The transfer of uranium from sediment to water along Jucar River, Spain

Abstract

The effect of sediment size, pH, temperature and conductivity on the transfer of uranium from sediment to water has been studied. The uranium concentration and the 234U/23SU, 235U/238U activity ratios were measured in water, sediments and suspended matter sampled from Jucar River, using low level alpha-spectrometry. Distribution factors were obtained from these measurements. A more detailed sampling was done in the neighbourhood of the Cofrentes Nuclear Plant (Valencia, Spain). Total uranium activity, 234U/23Su activity ratio and distribution factors for 234U and 23sU were found to vary with pH. Leaching and dilution, which depend on pH and salinity, are the probable mechanisms for these changes.

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

“…This correlation, being significant, is not so strong as the uranium correlation we found previously for uranium/pH in Jucar river. 4 However, thorium correlation activity with pH was not significant. This is probably due to the low solubility of thorium in water.…”

“…As explained in a previous paper, 1 Jucar River is one of the main important rivers in Eastern Spain (=500 km). There are, in principle, no local sources of uranium, thorium and radium affecting the river.…”

“…The extraction method used in this work is that previously developed in our laboratory 4,5 that's why only a brief description is given here. Solid samples are digested with an acid treatment, and finally dissolved in 500 ml of distilled water and treated as a liquid sample.…”

“…In this work we study thorium and radium activities in sediments, suspended matter and water along Jucar river in order to investigate if there is a behavior similar to that we found for uranium. A low level a-spectrometry procedure was developed 5 in our laboratory and used for these measurements. We have found a dependence between radium activities in water and pH, but no so correlated as in uranium case.…”

“…Our aim was to investigate if there was any dependence for thorium and radium distribution factors as we did previously for uranium. 5 …”