Atmospheric elements deposition and evaluation of the anthropogenic part; the AAEF concept

The atmospheric deposition on tree trunks is commonly used for evaluating air contamination on a large time scale. However, the deposits are mostly composed of organic matter (generally more than 80 %) and of minerals of geogenic origin. From the elemental composition of the whole deposit, measured by ICP-MS, a calculation was conceived which allows to separate the amounts of elements corresponding to organic matter, to geogenic compounds and, finally, to anthropogenic minerals. For this purpose, the weight of organic matter was obtained through incineration at 550°C. The elements composition of organic matter was deduced from plant composition. The weight of geogenic compounds was evaluated from the Si, Al content. The formula of geogenic elemental composition took into account the composition of the local soil. This calculation was carried out on four different situations showing the contribution of the main anthropic atmospheric contaminants (Sb, Cd, Sn, Pb, Cu, V, Zn, W, Cr, Ni, Co, As).