The influence of season and leaf age on concentrations of radiocaesium (137Cs), stable caesium (133Cs) and potassium in Agrostis capillaris.

The transfer of radioactive caesium from soils to plants has been well researched. In contrast there is limited knowledge on natural stable 133Cs and its potential role as a predictor for radiocaesium behaviour. In a pot experiment with Agrostis capillaris close correlations were found between plant 137Cs and plant 133Cs concentrations (R2 90-96%). Season and leaf age had significant effects with concentrations increasing 10-30-fold between June and December. Simultaneously the plant concentrations of K, the nutrient analogue of Cs, decreased to around one third. In the soil the exchangeable fractions of K and 137Cs declined. No clear relationships were found between 137+133Cs in the plant and exchangeable K in the soil. However, at the end of the experiment the K content of the above-ground biomass was higher than the exchangeable pool in the soil, suggesting that depletion of soil K could be a key factor in the observed increase of plant 137+133Cs over time.

Assessing potential secondary effects of countermeasures in agricultural systems: a review.

Secondary effects are defined as any positive or negative impacts resulting from the application of countermeasures other than radiological benefits or direct costs. They are categorised into environmental, radioecological, economic and social effects. Impacts on the environment may include changes in water, air and soil pollution or in the conservation and amenity value of an area. Radioecological effects occur when the countermeasure unintentionally alters the behaviour of the target radionuclide or any other radionuclide present. Economic effects may range from changes in agricultural income to environmental costs (e.g. impact of soil erosion on fisheries). Social effects relate to the acceptability of countermeasures, for example in terms of consumer confidence and animal welfare. Recent research into the identification and assessment of secondary effects is summarised. Non-quantitative and quantitative approaches are explained and formal evaluation procedures involving decision matrices and decision support systems are introduced. Examples of recent experimental and modelling work focusing on radiocaesium are given for the following countermeasures: soil application of potassium, administration of AFCF to livestock and ploughing techniques.

Managing radioactively contaminated land: implications for habitat diversity.

Radioactive contamination of agricultural land may necessitate long-term changes in food production systems, through application of selected countermeasures, in order to reduce the accumulation of radionuclides in food. We quantified the impact of selected countermeasures on habitat diversity, using the hypothetical case of two agricultural areas in Finland. The management scenarios studied were conversions from grassland to cereal production and from grassland and crop production to afforestation. The two study sites differed with respect to present agricultural production: one being predominantly cereal production and seminatural grasslands, while the other was dominated by intensive grass and dairy production. Some of the management scenarios are expected to affect landscape structures and habitat diversity. These potential changes were assessed using a spatial pattern analysis program in connection with geographic information systems. The studied landscape changes resulted in a more monotonous landscape structure compared to the present management, by increasing the mean habitat patch size, reducing the total habitat edge length and reducing the overall habitat diversity calculated by the Shannon diversity index. The degree of change was dependent on the present agricultural management practice in the case study sites. Where dairy production was predominant, the landscape structure changes were mostly due to conversion of intensive pastures and grasslands to cereal production. In the area dominated by cereal production and seminatural grasslands, the greatest predicted impacts resulted from afforestation of meadows and pastures. The studied management changes are predicted to reduce biodiversity at the species level as well as diminishing species-rich habitats. This study has predicted prominent side effects in habitat diversity resulting from application of management scenarios. These potential long-term impacts should be considered by decision-makers when planning future strategies in the event of radionuclide deposition.