Oxygen evolution in a hypersaline crust: in situ photosynthesis quantification by microelectrode profiling and use of planar optode spots in incubation chambers

Woelfel, Jana; Sørensen, Ketil Bernt; Warkentin, Mareike; Förster, Stefan; Oren, Aharon; Schumann, Rhena

doi:10.3354/ame01326

Cited by 9 publications

(6 citation statements)

References 37 publications

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“…In the specific case of benthic photosynthesis driving oxidative weathering, the O 2 produced is confined to a diffusionlimited environment where even today, reaction with reductants below the uppermost zone of oxygen production is more important than O 2 escape (i.e., net production << gross production) (51,52). We focus on net production to conservatively reflect the amount of O 2 that would be available to participate in reactions beyond those already consuming O 2 in modern benthic ecosystems.…”

Section: Benthic Oxygen Oases Before the Goe: Mechanistic And Numericmentioning

confidence: 99%

Benthic perspective on Earth’s oldest evidence for oxygenic photosynthesis

Lalonde

Konhauser

2015

Proc. Natl. Acad. Sci. U.S.A.

189

147

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The Great Oxidation Event (GOE) is currently viewed as a protracted process during which atmospheric oxygen increased above ∼10−5 times the present atmospheric level (PAL). This threshold represents an estimated upper limit for sulfur isotope mass-independent fractionation (S-MIF), an Archean signature of atmospheric anoxia that begins to disappear from the rock record at 2.45 Ga. However, an increasing number of papers have suggested that the timing for oxidative continental weathering, and by conventional thinking the onset of atmospheric oxygenation, was hundreds of million years earlier than previously thought despite the presence of S-MIF. We suggest that this apparent discrepancy can be resolved by the earliest oxidative-weathering reactions occurring in benthic and soil environments at profound redox disequilibrium with the atmosphere, such as biological soil crusts and freshwater microbial mats covering riverbed, lacustrine, and estuarine sediments. We calculate that oxygenic photosynthesis in these millimeter-thick ecosystems provides sufficient oxidizing equivalents to mobilize sulfate and redox-sensitive trace metals from land to the oceans while the atmosphere itself remained anoxic with its attendant S-MIF signature. As continental freeboard increased significantly between 3.0 and 2.5 Ga, the chemical and isotopic signatures of benthic oxidative weathering would have become more globally significant from a mass-balance perspective. These observations help reconcile evidence for pre-GOE oxidative weathering with the history of atmospheric chemistry, and support the plausible antiquity of a terrestrial biosphere populated by cyanobacteria well before the GOE.

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Section: Benthic Oxygen Oases Before the Goe: Mechanistic And Numericmentioning

confidence: 99%

Benthic perspective on Earth’s oldest evidence for oxygenic photosynthesis

Lalonde

Konhauser

2015

Proc. Natl. Acad. Sci. U.S.A.

189

147

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“…They exhibit the highest sensitivity at low O 2 concentrations and are not affected by hydrogen sulphide (Kühl and Polerecky 2008), which is often present in sediments. Optodes are especially recommended for on-line measurements over a long time with low oxygen change rates, chemically oxygen consumption, because they do not consume oxygen and do not require subsampling (Woelfel et al 2009b).…”

Section: Ex Situ Primary Productionmentioning

confidence: 99%

Microphytobenthos of Arctic Kongsfjorden (Svalbard, Norway): biomass and potential primary production along the shore line

et al. 2010

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During summer 2007, Arctic microphytobenthic potential primary production was measured at several stations around the coastline of Kongsfjorden (Svalbard, Norway) at B5 m water depth and at two stations at five different water depths (5, 10, 15, 20, 30 m). Oxygen planar optode sensor spots were used ex situ to determine oxygen exchange in the overlying water of intact sediment cores under controlled light (ca. 100 lmol photons m -2 s -1 ) and temperature (2-4°C) conditions. Patches of microalgae (mainly diatoms) covering sandy sediments at water depths down to 30 m showed high biomass of up to 317 mg chl a m -2 . In spite of increasing water depth, no significant trend in ''photoautotrophic active biomass'' (chl a, ratio living/dead cells, cell sizes) and, thus, in primary production was measured at both stations. All sites from B5 to 30 m water depth exhibited variable rates of net production from -19 to ?40 mg O 2 m -2 h -1 (-168 to ?360 mg C m -2 day -1 ) and gross production of about 2-62 mg O 2 m -2 h -1 (17-554 mg C m -2 day -1

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“…This small pool of residual oxygen was consistently observed in the morning in all profiles for both ponds. Further details concerning the oxygen measurements are given elsewhere (Woelfel et al 2009). Sulfide was observed below the phototrophic zone.…”

Section: Biogeochemical Measurementsmentioning

confidence: 99%

“…No sulfide was observed during the day in Pond 200. Most of the oxygen generated during the day is retained and respired within the crust , Woelfel et al 2009). …”

Section: Biogeochemical Measurementsmentioning

confidence: 99%

Distribution of benthic phototrophs, sulfate reducers, and methanogens in two adjacent saltern evaporation ponds in Eilat, Israel

Sørensen¹,

Řeháková²,

Zapomělová³

et al. 2009

Aquat. Microb. Ecol.

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The vertical distribution of phototrophic and non-phototrophic microorganisms was examined in 2 saltern evaporation ponds with salinities of 156 and 206 g l -1. The biogeochemistry of these 2 ponds was examined using microsensors for oxygen, pH and sulfide. These measurements showed that net rates of oxygen production/consumption were significantly higher at a salinity of 156 than at 206 g l -1. The distribution of phototrophic microorganisms was studied by microscopy, which revealed several differences between the 2 crusts. The relative amounts of Bacteria, Archaea, sulfate reducers and methanogens were studied by real-time quantitative PCR amplification of genes for 16S rRNA, dissimilatory sulfite reductase (DSR), and methyl coenzyme M reductase (MCR). Sulfate reducers and methanogens were detected only in the deepest part of the phototrophic zone and below. Sulfate reducers were most abundant in the zone just below the phototrophic layer, where the DSR gene copy number was ~1.5% that of the 16S rRNA gene copy number. Methanogens were much less abundant than sulfate reducers, and the number of MCR gene copies never exceeded 0.1% of the number of 16S rRNA gene copies. Methanogens were less abundant at a salinity of 206 than at 156 g l -1. Inter-pond and vertical variations in the composition of methanogenic and sulfate reducing communities were further characterized by DGGE analysis. The detected sulfate reducers were affiliated with 4 different phylogenetic groups that included members of the Desulfovibrionales, relatives of Desulfotomaculum, and 2 deeply branching groups with no close cultured relatives. The detected phylotypes were distributed in a distinct pattern in the crust according to both biogeochemical regimes and salinity. Methanogens were all affiliated with the known halophilic genera Methanohalophilus and Methanohalobium.

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Oxygen evolution in a hypersaline crust: in situ photosynthesis quantification by microelectrode profiling and use of planar optode spots in incubation chambers

Cited by 9 publications

References 37 publications

Benthic perspective on Earth’s oldest evidence for oxygenic photosynthesis

Benthic perspective on Earth’s oldest evidence for oxygenic photosynthesis

Microphytobenthos of Arctic Kongsfjorden (Svalbard, Norway): biomass and potential primary production along the shore line

Distribution of benthic phototrophs, sulfate reducers, and methanogens in two adjacent saltern evaporation ponds in Eilat, Israel

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