鄱阳湖南矶湿地沉积物粒级组成特征及搬运趋势分析

Analysis of Grain Size Characteristics and Trend of Sediments in the Nanji Wetland of Poyang Lake

沉积物的粒级组成特征对于分析湿地沉积环境和搬运趋势有着重要意义。基于自然保护区沉积物样品,利用粒度分析、Shepard三角图、C-M图、端元分析和GSTA搬运趋势模型,研究分析了鄱阳湖南矶湿地沉积物的粒级组成特征、沉积类型、动力环境和泥沙搬运趋势。结果表明,鄱阳湖南矶湿地沉积物主要以细粉砂为主,平均值为55.35%。沉积物粒度参数中平均粒径均值为5.24Φ,空间分布上具有由西南至东北Φ值逐渐减小的趋势。沉积物质地类型主要为粉砂、粘土质粉砂、砂质粉砂和粉砂质砂,其中粉砂约占62.5%。端元分析的结果显示EM1和EM2可能与鄱阳湖本身湖流带来的沉积物搬运有关,EM3则指示了赣江泥沙来源,EM4可能与局地小环境的水动力变化有关。鄱阳湖南矶湿地沉积物粒径趋势格局以东部向西部、北部向南部最为显著,鄱阳湖南矶湿地是在赣江与鄱阳湖之间复杂交互作用下形成。

The grain size characteristics of sediments are very important for the analysis of wetland sedimentary environments and sediment transport trend.Based on the sediment samples of the Nanji wetland of Poyang Lake,this paper analyzes the composition,sedimentary type,dynamic environment and transport trend in the Nanji wetland using particle size analysis,Shepard triangle,C-M map,end member analysis and GSTA model.The results show that the sediments in the Nanji wetland are mainly fine silt,with an average percentage of 55.35%.The average particle size of the sediment is 5.24Φ,and the spatial distribution has a tendency of decrease from the southwest to the northeast.The types of sediments are mainly silt,clay silt,sandy silt and silty sand,of which silt accounts for 62.5%.The results of end member analysis show that EM1 and EM2 may be related to sediment transport caused by the lake current of Poyang Lake itself,EM3 indicates the source of sediment in Nanji wetland,and EM4 may be related to hydrodynamic changes of local environment.The pattern of the transport trend is most prominently from the east to the west and from the north to the south.The Nanji wetland formed by the complex interaction between the Ganjiang River and the Poyang Lake.