Trace elements at the intersection of marine biological and geochemical evolution

In the paper

“Even when the all samples are included, Zn/Fe ratios in IF tend to fall in a field that spans 2-3 orders of magnitude and is relatively consistent through time.”

In the paper

“It was first realized in 1988 that trace metal availability exerted significant control over phytoplankton productivity (Martin and Fitzwater, 1988).”

What the sources say

• Not checked yetcites Martin and Fitzwater, 1988

In the paper

“The trace elements utilized in metalloenzymes today are commonly thought to reflect, to some degree, the availability of trace elements in ancient seawater when those metalloenzymes first evolved.”

What the sources say

• Not checked yetcites Frausto da Silva and Williams, 2001

In the paper

“Frausto da Silva and Williams (2001) suggested that a cell's trace element inventory was directly related to the conditions under which the host organism evolved.”

What the sources say

• Not checked yetcites Frausto da Silva and Williams, 2001

In the paper

“It is now generally accepted that life evolved relatively early in Earth history, with putative evidence pointing to the existence of a biosphere as early 4.1 Ga (see Bell et al., 2015) and more convincingly by 3.7 Ga.”

What the sources say

• Not checked yetcites Bell et al., 2015 source

In the paper

“Saito et al. (2003) modeled the solubility of a suite of biologically essential trace elements (Fe, Mn, Zn, Ni, Cu, Cd, and Co) to evaluate plausible concentrations in ancient seawater under ferruginous (anoxic and Fe-rich), euxinic (anoxic and sulfide-rich), and oxic conditions (Fig. 1).”

What the sources say

• Not checked yetcites Saito et al., 2003 source

In the paper

“Some continuum likely exists between these two scenarios.”

In the paper

“This relative evolutionary stasis was punctuated by two critical events that occurred in relatively short order: first, the evolution of metazoans in the Cryogenian (e.g., Love et al., 2009;Erwin et al., 2011), and second, the rapid diversification of complex animal life in the Ediacaran and into the Cambrian”

What the sources say

• Not checked yetcites Love et al., 2009 source
• Not checked yetcites Erwin et al., 2011 source

In the paper

“These authors proposed that Proterozoic ocean chemistry and biological evolution may be viewed as linked via a 'bioinorganic bridge', whereby high concentrations of dissolved sulfide in the marine environment during much of the Proterozoic limited the bioavailability of critical trace elements in seawater, such as Mo.”

What the sources say

• Not checked yetcites Anbar and Knoll, 2002 source

In the paper

“The leading alternative to this model is that organismal elemental requirements are driven almost entirely by utility, i.e., cellular function, with shifts in biological requirements decoupled from corresponding environmental abundances (Scott et al., 2013;Robbins et al., 2013;Stüeken et al., 2015a).”

What the sources say

• Not checked yetcites Scott et al., 2013 source
• Not checked yetcites Robbins et al., 2013 source
• Not checked yetcites Stüeken et al., 2015a

In the paper

“In their 2001 book The Biological Chemistry of the Elements, Frausto da Silva and Williams suggested that trace element concentrations could have been significantly different on the early Earth (Fig. 2) and that trace element bioavailability may have been controlled by changes in the paleomarine concentration of dissolved sulfide.”

What the sources say

• Not checked yetcites Frausto da Silva and Williams, 2001

In the paper

“They pointed to the biological utilization of Ni and Co as examples, suggesting that prokaryotes evolved in a reducing environment where these trace elements could have acted as catalysts for early metabolisms, consistent with their use in methanogenesis and by hyperthermophiles.”

What the sources say

• Not checked yetcites Frausto da Silva and Williams, 2001

In the paper

“This idea is easily illustrated with iron, which is the most common metal co-factor and a limiting micronutrient in large regions of the oceans today, especially high-nutrient low chlorophyll (HNLC) regions (for reviews see Zahariev et al., 2008;Moore et al., 2013).”

What the sources say

• Not checked yetcites Zahariev et al., 2008 source
• Not checked yetcites Moore et al., 2013 source

In the paper

“This not only had a negative impact on global primary productivity, but it delayed the evolution of early eukaryotes.”

In the paper

“This billion-year stagnation in eukaryotic diversification is often attributed to the late rise of atmospheric oxygen (e.g., Nursall, 1959;Knoll and Carrol, 1999;Fedonkin, 2003;Planavksy et al., 2014a) to levels required by metazoans (i.e.0.5% to 4% PAL; Mills et al., 2014).”

What the sources say

• Not checked yetcites Nursall, 1959 source
• Not checked yetcites Knoll and Carrol, 1999 source
• Not checked yetcites Mills et al., 2014 source

In the paper

“Earth's history has been marked by the advent of plate tectonics, growth of the continental crust, and protracted oxygenation of the atmosphere-ocean system-among other fundamental transitions.”

In the paper

“The idea that evolution could be chemically constrained was furthered by Williams and Frausto da Silva (2003) who suggested that changes in mineral solubility may have driven increasing availability of trace elements, such as V, Cu, and Zn (amongst others), as the Earth became more oxidizing (Fig. 2).”

What the sources say

• Not checked yetcites Williams and Frausto da Silva, 2003

In the paper

“The GOE represents the permanent rise of oxygen to above 10 -5 of present atmospheric levels [PAL], an upper limit for the production of large isotopic signatures by sulfur massindependent fractionation (S-MIF) (Pavlov and Kasting, 2002)”

What the sources say

• Not checked yetcites Pavlov and Kasting, 2002 source

In the paper

“As life likely emerged in the Eoarchean (4.1-3.7 Ga), it would have been subjected to geochemical conditions in the oceans that were fundamentally different to those present today.”

