The state of suspended sediment in the freshwater fluvial environment: a method of analysis

Primary particles in rivers are frequently and perhaps characteristically transported as larger flocculated particles. Typically floc size has been determined by destructive, indirect laboratory methods or by laborious microscopic measurements.A unique direct observation digitizing method of floc characteristic analysis was developed and applied to suspended solids from Sixteen-Mile Creek in Southern Ontario. Suspended sediment particles in the creek are strongly flocculated, and the flocs are relatively stable within the realms of the sampling and analytical method.The digitizing method allowed for direct observation of floc structures which is impossible with conventional methods of sediment sizing. The method provides reasonable results with good precision on floc equivalent spherical diameter, surface area, perimeter and circularity. It is limited, however, by its labour intensive nature, possibility of sediment overlap, the individual investigator's criteria and by the photographic and microscopic instruments and techniques used. Other sizing techniques, or the use of the digitizing method by other investigators, may produce different results.