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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
张洪格
学位类型硕士
导师王珍岩
2017-05
学位授予单位中国科学院大学
学位授予地点北京
学位专业海洋地质
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)
其他摘要
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:
(1)由于海山地形的阻挡,使得流经其海域的洋流在海山顶部Y3-0站向上抬升,温盐等值线也发生了向上凸起的现象;海山与洋流相互作用也可以产生涡旋,使其周围水体温、盐分布发生改变。受温、盐跃层的控制,Y3海山上层水体中SCML的分布水深与温、盐跃层的位置(约50m~160m)基本一致,并同样呈现出在海山顶部呈上凸形态、在涡旋区呈下凹形态的分布特征。SCML中荧光叶绿素a(Chl-a)浓度的高值水层主要位于60~120m水深范围,其Chl-a浓度总体小于1μg/L。
(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。
(3)研究区5个峰值粒级悬浮体的平面分布有较大差异。其中,15.4μm在NE断面呈在断面两侧站位Y3-1、Y3-6站分布高,中间低的趋势;沿洋流方向,迎流面(东南)悬浮体体积浓度是背流面(西北)的20倍,整体呈自东南向西北逐渐降低的分布趋势。海山区虑食性浮游生物对悬浮体的摄食是造成该区域迎流面和背流面悬浮体体积浓度差异大的原因。
(4)研究区面向洋流的迎流面与背流面的SCML中生物组分显著不同:迎流面SCML中普遍存在长条状透明生物体,而背流面SCML中没有。

影响研究区上层水体中悬浮体分布特征以及粒度结构的因素主要有以下三个方面:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
(1)海山与洋流的相互作用:洋流经过海山,在海山顶部的水体向上凸起在Y3-12站水体下凹,引起SCML发生相应变化,从而改变了水体中对Chl-a 贡献最大的15.4μm粒级的悬浮体分布,最终导致该粒级的悬浮体在相应站位也出现上凸和下凹的分布特征。另外,洋流带来大量的悬浮颗粒物,海山区附着性生物对外来悬浮体的摄食导致海山中心悬浮体浓度减少,沿着洋流方向跨过海山后,背流面比迎流面的悬浮体明显降低,尤其是15.4μm粒级的悬浮体,其迎流面悬浮体含量是背流面含量的约20倍。Chl-a浓度以及悬浮体生物组成成分在迎流面和背流面也明显不同。
(2)涡旋:涡旋中心区域(Y3-12站)悬浮体总体积浓较其两侧站位(Y3-11和Y3-13)的悬浮体总体积浓度低,主要体现在15.4μm、95.5μm以及304μm粒级的悬浮体体积浓度分布上,而68.6μm和185μm粒级的悬浮体在暖涡活动中心其体积浓度却较高。说明该涡旋对不同粒级的悬浮体的影响不同。
(3)采样时间的昼夜差异可能是造成研究区较大峰值粒级(68.6μm、95.5μm、185μm、304μm)的悬浮体分布出现差异的因素:白天采样的站位,其68.6μm至304μm粒级的悬浮体大部分在SCML上部,而夜晚采样的站位其68.6μm至304μm粒级的悬浮体主要集中在SCML中部或偏下部。出现上述大颗粒物分布差异的原因可能是由于浮游动物昼夜迁移造成的。
; 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.
语种中文
文献类型学位论文
条目标识符http://ir.qdio.ac.cn/handle/337002/136626
专题海洋地质与环境重点实验室
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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.
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