Dissolved organic matter (DOM) has been shown to profoundly affect radionuclide mobility. Complexation of radionuclides by DOM in solution can increase the total amount of U available for transport. Organic compounds released during leaf litter drives major flows of DOM in soil systems. Based on the molecular composition of the leachable compounds that are present in the leaf litters at the time of senescence plants will exhibit contrasting ability to mobilize radionuclides.<br/>This work, through a series of leaf litter decomposition, batch sorption and dissolution experiments, investigated the differential ability of leachate produced from leaf litter of different plant species to solubilize U form uranyl-phosphate mineral, Chernikovite. The DOC content in litter leachate was higher during the initial stages of decomposition, which decreased during the later stages. The amount of DOC, DON, water-soluble phenolic and tannins varied widely between species and decomposition stage. In most species, a higher amount of DOC (20-50%) and tannin (20-40%) leached from the litter in the first 48 hours of the experiment. Initially the amount of leachable phenolics were relatively low, but increases after 4 weeks. Dissolution of U was enhanced (30-60%) in the presence of all individual litter leachate from different species and the extent of dissolution varied based on the species and decomposition stage. The amount of dissolved U was significantly higher in the presence of leachate collected after 48 hours of incubation comparison to the leachate collected at later harvesting points. Comparable experiments examining the influence of tannins, purified from different species, on dissolution of U indicate the potential of tannin in mobilizing U irrespective of species of origin. Ongoing molecular characterization of litter leachate would generate predictive understanding on specific reactive moieties within litter leachates that enhance radionuclide mobilization from stable mineral forms. These comprehensive approaches provide valuable insight into the chemistry and molecular dynamics of mineral-organic matter interactions, fate, and transport of radionuclides in terrestrial and subsurface ecosystems.<br/>

Differential ability of leachate produced from leaf litter of different plant species to solubilize U from stable mineral forms

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.