Sorption behavior of radium on sandy and clayey sediments of the upper Saxon Elbe river valley

Abstract

With the background of uranium mine restoration the adsorption of radium on different kinds of sandstone, claystone and lime marl was studied as a function of such parameters as water composition, acidity, phase contact time and the concentration of radium, barium and sulfate by static butch experiments at the mine temperature of 14 ~

Modeling radium distribution in coastal aquifers during sea level changes: The Dead Sea case

“…Previous studies (experimental and field data) show a large variability of aquifer K's ($10-100,000; Krishnaswami et al, 1982;Rama and Moore, 1996;Baraniak et al, 1999;Sturchio, 2001;Gonneea et al, 2008). These were mainly calculated for fine-grained sediments, glacial deposits, and sand and carbonate aquifers.…”

Kd Values for Agricultural and Surface Soils for Use in Hanford Site Farm, Residential, and River Shoreline Scenarios

“…In long contact tests (up to 21 weeks), the radium K d slowly increased but ~95% of the radium that adsorbed did so in the first 24 hours of contact. The very slow reaction that incorporates small additional amounts of radium was hypothesized by Baraniak et al (1999) 3.23 as being radium incorporation/substitution into crystals of barite (barium sulfate a very insoluble compound). In fact, the K d for radium is found to increase if additional barium (7 x 10 -7 to 2.5 x 10 -5 M) and sulfate (1.25 x 10 -4 to 1 x 10 -1 M) is added to the groundwater.…”

“…From the mentioned tabulations and all the generic radium studies just described, a radium K d value of 200 mL/g was chosen for the "best" or most probable value and a range of 5 to 500 mL/g for sensitivity analyses for the agricultural and river bank soil scenarios described earlier. A lower "best" K d value was selected than recommended by Napier and Snyder (2002) and to honor the lower K d values found by Baraniak et al (1999) and Sun and Torgersen (2001) and to stay consistent with classical ion exchange as being a dominant sequestration mechanism for radium. Because the future Hanford agricultural soils and river bank sediments will remain rather coarse in particle size, the K d might be lower than many contaminants that adsorb more so by variable charged hydrous oxides, or co-precipitate/adsorb with high pH sensitivity such as transition metals, lanthanides, and most lower valence state actinides.…”

“…Perhaps this inner-sphere complex reaction leads to relatively strong adsorption for large-size divalent cations, such as radium. Baraniak et al (1999) studied the adsorption of 226 Ra spiked into groundwater onto sand, clay, and lime marl sediments from the Saxon Elbe river valley. Batch K d tests were performed using from 1 to 10 grams of crushed solids into 5 to 50 mL of groundwater for contact times of up to 8 weeks at 14°C.…”

“…This range of K d values and the mean suggest that radium sorption in some environments can be relatively low and more similar to strontium than divalent transition metals in waters with high concentrations of competing cations. This report relied on the Baraniak et al (1999) and Sun and Torgersen (2001) to choose the range for the radium K d for this compilation. Aguado et al (2004) sampled riverbed sediments from an estuary historically affected by waste discharged by several phosphate fertilizer plants, which contained enriched uranium-series radionuclides.…”