Temporal Change in Fallout ¹³⁷Cs in Terrestrial and Aquatic Systems:  A Whole Ecosystem Approach

Abstract

During the years after a nuclear accident, the bioavailability and environmental mobility of radiocesium declines markedly, resulting in large changes in contamination of foodstuffs, vegetation, and surface waters. Predicting such changes is crucial to the determination of potential doses to affected populations and therefore to the implementation of radiological countermeasures. We have analyzed 77 data sets of radiocesium (137Cs) activity concentrations in milk, vegetation, and surface waters after the Chernobyl accident. Our results show that the rate of decline in 137Cs during the years after Chernobyl is remarkably consistent in all three ecosystem components, having a mean effective half-life, T eff ≈ 2 years. By comparing changes in 137Cs availability with rates of diffusion of 40K (a close analogue) into the lattice of an illitic clay () we have, for the first time, directly linked changes in the environmental availability of 137Cs to fixation processes at a mechanistic level. These changes are consistent with declines in the exchangeable fraction of 137Cs in soils (2, 3).

Modelling the long-term dynamics of radionuclides in rivers

“…As can be seen from In a real situation the experimental data for K value calculation are available only for the initial period of the contamination. However, it seems that this limitation will not significantly contribute into the uncertainty of the long-term prediction K values calculated using only data obtained in 1987 equal 0.50, 0 29 and 0.24 Bq.yr^.rn 3 for Uzh, Teterev and Irpen respectively. Differences of these values from those calculated for the whole period of observations do not exceed 10%.…”

“…For prediction of dynamics of radionuclide activity concentration in rivers either quite sophisticated models (see reviews [1] and [2]) or empirical dependencies are usually used [3][4][5][6]. The present-day geophysical models account for the totality of meteorological, hydrological, physical and chemical processes governing radionuclides wash-off from catchments and transport in river systems.…”

Reversibility of radiocaesium sorption on illite

“…However, observations on radiocaesium partitioning in anoxic freshwater sediments (Evans et al, 1983;Comans et al, 1989;Comans, 1999;De Koning et al, 2000) and the persistence of radiocaesium in water, fish, and plants after the Chernobyl accident (Jonsson et al, 1999;Smith et al, 1999;Smith et al, 2000), indicate that radiocaesium sorption must remain at least partly reversible.…”

Effective ecological half-lives of Cs-137 for fishes controlled by their surrounding sea-waters

“…To estimate the recovery time in radioactive contaminated area is very important at the view of radiation protection. Recently, the concept of the effective ecological half-lives has been introduced to estimate the recovery time and been applicable to various ecosystems [1][2][3]. The effective ecological half-lives describes the decrease in contaminant concentration in ecosystem over time.…”