Biomaterial Database

Nitrate-Stimulated Release of Naturally Occurring Sedimentary Uranium. 2023

Jeffrey P Westrop, and Pooja Yadav, and P J Nolan, and Kate M Campbell, and Rajesh Singh, and Sharon E Bone, and Alicia H Chan, and Anthony J Kohtz, and Donald Pan, and Olivia Healy, and John R Bargar, and Daniel D Snow, and Karrie A Weber

Department of Earth and Atmospheric Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States.

Groundwater uranium (U) concentrations have been measured above the U.S. EPA maximum contaminant level (30 μg/L) in many U.S. aquifers, including in areas not associated with anthropogenic contamination by milling or mining. In addition to carbonate, nitrate has been correlated to uranium groundwater concentrations in two major U.S. aquifers. However, to date, direct evidence that nitrate mobilizes naturally occurring U from aquifer sediments has not been presented. Here, we demonstrate that the influx of high-nitrate porewater through High Plains alluvial aquifer silt sediments bearing naturally occurring U(IV) can stimulate a nitrate-reducing microbial community capable of catalyzing the oxidation and mobilization of U into the porewater. Microbial reduction of nitrate yielded nitrite, a reactive intermediate, which was further demonstrated to abiotically mobilize U from the reduced alluvial aquifer sediments. These results indicate that microbial activity, specifically nitrate reduction to nitrite, is one mechanism driving U mobilization from aquifer sediments in addition to previously described bicarbonate-driven desorption from mineral surfaces, such as Fe(III) oxides.

UI	MeSH Term	Description	Entries
D009566	Nitrates	Inorganic or organic salts and esters of nitric acid. These compounds contain the NO3- radical.	Nitrate
D009573	Nitrites	Salts of nitrous acid or compounds containing the group NO2-. The inorganic nitrites of the type MNO2 (where M	Nitrite
D005290	Ferric Compounds	Inorganic or organic compounds containing trivalent iron.	Compounds, Ferric
D014501	Uranium	A radioactive element of the actinide series of metals. It has an atomic symbol U, atomic number 92, and atomic weight 238.03. U-235 is used as the fissionable fuel in nuclear weapons and as fuel in nuclear power reactors.
D014875	Water Pollutants, Radioactive	Pollutants, present in water or bodies of water, which exhibit radioactivity.	Pollutants, Radioactive Water,Radioactive Water Pollutants
D060587	Groundwater	Liquid water present beneath the surface of the earth.	Aquifers,Ground Water,Ground-Water,Subterranean Lakes,Underground Lakes,Underground Streams,Underground Water,Water Table,Aquifer,Ground Waters,Ground-Waters,Groundwaters,Lake, Subterranean,Lake, Underground,Lakes, Subterranean,Lakes, Underground,Stream, Underground,Streams, Underground,Subterranean Lake,Table, Water,Tables, Water,Underground Lake,Underground Stream,Underground Waters,Water Tables,Water, Underground,Waters, Underground
D019015	Geologic Sediments	A mass of organic or inorganic solid fragmented material, or the solid fragment itself, that comes from the weathering of rock and is carried by, suspended in, or dropped by air, water, or ice. It refers also to a mass that is accumulated by any other natural agent and that forms in layers on the earth's surface, such as sand, gravel, silt, mud, fill, or loess. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p1689)	Marine Oil Snow,Sediments, Geologic,Sediments, Marine,Geologic Sediment,Marine Snow,Sediment, Geologic,Marine Oil Snows,Marine Sediment,Marine Sediments,Oil Snow, Marine,Sediment, Marine,Snow, Marine Oil