Salts of microbiological origin
Microbial organisms produce a significant number of organic and inorganic acids. On Objects, they can transform into damaging salts.
The metabolism of microorganisms as well as higher organisms, produces acids and salts, which are excreted and can accumulate in buildings or in their proximity. The biogenic source of nitrate as a result of livestock has long be established. However, nitrate is also produced by microorganisms. Furthermore, a large number of other organic acids can be detected, particularly oxalates like calcium oxalate (weddellite) which has been found on wall paintings. The presence of oxalates, i.e. the salts of oxalic acids, is an indication for microbial activity.
Microorganisms, particularly bacteria, are morphologically similar to one another, but display a very distinct metabolically-physical variance in comparison to higher organisms. A group of widely occurring bacteria, which grow chemo-lithoautotrophically, i. e. with reduced inorganic compounds or ions as hydrogen or electron donors. These include:
- ammonium oxidants, oxidize ammonium into nitrite
- nitrite oxidants, oxidize nitrite into nitrate
Ammonia and nitrite oxidants are combined into the group of nitrifiers. At the present time, the majority of ammonia comes from intensive livestock farming.
Apart from the above mentioned bacteria, sulfur oxidizing bacteria from the genus thiobacillus are widely distributed. These organisms grow lithoautotophically, as well, and they can oxidize reduced sulfur compounds such as sulfides, molecular sulfur or thiosulfate into sulfate.