Much stone sculptural and architectural heritage is crumbling, especially in intense tropical environments. This is exemplified by significant losses on carvings made of tuff stone at the Classic Maya site of Copan. Here we demonstrate that Copan stone primarily decays due to stress generated by humidity-related clay swelling resulting in spalling and material loss, a damaging process that appears to be facilitated by the microbial bioweathering of the tuff stone minerals (particularly feldspars). Such a weathering process is not prevented by traditional polymer- and alkoxysilane-based consolidants applied in the past. As an alternative to such unsuccessful conservation treatments, we prove the effectiveness of a bioconservation treatment based on the application of a sterile nutritional solution that selectively activates the stone´s indigenous bacteria able to produce CaCO₃ biocement. The treatment generates a bond with the original matrix to significantly strengthen areas of loss, while unexpectedly, bacterial exopolymeric substances (EPS) impart hydrophobicity and reduce clay swelling. This environmentally-friendly bioconservation treatment is able to effectively and safely preserve fragile stones in tropical conditions, opening the possibility for its widespread application in the Maya area, and elsewhere.

许多石头雕塑和建筑遗产正在崩溃，尤其是在强烈的热带环境中。科潘经典玛雅遗址的凝灰岩雕刻品遭受重大损失就是例证。在这里，我们证明 Copan 石主要由于与湿度相关的粘土膨胀产生的应力而腐烂，从而导致剥落和材料损失，凝灰岩矿物（特别是长石）的微生物生物风化似乎促进了这种破坏过程。过去使用的传统聚合物和烷氧基硅烷基固结剂无法阻止这种风化过程。作为这种不成功的保护处理的替代方案，₃生物水泥。该处理与原始基质产生结合，以显着加强损失区域，而出乎意料的是，细菌外聚物质 (EPS) 赋予疏水性并减少粘土膨胀。这种环保的生物保护处理能够在热带条件下有效和安全地保存脆弱的石头，为其在玛雅地区和其他地方的广泛应用开辟了可能性。