The Bothnian Sea which is located between Finland and Sweden represents an important source of fresh water to the Baltic Sea. We here present new data on the radioactive isotope 129I species from water samples collected in December 2009 at different depths in the Bothnian Sea. Concentrations of 129I− (iodide) in the Bothnian Sea range from 14 × 108 to 32 × 108 atoms/L, while 129IO3 − (iodate) concentrations are relatively low and fluctuating at 1 × 108 atoms/L. For nutrients data determined in the same samples as 129I, significant correlations could be found between 129I− and total P, NO3–N, SiO3–Si, but rather poor with NH4–N. The correlations suggest comparable source pathway of 129I− and nutrient parameters, while the source of NH4–N may be different. The small amounts and negligible change of 129IO3 − indicate prevailing extensive reduction of iodate in the Baltic Sea.
Journal of Radioanalytical and Nuclear Chemistry, 2013, Vol 295, Issue 2, p. 1459-1463