FACTORS INFLUENCING THE CHEMICAL EXFRACTABILITY OF 7*lam FROM A CONTAMINATED SOIL H. Nishita and M. Hamilton Laboratory of Nuclear Medicine and Radiation Biology University of California, Los Angeles ABSTRACT Factors influencing the extractability of ?"Jam from an artificially contaminated soil were investigated. This was done with an equilibrium batch technique using a CH;COOH-NH,OH and HNO3-NaOH extracting systems. The influence of several soil components was determined indirectly by selectively removing them from the soil. The effect of water- and HCl-soluble salts and organic matter on 74 lam extractability was small. The most marked effect was due to the soil organic fraction that was not water- or HCl-soluble. This organic fraction was influential under both low and high pH conditions, but its influence was particularly marked under low pH conditions. The free iron-oxides had an appreciable effect under low pH conditions, but no observable effect in the high pH range. Though to a lesser extent, the free silica and alumina, amorphous alumino-silicate, and possibly residual organic matter also showed some influence. These results provide some implications on the conditions that influence the movement of ‘1am in soils and its availability to plants. A review of the literature on the behavior of Am in soils is included. INTRODUCTION It ig well recognized that with the increasing use of nuclear energy for different purposes, particularly power generation, there ts an increasing need to improve our understanding of the fate and the effects of the radionuclides that might be released into the biosphere. The major transuranium elements that are important from the long-term hazard standpoint are Np, Pu, Am, and Cm (McKay, 1961; Thomas and Perkins, 1974; Pigford, 1974; Pigford and Ang, 1975). The hazard stems from the fact that these elements are extremely toxic (Denham, 1969; Stannard, 1973; Bair and Thompson, 1974) and several of their isotopes are Long-lived. 77