珠江口季节性低氧区柱状沉积物中氧化还原敏感元素的分布及其环境指示意义  

Distribution of redox sensitive elements in a sediment core from the seasonal low-oxygen zone of the Pearl River Estuary and its paleo-environmental implications

作　　者：罗仿 叶丰[1,3,4] 黄超 韦刚健 曾提[3,4] 王志兵 王利伟 LUO Fang;YE Feng;HUANG Chao;WEI Gangjian;ZENG Ti;WANG Zhibing;WANG Liwei(State Key Laboratory of Isotope Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,China;Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,Guangdong,China;CAS Key Laboratory of Ocean and Marginal Sea Geology,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;College of Ocean and Meterology,Guangdong Ocean University,Zhanjiang 524088,Guangdong,China)

机构地区：[1]中国科学院广州地球化学研究所,同位素地球化学国家重点实验室,广东广州510640 [2]中国科学院大学,北京100049 [3]南方海洋科学与工程广东省实验室(广州),广东广州511458 [4]中国科学院广州地球化学研究所边缘海与大洋地质重点实验室,广东广州510640 [5]广东海洋大学海洋与气象学院,广东湛江524088

出　　处：《地球化学》2022年第4期377-388,共12页Geochimica

基　　金：南方海洋科学与工程广东省实验室(广州)人才团队引进重大专项(GML2019ZD0308);国家重点研发计划(2016YFA0601204);广州市科技计划项目(201904010431);国家自然科学基金项目(41991325,42073074);中国科学院青年创新促进会项目(2019346)联合资助。

摘　　要：本文基于珠江口季节性低氧区沉积物岩心(WS)中陆源碎屑指标、TOC含量和氧化还原敏感性元素等环境指标以及年代学的综合分析,重建了该河口近2000 a来水体氧化还原程度的演变历史,探讨其对气候环境变化和人类活动的响应机制。结果显示,珠江口不同类型的氧化还原敏感元素在垂向分布和富集特征上存在差异,其中V主要受有机质吸附控制,而Mo主要通过Fe、Mn氧化物结合在沉积物中富集。基于Fe-Mn-Mo的共变性作为判断古氧化还原程度的指标,珠江口水体在过去2000 a整体表现为微弱的氧化性减弱或还原性增强的趋势,而在主要暖期水体的氧化性趋强。进一步研究发现,近2000 a以来持续加强的人类活动促进了陆源营养盐输入的增加,不断提升了该区域海洋初级生产力,从而影响水体氧化还原程度的变化。因此,日益增强的人类活动和气候变化驱动的河口水动力条件的改变,共同控制着该区域水体溶解氧的长期演变。This study analyzed redox sensitive elements(Fe, Mn, Mo, and V) in a well-dated sediment core(WS)recovered from the seasonal low-oxygen zone of the Pearl River Estuary, South China, in an attempt to infer the evolutionary process of the redox status of the sedimentary environment during the last two millennia and elucidate its response to anthropogenic activity and natural climate variability. Our results showed that downcore redox sensitive elements Fe, Mn, Mo, and V exhibited distinct distribution patterns, among which the enrichment of V is predominantly controlled by increased terrestrial input, whereas Mo entered sediments by combining with Fe and Mn oxides after removing terrigenous debris inputs. The paleo-redox proxy, based on the authigenic enrichment/depletion of Fe-Mn-Mo, suggested a progressive decrease in sediment oxidation intensity, but an increase in reduction intensity during the last two millennia;however, the oxidized conditions aggravated during three warm periods, that is, the Roman, Medieval, and Current Warm Periods, as indicated by the enrichment of Fe-Mn-Mo coupled with significantly high terrestrial organic carbon content. Increased anthropogenically derived nutrient delivery from the Pearl River Basin during the last two millennia resulted in enhanced primary production,and consequently impacted the redox status in our study region. As a result, anthropogenic activities(e.g., land clearing and agriculture) and climate fluctuations are the primary drivers for the redox variations of the Pearl River Estuary during the last 2000 years.

关 键 词：氧化还原敏感元素 季节性低氧事件 珠江口 人类活动 沉积记录 

分 类 号：P734[天文地球—海洋化学] P597[天文地球—海洋科学]