Open questions on the environmental chemistry of radionuclides

Abstract

Understanding the biogeochemistry of radionuclides in the environment is essential for effective isolation of nuclear waste in repositories, management of contaminated sites, ensuring long-term protection of our ecosystems, and limiting impacts on human health. Here the authors discuss the extreme complexity of this multidimensional chemistry problem, highlighting the outstanding open questions for the next generations of environmental radiochemists.

High-energy resolution X-ray spectroscopy at actinide M4,5 and ligand K edges: what we know, what we want to know, and what we can know

“…More beamlines at various synchrotron facilities made an effort to construct the experiment stations for the tender X-ray range and to equip them with X-ray In this article we show how the XANES, HERFD and RIXS methods at the actinide M 4,5 edges and ligand K-edge can provide an unprecedented amount of detail regarding the actinide oxidation state, speciation, defects, nature of the actinide chemical bonding, 5f occupation and degree of the 5f localization. Such fundamental knowledge is a key step towards solving the extreme complexity of the chemistry problems with radionuclides [17][18][19][20][21][22][23][24][25][26] , safe disposal of nuclear wastes and prediction of the radionuclide behaviour in the environment 17,[27][28][29][30][31] .…”

Characterization of Americium and Curium Complexes with the Protein Lanmodulin: A Potential Macromolecular Mechanism for Actinide Mobility in the Environment

“…Transplutonium elements generally favor the +III oxidation state as their most stable state, as do the lanthanides. Consequently, the recent discovery of biological utilization of lanthanides , has opened new, as yet unexplored, possibilities for understanding actinide speciation in the environment …”

“…Consequently, the recent discovery of biological utilization of lanthanides 28,29 has opened new, as yet unexplored, possibilities for understanding actinide speciation in the environment. 30 Within the past decade, lanthanides have been shown to be utilized as cofactors in metal-and pyrroloquinoline quinonedependent alcohol dehydrogenases in methylotrophic bacteria that inhabit a range of environments: in soil and water, 31−33 associated with plants, 34 and even in volcanic mudpots. 35 Although related calcium-dependent enzymes also exist, the lanthanide-dependent ones have been proposed as the ancestral and most widespread of these enzymes, 36 implying that lanthanide utilization is ubiquitous in environmental bacteria 37 and perhaps even in some higher organisms.…”

Plutonium Co-precipitation with Calcite

“…2 The use of nuclear power for both civil and military applications has also led to Pu production, with 2630 t of Pu accumulated, 1 and an additional ≈70 t of Pu is added to the global inventory annually from electricity production. 4 Currently, at nuclear power plants across the U.S., 6000 t of spent fuel are stored temporarily with no permanent storage solution. 5 If geological repositories will be used as long-term storage, they will be required to isolate radioactive materials and waste from the environment for up to a million years.…”

“…For example, at the Hanford Reservation, WA, U.S.A., it is estimated that tens of kilograms of Pu and other actinide elements , were discharged into the subsurface between 1945 and 1990 at roughly 20 different locations . The use of nuclear power for both civil and military applications has also led to Pu production, with 2630 t of Pu accumulated, and an additional ≈70 t of Pu is added to the global inventory annually from electricity production . Currently, at nuclear power plants across the U.S., 6000 t of spent fuel are stored temporarily with no permanent storage solution .…”