The ability to robustly quantify the potential for strontium precipitation and scaling in both natural surface waters and water infrastructure systems is limited. In some regions, both surface and ground water supplies contain significant concentrations of naturally occurring radionuclides, such as strontium, that can accumulate in water, soils and sediments, media, and living tissues. Methods for quantifying and predicting the potential for these occurrences are not readily available nor have they been tested and calibrated to cold region aquatic environments. Through extensive literature review, it was determined that a modified calcium carbonate precipitation potential (CCPP) model offered a scientifically credible approach to filling that knowledge gap in both the science and engineering of strontium fate and transport in water. The results from previous field and laboratory experiments were compiled to not only elucidate the fate and transport of strontium in water systems, but also to calculate the logarithmic distribution coefficient, λ, for strontium under co-precipitation conditions. Lambda (λ) is both time- and water-quality sensitive and must be measured as water mixes from source to receiving environment to determine continuous loss of Sr from the water phase. The data were collected to develop the strontium precipitation potential model that can be used in surface water quality assessment. The tool was then applied to pre-existing, publicly available, and extensive datasets for several rivers in Saskatchewan, Canada, to validate the model and produce estimates for strontium precipitation potential in those rivers.
Quantification and scientific observations of the fate and transport of dissolved strontium in water systems, particularly cold climate water systems, are severely lacking. In this work, in an experiment conducted at a temperature of 6 °C, the observation of strontium precipitation along with calcium carbonate minerals from cold wastewater is investigated. ICP-MS is used for metal analyses where the distribution of the species and saturation state of minerals along with a surface complexation model was performed using the public-use USGS geochemical modeling software, PHREEQC (PH Redox Equilibrium (in C language)). Sample media were analyzed using XPS and Raman spectroscopy. The results suggest that the loss of strontium from natural waters is via the process of co-precipitation with calcite, a calcium carbonate polymorph. The observations and findings are intended to be useful to quantify the loss of 90Sr from the water, in the case of an unplanned release from a nuclear reactor-operated facility. The results indicate that the precipitation model is a robust and reliable approach to predicting and monitoring the behaviour and transport of strontium that may occur in natural environments as a result of an accidental nuclear release.
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