| 摘要: |
| 海山可以通过与洋流的相互作用改变水体结构, 促进悬浮体以及海洋生物的再分配, 进而影响海洋生物地球化学过程, 促进大洋物质和能量交换。西太平洋有着复杂的环流结构, 也是海山分布最多的海区之一。为研究西太平洋海山区的悬浮体分布及其控制机制, 2017年夏季在西太平洋卡罗琳M4海山区进行现场调查, 利用扫描电镜分析了该海山区悬浮体样品的物质组成及分布, 并结合温度、盐度和荧光叶绿素a浓度数据, 讨论了海山对悬浮体分布的影响。结果表明, M4海山区的悬浮体由生物碎屑、矿物颗粒和絮凝体等组成。海水的强烈层化阻碍了该海山区下层营养物质的上涌, 使上层水体呈现出寡营养的特征, 导致大部分站位悬浮体丰度较低; 但在海山顶部, 潮流和海山地形相互作用在山顶上方形成反气旋环流, 不仅促进了深水的营养物质向上扩散, 使得荧光叶绿素a浓度升高, 同时对平流输送来的以及从深水中上涌的悬浮体起到了滞留作用,使山顶上方的悬浮体丰度远高于离山顶较远的位置。随着水深的增大, 温、盐跃层的强度减弱, 水体中的营养盐浓度升高, 为浮游生物的生长提供了适宜的环境, 进而使生物碎屑及絮凝体的丰度升高。北赤道潜流挟带来自西太平洋近岸海区的陆源矿物颗粒到达M4海山区, 使该海山区300~500 m水层中的矿物颗粒丰度显著增加。 |
| 关键词: 悬浮体 卡罗琳M4海山 海水层化 洋流 西太平洋 |
| DOI：10.11693/hyhz20220800219 |
| 分类号:P736.21 |
| 基金项目:国家自然科学基金面上项目,42176090号；中国科学院战略性先导科技专项,XDB42010203号,XDA9060401号 |
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| DISTRIBUTION OF SUSPENDED PARTICULATE MATTER IN THE CAROLINE M4 SEAMOUNT IN THE WESTERN PACIFIC OCEAN AND ITS INFLUENCING FACTORS |
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SHI Xing-Yu1,2, WANG Zhen-Yan1,3,2,4, GAO Wei1, HUANG Hai-Jun1,3,2,4
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1.CAS Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;2.University of Chinese Academy of Sciences, Beijing 100049, China;3.Laboratory for Marine Mineral Resources, Laoshan Laboratory, Qingdao 266237, China;4.Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China
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| Abstract: |
| Seamounts can change hydrological structure via interaction with ocean currents, promote the redistribution of the suspended particulate matters (SPM) and marine organisms, and then affect the marine biogeochemical process and promote the exchange of materials and energy of the ocean. The Western Pacific has a complex circulation structure and is one of the ocean areas with the most seamounts. However, at present, little is known about the distribution of the SPM around the seamounts of the Western Pacific and its controlling mechanism. In summer 2017, a field survey was conducted over the Caroline M4 seamount of the Western Pacific Ocean. The material composition and distribution of the SPMs obtained from the M4 seamount were analyzed by using the scanning electron microscope, and the influence of the seamount on the distribution of the SPMs was discussed in combination with the temperature, salinity and fluorescence chlorophyll a concentration data. The results show that the SPMs in the M4 Seamount were composed of organic debris, mineral particles. and flocs. The strong stratification of seawater resisted the upwelling of nutrients and made the upper water oligotrophic. The abundance of suspended particles at most stations was low. However, the interaction between tidal current and the seamount generated anticyclone circulation atop the seamount, which not only promoted the upward diffusion of nutrients and increased the concentration of fluorescent chlorophyll a, but also retained suspended particles, so that the abundance of SPM on the top of the seamount was much higher than that far away from the seamount. As the strength of the thermocline weakening, the concentration of nutrients increased, providing a suitable environment for the growth of plankton. The abundance of organic debris and flocs also increased. The North Equatorial Undercurrent carried the terrigenous mineral particles from the coastal sea area of the Western Pacific Ocean to the M4 Seamount, which significantly increased the mineral particles abundance in 300~500 m of the seamount. |
| Key words: suspended particulate matter the Caroline M4 seamount seawater stratification ocean current Western Pacific Ocean |
