Carbon flow through oxygen and sulfate reduction pathways in salt marsh sediments1

Howes, Brian L.; Dacey, John W. H.; King, Gary M.

doi:10.4319/lo.1984.29.5.1037

Cited by 170 publications

(69 citation statements)

References 36 publications

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“…Thus, a sulfate reduction equivalent to about 5 0 % of the oxygen uptake was also found in other organic-rich sediments and marshes (Jsrgensen 1982, Howes et al 1984, Howarth 1984. Because of extensive reoxidation of produced sulfide by oxygen in such sediments, close to half of the measured oxygen uptake may be diverted to this process (Jsrgensen 1977).…”

Section: Uptake and S@-reductionmentioning

confidence: 91%

Seasonal cycles of 02, N03- and S042- reduction in estuarine sediments: the significance of an N03- reduction maximum in spring

Jørgensen¹,

Sørensen²

1985

Mar. Ecol. Prog. Ser.

163

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Rates of oxygen uptake, denitrification, nitrate reduction to ammonia, and sulfate reduction were measured in a Danish estuary over 1.5 yr. In sediments near the sea entrance, O2 and SO?, -reduction dominated and the relative contributions of the 4 processes were 65, 3. 5 and 27 %. respectively, of the total electron flow. In sediments near the river outlet, sulfate became limiting while nitrate was more abundant. This shifted the relative contributions towards nitrate reduction: 44. 4, 33 and 19%, respectively. At low salinities, depth of the sulfate reduction zone (4 to 10 cm), but not maximum reduction rate, was limited by low sulfate concentrations in the overlying water. The nitrate zone varied from 0.5 to 5 cm depth over the year. Oxygen uptake and sulfate reduction varied seasonally in accordance with temperature. Reduction of nitrate to N, and to NH:, as well as emission of N,O the atmosphere, showed a short maximum in spring and were relatively constant throughout the rest of the year. The spring maximum coincided with a rapid water-temperature increase and a high influx of nitrate from the main river. Annual emission of N 2 0 corresponded to only 1 to 5 % of the measured denitrification. Annual loss of combined nitrogen by denitrification in sediments corresponded to 5 % of nitrate influx from the river.

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Section: Uptake and S@-reductionmentioning

confidence: 91%

Seasonal cycles of 02, N03- and S042- reduction in estuarine sediments: the significance of an N03- reduction maximum in spring

Jørgensen¹,

Sørensen²

1985

Mar. Ecol. Prog. Ser.

163

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“…As an alternative to harvest methods, fluxes of CO2 and CH, have been used to estimate gross and net macrophyte productivity under ambient field conditions (Blum et al 1978, Giurgevich & Dunn 1978, Howes et al 1984 or under experimental conditions such as elevated atmospheric CO2 concentrations (Drake 1984, Curtis et al 1989, Azc6n-Bieto et al 1994 or manipulated soil salinities (Pezeshki 1991, Hwang & Morris 1994. The carbon gas flux technique integrates processes that occur within and between aboveground and belowground compartments (e.g.…”

Section: Introductionmentioning

confidence: 99%

Carbon cycling in a tidal freshwater marsh ecosystem:a carbon gas flux study

Neubauer¹,

Miller²,

Anderson³

2000

Mar. Ecol. Prog. Ser.

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A process-based carbon gas flux model was developed to calcuIate total macrophyte and microalgal production, and community and belowground respiration, for a Peltandra virginica dominated tidaI freshwater marsh in Virginia. The model was based on measured field fluxes of CO2 and CH,, scaled to monthly and annual rates using empirically derived photosynthesis versus irradiance, and respiration versus temperature relationships. Because the gas exchange technique measures whole system gas fluxes and therefore includes turnover and seasonal translocation, estimates of total macrophyte production will be more accurate than those calculated from biomass harvests. One limitation of the gas flux method is that gaseous carbon fluxes out of the sediment may underestimate true belowground respiration if sediment-produced gases are transported through plant tissues to the atmosphere. Therefore we measured gross nitrogen mineralization (converted to carbon units using sediment C/N ratios and estimates of bacterial growth efficiency) as a proxy for belowground carbon respiration. We estimated a total net macrophyte production of 536 to 715 g C m-' yr-', with an additional 59 g C m-' yr-' fixed by sediment microalgae. Belowground respiration calculated from nitrogen mineralization was estimated to range from 516 to 723 g C m-2 yr-' versus 75 g C m-' yr-l measured directly with sediment chambers. Methane flux (72 g C m-' yr-') accounted for 11 to 13 % of total belowground respiration. Gas flux results were combined with biomass harvest and literature data to create a conceptual mass balance model of macrophyte-influenced carbon cycling. Spring and autumn translocation and re-translocation are critical in controlling observed seasonal patterns of above and belowground biomass accumulation. Annually, a total of 270 to 477 g C m-2 of macrophyte tissue is available for deposition on the marsh surface as detritus or export from the marsh as particulate or dissolved carbon.

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“…The observed depth trends in the upper O-l 5 cm have also been recognized in other coastal sediments, notably in salt marshes of the cast coast of the United States (Howes et al 1984;King et al 1985;King 1988). The most extreme example was reported by King ( 1988) for a Georgia salt-marsh soil where the distribution of reduced 35S in AVS, So, and FeS, changed from 1.7, 95.3, and 4.6% at the surface to 35.1, 19.2, and 52.4% at lo-cm depth.…”

Section: Discussionmentioning

confidence: 68%

“…Howarth and coworkers concluded that pyrite is a much more dynamic pool than previously expected. Later studies have confirmed that the formation ofradiolabeled pyrite plays a significant role in salt marshes and coastal sediments (Howes et al 1984;King 1988). Elemental sulfur, So, was also found to accumulate much of the reduced label from 35S042-reduction (Howarth and Jerrgcnsen 1984;King et al 1985;King 1988).…”

Section: Acknowledgmentsmentioning

confidence: 83%

Untitled

1989

Limnology & Oceanography

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A comparative survey was done of the formation of radiolabeled end-products during 35S0,2-reduction measurements in coastal sediments of Denmark. The distribution of reduced 35S in acidvolatile sulfides (AVS), pyrite, and elemental sulfur in the upper O-15 cm of sediment depended on the sulfur chemistry and on the overall sulfate reduction rates. In sediments with relatively low metabolic rates, undetectable H,S, and low FeS : FeS, ratio (< 1 : 20), only 32-55% of the reduced 35S was recovered in the AVS pool. In sediments with high metabolic rates, high H2S, and high FeS : FeS, ratio (> 1 : lo), the 35S recovery in AVS was 63-92%. The relative contribution of Fe35S2 formation showed little depth dependence, whereas the formation of 35So was highest in the more oxidizing sediment layers near the surface. Inclusion of 35S-labeled FeS, and So in the sulfate reduction measurement yields more accurate rate data than are obtained from AVS alone. Due to possible isotopic exchange reactions and unknown pathways of H,S transformation into AVS, So, and FeS,, however, the radioactivities of the three pools cannot be used directly to calculate their differential rates of formation.

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Carbon flow through oxygen and sulfate reduction pathways in salt marsh sediments1

Cited by 170 publications

References 36 publications

Seasonal cycles of 02, N03- and S042- reduction in estuarine sediments: the significance of an N03- reduction maximum in spring

Seasonal cycles of 02, N03- and S042- reduction in estuarine sediments: the significance of an N03- reduction maximum in spring

Carbon cycling in a tidal freshwater marsh ecosystem:a carbon gas flux study

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