In the paper

“All these events likely had major impacts on seawater chemistry.”

In the paper

“Recent work by Mills et al. (2014), however, suggests that primitive metazoans, such as sponges, may have needed very little oxygen in the water column in order to thrive.”

What the sources say

• Not checked yetcites Mills et al., 2014 source

In the paper

“The period surrounding the GOE is likely better thought of as a long-lived dynamic transition rather than a discrete event (Lyons et al., 2014a).”

What the sources say

• Not checked yetcites Lyons et al., 2014a

In the paper

“For families whose proteins contain metal-binding domains, it is possible to predict which metals occupy these domains, such that evolutionary relationships between protein structures may be used to reveal trends in metal acquisition in biological systems.”

What the sources say

• Not checked yetcites Dupont et al., 2006 source

In the paper

“In today's oceans, trace element abundances vary both laterally and with depth, and these may vary over several orders of magnitude (Bruland and Lohan, 2003).”

What the sources say

• Not checked yetcites Bruland and Lohan, 2003

In the paper

“This is a scenario supported by the culture studies of Zerkle et al. (2006) and Glass et al. (2009).”

What the sources say

• Not checked yetcites Zerkle et al., 2006 source
• Not checked yetcites Glass et al., 2009 source

In the paper

“Conversely, Fe, Mn, Ni, and Co form weaker aqueous complexes with dissolved sulfide, and are more soluble in metal sulfide form.This would have permitted higher seawater concentrations under anoxic or euxinic conditions relative to Cd, Cu, and Zn.”

In the paper

“For instance, Stüeken et al. (2015a) presented nitrogen isotope data from ~3.0 Ga sedimentary units suggesting the activity of Mo-Fe nitrogenase, which might indicate that Mo was present at low but physiologically-sufficient levels in the early ocean.”

What the sources say

• Not checked yetcites Stüeken et al., 2015a

In the paper

“Similarly, based on eukaryotic cellular requirements, geochemical modeling, and the late emergence of eukaryotic Zn metalloenzymes, it was believed that Zn concentrations in the early oceans would have been a possible barrier to eukaryotic evolution (Williams and Frausto da Silva 2002;2003;Saito et al., 2003;Dupont et al., 2006;2010;Williams and Rickaby, 2012).”

What the sources say

• Not checked yetcites Williams and Frausto da Silva, 2002
• Not checked yetcites Saito et al., 2003 source
• Not checked yetcites Dupont et al., 2006 source

In the paper

“Molybdenum utilization in organisms may have developed in tandem with increasing Mo availability following the early stages of biospheric oxygenation, at which point it became critical to nitrogen fixation (Williams and Frausto da Silva, 2002;2004;Zerkle et al., 2005;Boyd et al., 2011)”

What the sources say

• Not checked yetcites Williams and Frausto da Silva, 2002
• Not checked yetcites Zerkle et al., 2005 source
• Not checked yetcites Boyd et al., 2011 source

In the paper

“Thus, in some cases in the deep past, trace elements may have been employed in biological systems despite strongly limiting seawater concentrations (the case of Mo), while in others, sedimentary records are at odds with marine trace metal histories suggested by geochemical models and protein structural phylogeny (the case of Zn).”

In the paper

“The predicted concentrations of trace elements available in the Archean oceans were in line with proposed cyanobacterial nutritional requirements but less so with the eukaryotes, which evolved much later.”

What the sources say

• Not checked yetcites Saito et al., 2003 source

In the paper

“This would have presented a challenge for many microbial clades, as Fe is the most common metal co-factor for both prokaryotes and eukaryotes (Dupont et al., 2010).”

What the sources say

• Not checked yetcites Dupont et al., 2010 source

In the paper

“Inspired by arguments for widespread marine euxinia during the Mesoproterozoic (1.8-1.0Ga) (Canfield, 1998), they suggested that such conditions would have limited the seawater Mo reservoir.”

What the sources say

• Not checked yetcites Canfield, 1998 source

In the paper

“Saito et al. (2003) emphasized that their projections of Precambrian seawater metal concentrations (Fig. 1) are based on thermodynamic models of mineral solubility and speciation in simulated seawater and are thus inherently limited.”

What the sources say

• Not checked yetcites Saito et al., 2003 source

In the paper

“Consequently, Mo limitation could have stifled primary productivity and perhaps even eukaryote evolution (Anbar and Knoll, 2002).”

What the sources say

• Not checked yetcites Anbar and Knoll, 2002 source

In the paper

“A further limitation is that many of these models assume a homogenous ocean, which is at odds with observations of the modern oceans.”

In the paper

“Although modeling has suggested that the S-MIF signal may be carried forward for 10-100 Ma through sedimentary recycling (Reinhard et al., 2013a), it remains a definitive marker for the first major rise in atmospheric oxygen and a fundamental change in the redox state of the Earth.”

What the sources say

• Not checked yetcites Reinhard et al., 2013a

In the paper

“Low concentrations of Al2O3 (<1 wt%) and incompatible elements (Ti, Zr, Th, Hf and Sc <20 ppm) are commonly observed in IF, indicating minimal detrital input during deposition, although this is not universal for all iron formations.”

In the paper

“These partitioning models are only applicable at the experimental conditions tested and say nothing about the chemical mechanisms of trace metal uptake (Sposito, 1982;Goldberg and Criscenti, 2007).”

