission estimation and corroborates the applicability of homologue patterns and isomer profiles as source tracking tools for PFCAs in surface water samples. Thirdly, the isomeric tissue distributions for PFOS, PFOA, and a known PFOS precursor (perfluorooctane sulfonamide, FOSA), were investigated in Crucian Carp from area highly polluted with PFOS or PFOA. The result showed that the linear isomers were predominant in all tissue and body fluid samples with proportions of 84.16-89.87% (L-PFOA), 65.00-90.83% (L-PFOS) and 64.48-81.78% (L-FOSA). The ratios for the concentrations of linear isomer in tissues to ones in blood (tissue/blood) were significantly higher than ones for branched isomer (Kruskal Wallis Test, P<0.05) of PFOS and PFOA, implying that linear isomers were inclined to distribute in deep-storage tissue (such as muscle, heart, brain, liver, heart, etc.) compared to their corresponding branched ones. The ratios for the concentrations of PFOS (PFOA) isomers in bile to ones in liver (bile/liver, BLR) were calculated to assess the potential of PFOS (PFOA) excreted through liver to bile, and thus to be excreted through feces. Higher values of BLR for branched isomers than their corresponding linear ones implied preferential excretion for branched isomers. Although significantly higher values for br-FOSA/br-PFOS in all tissues implied less contribution of FOSA transformation to total PFOS, the lower value for br-FOSA/br-PFOS in blood compared to other tissues testified that abundant enzyme existing in blood might be responsible for the metabolism of FOSA. In addition, F-53B was found at similar concentrations and tissue distribution to PFOS, further supporting more or similar bioaccumulation of F-53B than PFOS. Furthermore, BLR value for F-53B (mean:0.750) was lower than ones for PFOS (mean: 1.696), implying F-53B is more difficult to be excreted through bile relative to PFOS. Finally, crucian carp were exposed over a period of 60 days in Tangxun Lake,Hubei province, where several PFASs were found at very high levels, to determine compound-specific tissue distribution in field-based exposure. During the exposure period PFASs concentrations in Tangxun Lake water remained relatively stable, while most of PFASs, especially, PFBA, PFBS, PFOA and PFOS were taken up rapidly by fish from water and transferred to different tissues. During the whole exposure period, PFBA concentrations showed slightly increasing trend with minor fluctuation. The maximum concentrations (0.95-5.66 µg/kg ww) of PFBA were found at the end of the accumulation phase (day 60), which were only around or less than ten times as ones before exposure. The maximum concentrations of PFBS (7.33-69.99 µg/kg ww) were reached by day 25 or 60 for different tissue or body fluid, being 1.5-132 times higher than ones before exposure. Among the tissue and body fluids, liver and bile exhibited higher uptake rate for PFBS. PFOA showed similar uptake trend to PFBA, with the maximum values ranging from 0.20 to 8.34 µg/kg ww, which is no more than 16 times as ones before exposure. Among all PFASs, PFOS concentrations increased most significantly during the exposure time. All tissues and body fluid reached the maximum levels of PFOS at the end of exposure (day 60), ranging at 23.93-293 µg/kg ww, which is 40-162 times as ones before exposure. All these findings indicated that PFASs exhibited carbon chain length-, functional group-, and concentrations-dependent uptake. |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/34508]  |
| 专题 | 生态环境研究中心_环境化学与生态毒理学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 史亚利. 全氟化合物典型异构体特异性环境行为及其生物富集研究[D]. 北京. 中国科学院研究生院. 2015. |
入库方式： OAI收割
来源：生态环境研究中心
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