地学前缘 ›› 2022, Vol. 29 ›› Issue (4): 123-135.DOI: 10.13745/j.esf.sf.2022.1.6

• 深海生物地球化学过程 • 上一篇    下一篇

37 ka以来日本海沉积物有机质碳和氮稳定同位素变化及其古海洋学意义

邹建军1,2(), 宗娴1, 朱爱美1, 豆汝席1, 林锦辉1, 冯旭光1, 董智1, Sergey A. GORBARENKO3, 郑立伟4, 石学法1,2,*()   

  1. 1.自然资源部 第一海洋研究所 海洋地质与成矿作用重点实验室, 山东 青岛 266061
    2.青岛海洋科学与技术试点国家实验室 海洋地质过程与环境功能实验室, 山东 青岛 266237
    3.俄罗斯科学院远东分院 太平洋海洋研究所, 俄罗斯 符拉迪沃斯托克 690041
    4.海南大学 南海海洋资源利用国家重点实验室, 海南 海口 570000
  • 收稿日期:2021-09-30 修回日期:2021-11-10 出版日期:2022-07-25 发布日期:2022-07-28
  • 通讯作者: 石学法
  • 作者简介:邹建军(1979—),男,博士,研究员,主要从事中高纬海洋沉积和古环境研究。E-mail: zoujianjun@fio.org.cn
  • 基金资助:
    国家自然科学基金项目(41876065);国家自然科学基金项目(41420104005);国家自然科学基金委山东海洋科学中心项目(U1606401);泰山学者攀登计划(TSPD20181216)

Stable carbon and nitrogen isotope variations in sedimentary organic matter in the Sea of Japan since 37 ka: Paleoceanographic implications

ZOU Jianjun1,2(), ZONG Xian1, ZHU Aimei1, DOU Ruxi1, LIN Jinhui1, FENG Xuguang1, DONG Zhi1, Sergey A. GORBARENKO3, ZHENG Liwei4, SHI Xuefa1,2,*()   

  1. 1. Key Laboratory of Marine Geology and Metallogeny, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China
    2. Laboratory for Marine Geology, Pilot National Oceanography Laboratory for Marine Science and Technology(Qingdao), Qingdao 266237, China
    3. V.I. Il’ichev Pacific Oceanological Institute, Far East Branch of the Russian Academy of Sciences, Vladivostok 690041, Russia
    4. State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou 570000, China
  • Received:2021-09-30 Revised:2021-11-10 Online:2022-07-25 Published:2022-07-28
  • Contact: SHI Xuefa

摘要:

海洋沉积物有机质碳氮稳定同位素(δ13C、δ15N)广泛用于有机质来源示踪、古生产力和古海洋环境重建。日本海沉积物δ13C和δ15N值一个显著特征是在末次冰盛期(LGM)同步负偏,但是对这一现象产生的原因以及他们的演化过程的认识仍然存在明显不足。在本研究中,我们详细调查了37 ka以来日本海中部LV53-23-1岩心沉积物δ13C和δ15N演化历史。结果显示,沉积物δ13C和δ15N分别介于-26.3‰至-22.5‰和1.6‰至6.1‰,低值出现在LGM(26.5~17 ka)暗色层状泥发育时期,指示较强的陆源输入贡献。在Heinrich冰阶1时期(17~14.5 ka),δ13C和δ15N快速正偏,表明日本海海洋环境发生了明显的转换,对应于对马海峡淹没及对马暖流入侵。14.5 ka之后,沉积物δ15N值恢复到5‰,与开阔大洋海水硝酸盐的δ15N值近似。我们采用二端员混合模型粗略地估算了有机质来源的相对贡献。LGM时期陆源有机质贡献介于65%至80%,14.5 ka以后海源有机质贡献介于60%至80%。除了增加的陆源有机质贡献以外,LGM时期沉积物δ15N亏损还涉及如下过程:(1)较高的含Fe沙尘供给提高日本海表层海洋生物固氮效率;(2)缺氧环境盛行减弱成岩作用对沉积物δ15N影响。37 ka以来,日本海沉积物δ13C和δ15N变化与有机质来源、营养盐的供给、表层生产力和沉积物氧化还原条件相关,实际受海平面和全球气候制约。

关键词: 碳氮稳定同位素, 沉积物有机质来源, 海平面, 末次冰期, 日本海

Abstract:

Stable carbon and nitrogen isotopes in sedimentary organic matter (δ13C and δ15N) have been widely used in the organic matter source tracing and reconstruction of paleoproductivity and paleoenvironment. A pronounced feature of sedimentary δ13C and δ15N in the Sea of Japan is their synchronous negative excursions during the Last Glacial Maximum (LGM), yet the causes and mechanisms of this phenomenon are poorly understood. In this study, we investigated the evolutionary history of sedimentary δ13C and δ15N since 37 ka in core LV53-23-1 retrieved from the Oki Ridge of the central Sea of Japan. According to the results, sedimentary δ13C and δ15N ranged from 26.3‰ to 22.5‰ and 1.6‰ to 6.1‰, respectively, with the lower values coinciding with the deposition of dark laminated mud during the LGM (26.5-17 ka), indicating an increased contribution of terrestrial organic matter. Both δ13C and δ15N showed positive excursions during Heinrich Statidal 1 (17-14.5 ka), indicating distinct oceanic environmental changes in the Sea of Japan, which corresponds to the Tsushima Strait flooding and the Tsushima Warm Current invasion into the Sea of Japan at that time. After 14.5 ka sedimentary δ15N reached ~5‰, comparable to the average δ15N of nitrate in seawater. We estimated the relative contributions of organic sources using a binary mixing model. The contribution of terrigenous organic matter ranged between 65% to 80% in the LGM, while marine source contributed between 60% to 80% since 14.5 ka. Besides, sedimentary δ15N depletion during the LGM can be caused by (1) improved nitrogen fixation in the surface water of the Sea of Japan due to higher dust-borne Fe supply, and (2) decreased effects of early diagenesis on sedimentary δ15N due to prevailing suboxic or anoxic environment. Taken together, the variations of sedimentary δ13C and δ15N in the Sea of Japan since 37 ka are controlled by eustatic sea level and global climate changes, which modulate the organic source, nutrient supply, primary productivity, and redox conditions in water column and sediment.

Key words: stable carbon and nitrogen isotopes, sedimentary organic matter sources, sea level, last glacial period, Sea of Japan

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