Distributions and Characteristics of Saturated Aliphatic Alkanes in Zhuoshui River and Taiwan Strait Sediments

• Main Authors: Jung-Tai Lu, 盧榮泰
• Other Authors: Yuan-pin Chang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/6gmfqx

碩士 === 國立中山大學 === 海洋科學系研究所 === 102 === Vegetation changes caused by varied climatic conditions may leave fingerprint in sediments like lipids so-called molecular fossils or biomarkers. The concentration of n-alkanes and derived biological indicators (biomarkers) have been well-used on reconstructing paleoenvironment and paleoclimate variations, whereas degree of biodegradation/thermodegradation and dilutive influence from lithic organic compounds are still not constrained very well yet. In this study, we used biomarkers not only seeking for tracing sediment sources but also for reconstructing paleoenvironmental changes of source regions. For getting better understanding of the background knowledge of organic lipids and for evaluating the possibility of using biomarkers as indicators on reconstructing paleoclimatic and paleoenvironmental changes at the region of central part of Taiwan, riverine sediments, soils and rocks are recovered from the catchment of Zhuoshui River for analyzing total organic carbon and aliphatic lipids. In soil samples, the carbon distribution pattern of n-alkanes is dominated by n-C31 and n-C29, which are typical higher plants derived signals. However, the rock samples contain only minor organic matters and no predominant carbon species are found. Our results also have shown that hydrocarbon compounds in riverine sediments and suspended particles are mainly composted of short- and medium-carbon chain alkanes (n-C16-25), which might indicate to the possible contributions from unicellular organisms (such as diatoms). Concentrations of higher plant derived n-alkanes of surface sediments retrieved from the Taiwan Strait are low. This result indicates that there might be other sources of hydrocarbons besides the terrestrial plants and may be diluted by short-chain alkanes coming from marine organisms and lithic hydrocarbons. Therefore, we conclude that there are about 1.9-3.8 kt yr-1 (0.35-0.69 Mt TOC-1 yr-1) of rock-sourced hydrocarbons are discharged into the Taiwan Strait by Zhuoshui River.