Distribution of 129I in the Baltic Sea using a model approach

Full text: Anthropogenic input of 129I has provided a number of applications in the marine and terrestrial environments. The discharged quantities into the atmosphere and the oceans have not been of particular health concern for regions at considerable distance from the discharge sources, as the Baltic Sea. Marine currents and wind patterns affect the migration and distribution of 129I to and in the Baltic Sea, but there are no sufficient measured data to predict present day and future distribution of the isotope. Modeling may, in some cases, become an excellent alternative of prediction and later comparison with measured data, when they become available, can improve and correct the model results. Here we present a mass-balance model (SPM) originally established for phosphorus by Haekanson (2007), but slightly modified in this work to accommodate to calculation of 129I concentration the Baltic Sea from different depths. The model is based on conventional equations and the processes governing elemental dynamic in the Baltic Sea such as mixing and diffusion. The calculated values were assessed with the average empirical data and reasonably matched in most areas of Baltic Sea. Moreover, 129I fluxes corresponding to different parts of Baltic Sea are estimated which are, to our best knowledge, never done before but are the indispensable task for further research. Due to the semi-close characteristics of Baltic Sea, 129I has a relatively long residence time and model prediction failed to run as they largely rely on meteorological data (temperature, precipitation and winds) which are difficult to prognoses and thus doubtful on a long time span. Despite this difficulty, the model presented here seems successful for prediction on a long timescale as all derived variables are accessed from GIS maps. (author)