Effect of pH, temperature, conductivity and sediment size on thorium and radium activities along Jucar River (Spain)

Sánchez, F.; Rodríguez-Álvarez, M. J.

doi:10.1007/bf02347378

“…Once again, the sediment chemistry influences the amount of Ra release, with sediments from the bottom Mn (hydr)oxide rich layer releasing less Ra than sediments from the top and middle. It is likely that this increased release at pH 5 compared to pH 8 is not only due to desorption, but rather to dissolution of the oxides onto which surface Ra is bound, which explains why Ra release is observed at salinity 0, where significant Ra desorption is not expected (Lauria et al, 2004;Sanchez and Rodriguez-Alvarez, 1999). …”

Section: Ra Release and Groundwater Phmentioning

confidence: 99%

“…Ra release in surface estuaries has been mainly attributed to desorption of Ra from suspended and bottom sediments as salinity increases (Li and Chan, 1979;Elsinger and Moore, 1980). However, radium behavior within the STE has additional complexity including varying fractions of exchangeable sediment Ra (Porcelli and Swarzenski, 2003); grain size and porosity of sediments (Webster et al, 1995, Hancock et al, 2006; changes in ionic strength (salinity) (Elsinger and Moore, 1980;Webster et al, 1995); temperature effects (Rama and Moore, 1996); pH (Sanchez and Rodriguez-Alvarez, 1999;Lauria et al, 2004); and barite solubility (Ba and Ra are chemical analogs) (Langmuir and Riese, 1985;Grundl and Cape, 2006). Other controls have been suggested but not thoroughly examined including the redox state of groundwater (including Eh and pH) (Puigdomènech and Bergström, 1995;Porcelli and Swarzenski, 2003) and the presence Fe and, in particular, Mn (hydr)oxides, since Ra has a very high affinity for Mn and Fe (Bollinger and Moore, 1993;Sun and Torgersen, 2001;Charette and Sholkovitz, 2006).…”

Section: Introductionmentioning

confidence: 99%

New perspectives on radium behavior within a subterranean estuary

Gonneea

¹

,

Morris

²

,

Dulai

³

et al. 2008

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Abstract:Over the past decade, radium isotopes have been frequently applied as tracers of submarine groundwater discharge (SGD). The unique radium signature of SGD is acquired within the subterranean estuary, a mixing zone between fresh groundwater and seawater in coastal aquifers, yet little is known about what controls Ra cycling in this system. The focus of this study was to examine controls on sediment and groundwater radium activities within permeable aquifer sands (Waquoit Bay, MA, USA) through a combination of field and laboratory studies. In the field, a series of sediment cores and corresponding groundwater profiles were collected for analysis of the four radium isotopes, as well as dissolved and sediment associated manganese, iron, and barium. We found that in addition to greater desorption at increasing salinity, radium was also closely tied to manganese and iron redox cycling within these sediments. A series of laboratory adsorption/desorption experiments helped elucidate the importance of 1) contact time between sediment and water, 2) salinity of water in contact with sediment, 3) redox conditions of water in contact with sediment, and 4) the chemical characteristics of sediment on radium adsorption/desorption. We found that these reactions are rapid (on the order of hours), desorption increases with increasing salinity and decreasing pH, and the presence of Fe and Mn (hydr)oxides on the sediment inhibit the release of radium.These sediments have a large capacity to sorb radium from fresh water. Combined with these experimental results, we present evidence from time series groundwater sampling 2 that within this subterranean estuary there are cyclic periods of Ra accumulation and release controlled by changing salinity and redox conditions.

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Radium: Radionuclides

Vandenhove¹,

Verrezen²,

Landa³

2005

Encyclopedia of Inorganic Chemistry

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This article describes (1) the occurrence, chemistry, and bioavailability of radium (Ra) in terrestrial and aquatic environments, and its analysis in environmental samples, (2) the nature of naturally occurring radioactive materials (NORM) and their role in radium‐contamination scenarios, and (3) the geochemical processes and remedial measures associated with radium‐contaminated water and soil. Radium is the heaviest of the Group II, alkaline earth metals. Radium is exclusively divalent and its chemistry resembles that of barium. Radium has a limited environmental mobility due to sorption (e.g., by hydrous oxides of Fe, Mn, and Al) and coprecipitation reactions (e.g., with barite). All isotopes of radium (atomic number 88) are radioactive. The most important radium isotopes are 226 Ra (half life 1600 years) and 228 Ra (half life 5.7 years), decay products of, respectively, the 238 U and the 232 Th series. As members of natural radioactive decay series, these radium isotopes are found in uranium‐ and thorium‐bearing minerals. Concentrations of uranium and thorium in rocks can range from those of ore‐grade deposits to the trace levels typical of common rock‐forming minerals. In uncontaminated surface waters, radium content is generally low and within a narrow range (0.5–20 mBq l −1 ). Radium in groundwater is highly variable (<0.52–55 000 mBq l −1 ) and can arise from natural sources, resulting from the interaction of groundwater with radium‐bearing materials or indirectly from man's exploitation of the radioactive minerals of uranium and thorium. The major challenge associated with many NORM‐containing residues or NORM‐contaminated sites is the larger volumes of material and the relatively low specific activities.

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Radium: Radionuclides

Vandenhove¹,

Verrezen²,

Landa³

2011

Encyclopedia of Inorganic and Bioinorganic Chemistry

2

0

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This article describes (1) the occurrence, chemistry, and bioavailability of radium (Ra) in terrestrial and aquatic environments, and its analysis in environmental samples, (2) the nature of naturally occurring radioactive materials (NORM) and their role in radium‐contamination scenarios, and (3) the geochemical processes and remedial measures associated with radium‐contaminated water and soil. Radium is the heaviest of the Group II, alkaline earth metals. Radium is exclusively divalent and its chemistry resembles that of barium. Radium has a limited environmental mobility due to sorption (e.g., by hydrous oxides of Fe, Mn, and Al) and coprecipitation reactions (e.g., with barite). All isotopes of radium (atomic number 88) are radioactive. The most important radium isotopes are 226 Ra (half life 1600 years) and 228 Ra (half life 5.7 years), decay products of, respectively, the 238 U and the 232 Th series. As members of natural radioactive decay series, these radium isotopes are found in uranium‐ and thorium‐bearing minerals. Concentrations of uranium and thorium in rocks can range from those of ore‐grade deposits to the trace levels typical of common rock‐forming minerals. In uncontaminated surface waters, radium content is generally low and within a narrow range (0.5–20 mBq l −1 ). Radium in groundwater is highly variable (<0.52–55 000 mBq l −1 ) and can arise from natural sources, resulting from the interaction of groundwater with radium‐bearing materials or indirectly from man's exploitation of the radioactive minerals of uranium and thorium. The major challenge associated with many NORM‐containing residues or NORM‐contaminated sites is the larger volumes of material and the relatively low specific activities.

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Effect of pH, temperature, conductivity and sediment size on thorium and radium activities along Jucar River (Spain)

Cited by 16 publications

References 15 publications

New perspectives on radium behavior within a subterranean estuary

New perspectives on radium behavior within a subterranean estuary

Radium: Radionuclides

Radium: Radionuclides

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