Anthropogenic ~(129)I in the atmosphere: Overview over major sources, transport processes and deposition pattern

摘要

Wet and, to a lesser extent, dry deposition of atmospheric ~(129)I are known to represent the dominatingrnprocesses responsible for ~(129)I in continental environmental samples that are remote from ~(129)I sources andrnnot directly influenced by any liquid ~(129)I release of nuclear installations. Up to now, however, little is knownrnabout the major emitters and the related global deposition pattern of ~(129)I.rnIn this work an overview over major sources of ~(129)I is given, and hitherto unknown time-dependent releasesrnfrom these were estimated. Total gaseous ~(129)I releases from the US and former Soviet reprocessing facilitiesrnHanford, Savannah River, Mayak, Seversk and Zheleznogorsk were found to have been 0.53,0.27,1.05,0.23rnand 0.14 TBq, respectively. These facilities were thus identified as major airborne ~(129)I emitters.rnThe global deposition pattern due to the ~(129)I released, depending on geographic latitude and longitude, andrnon time was studied using a box model describing the global atmospheric transport and deposition of ~(129)I.rnThe model predictions are compared to ~(129)I concentrations measured by means of Accelerator MassrnSpectrometry (AMS) in water samples that were collected from various lakes in Asia, Africa, America andrnNew Zealand, and to published values.rnAs a result, both pattern and temporal evolution of ~(129)I deposition values measured in and calculated forrndifferent types of environmental samples are, in general, in good agreement This supports our estimate onrnatmospheric ~(129)I releases and the considered substantial transport and deposition mechanisms in our modelrncalculations.