Últimas tecnologías aplicadas a la conservación del patrimonio cultural:
Últimas tecnologías aplicadas a la conservación del patrimonio cultural:
problemática y soluciones
problemática y soluciones
Ana Z. Miller. Laboratorio HERCULES, Universidade de Évora (Portugal)
The conservation of cultural heritage is a major issue in modern societies, both from economic and cultural viewpoints. Natural and cultural heritage assets, such as stone monuments, caves and hypogea monuments (crypts, catacombs), are prone to biodeterioration processes, which might compromise their conservation state [1]. These habitats, many of them catalogued as natural or cultural heritage, have reduced organic matter input, favouring the proliferation of mineral-utilizing microorganisms.
By interacting with minerals, microorganisms induce dissolution and pitting, or can promote the precipitation of secondary mineral deposits. Both processes involve destruction and construction of mineral structures. Destructives processes arise via mechanical attachment and secretion of organic acids [2], whereas constructive processes comprise the formation of secondary minerals, such as calcite [3], opal-A [4], todorokite and birnessite [1,5]. Microorganisms may directly precipitate minerals as part of their metabolism or indirectly by altering the chemical microenvironment, such as pH and Eh, or providing nucleation sites through the production of organic polymers [1,5].
Electron microscopy techniques combined with ancillary chemical analyses and microbiological methods are essential tools to assess microbial diversity, microbe-mineral interactions, evaluate biodeterioration and rock-weathering processes. Despite the numerous studies on biomineralization of calcium-containing minerals, the formation mechanisms of biominerals containing other cations are poorly investigated. Moreover, while there are several reports on biominerals from surface and aqueous environments, examples from stone heritage are comparatively few. Here, the findings on the association of microorganisms with secondary mineral deposits from a number of case studies and which biominerals are most commonly found in subsurface rock environments are presented.
References:
[1] Saiz-Jimenez et al. 2012. Environ. Microbiol. 14, 3220-3231.
[2] Riquelme et al. 2015. Front. Microbiol. 6, 1342.
[3] Miller et al. 2018. Sedimentology, doi: 10.1111/sed.12431.
[4] Miller et al. 2016. J. Chromatogr. A 1461, 144-152.
[5] Miller et al. 2012. Chem. Geol. 322-323, 181-191.