<p>During recent decades, huge amount of radioactive waste has been dumped into the earth's surface environments. <sup>129</sup>I (T<sub>1/2 </sub>= 15.6 My) is one of the radioactive products that has been produced through a variety of processes, including atomic weapon testing, reprocessing of nuclear fuel and nuclear accidents. This thesis describes development of the Accelerator Mass Spectrometry (AMS) ultra-sensitive atom counting technique at Uppsala Tandem Laboratory to measure <sup>129</sup>I and discusses investigations of its distribution in the hydrosphere (marine and fresh water) and precipitation. The AMS technique provides a method for measuring long-lived radioactive isotopes in small samples, relative to other conventional techniques, and thus opens a new line of research. The optimization of the AMS system at Uppsala included testing a time of flight detector, evaluation of the most appropriate charge-state, reduction of molecular interference and imporvement of the detection limit. Furthermore, development of a chemical procedure for separation of iodine from natural water samples has been accomplished. </p><p>The second part of the thesis reports investigations of <sup>129</sup>I in natural waters and indicates that high concentrations of <sup>129</sup>I (3-4 orders of magnitude higher than in the pre-nuclear era) are found in most of the considered natural waters. Inventory calculations and results of measurements suggest that the major sources of radioactive iodine are the two main European nuclear reprocessing facilities at Sellafield (U.K.) and La Hague (France). This information provides estimates of the transit time and vertical mixing of water masses in the central Arctic Ocean. Results from precipitation, lakes and runoff are used to elucidate mechanisms of transport of <sup>129</sup>I from the point sources and its pathways in the hydrological environment. This study also shows the need for continuous monitoring of the <sup>129</sup>I level in the hydrosphere and of its future variability.</p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:uu-1077 |
| Date | January 2000 |
| Creators | Buraglio, Nadia |
| Publisher | Uppsala University, Department of Materials Science, Uppsala : Acta Universitatis Upsaliensis |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, text |
| Relation | Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1104-232X ; 570 |
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