Airborne uranium contamination - as revealed through elemental and isotopic analysis of tree bark

A new strategy for characterisation of airborne uranium contamination based on ICP mass spectrometric analysis of tree bark is described. The uranium content of tree barks (50 samples) obtained from diverse locations (remote, rural, industrial) varied over almost four orders of magnitude (0.001-8.3 mug/g U) with maximum concentrations recorded in the vicinity of a nuclear fuel fabrication plant (0.70-8.3 mug/g U). Elevated concentrations were als o observed near a coal-fired power station (0.25-0.38 mug/g U). Isotopic an alysis revealed significant deviation from the natural uranium isotope rati o (U-235/U-238, 0.00725) at four nuclear installations (U-235/U-238, 0.0055 -0.0097). These findings indicate that tree bark serves as an effective bio monitor for uranium and, with isotopic analysis, discrimination between nuc lear and non-nuclear emissions is realised. (C) 2001 Elsevier Science Ltd. All rights reserved.