夏季东海陆架不同水团对悬浮体物质组成及粒度分布的影响

IMPACT OF WATER MASSES ON COMPOSITION AND PARTICLE SIZE DISTRIBUTION OF SUSPENDED PARTICULATE MATTER OVER THE EAST CHINA SEA SHELF IN SUMMER

基于2012年7月东海陆架水文及悬浮体粒度等实测数据,分析不同水团内悬浮体物质组成和粒度分布特征,并探究其影响因素,为查明东海陆架海区陆源沉积物输运扩散机制、揭示海底沉积物来源和成因机制等提供理论依据。结果显示:夏季东海陆架悬浮体由两部分构成,即≤128μm的无机颗粒和128μm以浮游生物为主的颗粒,其平均体积浓度分别为3.5μL/L和8.4μL/L。悬浮体空间分布受到该海域水团类型的制约。长江冲淡水、台湾暖流表层水、台湾暖流深层水、台湾海峡暖水以及东海冷涡的悬浮体粒径均呈双峰分布,峰值位于27.7-74.7μm和391μm;苏北沿岸流影响海域悬浮体粒径呈单峰分布,小颗粒端含量极低。悬浮体粒度组成及其空间分布差异与水团挟带的无机颗粒、营养盐输送以及水体界面阻隔密切相关。其中,长江冲淡水挟带大量无机颗粒和营养盐进入东海,致使其无机颗粒和浮游生物含量均为研究区最高;苏北沿岸流经长距离扩散后挟带的无机颗粒大多已经沉降,因此无机颗粒含量在研究区最低,而其挟带的丰富营养盐,致使浮游生物含量为次高值;台湾暖流表层水、台湾暖流深层水、东海冷涡以及台湾海峡暖水中悬浮体均以无机颗粒为主,其中前三个水团的水体界面处浮游生物含量较高;不同水团垂向交界处常形成温、盐跃层,跃层能够抑制底层营养盐向表层的扩散,导致跃层位置成为浮游生物高含量区。

Based on hydrological data and suspended particle size data obtained in the East China Sea(ECS)shelf in July 2012,the composition and particle size distribution of suspended particulate matter(SPM)were analyzed,and the influence factors were explored.Results show that the fine components(≤128μm)of SPM were inorganic particles,while the coarse ones(128μm)of SPM were almost plankton,and the average volume concentrations were 3.5μL/L and 8.4μL/L,respectively.The spatial distribution of SPM was confined by different water masses.The particle size spectra of the Changjiang(Yangtze River)Diluted Water(CDW),Taiwan Warm Current Surface Water(TWCSW),Taiwan Warm Current Deep Water(TWCDW),Taiwan Strait warm water(TWSWC),and East China Sea Cold Eddy(ECSCE)all showed bimodal feature and two peaks were located at 27.7-74.7μm and 391μm,respectively.In the coastal current off north Jiangsu(NSCC),the particle size spectra presented unimodal feature,and the fine component of SPM was extremely low.The composition and distribution of SPM were closely related to the transport of inorganic particles,nutrients and the barrier of water interface.In summer,enormous terrigenous material and nutrients carried by the CDW contributed to the highest content of inorganic particle and plankton in the CDW.The settlement of fine inorganic particles after long-distance transport led to the lowest content of inorganic particles in the NSCC.In addition,the nutrients carried by the NSCC resulted in the secondary high value of plankton.In the TWCSW,TWCDW,ECSCE and TWSWC,SPM were mainly composed of inorganic particle,and plankton was seen only in water boundary of the first three former water masses.The thermocline could inhibit the nutrient diffusion from bottom layer to surface layer,which is beneficial to the growth of plankton,thus resulting in the high content of plankton in the thermocline.