Suchergebnisse

The presence and deteriorating action of micro-organisms on monuments and stone works of art have received considerable attention in the last few years. Knowledge of the microbial populations living on stone materials is the starting point for successful conservation treatment and control. This paper reviews the literature on cyanobacteria and chlorophyta that cause deterioration of stone cultural heritage (outdoor monuments and stone works of art) in European countries of the Mediterranean Basin. Some 45 case studies from 32 scientific papers published between 1976 and 2009 were analysed. Six lithotypes were considered: marble, limestone, travertine, dolomite, sandstone and granite. A wide range of stone monuments in the Mediterranean Basin support considerable colonization of cyanobacteria and chlorophyta, showing notable biodiversity. About 172 taxa have been described by different authors, including 37 genera of cyanobacteria and 48 genera of chlorophyta. The most widespread and commonly reported taxa on the stone cultural heritage in the Mediterranean Basin are, among cyanobacteria, Gloeocapsa, Phormidium and Chroococcus and, among chlorophyta, Chlorella, Stichococcus and Chlorococcum. The results suggest that cyanobacteria and chlorophyta colonize a wide variety of substrata and that this is related primarily to the physical characteristics of the stone surface, microclimate and environmental conditions and secondarily to the lithotype. © 2009 SGM. ; This work was supported by the Ministério da Ciência, Tecnologia e Ensino Superior, Portugal, with a doctoral grant (SFRH/BD/21481/ 2005), and has been partially financed by the CEPGIST FCT subproject DECASTONE. The work also received support from the Programa de Financiamento Plurianual da Unidade de Investigaçao da FCT, financed by the European Union FEDER and the national budget of the Portuguese Republic. This is also a TCP CSD2007- 00058 paper. ; Peer Reviewed

14 páginas, 7 figuras, 1 tabla, 23 referencias. ; [EN]: The importance of stone colonisation by microorganisms has led to an extensive literature on mechanisms and rates of physicochemical degradation of stone surface, both in laboratory and field contexts. Biological colonisation of a stone surface depends on intrinsic stone parameters like mineral composition, texture, porosity, and permeability, as well as on environmental parameters. In the present study, quantification of stone surface roughness and its relationship to epilithic colonisation was demonstrated for three types of limestones throughout non-destructive techniques, namely optical surface roughness instrument and digital image analysis. According to the roughness average (Ra) and mean roughness depth (Rz) determined for Ançã limestone, Lioz limestone and Lecce stone, it can be concluded that great surface roughness stones render them prone to microbial colonisation. ; [ES]: La colonización de la piedra por microorganismos ha generado una extensa literatura sobre los mecanismos y tasas de degradación fisicoquímica de las superficies pétreas, tanto en laboratorio como en estudios de campo. La colonización biológica de piedra de construcción depende de parámetros intrínsecos como son su composición mineral, textura, porosidad y permeabilidad, así como de parámetros ambientales. Este estudio demuestra la relación entre la rugosidad superficial de la piedra y la colonización epilítica, cuantificada en tres tipos de caliza mediante técnicas no destructivas: medida de la rugosidad superficial usando un perfilómetro óptico y análisis digital de imágenes. De acuerdo con la rugosidad media aritmética (Ra) y la amplitud media de rugosidad (Rz), determinadas para la caliza de Ançã, la caliza de Lioz y la piedra de Lecce, puede concluirse que las piedras con alta rugosidad superficial son más propensas a la colonización microbiana. ; Este estudio ha sido financiado por el Ministério da Ciência, Tecnologia e Ensino Superior, Portugal, con una beca postdoctoral (SFRH/BPD/63836/2009) y parcialmente financiado por CEPGIST-FCT subproyecto DECASTONE. Este trabajo recibió también financiación del Programa de Financiamento Plurianual de Unidades de Investigação da FCT, financiado por la Unión Europea, FEDER, y fondos nacionales de la República Portuguesa. Este es un trabajo del proyecto CONSOLIDER CSD2007- 00058. This study has been financed by the Ministério da Ciência, Tecnologia e Ensino Superior, Portugal, with a postdoctoral grant (SFRH/BPD/63836/2009) and partially financed by CEPGIST-FCT subproject DECASTONE. This work also received support from Programa de Financiamento Plurianual de Unidades de Investigação da FCT, financed by European Union, FEDER, and national budget of the Portuguese Republic. This is also a paper from the project CONSOLIDER CSD2007-00058. ; Peer reviewed