[en] The plutonium chemical species in two types of samples from the Savannah River Plant burial ground for radioactive waste were identified. Samples analyzed were water and sediment from burial ground monitoring well C-17 and soil from an alpha waste burial trench. Soluble plutonium in the monitoring well was less than 12A in diameter, was cationic, and contained about 43% Pu(VI) and 25% Pu(IV). The equilibrium distribution coefficient (K /sub d/) for soluble plutonium from the well water (pH 7) to burial ground soil was about 60. Soil plutonium from the waste trench was not cation-exchanged; 78% of the soil plutonium was associated with metallic oxides in the soil. Approximately 9% of the Pu was contained in the crystalline soil matrix. Thus, about 87% of the plutonium in the soil was in a relatively immobile form. Ion-exchangeable and organic acid forms of plutonium amounted to only about 2.5% each. The bulk of the plutonium now on burial ground soils will be immobile except for movement of soil particles containing plutonium. 6 tables