( Laboratory of Nanominerals and Environmental Materials, School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China)

Abstract: Sulfate-reducing bacteria (SRB) substantially constrains the cycles of C, S, Fe, Sr, and Ba. One important step for SRB's impact on elemental cycle is their function in decomposing sulfate minerals; thus to understand the mechanism of SRB-sulfate mineral interaction has important mineralogical, geochemical and geomicrobiological significances. In this study, anaerobic experiments were designed to investigate the process and mechanism of the decomposition of anhydrite by SRB. Results show that comparing with sterile experiment, obvious changes were happened in SRB experiment: the values of oxidation-reduction potential (EORP) decreased significantly; the concentrations of acid volatile sulfur (AVS) and protein increased; the decomposition of anhydrite was strengthened; popular dissolution pits and holes can be observed on the surface of anhydrite where SRB was adhered. Results demonstrate that anhydrite was decomposed by SRB through two processes. The first one is through using dissolved SO42- as electron acceptor; according to this process anhydrite can be dissolved consistently. The second one, which is generally neglected in previous studies, is through adhesion, where adhered SRB and their metabolic products can complex structural Ca and strengthen the decomposition. And SRB can also promote the dissolution of insoluble sulfate minerals(celestite, barite, et al.) and iron oxides by the adhesion mechanism, thereby restricting the geochemical behaviors of relevant elements.

Keywords: anhydrite; sulfate-reducing bacterium; decomposition; adhesion; complexation

E-mail: chentianhu168@vip.sina.com

ACTA MINERALOGICA SINICA Vol. 37, No. 4, 2017, Page 411-416