[en] Sorption coefficients have been determined using site-specific sediments and trench waters, collected from the Maxey Flats, Kentucky, and West Valley, New York, low-level radioactive waste disposal sites. Experimental apparatus and procedures are described to preserve the anoxic character of the liquid phases during experiments. Experiments using anoxic and oxidized trench waters were performed as functions of solution pH, soil/solution ratio, water and soil composition. The lowest sorption was observed with the combination of anoxic waters and untreated soil - the combination most closely resembling the immediate trench environment. For best results in predictive applications, sorption data should be determined under conditions which simulate those in the field as closely as possible. The total radionuclide retention capacity of reducing geochemical environments is the sum of sorption processes on solid phases, as well as precicipation, and coprecipitation reactions involving iron mineral phases