Lead-210 and Total Lead Uptake in Plants Growing on Abandoned or Inactive Uranium Mill Tailings

Abstract

Samples of wetland plants: cattails (Typha latifolia), sedges (Scripus cyperinus), trees [Trembling Aspens (Populus tremuloides) and White Birches (Betula papyrifera)] and two species of gasses Foxtail Barley (Hordeum jubatum) and Reflexed Saltmarsh Grass (Puccinellia distans) growing on abandoned or inactive uranium sites have been collected for the study of uptake of long-lived radionuclides belonging to the 4n+2 series starting from U-238. The plants were excavated and immediately segmented into aerial parts and below ground parts. Each part was analyzed for Pb-210 by following radiochemical techniques and for total lead by atomic absorption spectrophotometry. A tailings sample was collected around the stem of each plant and another one collected from the root region of the plant and Pb-210 and total lead were determined in each sample.

The ratio of Pb-210 to total lead, R, in various parts of plants and in the tailings has not been found to be significantly different. The transport of lead from the roots to the leaves and other aerial parts is found to be very small in cattails and sedges. In White Birches and Trembling Aspens the concentration of lead transported to aerial parts in higher than that in wetland plants. The concentration factor (roots/tailings concentration) in roots of the trees is lower by an order of magnitude in comparison to that in wetland plants. The absorption of lead by the aerial parts of the plants is not found to be a significant pathway of Pb-210 in vascular plants growing on uranium mill tailings.