NSF/CONACyT: Protection of Mayan Archeological Sites in Southern Mexico from Biodeterioration

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9906337 Mitchell The combination of high humidity and temperature, together with increased tourist activity, is causing rapid deterioration of Mayan archeological sites in southern Mexico. Much of the material used in the construction of these buildings was soft limestone, which is mechanically weak and susceptible to biodeterioration. The objective of this research is to test methods for protection of the building materials against further deterioration. The research will be carried out in close cooperation with the Escuela de Ingenieria, Universidad del Mayab. This project is jointly supported with the Division of International Programs and with the NSF/CONACyT Program.The importance of the microflora in the degradation of stone at sites at Chichen Itza and Uxmal has been determined in previously supported work. A large and diverse microbial population has been found growing on the stone, with deep penetration into the limestone. The local microflora has the capacity to degrade a number of polymeric consolidants. The objective of this continuing research is to test a number of polymeric consolidants combined with biocides under field conditions and to develop an appropriate control mixture that would resist biodeterioration under local conditions. The ultimate goal of this project is to test methods to protect these archeological sites from deterioration.The research is divided into three phases. The first phase will consist of laboratory tests of a wide range of consolidants combined with commercially-available environmentally-acceptable biocides to find an appropriate combination to provide maximum protection against the local stone microorganisms. In the second phase of the research, treated stone will be place in the field at two sites in southern Mexico. The degree of microbial contamination, penetration and degradation of the polymeric materials will be tested using both electron microscopy and electrochemical impedence spectroscopy. In the third phase, local stone treated with the most resistant combination of consolidants and biocides will be placed at a wide range of sites, both in Chichen Itza and Uxmal, in a variety of environmental conditions, including sunlight, shade, on external stone surfaces and in inner rooms of the buildings. Materials will be returned to Harvard at frequent intervals for detailed analysis of attack both by the microflora and biodeterioration. ***