Implications of the evolution of organic acid moieties for basalt weathering over geological time

Abstract

ABSTRACT. Concentrations of organic acids in prebiotic soils were presumably low, given limitations in abiotic synthesis and the limited lifetimes of organic molecules before the ultraviolet shield developed on early Earth. Prokaryotes, the first landcolonizing organisms, commonly secrete aliphatic carboxylic acids, and, less extensively, secrete aromatic compounds as siderophores and antibiotics. In contrast, secretion of aromatic acids is considerable for fungi, lichens, and vascular plants. Aromatic acids are also produced by degradation of high-molecular-weight compounds from lignin and tannin, both abundant in vascular plants. The proportion of aromatic carboxylic acids in soil solutions therefore probably increased with the evolution of higher order organisms. As biomass of organisms increased over geological time, concentrations of organic acids in soil solutions and, in turn, the extent of ligandpromoted dissolution of minerals probably increased.To

Relating Weathering Fronts for Acid Neutralization and Oxidation to pCO2 and pO2

“…However, element mobility or immobility depends upon the pH and organic ligand content of porewaters and the nature of the minerals hosting the element (Kurtz et al, 2000;Neaman et al, 2005bNeaman et al, , 2006. In contrast to components that form immobile or depletion profiles, some components become enriched at the land surface to form addition profiles due to addition by atmospheric deposition (Pb, Mn, etc.…”

“…In fact, organic ligands may have been present in soils as early as 2.76 billion years ago based on observations of Fe, Al, P, and Cu in paleosols (Driese et al, 2011;Neaman et al, 2005a). Since that time, the nature of organic ligands has changed and their significance has become more important over geological time (Neaman et al, 2005b). However, given that most of the Fe loss in the Piedmont soils could be explained by CO 2 and O 2 effects rather than ligand effects, the biggest effect of soil biota may not be due to ligand-promoted dissolution but rather due to effects on the soil gas atmosphere.…”

Microbially induced deterioration of architectural heritages: routes and mechanisms involved

“…Microbial-mineral interaction serves as a good ground for studying the role of microbes in the process of geochemical transformation of monumental stones and artworks. This interaction represents different methods which microbes utilize for the extraction of nutrients from the mineral surface [23,27,69,74,75]. The dissolution of stone provides essential trace-metals, phosphate, sulfate and metabolites to the inhabiting microbial communities which are crucial for the growth and development of inhabiting microbial consortia [76].…”

The fitness of the environments of air and water for photosynthesis, growth, reproduction and dispersal of photoautotrophs: An evolutionary and biogeochemical perspective

“…There is another potential feedback from the evolution of lignin degradation enzymes to global biogeochemical cycles. Lignin degradation releases aromatic acids that stimulate rock weathering (Neaman et al, 2005). This may have increased the availability of minerals, including nutrients, to photoautotrophs on land and in receiving waters, with consequences for mineral nutrition.…”