熊 伟,梅 西,韩宗珠,等. 东海表层沉积物正构烷烃特征及其对陆源有机碳运移分布的指示[J]. 海洋地质前沿,2020,36(10):22-31. DOI: 10.16028/j.1009-2722.2020.109
    引用本文: 熊 伟,梅 西,韩宗珠,等. 东海表层沉积物正构烷烃特征及其对陆源有机碳运移分布的指示[J]. 海洋地质前沿,2020,36(10):22-31. DOI: 10.16028/j.1009-2722.2020.109
    XIONG WEI, MEI Xi, HAN Zongzhu, WANG Zhongbo, ZHANG Yong. CHARACTERISTICS OF N-ALKANES IN THE SURFACE SEDIMENTS OF THE EAST CHINA SEA AND THEIR IMPLICATIONS FOR THE DISTRIBUTION OF TERRIGENOUS ORGANIC MATTER[J]. Marine Geology Frontiers, 2020, 36(10): 22-31. DOI: 10.16028/j.1009-2722.2020.109
    Citation: XIONG WEI, MEI Xi, HAN Zongzhu, WANG Zhongbo, ZHANG Yong. CHARACTERISTICS OF N-ALKANES IN THE SURFACE SEDIMENTS OF THE EAST CHINA SEA AND THEIR IMPLICATIONS FOR THE DISTRIBUTION OF TERRIGENOUS ORGANIC MATTER[J]. Marine Geology Frontiers, 2020, 36(10): 22-31. DOI: 10.16028/j.1009-2722.2020.109

    东海表层沉积物正构烷烃特征及其对陆源有机碳运移分布的指示

    CHARACTERISTICS OF N-ALKANES IN THE SURFACE SEDIMENTS OF THE EAST CHINA SEA AND THEIR IMPLICATIONS FOR THE DISTRIBUTION OF TERRIGENOUS ORGANIC MATTER

    • 摘要: 东海埋藏了通过长江、黄河以及台湾河流进入的巨量陆源有机碳,是重要的有机碳碳“汇”。识别东海沉积物中陆源有机碳的分布特征和搬运过程,是东海碳通量研究不可或缺的内容。目前关于陆源有机碳在东海沉积物中分布的研究区域主要集中在河口、内陆架以及水深<120 m的中、外陆架地区;针对东海外陆架和冲绳海槽陆坡的研究较少,仅少量研究对东海陆架与冲绳海槽南部沉积物的陆源有机碳特征进行了对比分析,对陆源有机碳的“源-汇”过程、分布特征、沉积动力机制等诸多问题尚缺乏系统性的认识。通过对东海外陆架-陆坡-冲绳海槽80个表层沉积物的长链正构烷烃含量及组成特征进行分析,并结合粒度、总有机碳(TOC)及稳定碳同位素(δ13C)指标,讨论了研究区沉积物中陆源有机碳的含量及运移分布。结果显示,δ13C和(ΣC27+C29+C31 n-alkane)/TOC指示的陆源有机碳相对含量在研究区变化范围很大,从外陆架到海槽,有先降低后增高的变化趋势,陆源有机碳在陆坡以及海槽的一些特定区域选择性的大量沉积。东海内陆架的陆源有机碳在横穿东海陆架后,可以在陆坡处通过搬运-沉积-再悬浮-再搬运的方式运移至冲绳海槽沉积。长链正构烷碳优势指数(CPI)的结果表明,来自东海内陆架的陆源有机碳主要在冲绳海槽28.5°—30°N范围内沉积,28.5°N以南的陆源有机质主要受到台湾物质的影响,而30°N以北沉积物中的陆源有机质主要是来源于黄河和日本岛。

       

      Abstract: The East China Sea (ECS) is an important sink of organic carbon with complicated and diverse sources, in which there is a huge amount of terrigenous organic carbon coming from the Yangtze River, the Yellow River and the rivers from Taiwan. Therefore, it is indispensable to identify the composition of terrigenous sedimentary organic carbon and trace its fluvial source for carbon flux research. Up to date, the study on the distribution of terrigenous organic carbon in sediments of the ECS is mainly concentrated in some areas such as the estuary areas and the middle and outer shelf regions in a water depth < 120 m, but rare is devoted to the slope of Okinawa Trough (OT) and the outer shelf of the ESC. Little is known about the source-sink process, distribution patterns, sedimentary dynamic mechanisms, and other problems concerning the origin of terrigenous organic carbon. In this paper, we discussed the distribution and transportation of terrigenous organic carbon in the sediment, through the distribution and composition of n-alkanes for 80 surface sediment samples from the ECS outer shelf, slop and trough, together with other indexes such as grain-size, total organic carbon (TOC) and stable carbon isotope δ13C. The results show that the terrigenous organic carbon content indicated by δ13C and(ΣC27+C29+C31,n-alkane)/TOC vary in a large range in the study area, and from the outer shelf to the trough, they decrease first and increase later. There is a great amount of terrigenous organic carbon deposited on slope and in some special areas of the OT. Dominated by the process of “transportation-deposition-resuspension-transportation” in the slope area, the terrigenous organic matter (TOM) is continuously transported from the interior shelf of ECS to the OT across the outer shelf. The results of CPI suggest that the TOM from ECS inner shelf was mainly sourced from the area of 28.5°—30°N in the Okinawa Trough. To the south of 28.5°N, the TOM in sediments was mainly affected by the materials from Taiwan, while to the north of 30°N, the TOM was mainly derived from the Yellow River and Japan Islands.

       

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