Physical and chemical characteristics of 137Cs in the Baltic Sea

Abstract

137Cs in seawater, suspended particles and bottom sediments was studied with the aim to better understand its behavior, redistribution and sink in the Lithuanian coastal area of the Baltic Sea. High massic activities of 137Cs (over 1000 Bq/kg dry weight) associated with fine particles of bottom sediments can be attributed to an increase in the specific surface area and variations in mineralogical composition of sediments participating in sorption processes. A clear correlation was found both between the 137Cs activity and the content of clay particles (r=0.95, n=16), as well as the amount of total organic carbon (r=0.75, n=16). 137Cs activity of particulates depends strongly on the sampling depth of seawater. The study has indicated a complicated sorption–desorption behavior of 137Cs in the Baltic Sea as a result of which it can be mobilized by suspended particles or released to seawater. The fate of 137Cs can be considerably affected by mineralogical composition of suspended particles and bottom sediments, as well as by geochemical characteristics of seawater.