The US’ national monuments are under attack – not from a foreign power or aliens, but from microscopic organisms called biofilm. The National Park Service announced biofilm is blackening landmarks around Washington DC, and they’re searching for a way to combat the biofilm and return the monuments to a shiny white state.

Biofilm, microscopic organisms, National Park Service, national monuments, monuments, Jefferson Memorial, Lincoln Memorial, memorials, Washington D.C., United States, marble, architects, molecular biologists

Biofilm is not only a menace to the Jefferson Memorial, but to monuments and old structures around the world. Angkor Wat, Egyptian monuments, and Hadrian’s Villa have all been victim to the microscopic organisms. Biofilm can be seen on many Washington, D.C. area monuments, including the Jefferson Memorial’s dome, the Congressional Cemetery tombstones and the Lincoln Memorial.

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Biofilm love to grow on stone. According to the National Park Service, the Jefferson Memorial’s once-smooth marble blocks eroded over time, creating an ideal environment for biofilm to thrive. The Jefferson Memorial biofilm “became noticeable” in 2006 and continued to grow. In 2014 a coalition of molecular biologists, architects, and conservators started to study the biofilm.

Chief of Resource Management Catherine Dewey said in a press release, “Treatment of biofilm is difficult, as there is no known permanent method for removing it, and we have to ensure that any treatment must not do further damage to the soft marble of the memorial nor encourage further growth. We are testing a variety of treatment techniques to find the option that is least damaging to the stone, safe for the environment and visitors, and cost effective.”

Biofilm has been dealt with successfully before in 2011 at the D.C. War Memorial. Now the National Park Service is testing “10 different chemical biocides” along the Jefferson Memorial’s base to see how well they work. They’ll also test out non-traditional methods like laser irradiation.

+ National Park Service

Images via National Park Service and Wikimedia Commons