What the sources say

• Not checked yetcites Sposito, 1982 source
• Not checked yetcites Goldberg and Criscenti, 2007

In the paper

“This may include the development of siderophores to assist in scavenging any Fe present, or even the exclusion of certain trace metals traditionally used in a metalloenzymes in favor of a metal free variety.”

In the paper

“However, once oxygenic photosynthesis leads to an accumulation of appreciable oxygen, above 10 -5 PAL, this allows an ozone layer to form, shielding the Earth from harmful UV rays and suppressing S-MIF.”

In the paper

“As well, Morel (2008) related the elemental stoichiometry of modern phytoplankton to the cycling of trace elements in the oceans, and further suggested that the trace metal cycles may have been affected by the advent of strong biological recycling in order to fulfill microbial needs.”

What the sources say

• Not checked yetcites Morel, 2008 source

In the paper

“BIF dominate the Archean and are more important in terms of total IF tonnage (Bekker et al., 2010).”

What the sources say

• Not checked yetcites Bekker et al., 2010 source

In the paper

“Two more traditional and key proxy records that have informed our understanding of the Earth's redox evolution include S-MIF and Fe speciation.”

In the paper

“However, many aspects of modeling approaches have yet to be fully explored for trace elements in the modern ocean, much less under ancient ocean conditions with dramatically different chemical and redox regimes.”

In the paper

“The latter is fundamentally tied to the activity and evolution of the biosphere.”

In the paper

“Fe speciation analyses have shed new light on the spatial complexity of water column redoxclines (e.g., Poulton et al., 2010), and have shown that the Proterozoic was likely dominated by ferruginous conditions (Planavksy et al., 2011;Poulton and Canfield, 2011).”

What the sources say

• Not checked yetcites Planavksy et al., 2011
• Not checked yetcites Poulton and Canfield, 2011 source

In the paper

“First, although trace metals may be biolimiting, levels vary between different organisms, and a universally biolimiting concentration for trace metals may not exist.”

In the paper

“In laboratory cultures with freshwater cyanobacteria, Zerkle et al. (2006) suggest that nitrogen assimilation through molybdenum-nitrogenase can occur at Mo levels as low as 5 nM, suggesting that these enzymes can be active over a broad range of concentrations.”

What the sources say

• Not checked yetcites Zerkle et al., 2006 source

In the paper

“A number of studies have utilized either pure cultures, industrial samples, or natural environments to test and examine the limiting effects of trace metals on biology; for a comprehensive example we draw the reader's attention to Glass and Orphan (2012) who discuss the trace metal limitations of methanogens and methanotrophs.”

What the sources say

• Not checked yetcites Glass and Orphan, 2012

In the paper

“Iron speciation is predicated on determining the amount of Fe in a given sample that has been partitioned into various phases -carbonates, ferric oxyhydroxides, magnetite, and sulfide -relative to the total amount in a sample; see Poulton and Canfield (2011) for a brief review.”

What the sources say

• Not checked yetcites Berner, 1970 source
• Not checked yetcites Canfield, 1989 source
• Not checked yetcites Poulton and Canfield, 2005

In the paper

“Ultimately, the studies of Frierdich et al. (2011) and Frierdich and Catalano (2012) are based on systems inherently at disequilibrium and that are unlikely to be truly representative of the formation of IF particles in equilibrium with contemporaneous ferruginous seawater.”

What the sources say

• Not checked yetcites Frierdich et al. (2011) source
• Not checked yetcites Frierdich and Catalano (2012)

In the paper

“Iron formations (IF) are iron-rich (15-40 wt%) and siliceous (40-60 wt%) sedimentary deposits that precipitated from seawater throughout much of the Archean and Paleoproterozoic (3.75-1.85Ga) (James, 1954;Trendall, 2002;Klein, 2005).”

What the sources say

• Not checked yetcites James, 1954 source
• Not checked yetcites Trendall, 2002
• Not checked yetcites Klein, 2005 source

In the paper

“GIF first appear in the rock record at ca. 2.4 Ga (Simonson and Goode, 1989) and are the most common type of iron formation in the Paleoproterozoic, reaching their peak abundance ca.1.88 Ga.”

What the sources say

• Not checked yetcites Simonson and Goode, 1989

In the paper

“Overall, when all lines of evidence are considered, it is reasonable to conclude that IF do indeed preserve authigenic signatures and thus record the abundances of biologically critical trace elements in ancient oceans with high fidelity.”

In the paper

“During the Paleoproterozoic to Neoproterozoic, this surface oxic layer probably persisted, but with a euxinic wedge on the shelf with underlying ferruginous waters (Li et al., 2010).”

What the sources say

• Not checked yetcites Li et al., 2010

In the paper

“They suggest that the oceans were dominantly ferruginous until the late Archean after which a surface oxic layer likely formed.”

What the sources say

• Not checked yetcites Poulton and Canfield, 2011 source

In the paper

“A significant advantage of the black shale record over the IF archives is that examples from modern settings, such as the Cariaco Basin and the Black Sea (e.g., Lyons and Berner, 1992;Lyons et al., 2003;Algeo and Lyons, 2006;Scott et al., 2008;2013;Reinhard et al., 2013b), can be used as analogues to understand the processes underpinning the formation and the pathways of trace metal uptake for the”

What the sources say

• Not checked yetcites Lyons and Berner, 1992
• Not checked yetcites Lyons et al., 2003 source
• Not checked yetcites Algeo and Lyons, 2006 source

In the paper

“Pyrite (FeS2) can form in sediments contemporaneous with deposition or during early diagenesis, and it may therefore incorporate trace element signatures characteristic of seawater (see Large et al., 2014).”

