Back

Carbonate dissolution without acid: carbonate hydrolysis, catalyzed by photosynthetic microorganisms, in deteriorating stone monuments

Sun, H. J.; Zhang, G.; Jibrin, Z.

2023-07-18 ecology
10.1101/2023.07.14.549033 bioRxiv
Show abstract

Rapidly deteriorating stone (marble) monuments are generally blamed on acid rain. We suggest an alternative, not necessarily exclusive, culprit: rock-inhabiting cyanobacteria and microalgae, which may enter via fissures and dissolve carbonates as they propagate under the translucent stone surface. Cyanobacteria and algae absorb CO2 and HCO - and, in so doing, catalyze the reaction between carbonates and water itself. The resultant calcium hydroxide is expected to react with atmospheric CO2 and with adhered dust on its way out. We tested this hypothesis at the Forbidden City in Beijing, China, by inspecting stone monuments (dolomitic marble) for telltale signs of colonization and by studying an exfoliation crust with molecular and imaging techniques. The results, reported here, are consistent. Deterioration began in, and spread from, stone joints, cracks, and shattered stone edges. A cyanobacterial biofilm visible to the naked eye was present under the deteriorating stone surface. Colonized mineral grains were dissolved in a surface-controlled manner, i.e. along crystallographic and twinning planes. Secondary calcite, as well as clay minerals, were detected in the crust.

Matching journals

The top 2 journals account for 50% of the predicted probability mass.

50% of probability mass above

"Similar papers" are the closest papers from that journal in the model's embedding space. They show what the match is built on, but the ranking comes mostly from a classifier over the whole training set, not from these examples alone.