本研究化學分析屏東縣牡丹鄉東源湖不同深度底泥岩芯中C14至C35直鏈烷濃度,利用生物指標(biomarker)概念去了解底泥沉積物中直鏈烷的來源與推測沉積物沉積時的環境與氣候。分析的樣品為岩芯中89個不同深度(3~650.3 cm及1,255~1,452 cm)的底泥樣品,年代為約30年前~7,000年前及13,500年前~15,600年前。底泥岩芯總直鏈烷平均為30.6±29.4 μg/g(1.3~200.1 μg/g),總直鏈烷中以長碳鏈奇數碳直鏈烷C31、C29、C33及C27為主。根據計算的環境指數CPI24-34(1.25~10.87)、CPIL(1.46~11.72)及TAR指數(1.0~194.0),顯示東源湖直鏈烷主要來源為周遭的陸生植物貢獻。短碳鏈中以偶數碳C16、C18佔42%為優勢,在少數深度上有出現奇數碳C17、C19高濃度事件,CPIS(0.69±0.47)亦可以顯示大部份樣品為短碳鏈偶數碳優勢。環境指標C27+C29+C31(0.4~143.0 μg/g)及C31/(C27+C29)比值(0.23~2.03),將東源湖氣候環境主要分出兩種類型,包含溫暖潮濕與寒冷乾旱的氣候,溫暖潮濕氣候類型出現時期和全球環境變遷中末次冰期回暖(Bølling-Allerød)及全新世最暖期(Holocene Hypsithermal)的溫暖事件吻合。
In this study, we analyzed the C14-C35 n-alkanes concentrations in sediments of Tung-Yuan Pond, Pintung, to identify n-alkanes source and reconstruct palaeoenvironment and palaeoclimate. There are eighty-nine samples of 3 cm to 650.3 cm and 1,255 cm to 1,452 cm in depth, corresponding two periods from 30 yr. B.P. to 7,000 yr. B.P. and 13,500 yr. B.P. to 15,600 yr. B.P., respectively. The average concentration of the total n-alkanes(C14-C35) was 30.6±29.4 μg/g(1.3~200.1 μg/g), with predominance of odd carbon-numbered n-alkanes, such as C31, C29, C33 and C27. The environmental index CPI24-34(1.25~10.87), CPIL(1.46~ 11.72) and, TAR ratio(1.0~194.0) also indicate the terrestrial plants biological origins. The CPIS of 0.69±0.47 indicate an even carbon-numbered predominance with C16 and C18. Index C27+C29+C31(0.4~143.0 g/g) and C31/(C27+C29) ratio (0.23~2.03) suggest two major of climate types, including warm-humid and cold-dry climate. The two periods of warm-humid climate type identified were consisted with the global environmental change of the Bølling-Allerød and Holocene Hypsithermal warm events.