What the sources say

• Not checked yetcites Large et al., 2014 source

In the paper

“Because dissolved Mo is efficiently removed from sulfidic seawater, it was suggested that Mo, amongst other elements (e.g., Fe, Cu), would have been biolimiting in the Proterozoic (Javaux et al., 2001;Anbar and Knoll, 2002) if the seafloor was covered by euxinic waters, as originally hypothesized by Canfield (1998).”

What the sources say

• Not checked yetcites Javaux et al., 2001 source
• Not checked yetcites Anbar and Knoll, 2002 source
• Not checked yetcites Canfield (1998) source

In the paper

“the Re-Os radioactive isotope system can provide precise and accurate depositional ages for black shales and, at the same time, confirm that redox-sensitive trace elements have not been significantly affected by post-depositional processes (e.g., Kendall et al., 2009).”

What the sources say

• Not checked yetcites Kendall et al., 2009 source

In the paper

“Abiogenic cherts are predominantly formed in the Precambrian due to high marine silica concentrations in the absence of a biological sink (Siever, 1992;Maliva et al., 2005).”

What the sources say

• Not checked yetcites Siever, 1992 source
• Not checked yetcites Maliva et al., 2005 source

In the paper

“The latter may be inferred from trace element enrichments that are intimately associated with organic carbon burial fluxes, which are in turn favored under anoxic depositional conditions (e.g., Ni, Cu, Zn, Cd; Tribovillard et al, 2006;Algeo and Rowe, 2012).”

What the sources say

• Not checked yetcites Tribovillard et al, 2006 source
• Not checked yetcites Algeo and Rowe, 2012 source

In the paper

“Konhauser et al. (2007) demonstrated that a high silica ocean would have attenuated phosphate adsorption to precipitating Fe oxyhydroxides, thereby keeping P in solution while still accounting for low P/Fe ratios in IF (Fig. 4) -and casting doubt on the idea of an Archean P crisis.”

What the sources say

• Not checked yetcites Konhauser et al. (2007) source

In the paper

“One of the additional advantages of black shales is that they have low permeability, which contributes to the retention of primary depositional signatures despite the potential for metals to be remobilized during diagenetic processes.”

In the paper

“This has led to the suggestion that the collapse of the paleomarine Ni reservoir and the resultant methanogenic famine at 2.7 Ga as described by Konhauser et al. (2009) may have actually occurred closer to the initiation of the GOE shortly before 2.45 Ga.”

In the paper

“Under more weakly euxinic conditions, Mo removal may not be quantitative, which can result in variable isotopic fractionation between the sediment and overlying water column.”

In the paper

“However, some caution must be exercised when viewing the Mo isotope record in black shales as a consistent tracer of seawater signatures.This is due to variability observed in the modern sediments of the euxinic Black Sea, where Mo isotope fractionations vary as a function of sulfide concentration”

What the sources say

• Not checked yetcites Neubert et al., 2008 source

In the paper

“This isotopic fractionation is due, at least in part, to the fractionation of Mo isotopes amongst various aqueous species (Tossell, 2005), and accordingly a critical amount of sulfide is required to ensure that all Mo is in the tetrathiomolybdate phase and that Mo is quantitatively scavenged.”

What the sources say

• Not checked yetcites Tossell, 2005 source

In the paper

“This decline was attributed to mantle cooling and, with that, the decreasing frequency of Ni-rich ultramafic eruptions.This subsequently limited the amount of Ni-source rocks susceptible to weathering, and perhaps even impacted atmospheric oxygenation by its effect on biological carbon cycling”

What the sources say

• Not checked yetcites Konhauser et al., 2009 source
• Not checked yetcites [2015]
• Not checked yetcites Kasting, 2013 source

In the paper

“These studies suggest not only a relatively early origin for Mo-nitrogenase but also have implications for the bioavailability of Mo at very low dissolved concentrations in the Mesoarchean.”

In the paper

“However, the history of Mo as recorded by the chemical sedimentary record is more consistent with an early origin for Mo-nitrogenase, or at least its precursor, and a subsequently consistent limitation of N-fixation by a Mo-depleted Proterozoic ocean”

What the sources say

• Not checked yetcites Lyons et al., 2014b

In the paper

“Asael et al. (2013) calculated the seawater Mo isotope composition (δ 98 Mo) to be 0.85 ± 0.20‰, which is significantly lighter than modern seawater (2.3‰) and thus consistent with an appreciable extent of euxinic waters in the Proterozoic ocean.”

What the sources say

• Not checked yetcites Asael et al., 2013 source

In the paper

“they nonetheless found that when biomass was present, the sorption of Ni onto ferrihydrite decreased, and therefore estimates for the paleomarine Ni concentrations based on IF may be too low.”

What the sources say

• Not checked yetcites Eickhoff et al., 2014 source

In the paper

“They argue that the only way to record such a signal is through a biological pathway utilizing Mo-nitrogenase and that any abiological pathway of nitrogen fixation or an alternative nitrogenase would inherently impart a substantially different N isotope fractionation.”

