Abstract

This paper studies the influence of Na⁺, Ca²⁺, and Al³⁺ which is familiar in natural river to the dry sediment bulk density by the experiments of sediment settling in still water. The results of the experiments show following conclusions. The influencing mechanism of metal cations on the dry sediment bulk density is similar, but the influence of highly charged ions was bigger. The influence of cations concentration to the dry sediment bulk density is biggish, the change of dry bulk density can be divided into three phases with the increasing of cations concentration: first phase is that the dry bulk density reduce, second phase is that the dry bulk density increase and get the maximal value, third phase is that the dry bulk density reduce and finally don’t change. When cations concentration is equal, the influence of sediment concentration to dry bulk density has different change with the increasing of cations concentration. As cations concentration and the sediment concentration are the same, the dry bulk density will get bigger when the median size of the sediment increase, and the sand which median size is big need litter cations when it’s dry bulk density get the maximal value.

Keywords: dry bulk density cations concentration；sediment concentration；median size