- 學位論文
多氯聯苯於二仁溪之暴露途徑及利用固相微量萃取測定環境介質中之活性
Exposure Pathways of Polychlorinated Biphenyls in Er-Jn River and Activities in Environmental Media Measured with Solid Phase Microextraction
摘要
雖然已有釵h研究指出二仁溪中底泥及魚體內之多氯聯苯(polychlorinated biphenyls, PCBs)濃度甚高，受到介質高吸附能力之影響，此污染物在環境中之流布方向，並非直接受其濃度高差所控制，活性才能決定多氯聯苯於二仁溪之流布途徑。而必須確立暴露途徑，始能估計當地居民食用二仁溪豆仔魚之健康風險。本研究利用固相微量萃取(solid phase microextraction, SPME)之概念，建立以聚二甲基矽氧烷(polydimethylsiloxan, PDMS)塗覆之光纖量測環境介質中多氯聯苯活性之方法。由於可以正確測量PCBs在水中之活性，故本實驗可以最少之干擾而得到較之以往更精確PDMS－水平衡分配常數(Kpw)、有機質－水平衡分配常數(Kom)及生物濃縮因子(BCFL)。 在排除玻璃吸附之影響後所得之logKpw與logKow具良好之線性關係(logKpw = 0.89logKow + 0.36, R2 = 0.92)。文獻中Kpw值較低之原因，應為其忽略玻璃吸附之影響而造成。 logKom與logKow之關係亦呈現與文獻類似之線性關係(logKom = 1.17logKow – 1.03, R2 = 0.86)，唯本實驗之logKom稍高於文獻。分布於5.88至8.53之logBCFL與logKow亦呈線性關係(logBCFL = 1.07logKow + 0.30, R2 = 0.77)，而非一些文獻中所言之當logKow > 6時為非線性關係或當logKow > 7.5 則logBCFL開始下降。前述之差異或鳥犰]於天然水體中均含有不易分離之懸浮顆粒或溶解性有機質，使傳統方法測得疏水性有機物之溶解濃度偏高，並導致低估Kom及BCFL之值。 多氯聯苯之活性研究顯示魚體、水及表層底泥處於約略平衡狀態。暴露途徑為由深層底泥至表層底泥，再至魚體，最後因人類攝食而進入人體。終生致癌風險為3.4×10-6，危害商數為0.40。兩者皆顯示二仁溪之風險潛勢值得注意。
並列摘要
Researches have shown high concentration of polychlorinated biphenyls (PCBs) in sediment and fish in Er-Jen River. The exposure pathways of PCBs are forward human bodies of concern. Infact, activity in each environmental phase governs PCBs’ migration directions. Understanding the activity of each compartment in the estuary, including sediment, water, and fish, is important for assessing the potential health risk residing near Er-Jen River. This study is aimed to establish a solid phase microextraction (SPME) method to measure the activities of PCBs in environmental media by using polydimethylsiloxan (PDMS) coated optical fibers. Partition coefficients of PDMS to water and organic matter to water (Kpw and Kom), and bioconcentration factor (BCFL) could be determined more accurately in this study with less artifacts and were compared with those from the literatures. Without the interference of adsorption on glass wall, logKpw obtained from this study shows a linear relationship with logKow (logKpw = 0.89logKow + 0.36, R2 = 0.92) even for PCBs with high chlorine number. The lower Kpw value from literatures might be due to neglecting the effect of glass wall’s adsorption. logKom increases linearly with logKow (logKom = 1.17logKow – 1.03, R2 = 0.86), however, is higher than the logKom reported in the literature. LogBCFL ranges from 5.88 to 8.53 and also has a linear relationship with logKow (logBCFL = 1.07logKow + 0.30, R2 = 0.77), while some literatures says logBCFL becomes nonlinear with logKow as logKow > 6 and even decreases as logKow > 7.5. These discrepancies might be resulted from overestimating the nature water’s concentration and underestimating BCFL, especially for substances with higher logKow values possibly, due to the nonseparable sorbing compartments in the aqueous phases. PCBs’ activities in fish, water, and surface sediment showed that they were about in equilibrium state. Pollutants were going from deeper sediment to surface layer sediment, fish, and finally uptaken by human. Estimated life time cancer risk of a resident in the estuary area is 3.4 10-6 and hazard quotient is 0.40.