Effects of wet acidic deposition on stony material at the 'Tajin' archaeological site in Veracruz, Mexico

摘要

The actual and future need for energy in the worldwide will bring into focus the acid deposition and the problems associated with it. Such effects could have a strong impact on the environment due to the emission of acid precursors from the operation of several sources of energy (electric power plants, refineries, combustion processes, etc). This could become a local, regional and transboundary potential problem, due to the long-range transport through the atmosphere for ecosystems, materials and vulnerable population. Therefore, it is an obligated environmental concem to investigate if regions where natural aquatic, terrestrial ecosystems and cultural monuments are affected already or if they are at risk to the effects of acidic deposition. Because of the cultural and historical value of Tajin archeological site located in the State of Veracruz, on the east coast of Mexico, there is a great concem on the potential effect of acidic deposition to these monuments. The stony material was analyzed by x-ray to know the composition of the samples. An experimental chamber was used to quantify the potential of acidic wet precipitation damage to stony material from that site. Simulated acid rain solutions were used during the experiment. The chemical composition of these solutions was formulated according the observed range of the anionic and cationic content as well as the lower pH (4.4) found in some of the rain samples collected at the Tajin archeological site during 2002. This pH value was selected in the acid rain because, at this value, the effect of deterioration on the material is greater.