Аннотация:In this work, the influence of biota and irradiation on the stability of iron colloids in swamp waters is studied. The dynamics of the processes of photo- and biotransformation of colloidal iron has been studied. It is shown that the mechanisms of these changes are different: during insolation, a decrease in the iron level in the colloidal fraction occurs due to the formation of larger poorly soluble hydroxide particles (>0.22 μm), while in the presence of biota, a part of iron passes into a fraction of a smaller size (<1.4 nm).