|关键词||热带西太平洋 雅浦海山 悬浮体 粒度 叶绿素最大值层（scml）|
2014年12月至2015年1月，中国科学院海洋研究所“科学”号考察船在雅浦Y3海山区布设的2个断面共14个站位开展水体和底质环境调查。利用CTD（Conductivity, Temperature, Depth）获得了该海域水体的温度、盐度、荧光叶绿素浓度；利用LISST（Laser In-Situ Scattering and Transmissometry）获得悬浮体质体积浓度、粒度数据，对该海区上层水体的温、盐特征以及次表层叶绿素最大值层SCML（Subsurface Chlorophyll Maximum Layer）特征和水体中悬浮体的分布情况、组分特征等进行了初步的分析讨论，结果表明：
（2）Y3海山从表层至50m水深处悬浮体很少，在SCML中体积浓度出现最大值，其体积浓度在0~120μl/L之间，在SCML以深悬浮体迅速减少，之后逐渐趋于零。SCML中悬浮体的分层平均体积浓度显示，存在5个体积浓度高值的粒级，分别为15.4μm、68.6μm、95.5μm、185μm和304μm；其中15.4μm粒级的悬浮体浓度最低，但其对水层中Chl-a浓度的贡献较大(r = 0.5241)，推断该粒级悬浮体主要由微型浮游植物构成；其他4个较大峰值粒级的悬浮体对水体中Chl-a浓度的影响很小，主要由小型和中型浮游生物（及其絮团）等构成。
; Between December 2014 and January 2015, the Hydrographic and bottom characteristics investigation were carried out in the Yap Y3 seamount setting two section of total 14 stations, during cruise of R/V Kexue. The temperature, salinity, concentration of fluorescent chlorophyll obtained by CTD (Conductivity, Temperature, Depth) Profiler and the volume concentrations and particle sizes of suspended particulate matter (SPM) measured by LISST-deep (Laser In-Situ Scattering and Transmissometry) were obtained. The characteristics of temperature and salty, SCML (Subsurface Chlorophyll Maximum Layer) characteristics, the distribution and composition of suspended particle matter in the upper layer were discussed. The results showed that:
(1) The currents in the mountain summit (Y3-0 station) raised up because of the Y3 seamount, creating a uplifted thermohaline contour in the water column; The topography-current interactions over the Yap Y3 seamount can also produce eddy, changing the water temperature and salinity. Due to controlled by the thermohaline, the distribution of the SCML over the seamount was consistent with the depth range of the thermohaline (approximately 50 to 160 m) and displayed a upwelling at the seamount summit and a downwelling in the eddy area. The high fluorescent chlorophyll a concentrations in the SCML was mainly within the depth range of 60 to 120 m. The fluorescent chlorophyll a concentration was generally less than 1 mg/L.
(2) The total volume concentration of the suspended particulate matter over the Y3 seamount varied between 0 and 120 ml/L. The high volume concentrations of the SPM were concentrated within the SCML. Then, the volume concentration of suspended particulate matter gradually tended to zero in the deeper layer. The size spectrum of the SPM in the SCML displayed 5 high volume concentrations. It’s 15.4 mm, 68.6 mm, 95.5 mm, 185 mm, and 304 mm fractions respectively. The volume concentration of the 15.4 mm size fraction was the lowest, but its contribution to the concentration of fluorescent chlorophyll a was the largest (r = 0.5241). We infer that the SPM of this size fraction consisted primarily of nanophytoplankton. The SPM of the other 4 peak size fractions had little effect on the concentration of the fluorescent chlorophyll a. We infer that this matter consisted of micro- and meso- plankton (and their flocs).
(3) The horizontal distribution of the five peak fractions differed from each other. Among them, the volume concentration of 15.4 μm fraction was high on both sides (Y3-1 and Y3-6 station) of the NE section, and low in the center; In NW section, the volume concentration of 15.4 μm fraction was high on station Y3-14 locating in the southeast, and low on station Y3-7 locating in the the northwest. Overall, the distribution gradually reduced from southeast to northwest. The volume concentration of 68.6 μm fraction was high in the center and low on both sides (Y3-1 and Y3-6 station) of the NE section; In NW section, it’s contrary. The distribution of 95.5 μm fraction was similar with the 15.4 μm fraction just with less obvious trend. The rest of the two larger fractions, 185 μm and 304 μm fraction with higher volume concentration had the same distribution: The volume concentration was high on both sides and low in the center of the NE section; In NW section, it’s contrary
(4) The biological components significantly different in upstream and downstream of the upper layer. The long strip transparent organisms were widespread in upstream. But they were not appear in the downstream.
The controlling factors of the particle size distribution of the suspended particulate matter of upper water in the Yap (Y3) seamount area mainly were the following three aspects:
(1) The topography-current interactions: the upper layer water uplifed in the seamount summit and sinked in the anticyclonic eddy (Y3-12) under the influence of topography-current interactions, causing the SCML change correspondingly, thus changing the distribution of 15.4 μm fraction SPM which was the major contributor to fluorescent chlorophyll a. Eventually, leading to the SPM of this fraction also appeared upwelling in the seamount summit and downwelling in the anticylconic eddy. In addition, the feeding biology in the seamount summit ingested lots of exotic SPM which taken by the currents leading to the SPM decrease in the seamount centre. Along the direction of currents, the volume concentration of SPM in the upstream was higher than that in the downstream, especially the 15.4 μm fraction SPM. The volume concentration of 15.4 μm fraction SPM in the upstream was about 20 times of the downstream. the incident flow surface slurry content is the size of back flow surface content. Chlorophyll a concentration and the biologic components of SPM in upstream and downstream were also different.
(2) Eddy: The total volume concentration of SPM in the anticyclonic eddy centre (Y3-12 station) was lower than that on its both sides stations (Y3-11 and Y3-13 station). But the effects of the anticyclonic eddy on the SPM were different with different particle sizes. The volume concentration of 15.4 μm, 95.5 μm and 304 μm fraction were lower in the eddy centre. But the volume concentration of 68.6 μm and 304 μm fraction were higher in the eddy centre. It showed that the influences of the eddy on the SPM were different along with various particle sizes in the study area.
(3) Different day-night sampling time may be the factor which controlling the distribution of larger particle sizes (68.6 μm, 95.5 μm, 185 μm, 304 μm) SPM in the study area. During the day, the SPMs from 68.6 μm to 304 μm fraction were mainly in the upper SCML. But during the night, they were mostly concentrated in the middle or deeper SCML. The migration of zooplankton night and day may make a contribution to the above different distribution of lager particle sizes.
|张洪格. 西太平洋雅浦（Y3）海山区上层水体中悬浮体粒度结构及其影响因素[D]. 北京. 中国科学院大学,2017.|