What the sources say

• Not checked yetcites Stüeken et al., 2015a

In the paper

“Algeo and Lyons (2006) demonstrated that the Mo/TOC ratio of sediments in modern euxinic settings is positively correlated with the concentration of dissolved Mo in the water column, which scales with local controls and/or the global extent of euxinia.”

What the sources say

• Not checked yetcites Algeo and Lyons (2006) source

In the paper

“Under such a scenario, the Mo isotope composition of sediment deposited under non-to weakly-euxinic conditions would depart from that of the source (i.e., contemporaneous seawater), thereby affecting the ability of euxinic sediments to track the Mo isotope composition of the early oceans.”

In the paper

“Large et al. (2014) further noted a correlation between Ni and Co in the pyrite record, and suggested that this may be tied to the emplacement and subsequent erosion of large igneous provinces.”

What the sources say

• Not checked yetcites Large et al., 2014 source

In the paper

“Conversely, Mo is enriched in middle Proterozoic black shales to an intermediate degree relative to Archean and Phanerozoic samples (Fig. 5), which indicates the presence of euxinic conditions that were relatively limited on the seafloor-although still far greater than the extents observed today.”

What the sources say

• Not checked yetcites Reinhard et al., 2013b

In the paper

“Zn reservoir on the order of 10 nM.This value is several orders of magnitude above the ~10 -13 M concentration considered as biolimiting (Brand et al., 1983) and in excellent agreement with the black shale record”

What the sources say

• Not checked yetcites Scott et al., 2013 source
• Not checked yetcites Brand et al., 1983 source

In the paper

“As such, variations in Cr abundances and isotopic compositions are likely to represent changes in the redox state of the oceans or atmosphere, as well as associated changes in the mechanisms of Cr mobility and changes in sediment provenance.”

In the paper

“Despite the predicted decreases in the seawater concentration of Co over time, the biological utilization of Co is suggested to have increased over time, and remains relatively high”

What the sources say

• Not checked yetcites David and Alm, 2011
• Not checked yetcites Swanner et al., 2014 source

In the paper

“A study on a Neoproterozoic (Marinoan) cap carbonate sequence shows variations in δ 66 Zn that are suggested to record an increase in surface runoff and continental weathering coincident with the onset of deglaciation and a subsequent increase in primary productivity caused by development of nutrient-rich surface waters”

What the sources say

• Not checked yetcites Kunzmann et al., 2013 source

In the paper

“This utility is due to reduced Cr in the form of Cr(III) being effectively immobile at neutral to alkaline pH; Cr becomes mobile when it is oxidized to Cr(VI).”

In the paper

“In Lake Matano, Ni and Co exhibit divergent behavior implying that different biogeochemical process govern concentrations of each metal”

What the sources say

• Not checked yetcites Crowe et al. 2008 source

In the paper

“Modeling efforts have indicated that seawater Co concentrations could have been relatively high in the Archean, decreased in the Proterozoic, and then further decreased following Neoproterozoic ocean oxygenation”

What the sources say

• Not checked yetcites Saito et al., 2003 source

In the paper

“In previous modeling work, researchers have pointed to the antiquity of the cobalamin cofactor, suggesting that its origin somewhere between 3.5 and 2.7 Ga is consistent with the evolution of cyanobacteria in a Co-rich ocean”

What the sources say

• Not checked yetcites Saito et al., 2003 source

In the paper

“In contrast, it was noted more recently by Lohan et al., (2005) that marine phytoplankton appear to be much more tolerant of low dissolved Zn concentrations than in culture studies.”

What the sources say

• Not checked yetcites Lohan et al., 2005 source

In the paper

“Alternatively, Robbins et al. (2013) proposed that an increased proportion of hydrothermal fluxes relative to riverine fluxes and the transport of hydrothermal Fe-and Zn-rich fluids to more distal environments in anoxic Archean and Paleoproterozoic oceans could have helped maintain a large marine Zn reservoir.”

What the sources say

• Not checked yetcites Robbins et al., 2013 source

In the paper

“The most recognized biochemical role of cobalt (Co) is its participation as a cofactor in cobalamin (vitamin B12), which is essential for a number of metalloenzymes, including methionine synthase and ribonucleotide reductase”

What the sources say

• Not checked yetcites Marsh, 1999 source
• Not checked yetcites Frausto da Silva and Williams, 2001

In the paper

“This modeling work was consistent with the emergence of eukaryotic metalloenzymes and rapid diversification of eukaryotes in the Neoproterozoic following a transition from a widely anoxic ocean with expanded euxinia to a well-oxygenated ocean”

What the sources say

• Not checked yetcites Dupont et al., 2010 source

In the paper

“The authors then went on to propose that Zn binding organic ligands may be produced by phytoplankton in order to facilitate biological uptake, and to regulate ambient Zn concentrations.”

What the sources say

• Not checked yetcites Lohan et al., 2005 source

In the paper

“This work highlights a gap in our understanding of Zn forms available for biological use, and complicates predictions on its past bioavailability.”

In the paper

“An expansion of the marine nickel reservoir, coincident with massive eruptions of the Siberian flood basalts around 252.8 Ma, is suggested to have contributed to the severity of the mass extinction”

What the sources say

• Not checked yetcites Rothman et al., 2014 source

In the paper

“Variations were considered to be rapid and governed by two factors: preferential incorporation of isotopically heavy Zn into carbonates and a significant increase in the amount of marine sediments exposed to weathering around 2.7 Ga coincident as the result of increased continental land mass.”

