夏季北黄海不同性质悬浮体分布特征及其控制因素分析

摘要

为了探讨夏季不同性质悬浮体在研究区的分布特征及其控制因素,于2016年6-7月在北黄海使用LISST-100X(C)型激光粒度仪和CTD测量了悬浮体浓度和水体温度、浊度、荧光叶绿素浓度数据.结合现场水文数据对不同粒径悬浮体的分布规律进行分析.结果表明,夏季研究区悬浮体含有大量以生源颗粒为主的粗颗粒(＞128 μm),其浓度在下层水体较低,在远岸层结水体的温跃层附近最高.粒径＜128 μm的细颗粒浓度与浊度分布趋势一致,主要反映陆源无机颗粒的变化.其浓度整体呈近岸高远岸低、下层高上层低的分布特征;在成山头近岸海域最高,并且在鲁北沿岸浅水与远岸深水之间存在浓度锋.潮混合作用和温跃层是影响悬浮体浓度空间分布的主要控制因素.潮混合作用促使鲁北沿岸出现陆架温度锋,阻碍沿岸细颗粒物质向海输运;成山头近岸较强的潮混合作用导致当地沉积物再悬浮,使该区域细颗粒浓度最高.温跃层不仅阻碍了下层细颗粒物质向上扩散,还对上层沉降下来的颗粒有“累积”作用.此外,跃层附近丰富的浮游植物对粗颗粒浓度高值区的形成有促进作用.%To better understand the distribution of different kinds of suspended particulate matter (SPM) in the North Yellow Sea and the key factors controlling them,in June and July 2016,we measured the SPM volume concentrations and sizes with an in-situ laser particle sizer,LISST-100X(C).We obtained the chlorophyll fluorescence concentration,turbidity,and temperature of the entire water column with a CTD device.The results indicate that coarse particles (＞128 μm) of predominately biogenic matter account for most of the SPM,with the concentrations substantially higher in the thermocline of the stratificated offshore water.The concentration distributions of fine particles (＜128 μm) exhibits the same tendency as turbidity,and accordingly,verify the mainly inorganic terrigenous particles of the area.Generally,the concentrations are high along the Shandong Peninsula coast and lowin the offshore deep water where there is a concentration front along the coast.The concentrations are low in the upper water and high in the water below.The highest concentration is at the bottom near the Chengshantou area.Tidal mixing and the thermocline are key factors controlling the SPM distribution in the study area.Tidal mixing prompts shelf thermal fronts,which prevent coastal fine particles from spreading seaward.The strong tidal mixing near the Chengshantou area results in a resuspension of the local sediments,so the fine-particle concentration here is highest.The thermocline not only impedes the upward spreading of fine particles,but also delays the settling of particles from the upper water.Moreover,phytoplanktons gathered near the thermocline also have a significant promoter effect on the formation of high coarse-particle concentrations.