The radiological environment of Svalbard

This paper presents a detailed survey of the radiological environment of the Svalbard area carried out from 2000 to 2002, in both the marine and terrestrial environment. In the marine environment in 2001, 99Tc activity concentrations in seawater were 0.13 to 0.36 Bq/m3, 5 fold higher than those in 1994, refl ecting the increase in 99Tc discharges from Sellafi eld in the mid 1990s. Cs-137 activity concentrations in seawater were 2.23 to 2.43 Bq/m3, ca. 10 fold lower than those in the 1980s, refl ecting the reduction in discharge of this radionuclide. Pu-238, 239+240Pu and 241Am activity concentrations in seawater were < 0.3 to 0.7 mBq/m3, 5.6 to 8.9 mBq/m3 and 0.6 to 2.4 mBq/m3 respectively, with activity ratios suggesting global fallout to be the dominant source. Tc-99 activity concentrations in brown algae were up to 18 fold higher than those in the 1980s with highest concentrations in Fucus distichus (25.7 to 58.7 Bq/kg d.w.). In the terrestrial environment, typical 137Cs activity concentrations in soil were between < 0.5 and 63 Bq/kg d.w. whilst activity concentrations of the natural radionuclides 238U (17 to 72 Bq/kg d.w.), 226Ra (21 to 70 Bq/kg d.w.), 232Th (10 to 57 Bq/kg d.w.) and 40K (115 to 818 Bq/kg d.w.) were similar to global averages. In terrestrial vegetation, 137Cs activity concentrations varied from 29 to 292 Bq/kg d.w. in mosses, 30 to 140 Bq/kg d.w. in lichen and 19 to 109 Bq/kg d.w. in fl owering plants. Elevated activity concentrations of 137Cs, 238U, 226Ra, Pu isotopes and 241Am were found in some matrices associated with seabird colonies

Optimization of sampling for the temporal monitoring of Technetium-99 in the Arctic marine environment

Monitoring of the marine environment for radioactivity, for both radiological protection and for oceanographic purposes, remains an expensive and labour intensive activity due to the large sample volumes needed and the complex and lengthy analytical procedures required to measure low levels of contamination. Because of this, some consideration must be given to the design of sampling plans to ensure effective and efficient sampling that can be defended on the basis of scientific rationale. This article tests the hypothesis that geostatistical techniques may prove of use in the optimisation and design of sampling regimes for the monitoring of temporal fluctuations in the levels of technetium at a location in the Norwegian Arctic marine environment. The level of temporal correlation exhibited by two relevant time series was investigated and the information used to observe the effect of sampling frequency on the production of monthly estimates of activity of technetium in both seawater and seaweed. The results indicate that reduced sampling frequency allows production of estimates that acceptably replicate the actual data and that use of geostatistical procedures may offer advantages in the planning of monitoring systems for marine radioactivity. The use of an oceanographic model was also investigated as a means of assessing the temporal correlation prior to actual sampling, an approach that may offer significant advantages by reducing the need to have lengthy time series prior to designing sampling regimes