末次冰消期以来东海内陆架沉积物活性铁命运及其环境响应  

Fate of reactive iron in inner shelf sediments of the East China Sea in response to environmental evolution since the last deglaciation

作　　者：孔凡兴 张哲远 徐方建 董江 李安春[5] 谷玉 胡利民[1] 陈天宇[2] 刘喜停 KONG Fanxing;ZHANG Zheyuan;XU Fangjian;DONG Jiang;LI Anchun;GU Yu;HU Limin;CHEN Tianyu;LIU Xiting(Key Laboratory of Submarine Geosciences and Prospecting Technology,College of Marine Geosciences,Ocean University of China,Shandong Qingdao 266100,China;Center for Marine Geochemistry Research,State Key Laboratory for Mineral Deposit Research,School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China;School of Marine Science and Engineering,Hainan University,Haikou 570228,China;Key Laboratory of Marine Geology and Metallogeny,First Institute of Oceanography of Ministry of Natural Resources,Shandong Qingdao 266061,China;Key Laboratory of Marine Geology and Environment,Institute of Oceanology of Chinese Academy of Sciences,Shandong Qingdao 266071,China)

机构地区：[1]中国海洋大学海洋地球科学学院,海底科学与探测技术教育部重点实验室,山东青岛266100 [2]南京大学地球科学与工程学院,内生金属矿床成因机制国家重点实验室海洋地球化学研究中心,江苏南京210023 [3]海南大学海洋科学与工程学院,海南海口570228 [4]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 [5]中国科学院海洋研究所海洋地质与环境重点实验室,山东青岛266071

出　　处：《古地理学报》2024年第6期1483-1497,共15页Journal of Palaeogeography：Chinese Edition

基　　金：国家自然科学基金项目(编号:42276060);山东省优秀青年基金项目(编号:ZR2021YQ26)资助。

摘　　要：陆架沉积物活性铁在海洋铁生物地球化学循环中扮演着重要角色,但是其对陆架沉积环境演化的响应机制还不明确。本研究以东海内陆架EC2005岩心沉积物为例,探讨末次冰消期以来沉积环境演化对东海内陆架活性铁命运的影响。EC2005岩心沉积物总铁/铝(Fe_(T)/Al)比值平均为0.54,活性铁/总铁(Fe_(HR)/Fe_(T))比值平均为0.29,表明长江输入的陆源细粒沉积物是研究区主要的颗粒铁来源。活性铁组分的平均含量由高到低依次为易还原的(氢)氧化物铁(Fe_(ox1),0.64%)、黄铁矿铁(Fe_(py),0.32%)、可还原的(氢)氧化物铁(Fe_(ox2),0.23%)、碳酸盐铁(Fe_(carb),0.09%)。其中,Fe_(py)和Fe_(carb)含量随深度变化呈现出此消彼长的趋势,这是碳酸(氢)根离子和硫化物竞争亚铁离子的结果,受末次冰消期以来沉积环境和氧化还原状态的控制。Fe_(ox1)与有机碳含量的变化密切相关,并对Fe_(py)和Fe_(carb)含量的变化起着重要的控制作用。在陆相沉积环境中(17.3~13.1 ka),Fe_(ox1)主要转化为Fe_(carb),Fe_(py)含量几乎为0;在海陆过渡环境中(13.1~7.3 ka),Fe_(carb)含量减少,Fe_(py)含量增加;在海相沉积环境中(7.3 ka至今),Fe_(py)含量达到最大值,Fe_(carb)含量在表层显著增加。本研究强调了沉积环境演化对陆架活性铁命运的控制,为研究现代和深时海洋的C-S-Fe生物地球化学循环提供了新的视角。The reactive iron in shelf sediments plays an important role in the marine iron biogeo-chemical cycle,however,its response mechanism to the evolution of shelf sedimentary environments is still unclear.This study focuses on shelf sediments of core EC2005 from the East China Sea inner shelf to explore the influence of sedimentary environmental evolution on the fate of reactive iron since the last de-glaciation.The average ratio of total iron to aluminum(Fe_(T)/Al)in core EC2005 sediments is 0.54,and the average ratio of reactive iron to total iron(Fe_(HR)/Fe_(T))is 0.29,indicating that terrigenous fine-grained sediments input from the Changjiang River are the main source of particulate iron in the study area.The average content of reactive iron speciation from high to low is easily reducible(oxyhydr)oxide iron(Fe_(ox1),0.64%),pyrite iron(Fe_(py),0.32%),reducible(oxyhydr)oxide iron(Fe_(ox2),0.23%)and carbonate iron(Fe_(carb),0.09%).The relative contents of Fe_(py)and Fe_(carb)exhibit opposite trends along the core depth,indicating competition between carbonate(bicarbonate)ions and sulfide ions for ferrous iron during the early diagenetic process.This competition is primarily controlled by the sedimentary environment and redox state of the East China Sea inner shelf since the last deglaciation.Fe_(ox1)is closely related to the change of organic carbon content and plays an important role in controlling the variations of Fe_(py)and Fe_(carb)contents.In continental environments(17.3-13.1 ka),Fe_(ox1)is mainly converted into Fe_(carb),and Fe_(py)content is almost zero.In transitional environments(13.1-7.3 ka),Fe_(carb)content decreases accompanied by an increase in Fe_(py)content.In marine environments(7.3 ka to present),Fe_(py)content reaches a maxi-mum,and Fe_(carb)content increases significantly in the surface layers.Our findings highlight the control of the sedimentary environment on the fate of reactive iron in shelf sediments,providing a new perspective for studying modern and deep-time marine C-S-Fe biogeochemical

关 键 词：活性铁 东海内陆架 沉积环境 海平面变化 有机碳矿化 

分 类 号：P512.2[天文地球—地质学]