南海北部表层沉积物中甘油二烷基甘油四醚随水深的分布特征

(1.上海海洋大学 海洋科学学院,上海深渊科学工程技术研究中心,上海 201306; 2.同济大学海洋地质国家重点实验室,上海 200092)

甘油二烷基甘油四醚; 古菌; 细菌; 表层沉积物; 水深; 南海北部

Distribution Characteristics of Glycerol Dialkyl Glycerol Tetraethers in Surface Sediments with Water Depth in the Northern South China Sea
GE Huangmin1*,WU Weiyan2,XING Jilian1

(1.Shanghai Engineering Research Center of Hadal Science and Technology,College of Marine Sciences,Shanghai Ocean University,Shanghai 201306,China; 2.State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China)

glycerol dialkyl glycerol tetraethers(GDGTs); archaea; bacteria; surface sediments; water depth; northern South China Sea

DOI: 10.1016/j.jseaes.2018.04.035

备注

甘油二烷基甘油四醚(glycerol dialkyl glycerol tetraethers,GDGTs)是来源于古菌和细菌的生物标志化合物,广泛应用于海洋科学研究.南海北部有机质来源复杂,解析南海表层沉积物中GDGTs的组成及来源有助于更好地应用GDGTs进行环境重建.通过高效液相色谱-质谱(HPLC-MS)检测了南海北部湾7个表层沉积物样品的脂类组成,结合已发表的南海北部55个表层沉积物的相关数据,详细分析了古菌和细菌GDGTs随水深在南海北部的分布特征,并通过多种指标探讨了GDGTs的来源.结果表明,以200 m为界,GDGTs各组分及相关指标均出现显著的分段式分布趋势.古菌GDGTs随水深的分布特征可能是浅水和深水奇古菌类群产生的GDGTs组成不同导致的; 细菌GDGTs随水深的分布特征则指示浅水区的GDGTs主要来源于陆源贡献,而深水区则同时包括陆源和水体自生两个来源.

Archaeal and bacterial biomarkers,glycerol dialkyl glycerol tetraethers(GDGTs),have been widely applied to paleoenvironmental research in the South China Sea(SCS).Marine sediments are a commonly-used archive to detect GDGTs.Considering complicated sources of organic matter in the SCS,it is necessary to unravel the compositions and sources of GDGTs to better use GDGTs-based proxies.This study determines the abundances of GDGTs in 7 surface sediments from Tonkin Gulf using high-performance liquid chromatography-mass spectrometry(HPLC-MS).Integrated with the published abundances of GDGTs in 55 surface sediments from the SCS,we find two significant patterns in the distributions of GDGTs at above and below 200 m water depth.Variations in isoGDGTs distribution may be attributed to the different preferences in the GDGTs composition synthesized by shallow and deep water thaumarchaeota.The different brGDGTs distributions indicated a dominant terrestrial input to brGDGTs in shallow water sediments,while in deep water sediments,in situ production of brGDGTs promotes its contribution to the brGDGTs pool as well.Our study demonstrates the significance of assessing the GDGTs sources before using them as environmental proxies.