AIC’s 39th Annual Meeting – Architecture/Research and Technical Studies Joint Session, June 3, Biodiversity and Control Methods of Phototrophic Colonization on Artistic Fountains, Oana A. Cuzman and Piero Tiano

This talk focused on research studies of biodiversity and treatments to control biogrowth on fountains, thus slowing the deterioration of stone. Cuzman explained several factors that affect micro-environmental conditions including: water regime (continuous or sporadic), materials (intrinsic properties), location (colonizers) and treatments (to water or fountains). Four fountains were selected in this study – two in Florence, Italy and two in Grenada, Spain (Patio de la Sultana and Patio de la Lindaraja). Microbial diversity of the colonized surfaces (green algae, cyanobacteria, and diatoms) was identified on the surface, forming a complex structure (biofilm); DNA sequencing was used to characterize sampled biofilms, and similarities were found between the two different geographic areas.
Regarding removal of biofilms, mechanical removal or water treatments can be effective. For this experiment a chemical treatment was also explored by adding an antifouling agent to a commercial waterproof coating (Wacker Chemie AG, SILRES® BS 290). Antifouling agents considered include: poly-alkyl pryidium salts, zosteric acid, capsaicin, and algophase.
Two fountains were selected for treatment (Tacca’s fountain in Italy and Patio de la Lindaraja in Spain), and both fountains were drained and mechanically cleaned. Afterwards, the modified waterproof coating was applied and allowed to cure for two weeks before adding water back to the fountains. Both fountains were visually observed, and at four months slow growth was observed, while at six months significant green growth was observed. Sample analysis from both fountains found a decreasing number of colonizing organisms, so even though growth was observed the diversity of organisms in the biofilm was affected. Cuzman found that the treatment only affected specific colonizers and that the unaffected ones flourished with less competition. Research on this subject will continue, perhaps modifying the antifouling agents (amount or types) added to the coating.