Flocculation of suspended sediment in rivers of Southeastern Canada

Abstract Flocculation has been studied extensively within marine science and sanitary engineering and the controlling processes are generally well known. Less research, however, has focused on flocculation within the freshwater river environment. Consequently the occurrence, importance and controlling mechanisms are poorly understood. We examine the suspended sediment characteristics of six rivers in southeastern Canada in order to determine the nature and significance of flocculation in finegrained suspended sediment transport and the factors that may influence it. While flocs may not always comprise the majority of particles in transport, they always represent more than 90% of the total volume of sediment transported. Independent variables that may influence flocculation, such as temperature, pH, major ions, dissolved and particulate organic carbon, suspended solids concentration and bacteria were measured in conjunction with floc size for one of the rivers. Particulate organic carbon concentration, suspended solids concentration and attached bacteria may be important controlling factors of riverine flocculation.

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