Environmental effects on monuments exposed in the Panamanian Climate: the Archaeological Site of Panamá Viejo

In the Isthmus of Panama several natural and cultural UNESCO sites are present [1], which unfortunately are at risk for the increase of human pressure and climate impact. Specifically, this region has been classified as an equatorial zone [2], therefore it implies no significant variations of temperature during the whole year, which shows 27°C as annual mean value, in both the dry and rainy season, and yearly precipitation amounts of 3500 mm, on the Caribbean coast, and 2300 mm on the Pacific littoral [3]. Aim of this work is to analyze problems related to the preservation of the UNESCO archaeological site of Panamá Viejo, the first Spaniard settlement on the Pacific coast (XVI cent.), now located in the downtown of Panama City [4] . Petrographic approach, carried out through observations in Optical Microscopy (OM) and Scanning Electron Microscopy (SEM-EDX), and non invasive X-Ray Fluorescence microanalysis (XRF), was used for the characterization of the materials, identifying principally silicate and carbonate rocks at the site. In addition, these chemical and mineralogical analyses were used to evaluate the state of conservation of materials, to identify the responsible agents of their deterioration and to highlight which are the effects and the degradation processes developed in these environmental conditions. The main decay causes observed are due to biodeterioration and chemical-physical decay, connected with the presence of high humidity, which can lead to cracks and detachments. Furthermore, the investigations allowed us to recognize quarries of raw materials supply, fundamental for future compatible restoration works. Finally, monitoring stations of climate parameters were selected in the area under study, with the purpose of collecting data suitable for the application of damage functions with the aim of achieving a quantitative evaluation of the identified deterioration processes, such as biomass accumulation on stones [5] and surface recession [6]. [1] http://whc.unesco.org/en/list/ [2] Kottek, M., J. Grieser, C. Beck, B. Rudolf, And F. Rubel, World Map Of Köppen-Geiger Climate Classification Updated. Meteorol. Z. (15), (2006), 259-263. [3] Gobierno Nacional - República de Panamá, Autoridad Nacional del Ambiente, Atlas Ambiental, (2010) 26-31 [4] Patronato de Panama Viejo e Emajada de Espana en Panama, (2006). Panama Viejo, de la aldea a la urbe, from village to city. [5] Gómez-Bolea A., Llop E. , Ariño X., Saiz-Jimenez C., Bonazza A., Messina P., Sabbioni C., Mapping the impact of climate change on biomass accumulation on stone, Journal of Cultural Heritage 13 (2012) 254-258 [6] Bonazza A., Messina P., Sabbioni C., Grossi C. M., Brimblecombe P. Mapping the impact of climate change on surface recession of carbonate buildings in Europe. Science of the Total Environment 407, (2009) 2039-2050