ENVIRONMENTAL IMPACT ON UNESCO HERITAGE SITES IN PANAMA

The Panamanian isthmus, nowadays mostly known for its famous Canal, hosts two sites inscribed on the World Heritage List: the Archaeological site of Panama Viejo (XVI cent.) and the Fortresses of Portobelo and San Lorenzo (XVII-XVIII cent.). In order to support the conservation and valorisation of these places, in 2014 a collaboration work has been started among the Patronage of Panama Viejo, the Patronage of Portobelo and San Lorenzo, the Institute of Atmospheric Sciences and Climate of the Italian National Research Council (ISACCNR) and the Department of Physics and Earth Sciences of the University of Ferrara (Italy). Firstly, the project was focused on the characterization of rocks belonging to the masonries, in conjunction with the evaluation of their state of conservation and damage estimation in relation with the environmental impact. Furthermore, potential quarries of raw material supply have been identified and sampled, in order to define the provenance of the materials employed in the buildings and to compare the differences between the preservation of the rocks utilized in the masonries with the outcropping ones. Therefore, after a survey and sampling campaign, specimens underwent mineralogical-petrographic, physical and chemical analyses (Stereomicroscope, PLM, XRPD, SEMEDX, XRF, MIP and IC), highlighting at Panamá Viejo masonries mainly composed of polygenic breccias, tuffites, basaltic andesites, rhyolites and sporadic rhyodacites. Only breccias and andesites outcrops were identified at the site of Panamá Viejo. Considering Portobelo fortifications, coral limestones and sandstones have been identified as principal construction materials; while basaltic andesite has been observed only at Fuerte de San Fernando, where an outcrop of this material was present. Finally, at Fort San Lorenzo, tuffites and grainstones have been detected in the masonries. These latter ones were mainly utilized for composing corners (as ornamental parts of the portals and the base blocks), moreover, possible quarries of both have been found. Concerning the state of conservation, the most diffused deterioration phenomena are due to biological growth, exfoliation and detachment, disintegration (sanding and pulverization), salt encrustations and chromatic alteration (in particular affecting rhyolites). Successively, in order to determine the environmental context, a selection of monitoring stations, near the sites of interest, recording climate parameters (near-surface air temperature, relative humidity and rainfall amount), have been selected among national Panamanian networks. Besides, the same parameters were collected from two climate models: EC-Earth, with a resolution of 25 km, and Arpege, with a resolution of 50 km, and compared with the monitored records. The climate variables were extracted both from historical simulations and future scenarios, in order to utilize them for possible upcoming damage predictions. Indeed, utilizing environmental data and applying specific damage functions it was possible to assess the deterioration phenomena occurring on heritage materials, as surface recession, cycles of salts transition and biomass accumulation. Considering the first one, it was utilized Lipfert function modified (related to the karst effect), valid for carbonate rocks having a porosity lower than 25%. It showed a higher surface recession in the Northern area, of Portobelo and San Lorenzo, especially considering the data extracted from ECEarth experiment, both for the past and the future situation. In consideration of the salts cycles of dissolution and crystallization, halite has been elected as a priority phase of investigation, since sodium and chloride resulted ones of the most abundant ions in the samples, detected in all sites, also taking into account their proximity to the sea. In the past (1979- 2008), transition cycles of halite highlighted that the higher frequency of this phenomenon is recorded ii during the dry season (end of November/December to April/beginning of May). In general, making a comparison between the past and future conditions and among the sites, Portobelo results the less interested by this phenomenon, while the area near San Lorenzo seems to be the most affected. In order to estimate the biomass accumulation on hard acid stones, calculated considering the organic carbon accretion on the surfaces, the function developed by Gomez-Bolea et al. (2012) was applied. The highest yearly biomass values are recorded, both in the past and future, in the areas on the North shore, especially at Portobelo, reaching 21 g cm-2. In conclusion, the obtained results contribute significantly to the formulation of guidelines and development of strategies for current and future preservation of the sites, and represent a fundamental knowledge for further related analysis, in order to increase the awareness of the possible risks connected with the climate change impact on Cultural Heritage.