A one-dimensional dispersion model for radionuclides in the marine environment applied to the chernobyl fallout over the Northern Baltic Sea

Abstract

The Baltic Sea was the marine ecosystem most affected by Chernobyl fallout. The occurrence of ‘hot spots’ at the water surface was characteristic of the contamination. A one-dimensional vertical dispersion model has been used to explain the distribution of the radionuclides, cesium-137 and cesium-134, in the water column of the central Bothnian Sea for the first six months after the contamination event. In addition to physical dispersion processes, specific chemical characteristics of the radionuclides were taken into account. The simulation shows that, in the six-month period, 5% of the cesium-137 and cesium-134 was trapped in the sediment, while 50% of the plutonium-239/240 activity was deposited. The activity concentration of plutonium in the water column was, however, close to the limit of detection.