Electrochemical determination of dissolved uranium in Krka river estuary

The applicability of the previously developed method for electrochemical de termination of dissolved uranium concentration has been tested on natural w ater samples taken from the Krka river estuary during various seasons and a long different depth profiles. The method is based on the following treatme nt of the sample: destroying the uranyl-carbonato complexes by adjusting th e pH to 3. enabling the formation of adsorbable uranyl-hydroxo complexes by adjusting the pH to 6.5-7.0 and measurement by cathodic stripping voltamme try technique. As the signal of the dissolved uranium reduction is sometime s masked by the signal of the matrix of the sample, a resolution enhancemen t including digestion and:or deconvolution has to be applied. The measured concentration of dissolved uranium varies in the range from 0.4 to 3.3 x 10 (-8) mol l(-1), corresponding to the data found in the literature. The dept h profile of dissolved uranium concentration distributions shows conservati ve behaviour. The X-ray fluorescence spectroscopy (XRF) confirmed the applicability of th e method, yet pointing out to its limitations caused by the matrix of the s olution. (C) 2001 Elsevier Science Ltd. All rights: reserved.