| 摘要: |
| 利用2015年09号台风“灿鸿”过境前后长江口外海域现场调查数据,分析台风前后长江口外水体结构和悬浮体粒度分布变化,结合同期环境观测数据与开源数据,阐明台风对河口外海域悬浮体分布的影响机制。结果表明：长江口外海域悬浮体中细颗粒组分(≤128 μm)主要为无机矿物颗粒,而粗颗粒组分(＞128 μm)主要是生源有机颗粒。生源有机粗颗粒主要分布于中上层水体,而无机细颗粒主要分布于底层水体,使得长江口外海域悬浮体平均粒径分布呈双层结构。台风前后悬浮体粒度分布变化反映了台风对长江口外海域物理和生物过程的双重影响,其中物理过程主要影响无机细颗粒分布变化,生物过程主要影响有机粗颗粒。台风期间强烈的偏北风使得长江冲淡水在口门外海域由东北输运转为往东输运,与长江冲淡水输运方向一致的表层无机细颗粒物在台风后输运方向同样往东。另外,台风作用在河口区产生的下降流将12250-4站位底部再悬浮的泥质沉积物向东搬运至12300-4站,导致12300-4站底层悬浮体浓度增加、粒度变细。台风过境还造成长江口外海域初级生产力提高,而浮游植物生长对悬浮体中有机粗颗粒的形成有促进作用,使得口门外海域上层水体中有机粗颗粒体积浓度升高。长江口外海域由于台风过境导致悬浮体中无机细颗粒和生源有机颗粒含量均增加,使得其平均粒径整体变化不大。 |
| 关键词: 台风 悬浮体 粒度 体积浓度 长江口外 |
| DOI：10.11693/hyhz20220300062 |
| 分类号: |
| 基金项目:中国科学院战略性先导科技专项, 国家自然科学基金项目（面上项目） |
附件 |
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| The impact of typhoon Chan-hom on the distribution of suspended particulate matter off the Changjiang River Estuary |
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Long Xiaozhi, Wang Zhenyan
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Institute of Oceanology, Chinese Academy of Sciences
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| Abstract: |
| Based on the field survey data, environmental observation data and open source data before and after the passage of Typhoon Chan-hom which is No.9 typhoon in 2015, we analyzed the variations of water column structure and particle size distribution of suspended particulate matter off the Yangtze Estuary before and after typhoon and clarified the influencing mechanism of typhoon on the distribution of suspended particulate matter. The results show that fine particles(≤128 μm) are mainly composed of inorganic particles, while coarse particles(> 128 μm) are mainly dominated by organic aggregates. The organic coarse particles are mainly distributed in the upper layer, while the inorganic fine particles are mainly distributed in the bottom layer, which makes the mean particle size distribution of suspended particulate matter off the Yangtze Estuary show a double-layer structure. The variation of particle size distribution of suspended particulate matter before and after typhoon reflects the impacts of typhoon on both physical and biological processes. Moreover, the Physical processes mainly affect the distribution of inorganic fine particles and biological processes affect organic coarse particles. The Changjiang diluted water off the Changjiang River Estuary transported from northeast to east due to the strong northerly wind during typhoon, and the surface inorganic fine particles also transported to east after the typhoon in the same direction as the Changjiang diluted water. In addition, the suspended muddy sediments transported from the bottom layer of 12250-4 station to 12300-4 station because of the downwelling generated during typhoon, resulting in finer of the suspended particulate matter at the bottom layer of 12300-4 station. The primary productivity off the Changjiang River Estuary increased after typhoon, then phytoplankton growth promoted the formation of coarse organic particles, so the volume concentration of coarse organic particles of upper layer off the Changjiang River Estuary increased. The mean particle size of suspended particulate matter off the Changjiang River Estuary has little change due to the increase of both inorganic and organic particles after typhoon. |
| Key words: typhoon suspended particulate matter grain size volume concentration off the Changjiang River Estuary |