The Jefferson Memorial, originally built from smooth marble, has become pitted due to rain water ove

The Jefferson Memorial, originally built from smooth marble, has become pitted due to rain water over its 73 years. A biofilm has grown in those pits and taken over the outside of the building, leaving it black and dingy. Scientists are still figuring out the composition of the microbial invasion. It’s unclear at this point whether the microbes are eating the stone, though it is clearly growing at alarming rates. The Park Service says that the film also appears to be on the memorial amphitheater at Arlington National Cemetery, the Washington Monument and the Lincoln Memorial.From The Washington Post: The film is actually a “multicultural” community of organisms living in the relatively harsh environment of the sun-blasted stone, said Federica Villa, a Milan-based microbiologist who has been studying the memorial’s surface. The black pigment is produced by the organisms to protect themselves from solar radiation, she said in an interview Tuesday.But does the biofilm damage stone?“We don’t know,” Villa said from Montana State University’s Center for Biofilm Engineering. “If you read the scientific literature, most of the scientists correlate the presence of a biofilm with deterioration.”But she said her experiments have shown that biofilm may have a protective impact on stone.“To be honest, we have a lot of work to do,” she said.Ten chemical treatments of biocides are currently being tested on the side of the memorial to determine the best route to clean the monument without harming the marble, as shown in the image above. -- source link

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