Geochemistry and microbial community composition across a range of acid mine drainage impact and implications for the Neoarchean‐Paleoproterozoic transition. Issue 6 (15th June 2017)

• Record Type: Journal Article
• Authors: Havig, Jeff R.; Grettenberger, Christen; Hamilton, Trinity L.
• Is Part Of: Journal of geophysical research. Volume 122:Issue 6(2017)
• Page Start: 1404
• Page End: 1422
• Publication Date: 2017-06-15
• Subjects: acid mine drainage -- Great Oxidation Event -- pyrite weathering -- Ferrovum -- Archean -- Paleoproterozoic; Geobiology -- Periodicals; Biogeochemistry -- Periodicals; Biotic communities -- Periodicals; Geophysics -- Periodicals; 577.14
• DOI: 10.1002/2016JG003594
• Languages: English
• ISSNs: 2169-8953

Abstract

Abstract: Streams impacted by acid mine drainage (AMD, also known as acid rock drainage) represent local environmental and ecological disasters; however, they may also present an opportunity to study microbial communities in environments analogous to past conditions. Neoarchean continents had streams and rivers replete with detrital pyrites. Following the emergence of oxygenic photosynthesis, Cyanobacteria colonized streams and rivers on continental surfaces. The combination of labile detrital pyrite grains and locally produced O2 generated by Cyanobacteria produced ideal conditions for pyrite oxidation similar to that found at modern AMD‐impacted sites. To explore the connection of modern sites to ancient conditions, we sampled sites that exhibited a range of AMD‐impact (e.g., pH from 2.1 to 7.9 [Fe 2+ ] up to 5.2 mmol/L [SO4 2− ] from 0.3 to 52.4 mmol/L) and found (i) nearly all analytes correlated to sulfate concentration; (ii) all sites exhibited the predominance of a single taxon most closely related to Ferrovum myxofaciens, an Fe‐oxidixing betaproteoabacterium capable of carbon and nitrogen fixation, and (iii) signs of potential inorganic carbon limitation and nitrogen cycling. From these findings and building on the work of others, we present a conceptual model of continental surfaces during the Neoarchean and Paleoproterozoic linking local O2 production to pyrite oxidation on continental surfaces to sulfate production and delivery to nearshore environments. The delivery of sulfate drives sulfate reduction and euxinia—favoring anoxygenic photosynthesis over cyanobacterial O2 generation in near‐continent/shelf marine environments. Plain Language Summary: Recent work has speculated on the influence of microbial communities driving continental surfaces on chemical weathering of sulfide minerals, and the effects of the resulting delivery of chemicals to the oceans when the Earth's atmosphere transitioned from reducing to oxic. In this study we looked at acid mine drainage sites as proxies for the conditions that may have existed during that time to assess the extant microbial communities and the geochemistry of the water. We then use our results to explain how microbial communities like the ones we studied might have influenced the weathering of minerals on continental surfaces, had similar types of microbial communities been present during that time. Key Points: We found one predominant OTU across a range of AMD impact and biofilm types We suggest a role for AMD‐like microbial communities in sulfate delivery to the oceans on the early Earth around the time of the GOE We provide a conceptual model linking continental sulfide oxidation to enhancement of anoxygenic photosynthesis along continental margins to the detriment of oxygenic phototrophs across the GOE