通过对比鸭绿江河口不同地区柱状样的粒度参数及敏感组分变化规律,分析了河口不同地区沉积动力环境和沉积特征的差异;结合代表性柱状样的210Pb测年,分析了柱状样在不同时期自然和人类活动影响下的沉积特征变化。结果表明,西水道主要受潮流作用而含有泥沙互层,粒度参数变化小;西岸潮滩受潮流和波浪作用含有贝壳碎屑,并在顶部出现粗化层。近几十年来,鸭绿江河口地区沉积特征的变化主要由于人类活动对水沙入海通量的影响:1941年以前柱状样的波动沉积特征反映了河流山溪性特征;1941—1970(1980)年随水沙入海通量减少而呈现砂含量降低、粉砂增加的特征;1970(1980)—1990年由于水沙入海通量变化较小,而呈现沉积物组成和敏感组分保持稳定的特征;但1990年后随水沙入海通量的进一步降低,邻近河口区域的沉积物出现明显的粗化。
The gain size parameters and sensitive components of the core sediments in the Yalu river estuary were analyzed in order to reveal the depositional characteristics under changing dynamic environment.The depositional characteristics in the estuary areas are influenced by both the nature and human activities.210Pb was used for dating the cores.The sediments in the west Yalu River channel are dominated by mud and sand under the action of tidal current,and the vertical variation of gain size parameters is small.The cores in western tidal flat of the estuary,controlled by tide and wave,contained shell fragments,and the,gains became coarser from certain depth to the surface.The variation of the sediments characteristics in the Yalu river estuary was mainly affected by the variations of water and sediment discharges induced by human activities in recent decades.The wavy characteristics of the core sediments indicate the unstable feature of the river before 1941.Due to the decrease in both the sediment and water discharges,the sandy sediment had been decreasing and instead silt component increasing during the period from 1941 to 1970(1980).The grain composition and sensitive components remained stable during the period of 1970(1980) and 1990 since the sediment and water flux had little change.However,with the further decreasing of the sediment flux,the trend of sediment coarsening upwards have been recorded near the Yalu River mouth after 1990.