Factors inducing bryophyte growth on prehistoric pigments and effect of UV-C treatment
Résumé
In La Glacière cave (France), the touristic activity has been conducted to an environmental parameter change that has led to
photosynthetic organism proliferation (microalgae, diatoms, cyanobacteria, bryophytes). The present study is focused on bryophyte development occurring in the show cave that was responsible of limestone biodeterioration. In order to understand the
colonization process of limestone, we have maintained limestone blocks under optimal Lampenflora growth conditions.
Moreover, some limestone blocks were painted with several pigments that were used in the prehistory (e.g., red ocher, bone
char). Microorganisms and bryophyte growth were monitored during 1 year, and then, the block samples were treated using UVC light (254 nm). Thus, obtained results were compared with in situ treatment in La Glacière cave. Results have showed dense
bryophyte propagation on the several blocks. However, the growth rate was correlated with the chemical composition of the
pigment. In fact, the presence of some chemical elements such as As, Cr, Ti, and Co contributed to reduce bryophyte growth.
Finally, moss treatment using UV-C light has demonstrated high efficiency under in situ condition, while a fast recolonization has
been observed for samples maintained in laboratory. This difference was explained by the high bryophyte density under
laboratory conditions that make UV-C light penetration difficult.