摘要
认识沉积环境有机碳留存状况是阐述油气形成过程中有机碳早期成岩的关键内容。以南海珠江口盆地及其邻近海域为背景,通过研究表层沉积物中脂类化合物的形态组成,认识脂类有机碳的来源和留存状态,阐述特征脂类分子的早期成岩特征。结果表明,研究区域表层沉积物有机碳含量为0.22%～0.66%,有机碳稳定同位素分布在-20.88‰～-22.93‰之间,表现为显著的海源特征。沉积物中共检测出21种脂肪酸、6种脂肪醇、8种甾醇和植醇;总脂肪酸、脂肪醇、甾醇和植醇含量分别为12.57～40.27μg/g、5.35～8.98μg/g、0.15～3.75μg/g和0.01～3.99μg/g干重,总体表现为靠近珠江口和台湾海峡略高。脂类化合物的存在形态以游离态(FR)和碱性水解态(BH)为主,酸性水解态(AH)贡献较低;其中植醇和甾醇呈现显著的BH优势,植醇中未检出AH组分的贡献。脂类化合物主要来自于海洋现场生产,海洋微藻和细菌的相对贡献率分别为21.18%～33.78%和11.02%～15.64%,陆源高等植物贡献低于5%。来源于硫酸盐还原菌的支链脂肪酸在靠近珠江口海域高达1.79～2.62μg/g,占总脂肪酸的5.14%～6.50%,并与硫酸盐还原过程相关的古菌分布相一致。
Distribution and composition of organic carbon is the key to demonstrating the early diagenesis of organic carbon in the formation of oil and gas. Surface sediments were collected and analyzed to determine the content and form composition of lipid biomarkers in the estuary of the Pearl River Basin and adjacent areas in the South China Sea. The sources and occurrence of lipid compounds are also discussed. Results show that the organic carbon content range was 0.22%-0.66% in the sediment samples. The δ 13 C was -20.88‰ to -22.93‰, which implies a marine source of organic carbon. In total, 21 fatty acids, 6 fatty alcohols, 8 sterols and phytol were detected in the sediments. The content of total fatty acids, fatty alcohols, sterols and phytol ranged from 12.57 to 40.27 μg/g, 5.35-8.98 μg/g, 0.15- 3.75 μg/g and 0.01-3.99 μg/g dry weight, respectively. The higher contents were located at the stations closest to the Pearl River estuary and Taiwan Strait. Lipid compounds mainly existed as free (FR) and base hydrolytic (BH) forms, with very little in acidic hydrolytic (AH) form. Phytol and sterols dominated BH components, but AH phytol was not detected. Lipid compounds primarily originate from marine microalgae and bacteria, with a small contribution from higher plants. The specific fatty acids produced by marine microalgae and bacteria contributed 21.18%-33.78% and 11.02%-15.64% to total fatty acids, respectively. The content of branched chain fatty acids (possibly derived from sulfate-reducing bacteria) was higher, at 1.79-2.62 μg/g dry weight, and accounted for 5.14%-6.50% of total fatty acids in sediments closest to the Pearl River estuary. These consisted of archaea microbes, implying sulfate reduction.
作者
邱红
邹立
张民生
朱超祁
贾永刚
QIU Hong;ZOU Li;ZHANG MinSheng;ZHU ChaoQi;JIA YongGang(College of Environmental Science and Engineering,Ocean University of China,Qingdao,Shandong 266100,China;Education Key Laboratory for Marine Environment and Ecology,Ocean University of China,Qingdao,Shandong 266100,China;The Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering,Ocean University of China,Qingdao,Shandong 266100,China)
出处
《沉积学报》
CAS
CSCD
北大核心
2019年第2期416-423,共8页
Acta Sedimentologica Sinica
基金
国家自然科学基金项目(41176064
41427803)~~
关键词
脂类化合物
有机碳
沉积物
成岩作用
南海北部
lipid compounds
organic carbon
sediments
diagenesis
North South China Sea
