How to overcome inter-electrode variability and instability to quantify dissolved oxygen, Fe(II), mn(II), and S(−II) in undisturbed soils and sediments using voltammetry

Slowey, Aaron J.; Marvin-DiPasquale, Mark

doi:10.1186/1467-4866-13-6

Cited by 19 publications

(15 citation statements)

References 53 publications

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“…The electrodes were constructed and calibrated according to the methods outlined in Brendel & Luther (). Electrodes were calibrated in the laboratory for O 2 , HS − (noting the signal is for total sulphide, including all H 2 S, HS − and S 2− ; at the pH of the system 99.9% of this is HS − ) and Mn 2+ using water collected from Deer Lake, and each electrode's response was checked immediately before use by measuring the signal for 200 μ m Mn 2+ spiked into Deer lake water in the field, with corrections applied using the pilot ion method (after Meites, ; Slowey & Marvin‐DiPasquale, ).…”

Section: Sampling and Laboratory Analysissupporting

confidence: 87%

Isotopic biosignatures in carbonate‐rich, cyanobacteria‐dominated microbial mats of the Cariboo Plateau, B.C.

et al. 2013

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Photosynthetic activity in carbonate-rich benthic microbial mats located in saline, alkaline lakes on the Cariboo Plateau, B.C. resulted in pCO2 below equilibrium and δ(13) CDIC values up to +6.0‰ above predicted carbon dioxide (CO2 ) equilibrium values, representing a biosignature of photosynthesis. Mat-associated δ(13) Ccarb values ranged from ~4 to 8‰ within any individual lake, with observations of both enrichments (up to 3.8‰) and depletions (up to 11.6‰) relative to the concurrent dissolved inorganic carbon (DIC). Seasonal and annual variations in δ(13) C values reflected the balance between photosynthetic (13) C-enrichment and heterotrophic inputs of (13) C-depleted DIC. Mat microelectrode profiles identified oxic zones where δ(13) Ccarb was within 0.2‰ of surface DIC overlying anoxic zones associated with sulphate reduction where δ(13) Ccarb was depleted by up to 5‰ relative to surface DIC reflecting inputs of (13) C-depleted DIC. δ(13) C values of sulphate reducing bacteria biomarker phospholipid fatty acids (PLFA) were depleted relative to the bulk organic matter by ~4‰, consistent with heterotrophic synthesis, while the majority of PLFA had larger offsets consistent with autotrophy. Mean δ(13) Corg values ranged from -18.7 ± 0.1 to -25.3 ± 1.0‰ with mean Δ(13) Cinorg-org values ranging from 21.1 to 24.2‰, consistent with non-CO2 -limited photosynthesis, suggesting that Precambrian δ(13) Corg values of ~-26‰ do not necessitate higher atmospheric CO2 concentrations. Rather, it is likely that the high DIC and carbonate content of these systems provide a non-limiting carbon source allowing for expression of large photosynthetic offsets, in contrast to the smaller offsets observed in saline, organic-rich and hot spring microbial mats.

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Section: Sampling and Laboratory Analysissupporting

confidence: 87%

Isotopic biosignatures in carbonate‐rich, cyanobacteria‐dominated microbial mats of the Cariboo Plateau, B.C.

et al. 2013

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“…() and N 2 purged where O 2 is 0 μ m ) and standard additions of MnCl 2 standards to N 2 purged water. Calibration for other ions has been performed relative to Mn 2+ , with oxygen peaks at −1.3 and −0.3 V (O 2 and H 2 O 2 ), Mn(II) at −1.6 V, Fe(II) at −1.4 V, Fe(III) at −0.6 V, H 2 S/HS − at −0.8 V, and

{normalS}_{2} {normalO}_{3}^{2 -}

at −0.2 V. These ions can be calibrated for any electrode using the pilot ion method (Meites & Delahey, ; Brendel & Luther, ; Slowey & DiPasquale, ).…”

Section: Methodsmentioning

confidence: 97%

Spatial variability in photosynthetic and heterotrophic activity drives localized δ¹³C_org fluctuations and carbonate precipitation in hypersaline microbial mats

