Weathering of Basalts by Aspergillus sp. FS-4 Strain: Glass Compositions are Prone to Weathering

Mechanisms underlying microbe-induced dissolution of basalt and its effect on glass composition remain unclear. Two powdered basalts, with a glass composition of 27 vol% (Basalt-T) and 18 vol% (Basalt-F), respectively, were inoculated with Aspergillus sp. FS-4 in Czapek medium. Changes in pH, siderophores and main dissolved elements were examined. Basalt-F led to a greater decrease in pH and higher production of siderophores than Basalt-T mainly due to the fungi activity. Element dissolution was 2 to 3 fold higher in Basalt-T than in Basalt-F, and the dissolution was non-stoichiometric for both basalts. FS-4 appears important for basalt weathering. Composition of geologic material had a considerable impact on weathering. Materials with a higher glass percentage are prone to weathering. Further quantitative evaluation is required.