鄱阳湖丰水期水体悬浮颗粒物粒径空间分布特征

Spatial distribution of particle size of suspended particulate matters in Poyang Lake during wet season

悬浮颗粒物粒径作为一项重要湖泊水环境影响因子,掌握其分布特征对改善湖泊水体生态环境具有重要意义。以鄱阳湖为对象,通过2017年6月丰水期的全湖观测,利用LISST-100X现场激光粒度仪野外采集颗粒物粒径数据,从平面和垂向两个空间角度分析了鄱阳湖丰水期水体悬浮颗粒物粒径分布特征及其影响因素。结果表明,鄱阳湖丰水期悬浮颗粒物所测中值粒径分布3. 63～62. 77μm范围内,在垂向上,悬浮颗粒物粒径整体上表层低于底层;在平面上,悬浮颗粒物中值粒径值大小:北部>中部>南部;同时对鄱阳湖丰水期悬浮颗粒物进行粒径等级划分结果表明,粒径组分以粉砂(3. 79～53. 49μm)为主,约占70%;悬浮颗粒物黏土和细砂的空间分布差异较大,南部湖区的黏土占比为北部湖区的一倍,而大粒径的细砂、中砂呈现出北部湖区和中部主湖区多于南部湖区的现象。水动力、人为采砂作业是影响鄱阳湖悬浮颗粒物粒径分布的主要因素,此外还受到底质与浮游植物的影响。

Suspended particle size is an important influence factor of water environmental in lakes,and mastering the distribution characteristics is of great significance for improving the water ecological environment.We made in-site surveys by using LISST-100X in Poyang Lake during the wet season in June 2017,and spatial distribution of particle size of suspended particulate matters(SPM)was analyzed from vertical and horizontal perspectives.The results show that the median size of SPM varied from 3.63μm to 62.77μm.In the vertical,suspended particle size on the whole surface is lower than the bottom.In the plane,the median particle size is the biggest in northern lake,followed by central main lake,and least in southern lake.At the same time,the results of particle size classification of SPM in Poyang Lake during wet season indicate that:it is mainly composed of silty sand(3.79~53.49μm)and it accounts for about 70%.The spatial distribution of suspended particulates and fine sand is quite different.The proportion of clay in the southern is twice that of the Northern lakes.However,the fine sand and medium sand occur mostly in the north and central lakes.Hydrodynamic and artificial sand mining are the main factors which affect the particle size distribution of SPM in Poyang Lake.In addition,sediment erosion and phytoplankton are the other factors.