Journal of Radioanalytical and Nuclear Chemistry, Vol. 258, No. 1 (2003) 139142 02365731/2003/USD 20.00 AkadØmiai Kiad, Budapest ' 2003 AkadØmiai Kiad, Budapest Kluwer Academic Publishers, Dordrecht Environmental monitoring used to identify nuclear signatures J. H. Buchmann, J. E. S. Sarkis,* C. Rodrigues Grupo de Caracterizaªo Qumica e Isotpica, Instituto de Pesquisas EnergØticas e Nucleares, Travessa R, 400 5508-900, Sªo Paulo  SP, Brasil (Received March 24, 2003) The use of environmental monitoring as a technique to identify activities related to the nuclear fuel cycle has been proposed by international organizations as an additional measure to the safeguards agreements currently in force. The specific element for each kind of nuclear activity, or nuclear signature, inserted into the ecosystem by several transfer paths, can be intercepted to a greater or lesser degree by different living organisms. This work demonstrates the technical viability of using pine needles as bioindicators for some nuclear signatures (Co, Ni, La, Ce, Sm, Th, and U) associated with uranium enrichment activities using high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). The concentrations of the elements whose signatures were sought and were determined in pine needle samples collected at five specific sampling locations inside the area investigated demonstrate the potential of the instrument and of the method used to identify and quantify the sought signatures present in low quantities (traces) in the evaluated matrix. Introduction Analysis of environmental samples is one of the important measures for strengthening the safeguard system introduced in 1996 by the International Atomic Energy Agency (IAEA). These measurements are intended to provide information on the presence or absence of undeclared nuclear activities. Nuclear activities, like any other industrial activity, release small amounts of their products into the environment. The material, which has been released, carries information on the process it arose from. Therefore, these nuclear signatures are supposed to be characteristic for the process from which they originated. 1,2 Specifically for the identification of the elements characteristic of an environment, mosses, 3,4 lichens and fungi 5,6 show a marked capacity for accumulating certain metals. In contrast, trees are not normally considered as good bioaccumulators, since most species cannot concentrate elements derived from the soil or air. 7 Owing to the morphology of their leaves, however, some of them, such as the pines, have excellent interception characteristics, retaining contamination on the leaf surfaces. 7,8 Several techniques have been used for the determination of metals in environmental samples. Fluorimetry 9,10 and neutron activation analysis 11 are, generally, considered as techniques demanding a relative long analysis time and also presenting a very high cost. Alpha-spectrometry 12 and atomic absorption spectrometry, 5 widely used in this area, present low detection limits for metallic elements, but are, however, very susceptible to spectral interference effects. Owing to its low detection limits, high sensitivity and low levels of spectral interference, particularly in the high atomic mass spectral region, inductively coupled plasma * E-mail: jesarkis@net.ipen.br mass spectrometry has been used for the determination of metals in environmental samples. 13,14 The objective of this paper is to establish a non- intrusive control model for the monitoring of nuclear activities, by determination of the nuclear signatures of elements of interest present at low concentrations (traces), in pine needles (bioindicators) collected near nuclear installations using high resolution inductively coupled plasma mass spectrometer (HR-ICP-MS). This work demonstrates the viability of using the developed experimental protocol to identify, in a non-intrusive way, the signatures in the environment. To use this same protocol for the determination of the average concentration of individual chemical elements and their trends in plants, this protocol has to be improved with respect to representative sampling 15 and its uncertainties. 16 Experimental Bioindicator selection The high specific superficial area of pine-tree leaves makes them highly efficient to remove particulate materials from the aerosol of the atmosphere. Besides this, the needles of these conifers are covered with a wax to which particles readily adhere. Therefore, the pine tree (Pinnus ellioti) was selected as the bioindicator for this work. Signature of interest Mass fractions of Co, Ni, La, Ce, Sm, Th, and U were systematically measured in the collected samples. The criterion for choosing these elements, considered as a signature of interest, was the type of material usually handled in nuclear-fuel-cycle-related facilities.