东南极戴维斯站企鹅粪土沉积物有机地球化学特征

ORGANIC GEOCHEMISTRY OF PENGUIN ORNITHOGENIC SEDIMENT FROM VESTFOLD HILLS,EAST ANTARCTICA

研究了位于东南极西福尔丘陵地区Gardner Island企鹅粪土的沉积泥芯DG2的分子地球化学组成特征。DG2沉积物的正烷烃以短链为主,主要来源可能为淡水湖相沉积的藻类和细菌输入。脂肪酸组分偶奇优势明显,以C16,C18和C24一元饱和脂肪酸为主,主要来源可能是浮游动物、细菌及水生苔藓;不饱和脂肪酸含量很低,以C18∶1(Δ9)为主,表明沉积源单一稳定,无大波动。醇类组分以高浓度的植醇、胆甾烷醇和胆甾醇为主,分别代表了植被和企鹅数量,指示了研究区域历史时期的生态变化。综合DG2的生物标志物特征,反映该沉积物的有机质主要来源于企鹅粪、细菌和藻类;沉积环境在不同深度也有变化,0—30cm为氧化环境,30—63cm为还原环境。

We studied molecular geochemical compositions of penguin ornithogenic sediment DG2 from Gardner Island, Vesffold Hills, East Antarctica. The results showed that the aliphatic hy- drocarbons mainly consisted of short-chain n-alkanes which likely derived from freshwater algae and bacteria. Meanwhile, the even-carbon fatty acids, such as n-C16, n-Cls and n-C24, domi- nated alkenoic acids and they principally originated from bacteria, freshwater moss or zooplank- ton. However, unsaturated fatty acids were predominated by C1s：I acid from freshwater algae to show good preservation and simple sources of the sediments but trace amount in it. Further- more, the concentrations of cholestanol, cholesterol and phytol which came from penguin excre- ments and vegetation were high in the alcohols and the fluctuations of them in the lake core might respond to the historical changes of penguin populations and vegetations. In summary, the molecular geochemical compositions indicated that the organic matters of DG2 sediment mainly came from penguin guanoes and were well preserved. Key words penguin ornithogenic sediment, fecal sterol, fatty acid, East Antarctica.