Microbial communities modulate chemical weathering and carbon dioxide cycling in an active orogen in Taiwan

Chemical weathering modulates carbon transfer between the crust, hydrosphere, and atmosphere. The extent to which microbial processes are involved in mineral dissolution remains elusive. Here, we performed geochemical and molecular analyses of river water and other materials collected from a rapidly exhuming catchment in eastern Taiwan. In addition to solute generation driven primarily by pyrite-induced carbonate weathering, highly skewed microbial community compositions with abundant Sulfuricurvum and Thiobacillus members were detected during high-water periods. The yields of these taxa were also correlated with those of sulfate and sediments, suggesting that pyrite oxidation and carbonate dissolution were facilitated by sulfur-respiring microorganisms inhabiting erodible materials at a pace comparable to the supply of sulfur-bearing minerals through rapid exhumation. The net CO₂ export regulated by such potentially supply-limited, microbially-mediated mineral weathering greatly surpasses the global average, highlighting active orogens in high-standing islands as important CO₂ contributors rendered by tandem biotic and abiotic processes.