Evaluation de depot des polluants sur les monuments historiques (Maroc): caractérisation des produits d'alteration superficielle, premiers résultats et perspectives futures

Abstract

16 páginas, 4 figuras y 6 tablas.Air quality and climate quickly changed in the last years, requiring new researches focused on pollution effects, not only on environment and human health but also on outdoor historical heritage. As it is well known, daily exposure to atmosphere in urban and coastal areas causes degradation processes on the stone monument surfaces, being soiling, concretions, films and black crusts, and deposits the most diffused and investigated phenomena. The deposition of gaseous and particulate atmospheric pollutants known to have a destructive effect on the calcareous stones [Nava et al. 2010; Urosevic et al. 2012] seem to be originated from the contamination by atmospheric pollutants emitted by industrial sources and vehicular traffic, particularly sulfur dioxide and by the marine sprays. The objective of this work is to analyze the composition and the morphology of the superficial weathering products on the stone of some monuments, located very close to the Atlantic Ocean (Morocco). The techniques used in the evaluation of atmospheric contamination of the decay products are the Ion Chromatography (IC), the Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES), the X-ray diffraction and the Transmission Electron Microscopy coupled to energy dispersive X-ray spectrometer (TEM-EDX). The investigated stones are a calcarenite with porous texture, rich in calcium carbonates. Results indicate the precipitation of soluble salts and revealed the presence of different kinds of atmospheric particles: Fe, Na, Mg, Al, Si, P, S, Cl, K, Ca and O. However, the test results demonstrated the decrease in the contents of Calcium and Oxygen. These particulates contribute to extensive stone deterioration.Peer reviewe