Visitors to the National Mall in the historic heart of Washington drew attention to the unkempt appearance of the monuments are covered by a strange black goo.
The experts examined the marble memorials of Lincoln, Jefferson and Arlington cemetery and came to the conclusion that they suffered from the spread of biofilms — clusters of microorganisms that form on the surfaces of slime or black powder coating.
“Fight with the defeat of biofilm is very difficult, methods of its removal to date, no. The chemicals can damage the marble used in the monuments. We consider the possibility of destruction of mucus with a laser”, — said the representative of the National Park service Catherine Dewey.