Model simulation of inflow water to the Baltic Sea based on 129I

The semi-enclosed Baltic Sea represents a vital economic and recreational resource for more than 90 million people inhabiting its coasts. Extensive contamination of this sea by a variety of anthropogenic pollutants has raised the concern of the people in the region. Quantifying seawater inflow is crucial for estimating potential environmental risks as well as to find the best remedial strategy. We present here a model to estimate water inflow from the North Sea to the Baltic Sea by utilizing 129I as a tracer. The results predicted inflow range of 230–450 km3/y with best fit value around 330 km3/y from the North Sea to the Baltic Sea during 1980–1999. Despite limited time series data on 129I, the model presented here demonstrates a new management tool for the Baltic Sea to calculate inflow water compared to conventional methods (such as salinity, temperature and hydrographic models). - Highlights: • We present a model to estimate water inflow from North Sea to Baltic Sea by utilizing 129I as a tracer. • The model predicted inflow range of 230–450 km3/y from the North Sea to Baltic Sea during 1980–1999. • The model provides a new way of application of 129I isotope for the Baltic Sea