[en] The subsurface migration of radionuclides has been studied at a commercial, shallow-land burial site of low-level nuclear waste at Maxey Flats, Kentucky. A variety of radionuclides including ³H, ^238239240Pu, ⁶⁰Co, ¹³⁷Cs and ⁹⁰Sr have migrated short distances on-site (meters to tens of meters). A number of the mobile radionuclides, notably plutonium and ⁶⁰Co, appear to exist as anionic species with organic properties. As a result, we have studied the organic geochemistry of radioactive leachates pumped from a number of waste burial trenches throughout the site. The major aim of the organic research is to elucidate the role of organic compounds in mediating the subsurface migration of the mobile radionuclides in groundwater. A survey study of the hydrophilic and hydrophobic organic content of the waste leachates has revealed that organic compounds are readily leached from the buried waste. Organic chelating agents like EDTA, HEDTA and ED3A are the major hydrophilic organic compounds in the leachates, their concentrations ranging from 78 ppB to 19,511 ppB. A number of carboxylic acids are also present in the leachates, ranging from 675 ppB to 8757 ppB, collectively. A variety of hydrophobic organic compounds including barbiturates and other aromatic compounds, presumably waste-derived, are also present in the leachates, generally at lower ppB concentrations. A detailed chemical speciation study, aimed at determining whether any of the organic compounds identified in the survey study are associated with the mobile radionuclides, was undertaken using leachate from one of the waste trenches. It is clear that EDTA is chelated to plutonium and ⁶⁰Co in the leachate, potentially mobilizing these radionuclides. Other radionuclides, ¹³⁷Cs and ⁹⁰Sr, may be associated with polar organic compounds such as carboxylic acids. 14 references, 2 figures, 2 tables