Liquid scintillation counting of the alpha-radionuclides after pre-concentration by cation-exchange represents a simple and
robust method for the determination of total alpha-radioactivity in seawater. The total efficiency and the minimum detectable
activity were calculated to be 95% and 30 mBq, respectively, for a liter sample and 1000-minute measuring time. The method
has been applied successfully for the determination of alpha-radioactivity in seawater from five different coastal areas in
Cyprus. The average alpha-radioactivity and uranium concentration were found to be 124±8 mBq . l-1 and 3.2±0.2 mg . l-1, respectively.
Authors:S. Antoniou, C. Kolokassidou, K. Polychronopoulou, and I. Pashalidis
The stability of UO2CO3 has been studied as a function of the humic acid concentration in 0.1M NaClO4, in the weak acidic pH range (4.5–5) under CO2 atmosphere. The solid phase under investigation has been prepared by alkaline precipitation and characterized by TGA, ATR-FTIR,
XRD, SEM and solubility measurements. According to the experimental data, UO2CO3 is stable and remains the solubility limiting solid phase even in the presence of increased humic acid concentration in solution.
However, humic acid affects texture and particle size of the solid phase. Increasing humic acid concentration results in decreasing
crystallite size of the UO2CO3 solid phase. Based on the solubility data, the logKsp(UO2CO3) has been evaluated to amount −13.7±0.2 for the humic acid-free system and −13.2±0.3 for the humic acid containing system.