Millions of Boreal Shield Lakes can be used to Probe the Evolution of Archaean Ocean Life

摘要: Ancient oceans on Earth were rich in iron, low sulfur, and free of oxygen. The evolution life, the onset photosynthesis, subsequent oxidation Earth9s early atmosphere have long fostered intense debate. Very few analogous modern systems been identified for study most evidence has gleaned from sedimentary rock record, spurred by controversy surrounding origin globally ubiquitous extensive banded iron formations (BIFs). Here we provide first that Boreal Shield lakes can serve as analogues Archaean ocean. Specifically, combine isotopic molecular data to demonstrate photoferrotrophy, a process involving photosynthetic fixation carbon using reduced an electron donor, occurs anoxic zone stratified boreal are naturally sulfur iron. Further, anoxygenic processes active water column, prominent total metabolism these bottom waters, marked distinctive patterns occurring isotopes carbon, nitrogen, Most importantly, robust, returning after column re-oxygenation following lake turnover. Evidence coupled oxidation, reduction, methane implications both systems. Previous studies confined permanently but assumption photoferrotrophic bacteria oxygen intolerant. Given ponds number tens millions, several be manipulated experimentally, opportunities exploring life ancient now greatly expanded.