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(15-24) Effect of atmospheric deposition on heavy metals content and distribution on forest soils. Iņigo, Victoria1, Andrades, Marisol1, Marín, Alvaro1, Alonso-Martirena, Juan Ignacio*,1, 1 Departamento de Agricultura y Alimentacion. CCT. Universidad de La Rioja., Logroņo, Spain ABSTRACT- The region of La Rioja (in the NW of Spain) has several habitats with a community interest (Directive on habitats 92/43/ECC). In this context, the Basin of the River Najerilla, which has a high economic and landscape value, has been proposed for its incorporation into the Network Natura 2001. In this work, we have analysed the physicochemical properties and the Cd, Cu, Mn, Ni, Pb and Zn concentration, both total and bio-available, on the surface and depth of 28 profiles in order to assess their environmental quality. These soils have formed on materials from the Palaeozoic and, to a lesser extent, form the Mesozoic, which enrich the soil with heavy metals. The comparison between the surface content and the content in depth reveals that the total Cu and Ni contents are higher in depth, probably due to the geological origin of these metals. As for Cd, Pb and Zn, the content is higher on the surface: their origin seems to be exogenous, namely atmospheric deposition, a fact which is closely linked to the rain levels, that in this region stand at 800-1,100 mm a year-1. The origin of these high contributions might be the emission source located in the industrial region of Biscay, where the dominant winds are also originated. The Mn values are high both on the surface and in depth. This metal has an endogenous and exogenous origin: parental material, atmospheric deposition, edaphogenetic processes and annual foliar contribution. The data have been statistically processed thought descriptives and correlations. The total Cd value on the surface seems to be linked in a significant and positive way with the clays. The extractable parts of Cd, Cu, Pb y Zn are significantly and positively linked with the organic material of the soils and thus the changing forms of these metals are linked to the organic material. The concentrations of heavy metals are within the ranges established for forest soils in industrialised countries. Key words: heavy metals, soils, forest, atmospheric deposition |
