Radium geochemistry of ground waters in Paleozoic carbonate aquifers, midcontinent, USA

Sturchio, Neil C.; Banner, Jay L.; Binz, C. M.; Heraty, L. B.; Musgrove, MaryLynn

doi:10.1016/s0883-2927(00)00014-7

Cited by 114 publications

(76 citation statements)

References 44 publications

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“…The relatively high minimum values of apparent K D in fractured crystalline rocks (~10 3 ) indicate that Ra is rapidly adsorbed in fresh waters in bedrock fractures to balance input from alpha recoil, and that Ra does not exhibit the lower apparent K D commonly observed in sandstone aquifers (~10 1 -10 3 ; King et al, 1982;Lively et al, 1992;Reynolds et al, 2003) or saline aquifers (~10 0 -10 2 ; Sturchio et al, 2001). Net adsorption of Ra is less effective under the low-DO, higher-TDS conditions observed in this study because (1) anoxic fractures contain lower surface area of redox-sensitive Ra adsorption sites, such as Mn oxides; and/or (2) higher concentrations of alkaline earth metals, such as Ba, compete with recoil-generated Ra for adsorption sites.…”

Section: Overview Of Radionuclide Sources and Sinksmentioning

confidence: 99%

“…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%

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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: Overview Of Radionuclide Sources and Sinksmentioning

confidence: 99%

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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“…Relatively high 228 Ra levels in springs and the N well ( 228 Ra/ 226 Ra [ 1) could be explained by differences in Th/U ratios in the host carbonate rocks, e.g., 232 Th could be concentrated within relatively insoluble residue (silicates, phosphates and hydroxides) left behind after dissolution of carbonate aquifer rock rich in 228 Ra (Sturchio et al 2001). Another mechanism is the preferential solubility of 238 U relative to 232 Th, which is more closely attached to aquifer solids or sands (Von Gunten et al 1996;Ivanovich and Harmon 1992).…”

Section: Radium and Groundwater Sourcesmentioning

confidence: 99%

An assessment of karstic submarine groundwater and associated nutrient discharge to a Mediterranean coastal area (Balearic Islands, Spain) using radium isotopes

et al. 2009

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Short and long-lived radium isotopes (Ra-223, Ra-224, Ra-226, Ra-228) were used to quantify submarine groundwater discharge (SGD) and its associated input of inorganic nitrogen (NO3 (-)), phosphorus (PO4 (3-)) and silica (SiO4 (4-)) into the karstic Alcalfar Cove, a coastal region of Minorca Island (Western Mediterranean Sea). Cove water, seawater and groundwater (wells and karstic springs) samples were collected in May 2005 and February 2006 for radium isotopes and in November 2007 for dissolved inorganic nutrients. Salinity profiles in cove waters suggested that SGD is derived from shallow brackish springs that formed a buoyant surface fresh layer of only 0.3 m depth. A binary mixing model that considers the distribution of radium activities was used to determine the cove water composition. Results showed that cove waters contained 20% brackish groundwater; of which 6% was recirculated seawater and 14% corresponded to freshwater discharge. Using a radium-derived residence time of 2.4 days, a total SGD flux of 150,000 m(3) year(-1) was calculated, consisting of 45,000 m(3) year(-1) recirculated seawater and 105,000 m(3) year(-1) fresh groundwater. Fresh SGD fluxes of NO3 (-), SiO4 (4-) and PO4 (3-) were estimated to be on the order of 18,000, 1,140 and 4 mu mol m(-2) day(-1), respectively, and presumably sustain the high phytoplankton biomass observed in the cove during summer. The total amount of NO3 (-) and SiO4 (4-) supplied by SGD was higher than the measured inventories in the cove, while the reverse was true for PO4 (3-). These discrepancies are likely due to non-conservative biogeochemical processes that occur within the subterranean estuary and Alcalfar Cove waters

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“…Therefore, radium is significantly more mobile under reducing and acid conditions (Albu et al 1997;Ames et al 1983;Langmuir & Riese 1985;Martin et al 2003;Szabo & Zapecza 1991). Several studies revealed a positive correlation between radium and salinity or chloride (Gascoyne 1989;Herczeg et al 1988;Lauria et al 2004;Sturchio et al 2001), and between high radium content and low pH . Two isotopes of uranium ( 238 U and 234 U) are represented in the 238 U decay chain (fig 1).…”

Section: Introductionmentioning

confidence: 99%

Conceptual model for the origin of high radon levels in spring waters – the example of the St. Placidus spring, Grisons, Swiss Alps

2007

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A variety of geological, hydrochemical and isotopic techniques were applied to explain the origin of exceptionally high radon levels in the St.Placidus spring near the city of Disentis in the Swiss Alps, where an average of 650 Bq/L 222 Rn was measured. 222 Rn is a radioactive noble gas with a half-life of 4 days, which results from the disintegration of radium ( 226 Ra). The high radon levels can neither be explained by generally increased radium content in the fractured aquifer rock (orthogneiss), nor by the radium concentration in the spring water. It was possible to show that there must be a productive radium reservoir inside the aquifer but very near to the spring. This reservoir mainly consists of iron and manganese oxides and hydroxides, which precipitate in a zone where reduced, iron-rich groundwaters mix occasionally with oxygen-rich, freshly infiltrated rainwater or meltwater. The iron, as well as the reduced and slightly acid conditions, can be attributed to pyrite oxidation in the recharge area of the spring. Radium cations strongly adsorb and accumulate on such deposits, and generate radon, which is then quickly transported to the spring with the flowing groundwater.

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Radium geochemistry of ground waters in Paleozoic carbonate aquifers, midcontinent, USA

Cited by 114 publications

References 44 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)

An assessment of karstic submarine groundwater and associated nutrient discharge to a Mediterranean coastal area (Balearic Islands, Spain) using radium isotopes

Conceptual model for the origin of high radon levels in spring waters – the example of the St. Placidus spring, Grisons, Swiss Alps

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