Modelling the effect of salinity on radium desorption from sediments

Webster, Ian T.; Hancock, Gary; Murray, Andrew

doi:10.1016/0016-7037(95)00141-7

Cited by 161 publications

(119 citation statements)

References 11 publications

Supporting

Mentioning

110

Contrasting

Order By: Relevance

“…For an increase in salinity from 5 to 25, Ra desorption increased around 50%, a value that may be applicable for other settings with permeable siliceous sands. It is encouraging that this value agrees with that of Webster et al (1995), who reported a range from 0 to 66% increase in desorption between the same salinities for all four isotopes for sediment with a similar grain size from the Bega River.…”

Section: Ra Desorption and Salinity Of Groundwatersupporting

confidence: 88%

“…226 Ra displayed the opposite trend, with sediments from the bottom of PZ 11 desorbing 1 to 2.7 dpm/100g, with all other sediments desorbing 0.3 to 0.6 dpm/100g (Figure 3a-c). There are large ranges in the increase in desorption from salinity 5 to 25 (from 17 to 131%), but it is still apparent that increases in salinity result in increased radium desorption as has been previously observed (Elsinger and Moore, 1980;Webster et al, 1995). For an increase in salinity from 5 to 25, Ra desorption increased around 50%, a value that may be applicable for other settings with permeable siliceous sands.…”

Section: Ra Desorption and Salinity Of Groundwatersupporting

confidence: 57%

“…K d = Ra solid /Ra liquid Distribution coefficients are determined in a variety of ways, usually in laboratory experiments where Ra isotopes are spiked onto sediment/water slurries (Rama and Moore, 1996;Hancock et al, 2006) or in laboratory experiments where sediment and water are equilibrated (Webster et al, 1995 (Benes, 1990). It is also important to determine which fraction of the sedimentary Ra pool is being used to calculate K d .…”

Section: )mentioning

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%

See 3 more Smart Citations

New perspectives on radium behavior within a subterranean estuary

et al. 2008

View full text Add to dashboard Cite

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.

show abstract

Section: Ra Desorption and Salinity Of Groundwatersupporting

confidence: 88%

Section: Ra Desorption and Salinity Of Groundwatersupporting

confidence: 57%

Section: )mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

New perspectives on radium behavior within a subterranean estuary

et al. 2008

View full text Add to dashboard Cite

show abstract

“…Dukat & Kuehl (1995) used the radium activity ratio ( 226 Ra/ 228 Ra) for the estimation of the growth rate of the bottom sediments in the Amazon shelf. Based on the experiments on radium isotopes leaching from sediments and a model of the ion exchange, Webster et al (1995) stated that the leached radium fraction increases with increasing concentrations of Geology, Geophysics and Environment, 2016, 42 (3): 337-351…”

Section: Introductionmentioning

confidence: 99%

Factors controlling 226Ra, 228Ra and their activity ratio in groundwater – an application in Polish Carpathian mineral waters

Nguyen

Kopeć

Nowak

2016

geol

View full text Add to dashboard Cite

Abstract:The influences of aquifer formations and water chemical composition on the occurrence and activity ratio of radium isotopes in groundwater are discussed. Based on the model of desorption/adsorption processes of natural radionuclides in the rock-water system, the concentrations of radium isotopes and their activity ratio in groundwater are evaluated by the numerical Monte Carlo method (MC). In cases where the groundwater is of a similar age, limited flow (up to several meters/year), the physical conditions and the uranium and thorium activity ratios in host water formations are similar, the activity concentrations of radium isotopes ( 226 Ra, 228 Ra) and their activity ratio ( 226 Ra/ 228 Ra) are the highest in the water of high desorption coefficient for chloride sodium water (domination of Cl − , Na + ions), medium in water of moderate desorption (bicarbonate water -HCO 3 − , Ca 2+ ) and the lowest in waters with a low desorption coefficient (sulfate ions prevailing -SO 4 2− , Ca 2− ). The statements are well confirmed in the case of the natural mineral waters from the Polish Outer Carpathians. The total dissolved solids (TDS) of the Polish Carpathians waters varies from several hundred milligrams per liter to several tens of thousands milligrams per liter. The minimum, maximum and average concentrations of 226 Ra, 228 Ra and their activity ratio ( 226 Ra/ 228 Ra) are 82, 1340, 456 mBq/L, 19, 1240, 354 mBq/L and 0.89, 7.6 and 2.0 for chloride waters; 4, 140, 45.8 mBq/L, 12, 171, 62.7 mBq/L and 0.3, 1.7 and 0.70 for bicarbonate waters and 0.8, 9.3, 3.6 mBq/L, 5.3, 54, 20.1 mBq/L and 0.1, 1.0, 0.3 for sulfate ones, respectively. The desorption coefficients are the highest for the Cl-Na, moderate for the HCO 3 -Ca and the lowest for the SO 4 -Ca waters (in contrast to the adsorption properties of these waters).

show abstract

Determining groundwater Ra end‐member values for the estimation of the magnitude of submarine groundwater discharge using Ra isotope tracers

Cho

Kim

2016

Geophysical Research Letters

View full text Add to dashboard Cite

Radium isotopes (228Ra and 226Ra) are excellent tracers of submarine groundwater discharge (SGD). To estimate SGD magnitudes, information on the end‐member values of Ra concentrations in groundwater is critical; however, the distribution characteristics of Ra in coastal aquifers are poorly understood. In this study, we show that Ra concentrations in coastal groundwater are primarily dependent on salinity based on the data (n > 500) obtained from global coastal aquifers, although previous end‐member calculations averaged all Ra concentrations without considering salinity. If we assume that SGD is composed mainly of seawater infiltrating the aquifer, previous estimates of SGD for the Atlantic Ocean and the global ocean were overestimated twofold to threefold. This may be similar for other applications using different Ra isotopes. Our study highlights that the end‐members of Ra isotopes in groundwater should be carefully considered when estimating SGD using Ra isotope mass balances in the ocean.

show abstract

Modelling the effect of salinity on radium desorption from sediments

Cited by 161 publications

References 11 publications

New perspectives on radium behavior within a subterranean estuary

New perspectives on radium behavior within a subterranean estuary

Factors controlling 226Ra, 228Ra and their activity ratio in groundwater – an application in Polish Carpathian mineral waters

Determining groundwater Ra end‐member values for the estimation of the magnitude of submarine groundwater discharge using Ra isotope tracers

Contact Info

Product

Resources

About