海洋沉积物动力学的示踪物方法

本文的论题是示踪物方法在海洋物源追踪和沉积物输运率计算中的应用 ,以及示踪物方法的普适性理论框架。定量的物源追踪需要适当的示踪标记和物质混合模型 ,有必要根据沉积动力过程的研究来确定示踪标记的变换函数 ,从而将改进的示踪标记用于混合模型分析。人工示踪物实验的现有方法以空间积分法最为常用 ,其关键是示踪物质心运动和沉积物活动层的界定。天然示踪物的质心位置是无法定义的 ,因此不能借用传统人工示踪物方法来估算物质输运率 ;在某些特殊情形下 ,可以利用天然示踪物的质量守衡原理来获得物质输运信息。今后 ,以示踪物质的连续方程为基础 ,有可能建立一种同时适用于人工和天然示踪物的普适理论框架。其中需解决的问题包括示踪物与现场物质的差异、沉积速率和活动层厚度的时间尺度、沉积物扩散过程等。

Tracer Methods in Marine Sediment Dynamics

The present contribution is concerned with the application of tracer methods to marine sediment dynamics, in terms of material source identification, sediment transport rate calculations and the problem of a universal theoretical framework. For the tracing of material sources, mixing models that are originally established for river basin systems should be modified to fit marine environments; in particular, changes in the fingerprinting particles during transport must be considered. In the research field of sediment transport rate determination, artificial tracers have been used, on the basis of the spatial integration method (SIM), the time integration method (TIM), or the continuous injection method (CIM), with the SIM being the most popular. In the application of these methods it is crucial to define the centroid movement and the depth of disturbance. In the case of natural tracers, these methods are no longer applicable because the centroid movement cannot be defined. Nevertheless, in some circumstances, natural tracers can provide information on transport, on the basis of a mathematical model. Further investigations are required in the future to establish a universal theoretical framework for both artificial and natural tracers for sediment transport studies, in which solutions must be found to the problems associated with the differential dynamic behaviors of the tracer and the bulk sediment, deposition rates and the depth of disturbance as functions of the temporal scale, and sediment dispersive processes.