The mobility of radium-226 and trace metals in pre-oxidized subaqueous uranium mill tailings

Martin, Alan J.; Crusius, John; McNee, J.Jay; Yanful, Ernest K.

doi:10.1016/s0883-2927(02)00243-3

Cited by 61 publications

(43 citation statements)

References 38 publications

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“…Radium mobility or adsorption effectiveness is understood to vary with chemical parameters including pH (Cecil et al, 1987;Dickson and Herczeg, 1992;Bolton, 2000;Szabo et al, 2005), salinity (Kraemer and Reid, 1984;Sturchio et al, 2001;Wood et al, 2004), reduced conditions (Szabo and Zapecza, 1987;Herczeg et al, 1988), supersaturation with respect to barite (Gilkeson et al, 1984;Grundl and Cape, 2006), microbial sulfate reduction affecting barite stability (Phillips et al, 2001;Martin et al, 2003), and microbial Fe oxide reduction (Landa et al, 1991). Ra adsorption is a rapid influence in freshwater at nearneutral pH (Krishnaswami et al, 1982), but the effects of redox processes and relatively low ion concentrations on adsorption and desorption are not well constrained in existing field investigations.…”

Section: Introductionmentioning

confidence: 99%

Relationships between radium and radon occurrence and hydrochemistry in fresh groundwater from fractured crystalline rocks, North Carolina (USA)

et al. 2009

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a b s t r a c t a r t i c l e i n f oNaturally-occurring radionuclides (uranium, radium, and radon), major dissolved constituents, and trace elements were investigated in fresh groundwater in 117 wells in fractured crystalline rocks from the Piedmont region (North Carolina, USA). Chemical variations show a general transition between two water types: (1) slightly acidic (pH 5.0-6.0), oxic, low-total dissolved solids (TDS) waters, and (2) near neutral, oxic to anoxic, higher-TDS waters. The uranium, radium, and radon levels in groundwater associated with granite (Rolesville Granite) are systematically higher than other rock types (gneiss, metasedimentary, and metavolcanic rocks). Water chemistry plays a secondary role on radium and radon distributions as the 222 Rn/ 226 Ra activity ratio is correlated with redox-sensitive solutes such as dissolved oxygen and Mn concentrations, as well as overall dissolved solids content including major divalent cations and Ba. Since 224 Ra/ 228 Ra activity ratios in groundwater are close to 1, we suggest that mobilization of Ra and Rn is controlled by alpha recoil processes from parent nuclides on fracture surfaces, ruling out Ra sources from mineral dissolution or significant long-distance Ra transport. Alpha recoil is balanced by Ra adsorption that is influenced by redox conditions and/or ion concentrations, resulting in an approximately one order of magnitude decrease (~20,000 to~2000) in the apparent Ra distribution coefficient between oxygensaturated and anoxic conditions and also across the range of dissolved ion concentrations (up to~7 mM). Thus, the U and Th content of rocks is the primary control on observed Ra and Rn activities in groundwater in fractured crystalline rocks, and in addition, linked dissolved solids concentrations and redox conditions impart a secondary control.

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Section: Introductionmentioning

confidence: 99%

Relationships between radium and radon occurrence and hydrochemistry in fresh groundwater from fractured crystalline rocks, North Carolina (USA)

et al. 2009

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“…Because sulfuric acid is the most commonly used extracting agent at conventional U-mills, an understanding of geochemical processes influencing sulfate phases is key in assessing contaminant mobility in the disposal environment. Microbially mediated reductive dissolution of sulfate phases in UMT is recognized as a possible release mechanism for 226 Ra from UMT residing in anaerobic environments (Landa et al, 1986;Martin et al, 2003). Sulfate reducing bacteria can grow with gypsum (Karnachuk et al, 2002), anglesite (PbSO 4 ) (Karnachuk et al, 2002;Schröder-Wolthoorn et al, 2008), or barite (Fedorak et al, 1986;Karnachuk et al, 2002) as electron-accepting substrates, thereby leading to the dissolution of these minerals and the soluble release of bulk or trace constituents that are not readily precipitated as insoluble sulfides.…”

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confidence: 99%

Biogeochemical aspects of uranium mineralization, mining, milling, and remediation

Campbell¹,

Gallegos²,

Landa

2015

Applied Geochemistry

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aspects of uranium mineralization, mining, milling, and remediation" (2014 U is overwhelmingly the most abundant at greater than 99% of the total mass of U. Prior to the 1940s, U was predominantly used as a coloring agent, and U-bearing ores were mined mainly for their radium (Ra) and/or vanadium (V) content; the bulk of the U was discarded with the tailings (Finch et al., 1972). Once nuclear fission was discovered, the economic importance of U increased greatly. The mining and milling of U-bearing ores is the first step in the nuclear fuel cycle, and the contact of residual waste with natural water is a potential source of contamination of U and associated elements to the environment. Uranium is mined by three basic methods: surface (open pit), underground, and solution mining (in situ leaching or in situ recovery), depending on the deposit grade, size, location, geology and economic considerations (Abdelouas, 2006). Solid wastes at U mill tailings (UMT) sites can include both standard tailings (i.e., leached ore rock residues) and solids generated on site by waste treatment processes. The latter can include sludge or ''mud'' from neutralization of acidic mine/mill effluents, containing Fe and a range of coprecipitated constituents, or barium sulfate precipitates that selectively remove Ra (e.g., Carvalho et al., 2007). In this chapter, we review the hydrometallurgical processes by which U is extracted from ore, the biogeochemical processes that can affect the fate and transport of U and associated elements in the environment, and possible remediation strategies for site closure and aquifer restoration. This paper represents the fourth in a series of review papers from the U.S. Geological Survey (USGS) on geochemical aspects of UMT management that span more than three decades. The first paper (Landa, 1980) in this series is a primer on the nature of tailings and radionuclide mobilization from them. The second paper (Landa, 1999) includes coverage of research carried out under the U.S. Department of Energy's Uranium Mill Tailings Remedial Action Program (UMTRA). The third paper (Landa, 2004) reflects the increased focus of researchers on biotic effects in UMT environs. This paper expands the focus to U mining, milling, and remedial actions, and includes extensive coverage of the increasingly important alkaline in situ recovery and groundwater restoration.Ó 2014 Published by Elsevier Ltd.

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“…Radium is an issue for spent nuclear fuel repositories that use bentonite as a sorbent since radium does not adsorb strongly to clay minerals (Curti et al 2010). However, there is evidence that the mobility of radium is effectively controlled by barite solubility (Martin et al 2003) because so much radium can incorporate into barite and barium is more common than radium. Already a method that takes advantage of the low solubility of Ba-Ra-Sr sulfate minerals has been proposed as an aboveground treatment strategy for hydraulic fracturing wastewater (Zhang et al 2014), but it may be possible to utilize this for subsurface applications in porous media.…”

Section: Rationalementioning

confidence: 99%

Precipitation in Pores: A Geochemical Frontier

Stack

2015

Reviews in Mineralogy and Geochemistry

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The mobility of radium-226 and trace metals in pre-oxidized subaqueous uranium mill tailings

Cited by 61 publications

References 38 publications

Relationships between radium and radon occurrence and hydrochemistry in fresh groundwater from fractured crystalline rocks, North Carolina (USA)

Relationships between radium and radon occurrence and hydrochemistry in fresh groundwater from fractured crystalline rocks, North Carolina (USA)

Biogeochemical aspects of uranium mineralization, mining, milling, and remediation

Precipitation in Pores: A Geochemical Frontier

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