The effects of the suspended sediments found in many natural waters on the microbial processes involved in the self-purification of those waters are not known. Clays and silts with their large surface area per unit weight have an immense capacity for adsorbing nutrient molecules from solution, but the extent to which such adsorption takes place is largely unknown. Results are reported of adsorption experiments with soil materials found in some Alaskan waters which are typically heavily sediment-laden. The affinities of these soils for the protein bovine serum albumin were measured as a function of pH, temperature, and protein concentration. An empirical relationship was discovered, for a given soil material, between the equilibrium protein concentration and the initial protein-to-soil ratio.