The first dataset of 236 U/ 238 U in the water column of the Arctic Ocean (AO) is presented and shows the widest range of ratios reported so far in the open ocean, from (5±5) to (3840±260) ×10-12. Surface samples and depth profiles were collected during two GEOTRACES expeditions in 2011-2012 and analyzed for the concentrations of 236 U and 129 I, with the aim of investigating whether the combination of 236 U/ 238 U and 129 I/ 236 U can be used as a new oceanographic tool in the AO. Results show that the distributions of the 236 U/ 238 U and 129 I/ 236 U atomic ratios are consistent with the different water masses in the AO. High 236 U/ 238 U and 129 I/ 236 U ratios in the upper water column (>2000 ×10-12 and >200, respectively) illustrate the penetration of Atlantic waters (AW) into the AO. Lower values were found in Pacific waters (PW) and deep waters of the AO. Rivers seem to represent a temporally and spatially-constrained third anthropogenic source of 236 U but more data is needed to confirm this. In a simple

No abstract

No abstract

a b s t r a c tThe radiation exposure of thyroid glands due to 131 I as a consequence of the Chernobyl accident was investigated retrospectively based on 129 I and 137 Cs inventories in soils in Northern Ukraine. To this end, soil samples from 60 settlements were investigated for 129 I, 127 I, and 137 Cs by AMS, ICP-MS and gammaspectrometry, respectively. Sampling was performed between 2004 und 2007.In those parts of Northern Ukraine investigated here the 129 I and 137 Cs inventories are well correlated, the variability of the individual 129 I/ 137 Cs ratios being, however, high. Both the 129 I and 137 Cs inventories in the individual 5 samples for each settlement allowed estimating the uncertainties of the inventories due to the variability of the radionuclide deposition and consequently of the retrospective dosimetry.Thyroid equivalent doses were calculated from the 129 I and the 137 Cs inventories using aggregated dose coefficients for 5-year old and 10-year-old children as well as for adults. The highest thyroid equivalent doses (calculated from 129 I inventories) were calculated for Wladimirowka with 30 Gy for 5-years-old children and 7 Gy for adults. In 35 settlements of contamination zone II the geometric mean of the thyroid equivalent doses was 2.0 Gy for 5-years-old children with a geometric standard deviation (GSD) of 3.0. For adults the geometric mean was 0.47 Gy also with a GSD of 3.0. In more than 25 settlements of contamination zone III the geometric means were 0.82 Gy for 5-years old children with a GSD of 1.8 and 0.21 Gy for adults (GSD 1.8).For 45 settlements, the results of the retrospective dosimetry could be compared with thyroid equivalent doses calculated using time-integrated 131 I activities of thyroids which were measured in 1986. Thus, a critical evaluation of the results was possible which demonstrated the general feasibility of the method, but also the associated uncertainties and limitations.