Temporal
Variation of Iodine Isotopes in the North
Sea
- Publication date
- Publisher
Abstract
Monitoring temporal
variability of <sup>129</sup>I in the North
Sea, a relatively large reservoir of radioactive discharges from the
nuclear fuel reprocessing facilities, is vital for the environmental
situation in the region. New information on concentration levels and
distribution of <sup>129</sup>I and <sup>127</sup>I and their species
forms (iodide and iodate) are gained here through sampling of surface
water in 2010. The results show generally large spatial and temporal
(compared to data from 2005) fluctuations of total <sup>129</sup>I
and <sup>127</sup>I, and iodide and iodate. In samples south of 53°N,
the level of <sup>127</sup>I<sup>–</sup> in 2010 was generally
comparable or higher than in 2005. The results also show total <sup>129</sup>I concentrations comparable in the south, but 2–8
times lower in the north, to the analyses made in 2005. Different
from total <sup>129</sup>I, the <sup>129</sup>I<sup>–</sup>/<sup>129</sup>IO<sub>3</sub><sup>–</sup> values in the northern
part were 2 times higher in 2010 than values observed in 2005. These
variations in total <sup>129</sup>I and <sup>127</sup>I and their
species are related to coastal water offshore propagation and surface
currents that are linked to long-term and seasonal climatic changes
over the North Atlantic and North Sea. Inventory estimation shows
that >90% of <sup>129</sup>I resides in the Southern and German
Bights,
which also suggests negligible contribution from the Sellafield facility
discharges when compared with that from the La Hague. Variability
in discharge rate from La Hague may also affect the distribution patterns
of <sup>129</sup>I in the North Sea on the monthly scale