DYNAMICS OF CAESIUM IN THE SYSTEM OF THE BALTIC SEA - THE

0,66

MB

CURONIAN LAGOON

29

stron

2503

ID

Helsinki Commission

2005

rok

Chapter I. Characteristics of caesium dynamics and problems of their estimation (Review)

1.1. Characteristics of caesium and its distribution in the environment. A review of caesium

chemical properties and distribution is presented.

1.2. Peculiarities of caesium migration in different environments. The importance of the solid –

aqueous phase distribution coefficient Kd is presented. Influence of organic matter and other

factors on caesium migration is described. Caesium migration in solid phase and problems related

to the vertical migration are discussed.

1.3. Processes and peculiarities of caesium sorption – desorption. Importance of clay minerals.

Role of clay minerals in caesium sorption - desorption processes is described. Different types of

sorption places are discussed.

1.4. Caesium in water systems. Peculiarities of its behaviour. Differences in characteristics and in

mineralogical composition of freshwater systems and marine environment are presented. The Baltic

Sea is described as the most polluted with radiocaesium distinguished for slow self-cleaning.

1.5. Physical – chemical forms. Methods of determination. Possible physical and chemical forms

of radionuclides in the environment are described. Methods of determination of speciation are

presented.

1.6. Sequential extraction. Schemes of sequential extraction, their advantages and disadvantages

are described.

1.7. Models of caesium interaction with environment components. Types of modern models are

described. Some examples are presented.

Chapter II. Object of the study and used methods.

Two topics of the study are presented:

1) analysis of radiocaesium in natural samples (water, suspended matter and bottom sediments

from the Baltic Sea and Curonian Lagoon);

2) Laboratory experiments on sorption and desorption of radiocaesium.

2.1. Studied area. The studied area is characterized by:

1) horizontal and vertical salinity gradient (in surface waters – 0.5–7.5 ‰; in near bottom waters –

5.6–11 ‰);

2) strong loading by particulate matter (in the Curonian Lagoon from 1 to 103mg/l; in the Baltic

Near-mouth from 2 to 29mg/l; in the Baltic Sea Open Waters - 1 to 41mg/l);

3) the transitionalaccumulation zone;

4) complex current regime;

5) intrusions of the Baltic sea water to the Curonian Lagoon caused by differences in the water

level, hydro-meteorological conditions, anthropogenic activities. A scheme of sampling stations is

presented in Fig. 2.1.