What the sources say

• Not checked yetcites Pons et al., 2013 source

In the paper

“It has been shown that brown algae assimilate iodine as iodide, which is excreted to react with ozone and other reactive oxygen species, providing protection against oxidative stress”

What the sources say

• Not checked yetcites Küpper et al., 1988

In the paper

“Large et al. (2014) also investigated Cr and Mo concentrations in sedimentary pyrite and found patterns consistent with the dominance of anoxic settings in the Proterozoic from 2.15 to 0.7 Ga, with euxinic settings more prevalent between 1.2 and 0.8 Ga.”

What the sources say

• Not checked yetcites Large et al., 2014 source

In the paper

“In this regard, Reinhard et al. (2013b) estimated at least 30-40% of the middle Proterozoic seafloor was anoxic, and possibly much more, with only 1-10% of the seafloor being euxinic.”

What the sources say

• Not checked yetcites Reinhard et al., 2013b

In the paper

“When dissolved oxygen concentrations are ≥1 µM, iodate (IO3 -) is formed (Farrenkopf and Luther III, 2002;Luther III and Campbell, 1991;Rue et al., 1997) and is incorporated into carbonate minerals”

What the sources say

• Not checked yetcites Farrenkopf and Luther III, 2002
• Not checked yetcites Luther III and Campbell, 1991
• Not checked yetcites Rue et al., 1997 source

In the paper

“Those authors argued that increases in δ 53 Cr of +0.04 to +0.29‰ in IFs at 2.7, and again at 1.8 Ga, are the direct result of Cr(III) being oxidized to Cr(VI) and that oxidation of Cr must have been catalyzed by oxidized Mn 2+ in the form of MnO2.”

What the sources say

• Not checked yetcites Frei et al., 2009 source

In the paper

“For instance, small variations in Cr isotope composition in 2.8-2.6 Ga IF were first suggested to document brief pulses in atmospheric oxygen, which mobilized Cr via oxidative weathering and led to Cr sequestration in IF prior to the GOE”

What the sources say

• Not checked yetcites Frei et al., 2009 source

In the paper

“Muted δ 53 Cr variations (-0.3 to +0.3‰) at this time were taken as being indicative of Cr cycling in reduced form (Konhauser et al., 2011), in contrast with highly variable values coincident with ocean oxygenation in the Neoproterozoic (up to +4.9‰; Frei et al., 2009).”

What the sources say

• Not checked yetcites Konhauser et al., 2011 source
• Not checked yetcites Frei et al., 2009 source

In the paper

“Regardless of this and other roles, the end result is that biological assimilation and burial act as the main marine iodine sink, with no known quantitatively important mineralogical sinks.”

In the paper

“Beyond redox chemistry at biologically critical O2 levels, iodine is a bioessential element (Frausto da Silva and Williams, 2001), specifically within marine algae that accumulate iodine primarily in the form of iodide to reach total iodine concentrations up to several hundred ppm”

What the sources say

• Not checked yetcites Frausto da Silva and Williams, 2001
• Not checked yetcites Elderfield and Truesdale, 1980
• Not checked yetcites Fuse et al., 1989

In the paper

“Large et al. (2014) attributed a decrease in Cr concentrations, from the Archean to the Proterozoic (Fig. 9), as reflective of a change in source availability.”

What the sources say

• Not checked yetcites Large et al., 2014 source

In the paper

“Diagenesis of organic matter is thought to release >99% of bound iodine back to seawater, such that internal cycling dominates the marine iodine budget; contributions from continental weathering and hydrothermalism appear negligible today”

What the sources say

• Not checked yetcites Lu et al., 2010

In the paper

“Under anoxic conditions iodine occurs in the form of iodide (I -), which is excluded from the crystal lattice of carbonates during their precipitation.”

In the paper

“However, the level of oxygen at depth remains unconstrained by the I record, and may still have posed a challenge to complex life.”

In the paper

“These values are far greater those found in limestones (a few ppm) (Lu et al., 2010;Muramatsu and Hans Wedepohl, 1998;Zhou et al., 2014;2015), and this organically bound iodine can ultimately end up as a component of organic-rich rocks, particularly black shales, where iodine-to-carbon ratios are slightly elevated relative to those found in algae: ~1-5 X10 -4”

What the sources say

• Not checked yetcites Elderfield and Truesdale, 1980

In the paper

“where filamentous microfossils suggest red algae rhodophytes in carbonates up to 1200 Ma old (Butterfield, 2000;Knoll et al., 2013) and potential green algae chlorophytes as old as 1800 Ma”

What the sources say

• Not checked yetcites Butterfield, 2000 source
• Not checked yetcites Knoll et al., 2013 source
• Not checked yetcites Knoll, 2014 source

In the paper

“The reason for such high concentrations in marine algae is still unclear, but at least one primary role is as an antioxidant”

What the sources say

• Not checked yetcites Küpper et al., 1988
• Not checked yetcites Venturi et al., 2000 source

In the paper

“these studies found that patterns and decreases in I/(Ca+Mg) varied from section to section, and in most cases decrease prior to the δ 13 C excursionthe opposite of what is expected given that the residence time of iodine exceeds that of dissolved inorganic carbon by an order of magnitude”

What the sources say

• Not checked yetcites Broecker et al., 1982

In the paper

“Recent studies have tested the idea that organic carbon burial provides a secondary control on I/(Ca+Mg) ratios on shorter timescales by evaluating I/(Ca+Mg) in association with positive δ 13 Ccarb excursions during Phanerozoic Oceanic Anoxic Events (OAE's), particularly OAE-2”

What the sources say

• Not checked yetcites Lu et al., 2010
• Not checked yetcites Zhou et al., 2015 source

In the paper

“This discrepancy can be explained by uptake and burial in association with marine algae, whose affinity for iodine is high relative to Br and Cl (Elderfield and Truesdale, 1980;Sharp and Draper, 2013), but this possibility requires that marine iodine concentrations have decreased through time.”

