Arsenic stress after the Proterozoic glaciations

Abstract

Protection against arsenic damage in organisms positioned deep in the tree of life points to early evolutionary sensitization. Here, marine sedimentary records reveal a Proterozoic arsenic concentration patterned to glacial-interglacial ages. The low glacial and high interglacial sedimentary arsenic concentrations, suggest deteriorating habitable marine conditions may have coincided with atmospheric oxygen decline after ~2.1 billion years ago. A similar intensification of near continental margin sedimentary arsenic levels after the Cryogenian glaciations is also associated with amplified continental weathering. However, interpreted atmospheric oxygen increase at this time, suggests that the marine biosphere had widely adapted to the reorganization of global marine elemental cycles by glaciations. Such a glacially induced biogeochemical bridge would have produced physiologically robust communities that enabled increased oxygenation of the ocean-atmosphere system and the radiation of the complex Ediacaran-Cambrian life.

Arsenic and high affinity phosphate uptake gene distribution in shallow submarine hydrothermal sediments

“…There is therefore a general consensus that where Fe(III)(oxyhydr)oxides form, they coprecipitate As in its +3 and +5 oxidation states (Cullen and Reimer 1989; Smedley and Kinniburgh 2002; Henke et al 2009; Kilias et al 2013; Chi Fru et al 2015a; Hemmingsson et al 2018). The increase in Fe(III)(oxyhydr)oxides precipitation from the white-capped hydrothermal center to the bordering sand-capped sediment, counterbalanced by a drop in sulfide production (Fig.…”

“…Crucially, most shallow submarine hydrothermal vent fluids are generally depleted in P, implying that unlike As, hydrothermal fluids are not a major P source but rather a strong seawater P sink (Wheat et al 1996; Edmonds and German 2004; Poulton and Canfield 2006; Hawkes et al 2014). Indeed, significant variation in As and P concentrations through Earth’s geological history have been linked to changing levels of submarine hydrothermal influence, Fe(III)(oxyhydr)oxide precipitation and sulfide content (Poulton and Canfield 2011; Chi Fru et al 2015a; Reinhard et al 2017; Chi Fru et al 2016a; Hemmingsson et al 2018). Importantly, shallow submarine hydrothermal activity in the modern oceans are suggested to account for up to 57% of global hydrothermal P removal from the ocean via Fe(III)(oxyhydr)oxide precipitation (Hawkes et al 2014).…”

The rise of oxygen-driven arsenic cycling at ca. 2.48 Ga

“…Drill-core shale samples, aged ca. 2.7-2.0 Ga, are from near-continental-margin deposits associated with biological activity (Table DR1; Bekker et al, 2004;Canfield et al, 2013;Martin et al, 2015;Chi Fru et al, 2015, 2016a. X-ray absorption near edge spectroscopy (XANES) was performed to evaluate the As speciation (see supplementary methods in the Data Repository).…”

Bacterial resistance to arsenic protects against protist killing

“…Notably, Cu(I) and As(III) are far more toxic than Zn(II) and if available would be a more toxic mix. It is known that Great Oxidation Event increased the concentrations of both copper and arsenic but peaking at different time points (Chi Fru et al 2015, 2016). Therefore we suggest that arsenic and copper poisoning to be a potent weapon for protists, beginning after the onset of the Great Oxidation.…”

“…The Great Oxidation Event changed the bioavailability of many metals and metalloids and increased the concentrations of both copper and zinc but also arsenic but peaked at different time points (Chi Fru et al 2015, 2016). Recent data show that at least some protists forage on bacteria using toxic metals such as copper and maybe zinc in their phagosomes (Hao et al 2016).…”