臺灣油品之鉛同位素特徵及其環境鑑識應用

Abstract

油品含鉛一直被視為人體鉛暴露之主要途徑之一，雖然無鉛汽油之使用後已大幅降低此風險，但依然未能完全排除。本研究建立油品之穩定性鉛同位素分析技術，分析臺灣地區不同廠牌之市售油品穩定性鉛同位素特徵值，並將之與環境介質鉛同位素特徵加以比對研析。採集樣品包含中油公司和台塑公司所販售之92無鉛汽油、95無鉛汽油、98無鉛汽油及超級柴油，以多頻道感應耦合電漿質譜儀（MC-ICP-MS）進行高精度之油品鉛同位素分析，測定208Pb/207Pb、208Pb/206Pb、207Pb/206Pb、206Pb/ 204Pb等4種比值；油品鉛含量另以磁場式感應耦合電漿質譜儀（ICP-SF-MS）進行測定。 研究結果發現，臺灣油品之鉛濃度為5 ng g-1至50 ng g-1之間。各鉛同位素比值利用T檢定（T-test）分析數據得知，同一廠牌不同加油站之油品鉛同位素比值特徵與兩種廠牌市售各油品類別間之鉛同位素比值特徵皆無顯著差異。另以T檢定檢視中油公司及台塑公司之油品鉛同位素比值，結果顯示在不考慮油品類別之情況下，兩廠牌的鉛同位素特徵具鑑別度。以銷售比例及加油站數比例加權，估算整體油品各鉛同位素比值，其中（208Pb/207Pb、207Pb/206Pb）分別為2.4269、0.8710，與臺北地區氣膠之鉛同位素比值特徵2.4270、0.8720極為相似，顯示臺北地區氣膠中鉛來源受地域性之油品影響。

Leaded gasoline has been regarded as one of the major source of human lead exposure. Nowadays, people reduce this risk by using unleaded gasoline, but we can’t eliminate them all. This study established a lead isotope analyze technique of gasoline. We analyzed and compared the characteristics of stable lead isotopes between gasoline of different brands and environmental media. Set 92 unleaded gasoline, 95 unleaded gasoline, 98 unleaded gasoline, and diesel fuel samples are collected from the Chinese Petroleum Corporation （CPC）and Formosa Plastics Corporation（FPCC）. High-precision lead isotope ratios of gasoline samples were obtained by using Multi Collector-Inductively Coupled plasma Mass Spectrometry （MC-ICP-MS）. Four lead isotope ratios： 208Pb/207Pb, 208Pb/206Pb, 207Pb/206Pb, and 206Pb/204Pb, were determined. Meanwhile, lead concentrations in gasoline were measured by using Inductively Coupled Plasma Sector Field Mass Spectrometer （ICP-SF-MS）. Results reveal the lead concentrations in gasoline ranged from 5 ng g-1 to 50 ng g-1. The lead isotope ratio data analysis via T-test shows that the ratio characteristics have non-significant difference between different sites of gas station under the same brand. Furthermore, there is significant difference between two brands of gas products on its lead isotopic ratios. To estimate the lead isotope ratios of overall vehicle exhaust based on sales ratio and gas stations number, the lead isotope ratios （208Pb/207Pb and 207Pb/206Pb） are 2.4269 and 0.8710, it’s very similar to Taipei area aerosols lead isotope ratios of 2.4270 and 0.8720, respectively. Represent that the lead in Taipei area aerosols mainly from local gasoline combustion.