北江水体镉沉降影响因素及容量计算研究

以珠江流域北江水体-沉积物中重金属镉综合沉降行为作为研究对象。文章通过总结前人研究成果,综合分析认为沉积物中镉的吸附-释放主要影响因素为沉积物特性、水体文水动力条件和水体物理化学性质变化;对重金属影响因素研究可知沉积物对重金属具有决定性作用,而镉在水体中的综合沉降系数的意义则区别于其它降解性污染物,采用1(/d·m)2作为综合沉降系数k的表达形式,可以充分反映河床表面积的作用,并且应有正负之分;结合实测数据对镉综合沉降系数的计算,得到北江干流段综合沉降系数为0.0049~0.0570d-1;在此基础上采用两种方法计算北江水体重金属环境容量,得到北江长度约202km的河段镉的天然环境容量为24.8~26.3kg/d;最后对深入研究方向提出展望。

Sedimentation and Capacity of Cadmium in Beijiang River

Beijiang Rivers in Pearl River Valley were chosen as the research objective to study heavy metal emission,with Cd in sediment as major pollutant.Other studies indicated the most important factors that influencing heavy metal transport and transformation included characters of sediment-water,changes of hydrodynamics and physico-chemical changes of water bodies.The synthetically sedimentation coefficient of Cd is essentially different from other degradable pollutants,considering the effect of surface area in the process of sedimentation,and the coefficient could be expressed as 1(/d·m2)with sign of positive and negative.Aiming at local hydrological feature,the coefficient of heavy metal in main stream of the River was computed in the range of 0.0049~0.0570d-1.According to calculating results,two methods of computing capacity of heavy metals were used in the River to obtain natural environment capacity of Cd as 24.8~26.3kg/d for about 202km long river section.The future direction and approaches were also proposed.