What the sources say

• Not checked yetcites Elderfield and Truesdale, 1980
• Not checked yetcites Sharp and Draper, 2013

In the paper

“A study of iodine concentrations in the carbonate record from the Neoarchean through Paleoproterozoic, indicate oxidation of the surface coincident with the GOE.This is reflected by a switch from the absence to presence of carbonate-bound iodine”

What the sources say

• Not checked yetcites Hardisty et al., 2014 source

In the paper

“Crowe et al. (2013) found that the δ 53 Cr isotope compositions of 2.96 Ga paleosols were fractionated relative to the crustal values, indicating oxidative mobilization of Cr and the presence of low levels of atmospheric oxygen (~10 -4 PAL; the level required to prevent reduction of Cr[VI] by Fe[II] during transport to the ocean).”

What the sources say

• Not checked yetcites Crowe et al., 2013 source

In the paper

“They argued that Cr should be sourced from ultramafic rocks similar to Ni and Co, and that this decrease may reflect a decrease in the abundance of the source”

What the sources say

• Not checked yetcites Large et al., 2014 source

In the paper

“This peak was suggested to indicate the onset of acidic weathering triggered by microaerophilic iron-oxidizing bacteria which accelerated the weathering of pyrite as soon as some atmospheric oxygen became available.”

What the sources say

• Not checked yetcites Konhauser et al., 2011 source

In the paper

“Stüeken et al. (2015d) interpreted a profile from an outcrop in southern Alberta, Canada to indicate a brief period of euxinia, followed by a highly productive oxic period before the end-Permian mass extinction.”

What the sources say

• Not checked yetcites Stüeken et al. (2015d)

In the paper

“Mitchell et al. (2012) examined Se abundances and d 82/76 Se from a series of Cambrian to Holocene marine sediments and found significant variability in Se concentrations, but a narrow range of Se isotopes values (between -1 to 1‰).”

What the sources say

• Not checked yetcites Mitchell et al., 2012 source

In the paper

“This rise and fall in oxygen levels in the Paleoproterozoic is now the generally accepted paradigm in the evolution of the oxygenation of the Earth's surface (see Lyons et al., 2014a)”

What the sources say

• Not checked yetcites Lyons et al., 2014a

In the paper

“suggesting that productivity was high and nutrient limitation was likely not a cause of the extinction, at least locally.”

In the paper

“In the black shale record (Fig. 11), the rise in oxygen associated with the GOE is reflected in a marked increase in U and U/TOC values, followed by a dramatic decrease in the late Paleoproterozoic and a second increase in the latest Neoproterozoic”

What the sources say

• Not checked yetcites Partin et al., 2013b

In the paper

“They observed a large negative d 82/76 Se excursion and interpreted it to reflect a large export of organic Se to the sediments immediately prior to the extinction”

What the sources say

• Not checked yetcites Stüeken et al. (2015d)

In the paper

“Temporal changes in U abundances in the IF and black shale datasets provide highly complementary records that document the rise and accumulation of oxygen associated with the GOE and yield insights into post-GOE oxygen dynamics (Partin et al., 2013a,b).”

What the sources say

• Not checked yetcites Partin et al., 2013a,b

In the paper

“The proliferation of selenoproteins in select lineages, including the smallest free living eukaryote, Ostreococcus, has been suggested to be due to the selenocysteinecontaining proteins being more efficient than the corresponding cysteine version”

What the sources say

• Not checked yetcites Palenik et al., 2007 source

In the paper

“Those same authors also suggested that the peak in Se at ~3.0 Ga in the pyrite record is consistent with Cr and Mo isotope data at that time”

What the sources say

• Not checked yetcites Crowe et al., 2013 source
• Not checked yetcites Planavsky et al., 2014b

In the paper

“More recent work has also demonstrated that U isotopes can potentially be used to track the biotic reduction of U(VI), providing the potential for a novel redox biosignature proxy in the rock record (Stylo et al., 2015).”

What the sources say

• Not checked yetcites Stylo et al., 2015 source

In the paper

“They attributed d 238 U values above average upper crustal values that coincide with Mo and Re enrichments (Anbar et al., 2007) to be indicative of the oxidative mobilization of U, possibly within the water column itself.”

What the sources say

• Not checked yetcites Kendall et al., 2013 source
• Not checked yetcites Anbar et al., 2007 source

In the paper

“In their analyses of syngenetic and early diagenetic pyrite, Large et al. (2014) showed a temporal trend in Se with several small peaks at 3.0 and 2.4 Ga, along with a Paleoproterozoic to Mesoproterozoic perturbation between 1800-1300 Ma, and finally a rise in the Neoproterozoic to Phanerozoic.”

What the sources say

• Not checked yetcites Large et al., 2014 source

In the paper

“Selenocysteine is used in a variety of oxidoreductases involved in regulating oxidative stress, including methionine sulfoxide reductase and glutathione peroxidase.”

In the paper

“Stüeken et al. (2015d) do suggest that nutrient limitation may have played a role in the recovery from the mass extinction.”

