【作者】 杨泽玉；

【导师】 曾永平；

【作者基本信息】 中国科学院研究生院（广州地球化学研究所） ， 环境科学， 2007， 博士

【摘要】 本文以一系列疏水性有机污染物（hydrophobic organic chemicals，HOCs）为目标化合物，建立了两种HOCs在非极性的聚二甲基硅氧烷（poly（dimethyl）siloxane，PDMS）固相微萃取（solid phase microextraction，SPME）涂层与水之间的分配系数(K_fw)的测量方法，研究了强疏水性有机污染物在PDMS涂层上的吸附行为，并从理论和实验两方面验证了利用SPME评估沉积物孔隙水中HOCs生物可给性的可行性。主要内容包括：建立了静态SPME结合液-液萃取（liquid-liquid extraction，LLE）测定一系列疏水性程度不同的多氯联苯（polychlorinated biphenyls，PCBs）的K_fw值的方法，为了确保LLE方法能够准确地测量水相中待测物的量，本方法采用与目标物一对一的¹³C-标记的PCB的对应体作为回收率指示物。随后为了验证上述方法所测K_fw值的准确性，又建立了¹⁴C放射性同位素结合静态SPME技术测定HOCs的K_fw值的方法，并研究了目标物在各介质中（如水，SPME涂层及玻璃壁等）的分配。两种方法所测K_fw值与文献报道值具有较好的一致性。结果表明，涂层厚度只是对高氯取代的PCBs的K_fw值有显著影响，而试样体积对K_fw值则没有显著影响。¹⁴C放射性同位素方法测得的目标物在SPME萃取前后的总回收率（80％-120％）明显优于静态SPME结合LLE的方法所测值（53％-106％）。在PCBs的log K_ow大于约7-7.5之后，所测log K_fw与log K_ow之间呈现出非线性关系。造成这种现象的原因可能是由于PDMS涂层与辛醇之间物理结构的差别所引起的。同样，该理论也适用于解释log BCF与log K_ow之间的非线性关系。为了确定满足SPME用于评估沉积物孔隙水中HOCs生物可给性的条件，首先从理论上对决定相关参数的条件进行了探讨。然后利用¹⁴C放射性同位素技术结合动态SPME，从实验上验证了该理论模型的正确性，并发现介质对SPME的测量没有干扰。另外，还成功地开发出了一种基于SPME原理的原位沉积物孔隙水中HOCs的采样器。更多还原

【Abstract】 The theory for sorption of very hydrophobic organic chemicals （VHOCs） into poly（dimethyl）siloxane （PDMS） coated solid-phase microextraction （SPME） fiber and the feasibility for application of SPME in assessing the bioaccessibility of hydrophobic organic chemicals （HOCs） in sediment porewater have yet to be fully examined. The purpose of this study was to address these two issues. The main results are summarized as follows:A static SPME procedure combined with liquid-liquid extraction （LLE） was used to determine the PDMS-water partition coefficients (K_fw) for polychlorinated biphenyls with different hydrophobicities. The accuracy for the measurements of analyte concentrations in the aqueous phase was ensured with a one-to-one recovery correction strategy employing one ¹³C-labeled PCB counterpart as a surrogate standard for each native PCB congener. To verify the accuracy of K_fw values measured with the above procedure, a ¹⁴C-radioactivity approach combined with the static SPME procedure was also successfully developed to determine the K_fw values of several ¹⁴C-labeled HOCs and analyze the relative distribution among various matrix, including water, glassware/stir, and SPME coating.The measured log K_fw values using the two methods mentioned above were consistent with those reported in the literature. The effects of coating thickness were significant only on heavily chlorinated biphenyls, and sample sizes had no significant effect on the measured K_fw for any targhet analytes. The total recoveries before and after SPME of using the ¹⁴C-radioactivity technique （80%-120%） were better than those using native HOCs combined with the LLE procedure （53%-106%）. A nonlinear relationship between log K_fw and log K_ow was found for PCB congeners representing all isomeric homologs with the cut-off occurring at log K_ow > -7-7.5, which was attributed to the difference between the structures of PDMS coating and octanol. This explanation can also be used to describe the physical origin of the nonlinear relationship between log BCF （bioconcentration factor） and log K_ow.Two governing equations were derived to predict what experimental parameters are appropriate to satisfy the conditions for the application of SPME in assessing the bioaccessibility of HOCs in sediment. To verify the ultimate utility of this modeling framework, sediment spiked with several ¹⁴C-labeled HOCs combined with disposable PDMS-coated SPME fibers was applied to verify the consistency between the theoretical predications and experimental results. The results indicated that the theoretical predications can be used effectively to guide future experiment designs, and no matrix effect was found in the measurement of SPME. Finally, an in situ sampler based on SPME was successfully developed to examine the feasibility of assessing the bioaccessibility of HOCs in sediment porewater.更多还原