Investigation of spatial and temporal patterns of 137Cs partitioning in Eriophorum vaginatum L. In relation to its nutrient retrieval and storage strategy

Relatively high levels of Cs-137 from the Chernobyl accident in indigenous vegetation in infertile upland habitats in the UK have been partly attributed to strategies that permit efficient use of limited nutrient resources. This study investigated temporal and spatial patterns of Cs-137 allocation in Eriophorum vaginatum L. (hare's-tail cotton-grass) in relation to its nutrient retrieval and storage strategy. Plants were labelled with Cs-137 via root uptake in April 1995 and dissected components were analysed on six occasions over the following 16 months. Cs-137 remained relatively mobile in the plants and was recirculated to new leaves and roots that were initiated after the labelling event. The retrieval of Cs-137 from maturing leaves was less efficient than that documented for K and this represented a significant loss process of Cs-137 from the biomass. A greater loss of Cs-137 occurred through the roots. Consequently, successively produced leaves contained progressively less Cs-137 and an exponential decline in the maximum pool of Cs-137 (i.e. the maximum accumulation of Cs-137 activity measured in a leaf) in successively produced leaves was observed. This study provides dir ect evidence that strategies that minimise nutrient losses and permit efficient use of limited nutrient resources in deciduous graminoids also prolong the presence of Cs-137 in the vegetation of E. vaginatum. (C) 1998 Elsevier Science Ltd. All rights reserved.