環境法醫指紋圖譜技術鑑識加油站洩漏油品污染源之應用探討：以柴油污染源為例

Application of Forensic Fingerprinting for Oil Spill Characterization and Source Identification at Gas Stations

劉文堯(Wen-Yao Liu) ； 廖珮瑜(Pei-Yu Liao) ； 張至懿(Chih-Yi Chang) ； 林純玉(Chun-Yu Lin)

《土壤及地下水污染整治》 1卷1期 (2014/07) Pp. 51-67

https://doi.org/10.6499/JSGR.2014.0101.004

摘要

本研究使用4項指紋圖譜分析比對指標項目，並以國內4處加油站為試驗場址，探討環境法醫指紋圖譜技術鑑識加油站柴油洩漏污染源之應用性。藉由特徵因子比值（Pristane/Phytane, Pr/Ph）及特徵化合物不同的質荷比（m/z）互相比對判釋結果顯示，Pr/Ph之比值差異做為本研究柴油油品污染鑑定判讀有很大的助益。m/z 123及198可作為時間判釋依據，初步研判4處場址洩漏時間發生於1989年至2008年之間。m/z 206有助於場址C的油源判斷。m/z 220指標於本研究場址樣品中皆具判釋鑑別度，為本研究油源判釋重要的依據之一。另外在應用環境法醫技術鑑定油品污染源時，需謹記不能僅以單項證據驟下結論，而須考量各場址不同之狀況，配合不同鑑識方法及證據支持所獲得的結論，較可能反映真實的狀況。

關鍵字

環境法醫 ； 指紋圖譜 ； 污染源鑑定 ； 柴油 ； 特徵化合物

並列摘要

Petroleum hydrocarbons released into the environment are subjected to biotic and abiotic transformation reactions in the soil and groundwater media. The fate and behavior of these hydrocarbons depends on the processes of adsorption, volatilization, dissolution, and microbial and photochemical degradation. The combination of these processes reduces the concentration of released hydrocarbons in soil and groundwater and alters their chemical compositions. Such changes to hydrocarbon contaminants increase the difficulty in identifying the related sources and the distributions of the contaminants in the subsurface environment. Fingerprinting uses a variety of instrument-based techniques in the analysis of petroleum hydrocarbons. These include gas chromatography (GC), gas chromatography-mass spectrometry (GCMS), high-performance liquid chromatography (HPLC), infrared spectroscopy (IR) and so on. Of all these techniques, GC techniques are the most widely used, and GC-MS is capable of analyzing oilspecific biomarker compounds and polycyclic aromatic hydrocarbons. Even though this approach is primarily qualitative, it can be used to quickly screen the oil product type, because each petroleum product demonstrates its unique compounds' fingerprint. Fingerprinting of hydrocarbons allows identification of discrete fuel types, such as gasoline, diesel fuel, fuel oil, jet fuel, and marine fuel. If sufficient samples are available, this technique can sometimes discriminate among a chemical release that was a single event, a series of events, or a continuous release of single or multiple products (Alimi et al., 2003; Zemo et al., 1995). Since 1991 a method called ＂Nordtest＂ has been developed to provide the Scandinavian countries, other European countries, the USA and Canada with an important forensic standardization process for oil spill identification. In 2002, the method was revised and divided into three tiered levels of analyses and data treatment, shown in Figure 1 and described as follows (Daling et al., 2002). Level 1: After sample preparation, all samples are initially characterized by a gas chromatography - flame ionization detector (GC-FID), and the overall carbon range (C_(10) ~ C_(40)) of the petroleum hydrocarbons in the oil samples is obtained. The GC-FID chromatograms can provide information on the extent of weathering of the oil samples, as well as on any characteristic features or contaminating components present in the samples. At this level of the investigation, the spill samples can be qualitatively and numerically compared to candidate source samples, and obviously nonmatching samples can be ruled out and eliminated from additional levels of analysis. However, if there is any doubt, then the identification process should continue to the next level of analysis. Level 2: This level carries out an analysis of the spill and candidate source samples using GCMS operated in the selected ion monitoring (SIM) mode. This analysis is used for characterizing and determining the content and distributions of a suite of petroleum biomarkers and polycyclic aromatic hydrocarbons (PAH) target analytes. Level 3: Level 3 assesses the impact of weathering, and evaluates the diagnostic ratios which are obtained from levels 1 and 2. The evaluation is conducted by a simple statistical test (examining the relative standard deviation of triplicate analyses) to identify those ratios that are unaffected by, for example, sample heterogeneity or low analytical precision. Another approach to this is to apply a Student's t-test to the triplicate analyses. This protocol defines the matching criteria as follows: (1) positive match, (2) probable match, (3) indeterminate, and (4) non-match. The results and overall conclusions should be reported for the combined qualitative and quantitative results of the Nordtest methodology. The objective of this study was to apply the fingerprinting technology to source identification of diesel spills from gas stations. Environmental forensic investigations typically aim at identifying the nature of contamination, its sources, and the timing of its release to determine the responsible parties. Definitive answers to these questions are not always achieved through forensic investigations, but combining chemical fingerprinting with other types of forensic data, including an understanding of the site-specific geological and hydrogeological conditions and operational and regulatory histories of the site, can produce highly effective and defensible arguments. Collectively, the effects of these factors must be considered and accounted for in any comparison of chemical fingerprints before any determination as to the source or impact of spilled or discharged petroleum can be established.

並列關鍵字

environmental forensic ； fingerprints ； contamination source identification ； diesel fuel ； specific compounds