Soluble and particle-bound U-234,U-238, Ra-226 and Po-210 in ground waters

Water of five drilled wells was filtered with three membranes (pore size 0.45 mum - 5 kD) to determine the soluble and particle-bound forms of U-234,U-238, Ra-226 and Po-210. Three of the waters were of Ca-HCO3 type and two of Na-Cl type. Some of the waters also exhibited high concentrations of Fe, Mn and humic substances. U-234,U-238 was present entirely in soluble form in all waters, probably as uranyl ion (UO22+) in soluble carbonate complexes. Ra-226 was in soluble form in the waters with low concentrations of Fe and Mn, but 10% of the total Ra-226 activity was bound to particles in the Fe-Mn-rich waters. The behaviour of Po varied with water composition. Particle-bound Po-210 was observed to correlate with the combined concentration of iron and manganese in the raw waters. In the two of waters of Na-Cl type, in which the concentrations of Fe, Mn and humic substances were high, salinity of the waters did not enhance the solubility of polonium. Polonium was present in both soluble and particle-bound forms in all the ground waters.