Freshwater suspended particulate matter—Key components and processes in floc formation and dynamics

•analysis of mineralogical and organic composition of riverine suspended matter.•identification of key components governing freshwater floc formation.•phyllosilicates, iron oxides/(oxy)hydroxides & microbial exopolymers are key.•they enhance physicochemical surface heterogeneities and consequently flocculation.•floc formation mechanisms and dynamics in composition and morphology explained.