What the sources say

• Not checked yetcites Stüeken et al. (2015d)

In the paper

“They attribute this rise to enhanced oxidative weathering of U-rich granites.”

What the sources say

• Not checked yetcites Large et al., 2014 source

In the paper

“Large et al. (2014) further suggested that this trend in Se may be used as a paleoproxy for tracking oxygenation.”

What the sources say

• Not checked yetcites Large et al., 2014 source

In the paper

“In 2.8-2.7 Ga non-marine samples, Stüeken et al. (2015b) found negatively fractioned d 82/76 Se values, as opposed to coeval marine samples which are generally positive”

What the sources say

• Not checked yetcites Stüeken et al. (2015b)

In the paper

“Anbar and Knoll (2002) suggested that declining seawater Fe concentrations after the Paleoproterozoic, triggered by the increased precipitation of Fe-oxides and sulfides (Canfield, 1998), may have suppressed the activity of nitrogenase (whose different versions all depend on Fe), and in turn, potentially limited Mesoproterozoic primary productivity via a dearth of fixed N.”

What the sources say

• Not checked yetcites Anbar and Knoll (2002) source
• Not checked yetcites Canfield, 1998 source

In the paper

“The effect could have been a build-up of N2O with significant climatic implications because N2O is a potent greenhouse gas.”

In the paper

“Copper is used in 'blue' copper proteins for electron transfer, energy capture, and in other oxidative enzymes (e.g., Solomon et al., 1996).”

What the sources say

• Not checked yetcites Solomon et al., 1996 source

In the paper

“In the modern ocean, Cu-metalloproteins are involved in the first step of nitrification, last step of denitrification, and during ammonia oxidation; the net result is a substantial bacterial Cu requirement (Amin et al., 2013).”

What the sources say

• Not checked yetcites Amin et al., 2013 source

In the paper

“Tungsten is used by primitive anaerobic prokaryotes and mostly filled roles now played by Mo (Williams et al., 2002;Pushie et al., 2014).”

What the sources say

• Not checked yetcites Williams et al., 2002 source
• Not checked yetcites Pushie et al., 2014 source

In the paper

“Overall, it appears that the black shale record for V mirrors that of Mo, and is relatively consistent with Neoproterozoic enrichments seen in the pyrite record (Large et al., 2014).”

What the sources say

• Not checked yetcites Large et al., 2014 source

In the paper

“Low seawater Cu concentrations and bioavailability may also have had significant implications for the Precambrian atmosphere.”

In the paper

“This evolution towards heavy δ 65 Cu values coincides with a shift to negative sedimentary δ 56 Fe values and increased marine sulfate after the GOE, and is traceable through Phanerozoic black shales to modern marine settings, where marine dissolved and sedimentary δ 65 Cu values are universally positive.”

In the paper

“The emergence of Cumetalloproteins is thought to have been quite late (Dupont et al., 2010).”

What the sources say

• Not checked yetcites Dupont et al., 2010 source

In the paper

“Additional biologically relevant elements whose concentrations in sedimentary archives have not yet been investigated on billion-year timescales (Fig. 3) include cadmium (Cd) and tungsten (W).”

What the sources say

• Not checked yetcites Fig. 3

In the paper

“Both Anbar and Knoll (2002) and Zhang et al. (2014) suggested that the V-Fe nitrogenase varieties might have contributed to nitrogen fixation during the Paleoproterozoic, although the V variety is less efficient (Eady, 1996).”

What the sources say

• Not checked yetcites Anbar and Knoll (2002) source
• Not checked yetcites Zhang et al. (2014) source
• Not checked yetcites Eady, 1996 source

In the paper

“Zhang et al. (2014) indicated that low δ 15 N values in Archean cherts may be more consistent with alternative nitrogenases using Fe or V instead of Mo, suggesting a more important role for these variants in deep time”

What the sources say

• Not checked yetcites Zhang et al. (2014) source

In the paper

“In modern bacteria and archaea, W is generally important for hyperthermophiles, suggesting that W bioavailability may have been critical for early life given the ancient origin of these organisms.”

In the paper

“Buick (2007) proposed that in a Cu-limited ocean, denitrification would be incomplete since Cu is an essential component of the enzymes involved in that metabolism.”

What the sources say

• Not checked yetcites Buick (2007) source

In the paper

“There are several pathways that have evolved to utilize alternative trace metals in place of Fe (see below).”

In the paper

“Zerkle et al. (2005) suggested that since the onset of widespread ocean oxygenation in the Neoproterozoic, the biological utilization of Cu enzymes doubled, likely as a result of increased Cu availability.”

What the sources say

• Not checked yetcites Zerkle et al. (2005) source

In the paper

“The preferential sequestration of 65 Cu by iron oxides (e.g., Balistrieri et al., 2008) likely enriched seawater in residual 63 Cu, which would have been incorporated into planktonic biomass and ultimately deposited into black shales depleted in 65 Cu.”

What the sources say

• Not checked yetcites Balistrieri et al., 2008 source

In the paper

“The evolving picture for widespread nitrogen fixation on the early Earth is becoming more sophisticated and complex, and ultimately may have been influenced by the intricate interplay of several key trace metals in the early oceans.”

In the paper

“Further, and perhaps most importantly, the cellular stoichiometry and specific requirements for V remain unclear.”

In the paper

“This, in turn, has profound effects for the evolution of the biosphere, and perhaps even for tracking the biotic signature of U reduction in the rock record (Stylo et al., 2015).”

What the sources say