The National Park Service is studying rapidly growing colonies of microorganisms that are blackening the dome of the Thomas Jefferson Memorial and other landmarks like the Lincoln Memorial and tombstones at the Congressional Cemetery. A multidisciplinary team of molecular biologists, conservators, and architects is analyzing the growth of the biofilm to hopefully identify a method to stop it that won't further damage the stone that the microbes have claimed as their home. One option is to battle the tiny beasts with lasers. From the National Park Service:
National Park Service officials recently began testing ten different chemical biocides in small patches affected by biofilm at the base of the Jefferson Memorial and will monitor how effective each one is in the coming days and weeks. They will also experiment with more non-traditional treatment options, including ozonated water and irradiation with lasers.
