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| 深海大洋最小含氧带(OMZ)及其生态环境效应 |
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李学刚1,2,3, 宋金明1,2,3, 袁华茂1,2,3, 李 宁1,2,3, 段丽琴1,2,3, 王启栋1
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1.中国科学院 海洋研究所 海洋生态与环境科学重点实验室;2.中国科学院大学;3.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
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| 摘要: |
| 大洋最小含氧带(Oxygen minimum zone, OMZ)通常是指大洋水体中氧含量缺乏的水层, 一般在水深200～1000 m之间, 其形成主要与厌氧细菌降解有机物导致的溶解氧消耗有关。但到目前为止对OMZ的浓度及水层都没有一个统一的标准, 如以DO 低于20 μmol/L为标准, 低于此标准的海域面积可占全球大洋面积的8%, 水体体积可达大洋体积的7%, 分布的主要区域包括东北太平洋(ENP)、东南太平洋(ESP)、阿拉伯海(AS)和孟加拉湾(BB)等海域。OMZ在全球海洋氮循环中有极为重要的作用, 在那里不同化学形态的氮(NH4+、NO2-、NO3-、N2O、N2)在微生物的参与下会发生多种复杂反应。在OMZ的上部混合层, 硝化作用将NH4+转化为NO3-, 但在OMZ核心区主要进行着反硝化作用和厌氧氨氧化作用过程, 可以将NO3-、NO2-和NH4+转化为气态氮(如N2、N2O), 释放到大气中, 造成大洋生物可利用氮含量更加不足。大洋OMZ区的存在不仅影响浮游生物的丰度、分布、多样性, 而且影响生物的生存和迁移行为, 但低氧区并不意味着是生物的贫乏区。同时, OMZ有利于有机质在沉积物中的保存, 影响Fe、Mn、S等对氧化还原环境敏感元素的迁移与转化。尽管已有研究揭示了大洋OMZ对全球物质循环、大洋生态系统和极端环境下生物演化过程有重要作用, 但对大洋OMZ可能带来的复杂生态环境效应的认识仍然很有限, 目前亟须深入探讨大洋OMZ的形成过程及其生态环境效应。 |
| 关键词: 最小含氧带(Oxygen minimum zone, OMZ) 分布与成因 生态环境效应 大洋 |
| DOI：10.11759/hykx20170821003 |
| 分类号: |
| 基金项目:青岛海洋科学与技术国家实验室鳌山科技创新计划项目(2016ASKJ14); 中国科学院战略性先导科技专项(XDA11030202); 科技基础资源调查专项(2017FY100802) |
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| The oxygen minimum zones (OMZs) and its eco-environmental effects in ocean |
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LI Xue-gang,SONG Jin-ming,YUAN Hua-mao,LI Ning,DUAN Li-qin,WANG Qi-dong
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| Abstract: |
| Oxygen minimum zones (OMZs) are the O2-deficient layers in the ocean water column that develops between 200 and 1000 m below the sea level. The development of the OMZ in oceans is mainly related to the consumption of oxygen by aerobic bacteria degrading dead organisms descending through the water column from the above oxygenated ocean layer. There is no currently agreed upon threshold in oxygen that defines an OMZ. If the threshold were chosen as 20 μmol/L, all OMZs surface account for 8% of the present global ocean surface and a mean volume of OMZs account for 7% of the ocean volume. The main regions of OMZ are in the Eastern North Pacific, Eastern South Pacific, Arabian Sea, and Bay of Bengal. In addition, OMZs have been mainly known to play an essential role in the global nitrogen cycle in which various chemical species, according to their degree of oxidation (e.g., ammonium, NH4+; nitrite, NO2; nitrate, NO3; nitrous oxide, N2O; dinitrogen, N2), and different bacterial processes intervene. Under oxic conditions and at the upper boundary (oxycline) of an OMZ, nitrification transforms NH4+ into NO3-. However, the core of OMZs is especially associated with denitrification and anaerobic ammonium oxidation (anammox) that can convert NO3-, NH4+, NO2- into gaseous nitrogen (Ngas, for example, N2O, N2) that is lost to the atmosphere and contributes to the oceanic nitrate deficit. The OMZ affects the abundance, distribution, and diversity of plankton and affects the survival and migration of organisms. However, the low oxygen zone does not mean the lack of living organisms. At the same time, the oxygen deficiency in OMZ enhances the preservation of organic matter in sediments and affects the migration and transformation of elements, such as Fe, Mn, and S, that are most sensitive to the redox environment. Although the OMZ has been recognized the important role in the global material cycle and the biological evolution in the ocean ecosystem and extreme environmental conditions, there are still many questions to understand the ocean OMZ. Consequently, further research is needed. |
| Key words: oxygen minimum zones (OMZs) distribution and formation eco-environmental effects ocean |
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