黄河水下三角洲中晚全新世的有机碳埋藏及影响因素分析  

The Middle-And Late-Holocene burial history of organic carbon and its influencing factors in the Yellow River subaqueous delta

作　　者：王秀行 刘世昊 胡维芬 冯威 丰爱平 WANG Xiuhang;LIU Shihao;HU Weifeng;FENG Wei;FENG Aiping(State Key Laboratory of Estuarine and Coastal Research,East China Normal University,Shanghai 200241,China;Fourth Institute of Oceanography,Ministry of Natural Resources,Beihai 536015,China)

机构地区：[1]华东师范大学河口海岸科学研究院,上海200241 [2]自然资源部第四海洋研究所,北海536015

出　　处：《第四纪研究》2025年第1期74-90,共17页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:42276175和42078067)资助。

摘　　要：黄河作为世界性大河,在世界源-汇系统中扮演着举足轻重的角色,其汇区是探讨有机碳埋藏的热点区域。但目前对黄河水下三角洲的碳埋藏过程的研究多聚焦于其现代沉积过程,对千年尺度水下三角洲地区的碳埋藏过程的认识仍较为缺乏。鉴此,本研究在前期开展的、基于水下三角洲地区浅地层剖面资料的地震地层学研究的基础上,开展BHB1岩芯上部594.8 cm的岩性(包含沉积物粒度等指标)分析,构建地层年代框架,对各沉积单元沉积物开展BHB1岩芯总有机碳(TOC)、总碳(TC)、总氮(TN)和稳定碳同位素(δ13C)测试分析。结果表明,研究区中晚全新世以来的水下三角洲沉积系统自下而上可划分为3个沉积单元(DU1~3), DU1~3形成的时间大致分别分别对应7~6 cal.ka B. P.、 6~3 cal.ka B. P.和公元1855年以来(对应现代黄河三角洲)。BHB1岩芯中晚全新世以来的沉积物呈海陆源混合来源,双端元模型计算显示海源自生有机质占据主导(53%),但海陆源贡献相差不大。沉积速率对有机碳质量累积速率(OC_(MAR))起决定性作用。中晚全新世以来,黄河水下三角洲的平均OC_(MAR)为(13.75 g/(m^(2)·a)),低于黄河水上三角洲(66.55 g/(m^(2)·a)),推测主要受沉积运输距离所影响。此外,7~3 cal.ka B. P.的有机碳埋藏亦显著受控于气候因素;4.5 cal.ka B. P.以来陆源有机碳占比(TOM%)出现显著下降,推测与全新世中后期的两次季风急剧减弱事件有关;1855年以来,现代黄河三角洲的演化进程受人类活动影响剧烈,整体上加速了有机碳埋藏。Approximately 70%~90%of terrestrial organic carbon in the ocean is buried within coastal ocean areas,including river mouths,continental shelves,and particularly river deltas,which serve as crucial carbon sinks.As a globally significant mega-river,the Yellow River plays a central role in global source-to-sink systems,with its subaqueous delta serving as a key site for examining organic carbon burial patterns.However,earlier research on the subaqueous part of the Yellow River Delta(YRD)primarily focuses on modern to decadal sedimentary processes,understanding of carbon burial processes over millennial scales remains limited.To bridge this gap,this study examines the Middle-and Late-Holocene burial history of organic carbon in the subaqueous delta of the YRD.Building on previous seismic stratigraphy analyses of sub-bottom profiles in the Bohai Bay area,we analyzed comprehensively analyzed core BHB1(38°24'50″N,118°31'80″E,at water depth 15.8 m),collected in 2020,which penetrates well-defined seismic stratigraphy in the southern Bohai Sea.We conducted a comprehensive lithology analysis(upper 594.8 cm of BHB1),encompassing sediment granularity and other pertinent indicators,including 63 samples for grain size analysing at 8 cm intervals,19 samples for TOC/TN analysing and 5 samples for AMS 14C dating,and conducted a comparative assessment of seismic and lithologic stratigraphy.The findings reveal the formation of a subaqueous deltaic succession since the Middle-and Late-Holocene in our study area,which can be divided into three distinct depositional units(DU1~3)from oldest to the youngest.We establish the chronology framework through AMS 14 C dating,and then we analyzed the proxies of total organic carbon(TOC),total carbon(TC),total nitrogen(TN),and stable carbon isotope(δ13C)values within core BHB1 to gain a comprehensive insights into evolutionary history of in the organic carbon burial pattern within the Yellow River subaqueous delta.We further discussed the sources of the burial organic carbon as well as the

关 键 词：碳埋藏 沉积演化 黄河水下三角洲 中晚全新世 有机碳来源 

分 类 号：P512.22[天文地球—地质学] P593