Uranium sorption onto natural sediments within a small stream in central Japan

Abstract

In this study, we surveyed the uranium (U) load in stream water within a humid forest in Japan, and clarified the fact that changes in U load depended on the amount of sediment accumulated behind dams constructed along the stream. To elucidate the relationship between U and the accumulated sediments, we conducted U sorption experiments in the laboratory using stream water and sampled sediments. The chemistry of the stream water was analyzed in the field for pH, electrical conductivity (EC), and temperature, as well as laboratory analyses via inductively coupled plasma mass spectrometry (ICP-MS). We determined the amount of organic material, amorphous material, and total U contents in the sediments. Following the sorption experiments, we analyzed the pH and U concentrations in experimental solutions and determined the distribution coefficients of U for the sediments. The logarithm value of the distribution coefficients of U for amorphous material shows a positive correlation with pH, while the logarithm value of the distribution coefficients of U for organic material is independent of pH (4.7-6.9). Although the logarithm value of the distribution coefficient of U for amorphous material was 0.1-0.5 units larger than the value for organic material, U was effectively removed from the stream water by sorption onto organic material (humic substances and decomposing leaves), because the amount of organic material exceeded that of amorphous material.

The Role of Manganese Carbonate Precipitation in Controlling Fluoride and Uranium Mobilization in Groundwater

“…In the presence of high carbonate, UO 2 2+ forms even more favorable CaUO 2 (CO 3 ) 3 2– , Ca 2 UO 2 (CO 3 ) 3(aq) , and MgUO 2 (CO 3 ) 3 2– species . The mobilized U is also known to adsorb to minerals (e.g., Fe oxides, − MnO 2 , calcite, , clay , ) and organic matter. , U can also reprecipitate to form secondary minerals depending upon the availability of constituent co-ions …”

“…30 The mobilized U is also known to adsorb to minerals (e.g., Fe oxides, 31−33 MnO 2 , 34 calcite, 35,36 clay 37,38 ) and organic matter. 39,40 U can also reprecipitate to form secondary minerals depending upon the availability of constituent coions. 41 Co-occurrences of elevated fluoride and uranium levels in groundwater have been identified in many parts of India and also in Myanmar.…”

Geochemical Characteristics and Uranium Neutral Leaching through a CO2 + O2 System—An Example from Uranium Ore of the ELZPA Ore Deposit in Pakistan

“…A similar case has been reviewed and reported by Shamim Akhtar [43], showing that U deposits in Pakistan were formed in a reduced environment. Various studies have reported that U solubility is affected by its speciation and aqueous chemistry including organic matter (OM) concentrations [44][45][46]. Low OM concentration was shown to promote U solubility, whereas high OM concentration may immobilize U [47].…”

“…Various studies have reported that U solubility is affected by its speciation and aqueous chemistry including organic matter (OM) concentrations [44][45][46]. Low OM concentration was shown to promote U solubility, whereas high OM concentration may immobilize U [47].…”

Ion-Imprinted Polymers: Synthesis, Characterization, and Adsorption of Radionuclides

“…Uranium is known for its toxicity, apart from the fact that ingestion of uranium can damage the liver and cause acute renal failure in humans [ 1 ]. The uranyl ion (UO₂⁺) occurs in oxidation state 6+ and is the most stable form of uranium in aqueous solution [ 2 , 3 , 4 ]. According to safety regulations, uranium consumption in drinking water should be less than 0.015 mg/L [ 5 ].…”