Houghton¹,

Fike²,

Druschel

et al. 2014

Geobiology

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Modern laminated photosynthetic microbial mats are ideal environments to study how microbial activity creates and modifies carbon and sulfur isotopic signatures prior to lithification. Laminated microbial mats from a hypersaline lagoon (Guerrero Negro, Baja California, Mexico) maintained in a flume in a greenhouse at NASA Ames Research Center were sampled for δ(13) C of organic material and carbonate to assess the impact of carbon fixation (e.g., photosynthesis) and decomposition (e.g., bacterial respiration) on δ(13) C signatures. In the photic zone, the δ(13) C org signature records a complex relationship between the activities of cyanobacteria under variable conditions of CO2 limitation with a significant contribution from green sulfur bacteria using the reductive TCA cycle for carbon fixation. Carbonate is present in some layers of the mat, associated with high concentrations of bacteriochlorophyll e (characteristic of green sulfur bacteria) and exhibits δ(13) C signatures similar to DIC in the overlying water column (-2.0‰), with small but variable decreases consistent with localized heterotrophic activity from sulfate-reducing bacteria (SRB). Model results indicate respiration rates in the upper 12 mm of the mat alter in situ pH and HCO3- concentrations to create both phototrophic CO2 limitation and carbonate supersaturation, leading to local precipitation of carbonate minerals. The measured activity of SRB with depth suggests they variably contribute to decomposition in the mat dependent on organic substrate concentrations. Millimeter-scale variability in the δ(13) C org signature beneath the photic zone in the mat is a result of shifting dominance between cyanobacteria and green sulfur bacteria with the aggregate signature overprinted by heterotrophic reworking by SRB and methanogens. These observations highlight the impact of sedimentary microbial processes on δ(13) C org signatures; these processes need to be considered when attempting to relate observed isotopic signatures in ancient sedimentary strata to conditions in the overlying water column at the time of deposition and associated inferences about carbon cycling.

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“…The effects of scan rate on SCVs are confounded by multiple factors, so they were performed only at one, slow scan rate (25 mV s À1 , where time for decay of the capacitive current should provide more purely faradaic electrode response. 143,146 ). However, compared with SCV, the data obtained by SWV is less confounded with capacitive current and therefore the effect of scan rate on SWVs is better dened.…”

Section: Methods Application To Natural Organic Mattermentioning

confidence: 99%

Electrochemical characterization of natural organic matter by direct voltammetry in an aprotic solvent

Pavitt

Tratnyek

2019

Environ. Sci.: Processes Impacts

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How to overcome inter-electrode variability and instability to quantify dissolved oxygen, Fe(II), mn(II), and S(−II) in undisturbed soils and sediments using voltammetry

Cited by 19 publications

References 53 publications

Isotopic biosignatures in carbonate‐rich, cyanobacteria‐dominated microbial mats of the Cariboo Plateau, B.C.

Isotopic biosignatures in carbonate‐rich, cyanobacteria‐dominated microbial mats of the Cariboo Plateau, B.C.

Spatial variability in photosynthetic and heterotrophic activity drives localized δ¹³C_org fluctuations and carbonate precipitation in hypersaline microbial mats

Electrochemical characterization of natural organic matter by direct voltammetry in an aprotic solvent

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How to overcome inter-electrode variability and instability to quantify dissolved oxygen, Fe(II), mn(II), and S(−II) in undisturbed soils and sediments using voltammetry

Cited by 19 publications

References 53 publications

Isotopic biosignatures in carbonate‐rich, cyanobacteria‐dominated microbial mats of the Cariboo Plateau, B.C.

Isotopic biosignatures in carbonate‐rich, cyanobacteria‐dominated microbial mats of the Cariboo Plateau, B.C.

Spatial variability in photosynthetic and heterotrophic activity drives localized δ13Corg fluctuations and carbonate precipitation in hypersaline microbial mats

Electrochemical characterization of natural organic matter by direct voltammetry in an aprotic solvent

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Spatial variability in photosynthetic and heterotrophic activity drives localized δ¹³C_org fluctuations and carbonate precipitation in hypersaline microbial mats