Concentrations of 129I along a transect from the North Atlantic to the Baltic Sea
Large amounts of iodine-129 were, and still are, released to the environment from nuclear facilities, in particular from two reprocessing facilities located at the east coast of the North Atlantic Ocean (Sellafield and La Hague). The main transport path of the releases from the two facilities is towards Northern Europe and further into the Arctic Ocean. Here we present data of 129I concentrations observed along a transect from the Baltic Sea to the North Atlantic in 1999. Concentration of 129I in surface water samples are several orders of magnitude higher than the natural background level, with the highest enrichment found in the Skagerrak basin. Three profiles taken in the Baltic Sea show an increase of 129I with depth. Preliminary inventory calculations suggest that the major source of 129I in the Baltic Sea is via marine input from the North Sea. So far concentrations of this isotope do not constitute a source of environmental hazard.
Available from: Raul Periáñez
- "Among these radionuclides, 129 I is a very significant one since, due to its biophilic behaviour and very long half-life ð15:7 Â 10 6 yearsÞ, can even enter the food chain and remain there much longer than other short-lived isotopes. Thus, a number of studies concerning the distribution and fate of 129 I releases from the European reprocessing plants in the North Atlantic have been published (Smith et al., 2011; He et al., 2013; Michel et al., 2012; Alfimov et al., 2004, 2013; Gómez-Guzman et al., 2013). Some models have simulated the dispersion of 129 I in the northern Atlantic Ocean (Orre et al., 2009), as commented above. "
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ABSTRACT: A quantitative evaluation of the fate of (129)I, released from the European reprocessing plants of Sellafield (UK) and La Hague (France), has been made by means of a Lagrangian dispersion model. Transport of radionuclides to the Arctic Ocean has been determined. Thus, 5.1 and 16.6TBq of (129)I have been introduced in the Arctic from Sellafield and La Hague respectively from 1966 to 2012. These figures represent, respectively, 48% and 55% of the cumulative discharge to that time. Inventories in the North Atlantic, including shelf seas, are 4.4 and 13.8TBq coming from Sellafield and La Hague respectively. These figures are significantly different from previous estimations based on field data. The distribution of these inventories among several shelf seas and regions has been evaluated as well. Mean ages of tracers have been finally obtained, making use of the age-averaging hypothesis. It has been found that mean ages for Sellafield releases are about 3.5year larger than for La Hague releases.
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Available from: Xiaolin Hou
- "It is well established that marine discharges from Sellafield and La Hague (NRFs) are the main source of 129I in the North Sea, Baltic Sea, Nordic Seas and the Arctic Ocean81617. Whether the discharges have influenced the northeastern Atlantic Ocean and, if so, on what magnitude was not fully investigated. "
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ABSTRACT: Concentrations and species of iodine isotopes ((127)I and (129)I) provide vital information about iodine geochemistry, environmental conditions and water masses exchange in oceans. Despite extensive investigations of anthropogenic (129)I in the Arctic Ocean and the Nordic Seas, concentrations of the isotope in the Atlantic Ocean are, however, still unknown. We here present first data on (129)I and (127)I, and their species (iodide and iodate) in surface water transect along the northeastern Atlantic between 30° and 50°N. The results show iodate as the predominant species in the analyzed marine waters for both (127)I and (129)I. Despite the rather constant ratios of (127)I(-)/(127)IO3(-), the (129)I(-)/(129)IO3(-) values reveal variations that apparently response to sources, environmental conditions and residence time. These findings provide a new tracer approach that will strongly enhance the application of anthropogenic (129)I in ocean environments and impact on climate at the ocean boundary layer.
Available from: H.-A. Synal
- "The corresponding geometric mean of the 129 I/ 127 I ratios was 1.5 × 10 − 6 with a geometric standard deviation of 1.4. This value is four orders of magnitude higher than the ratio of 10 − 10 observed in oceanic mixing layer remote from 129 I sources (Yiou et al., 1994; Alfimov et al., 2004b). It is also much higher than the ratio of 4.6 × 10 − 8 observed by Yiou et al. (1994) in a sample of central North Sea water taken in 1992. "
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ABSTRACT: In order to obtain a comprehensive survey on the consequences of the marine (129)I discharges from the European reprocessing plants La Hague and Sellafield, the distribution of (129)I and (127)I in surface waters of the North Sea, the English Channel, the Irish Sea, and the Northeast Atlantic was studied using accelerator mass spectrometry for (129)I and ICP-MS for (127)I. Samples of seawater were taken in the German Bight in May, September, and November 2005 and in the entire North Sea and the English Channel in August 2005. Further samples were obtained from the Irish Sea in June and August 2006 and from Arctic waters between Spitsbergen and Southern Norway in September 2005. (129)I is a conservative tracer in seawater. The concentrations of (127)I are relatively constant with exceptions of coastal areas with high biological activity and of areas influenced by influx from rivers and the Baltic Sea. The variability of the (129)I/(127)I isotopic ratios is exclusively determined by admixture of (129)I released from the reprocessing facilities Sellafield and La Hague to the seawater. The (129)I/(127)I ratios were between 4 × 10(-9)and 3 × 10(-6): at least 3 orders of magnitude higher than the natural equilibrium isotopic ratio 1.5 × 10(-12). (129)I/(127)I ratios of a few times 10(-10) were only found in seawater from the Indian Ocean and from the Pacific at Hawaii. Comparison of the results obtained for seawater with those of a measurement of airborne iodine species and with iodine isotopes in precipitation in Northern Germany demonstrates the transfer of (129)I and (127)I from the sea into the atmosphere and the dominating role of the marine discharges for the atmospheric fallout of (129)I in Western Europe. The results are discussed with the goal to estimate the relevance of the marine discharges for the contamination of the continental areas.
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