| 全球海洋硅循环及研究中面临的主要挑战 |
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| 引用本文： | 朱东栋,Jill N.SUTTON,Aude LEYNAERT,Paul J.TREGUER,刘素美.全球海洋硅循环及研究中面临的主要挑战[J].地学前缘,2022,29(5):47-58. |
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| 作者姓名： | 朱东栋 Jill N.SUTTON Aude LEYNAERT Paul J.TREGUER 刘素美 |
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| 作者单位： | 1.中国海洋大学 深海圈层与地球系统前沿科学中心和海洋化学理论与工程技术教育部重点实验室, 山东 青岛 2661002.青岛海洋科学与技术国家实验室 海洋生态与环境科学功能实验室, 山东 青岛 2662373.法国西布列塔尼大学 海洋环境科学实验室, 普卢扎内 29280 |
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| 基金项目： | 国家自然科学基金项目(U1806211);国家自然科学基金项目(41776087);泰山学者工程经费资助专项(20151101);国家重点研发计划项目(2016YFA0600902) |
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| 摘 要： | 海洋硅循环是海洋生物地球化学循环的关键过程之一,对调控全球二氧化碳浓度、海洋酸碱度和多种元素(氮、磷、铁、铝等)的循环具有重要作用。在当今气候变化和人类活动影响日益增强的背景下,硅循环与“生物泵”及碳循环的紧密联系,是其成为地球科学领域研究热点的主要原因。海洋中硅的外部来源主要为河流、地下水、大气沉降、海底玄武岩风化作用和海底热液输送5个途径,在全球气温变暖趋势的影响下,极地冰川融化成为高纬度海域不可忽视的硅源。生物硅在沉积物中的埋藏、硅质海绵和生物硅的反风化作用是重要的海洋硅移除过程。海洋硅循环过程复杂,受生物(生物吸收、降解)、物理(吸附、溶解)和化学(矿化分解和反风化作用)多重因素的影响,针对海洋硅循环关键过程的研究有助于综合评估海洋硅的“源-汇”和收支。本文总结了海洋硅循环的主要过程及海洋硅的收支,根据国际和国内研究现状讨论了当前海洋硅循环研究中面临的主要问题和挑战。现有研究成果显示,海洋硅的外源输入和输出通量比以往的评估分别增加了2.4和2.2倍。在短时间尺度内(<8 ka),全球海洋中硅的收支大致平衡,海洋硅循环基本处于稳定状态。气候变化和人类活动导致河流输送至陆架边缘海的硅通量发生变化,可能影响硅藻等海洋浮游植物种群结构,是未来海洋硅循环研究需要关注的问题之一。陆架边缘海较高沉积速率和强烈的反风化作用提高了该区域生物硅的埋藏效率,准确评估该区域生物硅的埋藏通量仍是亟须解决的难题。目前的研究评估了全球海洋浮游硅藻、硅质海绵以及放射虫生产力,而海洋底栖硅藻生产力的贡献受到忽视,未来需要关注底栖硅藻对生物硅的贡献及其在海洋硅的生物地球化学过程中的作用。
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| 关 键 词： | 海洋硅循环 收支 生物硅 海洋 |
| 收稿时间： | 2020-07-30 |
The global marine silicon cycle and its major challenges |
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| ZHU Dongdong,Jill N.SUTTON,Aude LEYNAERT,Paul J.TREGUER,LIU Sumei.The global marine silicon cycle and its major challenges[J].Earth Science Frontiers,2022,29(5):47-58. |
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| Authors: | ZHU Dongdong Jill NSUTTON Aude LEYNAERT Paul JTREGUER LIU Sumei |
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| Abstract: | The marine silicon cycle is one of the key biogeochemical cycles in the marine realm. It can regulate the global atmospheric carbon dioxide concentration and seawater pH, and also plays a significant role in the geochemical cycles of many other elements, including nitrogen (N), phosphorus (P), iron (Fe) and aluminum (Al). The closely intertwined coupling relationships between the marine silicon cycle and “biological pump” as well as the carbon cycle have caused for substantial concerns under the looming threat of global climate change and increased anthropogenic influences. Silicon (Si) is transported into the ocean through rivers, submarine groundwater, atmospheric deposition, basalt weathering and hydrothermal vents, however, subpolar glaciers are becoming an important Si source to the high latitude ocean regions due to global warming. And Si is removed from the ocean through biogenic silica (bSi) deposition, silicious sponges and bSi reverse weathering. The marine silica cycle involves complex biological (organism-mediated absorption/degradation), physical (adsorption, dissolution) and chemical (mineralization, reverse weathering) processes, while studying these processes could strengthen our understanding of its “source-sink” and the silica budget. This study reviews the major processes and challenges in the marine silica cycle, re-evaluates the marine silica budget based on recent advances, and indicates the major scientific questions for future works. Current works indicated that the input and output fluxes of marine Si have increased 2.4 and 2.2 times, respectively, than the previous estimates. On a short geological time scale (< 8 ka), the total Si net inputs are approximately balanced by the total Si net output flux; therefore, the modern ocean Si cycle is generally at steady state. Nonetheless, the input fluxes of Si to marginal seas through rivers can be influenced by the climate change and human activities, which can then affect the structures of phytoplankton community, including diatoms. This issue is one of the major issues in the marine silicon cycle and requires further research in the future. The coastal and continental margin zones (CCMZ) are oceanic regions with characteristics of high sedimentation rate and rapid reverse weathering, where the bSi burial fluxes is still difficult to estimate accurately. Present studies have assessed the bSi production rates for planktonic diatoms, silicious sponges and rhizaria, but the role of benthic diatom in bSi production was ignored. This omission should be addresses in the future study of benthic diatom primary production and its role in the marine silicon cycle. |
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| Keywords: | silica cycle silica budget biogenic silica modern ocean |
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