南极半岛东北海域表层沉积有机质来源及其沉积环境

The source of organic matter and its sedimentary environment of the bottom surface sediment in northeast waters to Antarctic Peninsula based on the biomarker features

采用气相色谱-质谱技术对南极半岛东北海域海底表层沉积物的总有机碳、有机质碳同位素(δ13 Corg)和生物标志化合物等进行了测试分析。研究区表层沉积物总有机碳TOC平均值高于现代深海沉积物中的平均含量。δ13 Corg的变化说明该海域有机碳来源呈海洋水生生物来源和陆源混合的特征。正构烷烃的峰型分布、主峰碳、饱和烃轻重比C-21/C+22和(C21+C22)/(C28+C29)、甾烷组合和藿烷组合证实研究区西部表层沉积物有机质来源以陆源高等植物为主,其陆源可能来自于附近的南极半岛和南舍得兰群岛;研究区东部表层沉积物有机质来源偏以海源为主,且以低等浮游生物、藻类及细菌生物等海源输入为主。碳优势指数(Carbon preference index,CPI)、奇偶优势指数(Odd-even Predominance,OEP)和甾烷C29ααα20S/(20S+20R)比值显示研究区D1-7站位和D5-9沉积物有机质演化程度较高,D5-2和D2-4站位的有机质演化程度低,其他站位介于中间状态。饱和烃中姥鲛烷、植烷及其比值(Pr/Ph)等组合显示研究区西部以氧化-弱还原的沉积环境为主,其可能是受高温低盐别林斯高晋海水流和附近火山喷发的影响所致;研究区东部以还原—强还原沉积环境为主,可能是受低温高盐的威德尔底层水(WSBW)和威德尔海深层水(WSDW)影响所致。

The organic geochemical characteristics and molecular biomarker are tests analyzed by gas chromatogra- phy-mass spectrometry which are soluble extracted from the bottom surface sediments in the northeast waters to Antarctic Peninsula. Results show that the average contents of TOC （total organic carbon） of the surface sediment in the study is higher than the average contents of organic matter in modern deep-sea sediments. 313 Corg （Organic carbon isotope） values change means that the source of sediment organic carbon has feature of marine aquatic organisms mixed with terrigenous material input. The combination parameters of n-alkanes peak type distribution,nalkanes main carbon peak, the saturated hydrocarbon radio of ∑ C21 / ∑＋22, C＋22 and （ C21 ＋ C22 ） / （C28 ＋ C29 ）, sterane combination and hopance combination parameters confirm that the source of surface sediment organic matter of west part in the study area is given priority to with terrigenous higher plants,which maybe come from the Antarctic Peninsula and South Shetland Islands; conversely,the organic matter source of the east part are given priority to marine origin, the lower plankton,algae and bacteria, and the like. CPI （Carbon preference index）,OEP （Odd-even Predominance） and sterane C29 ααα20S/（20S-20R） ratio show that the sediment organic matter of position D1-7 and D5-9 has higher evolution degree, and the sediment organic matter of position D5 2 and D2-4 has lower e- volution degree-immature, other positions between the intermediate state-low mature. The saturated hydrocarbon compositions of pristance,phytance and their ratio （Pr/Ph） show that the sedimentary environment in west part of study area is oxidation and weak reduction environment,mainly affected by high temperature and low salt current： Bellingshausen Sea Water and nearby volcanic eruption. Oppositely, the east part sedimentary environment is reducing environment-strong reducing environment,which may being caused by WSBW （Weddell Sea Bottom Water） and WSDW （Weddell Sea Deep Water） with low temperature and high salt.