ABSTRACT
Much of the suspended particulate matter in rivers, lakes, and oceans exists in the form of flocs. These flocs are aggregates of smaller, solid particles that may be inorganic or organic. The emphasis here is on the dynamics of aggregates that are primarily inorganic — that is, fine-grained sediments. These are especially prevalent in rivers, in the near-shore areas of lakes and oceans, and throughout estuaries. Because they are fine-grained, these sediments have large surfaceto-mass ratios and hence adsorb and transport many contaminants and other substances with them as they move through an aquatic system. Flocculation is a dynamic process; that is, flocs both aggregate and disaggregate with time, and their sizes and properties change accordingly. The net rate of change of floc properties depends on the relative magnitudes of the rates of aggregation and disaggregation, with the steady state being a dynamic balance between the two. It is this dynamic nature of a floc that is particularly interesting and one of the major concerns in the present chapter.
