Influence of water circulation rate on in situ measurements of benthic community respiration

Boynton, Walter R.; Kemp, W. Michael; Osborne, Carl G.; Kaumeyer, K. R.; Jenkins, M. Christopher

doi:10.1007/bf00397084

Cited by 116 publications

(49 citation statements)

References 29 publications

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“…Our cores were unstirred because we deemed potential stirring effects on respiration to be slight, while the potential overestimation of nutrient fluxes could be substantial. Stirring can stimulate aerobic respiration by removal of low oxygen tensions (Boynton et al 1981). However, oxygen concentration changes in our experiments were small (f 2 mg 1-') and final oxygen concentrations were relatively high, 2 5 mg 1-' (vs 23.0 in Boynton et al 1981).…”

Section: Samplingcontrasting

confidence: 53%

“…Stirring can stimulate aerobic respiration by removal of low oxygen tensions (Boynton et al 1981). However, oxygen concentration changes in our experiments were small (f 2 mg 1-') and final oxygen concentrations were relatively high, 2 5 mg 1-' (vs 23.0 in Boynton et al 1981). Since oxygen tensions were never low stirring effects on respiration would probably have been minimal.…”

Section: Samplingmentioning

confidence: 49%

“…Stirring may (Boynton et al 1981) or may not (Pamatmat 1977, Hall et al 1979, Hargrave et al 1983 affect sediment oxygen metabolism. Our cores were unstirred because we deemed potential stirring effects on respiration to be slight, while the potential overestimation of nutrient fluxes could be substantial.…”

Section: Samplingmentioning

confidence: 99%

“…Since oxygen tensions were never low stirring effects on respiration would probably have been minimal. However, stirring may increase solute release especially when erosion velocities are reached (Boynton et al 1981). The potential resuspension of surface sediments or surface flocculations could result in overestin~ation of nutnent fluxes.…”

Section: Samplingmentioning

confidence: 99%

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Significance of euphotic sediments to oxygen and nutrient cycling in a temperate estuary

Rizzo¹,

Lackey²,

Christian³

1992

Mar. Ecol. Prog. Ser.

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Sediment-water nutrient and oxygen exchanges were measured under light and dark conditions at 1 oligohaline (Stn D) and 1 mesohaline (Stn A) shallow (1 m) site in the Neuse River estuary, North Carolina. USA. Mean respiration rates were very similar between sites (11 to 12 mg 0 2 m-' h-'), but maximum net productivity at the mesohaline site (74 mg Oz m-' h-') was nearly twice that of the oligohaline site (40 mg O2 m-2 h-'). NH4 fluxes were also significantly different. On average, releases of NH, from sediments at both sites occurred in the dark (13 to 22 pm01 N h-' for Stns D and A, respectively) and, slightly, at the lowest irradiance (67 E m-' S-'. 0.3 to 5 pm01 N h-'). NH, was taken up at average rates between 3 and 12 pm01 N m-' h-' at 3 higher irradiances. Mean NO, (nitrate + nitnte) fluxes were very low ( < l 0 pm01 N m-2 h-'), nearly always directed out of the sediment, and not significantly different. Filterable reactive phosphorus fluxes also did not follow any consistent response to changes in irradiance. Flux vs irradiance curves were used in conjunction with estimates of in situ light availability to the benthos to compute ecosystem-level influence of autotrophy on material exchanges. The autotropic-heterotrophic transitions were 1 to 2 m (oligohaline) and 3 to 4 m (mesohaline). When integrated over depth and area the mesohaline sediments were always net NH, sources to the water column, net O2 sources in fall and winter and net O2 sinks in spring and summer. Oligohaline sediments were O2 sinks except during fall, and NH, sources only in winter and summer. Cultural eutrophication has the potential to alter the balance of benthic autotrophy and heterotrophy which in turn may foster phytoplanktonic productivity.

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Section: Samplingcontrasting

confidence: 53%

Section: Samplingmentioning

confidence: 49%

Section: Samplingmentioning

confidence: 99%

Section: Samplingmentioning

confidence: 99%

See 2 more Smart Citations

Significance of euphotic sediments to oxygen and nutrient cycling in a temperate estuary

Rizzo¹,

Lackey²,

Christian³

1992

Mar. Ecol. Prog. Ser.

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“…The apparent diffusion coefficients were about 5 times the molecular diffusion coefficient (Broeker and Peng, 1982). Similar differences between Da and molecular diffusion coefficients have been observed by other researchers in both artificial and marine sediments, and the difference may be due to advection of headspace water through the sediments by stirring, irregular surface charactenstics, and variations in effective sediment porosity (Boynton, 1981;Güss, 1998). The higher Da in the artificial sediment may be due to the absence of the layer of fine organic material at the sediment surface found in sandy and muddy sediments which would have facilitated advection of headspace water through the sediments.…”

Section: Model Verificationsupporting

confidence: 84%

The role of denitrification in the nitrogen cycle of New England salt marshes

Hamersley¹

2001

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ACKNOWLEDGEMENTSAll that we know of Man, Nature, God, is just that which they are not; it is that which they throw off as repugnant.Aliester Crowley, "The Book Graduated (B.Sc.)with 1st Class Honors, University of Victoria 6 ABSTRACT I used direct measurements of nitrogen gas (Nz) fluxes and a 15N stable isotope tracer to determine the contribution of denitrification to salt marsh sediment N cycling. Denitrification in salt marsh tidal creekbottoms is a major sink for groundwater nitrate of terrestrial origin. I studied creekbottom denitrification by direct measurements of Nz fluxes in closed chambers against a low-Nz background. I undertook experiments and simulation modeling of sediment Nz fluxes in closed chambers to optimize the key experimental parameters of this approach. Denitrification in these sediments was driven by the degradation of labile organic matter pools which are depleted during long Incubations. Sediment thickness was the most important parameter controlling the required incubation time. Errors of up to 13% with gas headspaces and 80% with water headspaces resulted from headspace Nz accumulation and the resulting collapse of the sediment-water diffusion gradient. These errors could be eliminated by using headspaces of sufficient thickness. Headspace flushing to reduce ammonium accumulation did not affect denitrification rates, but caused transient disturbance of Nz flux rates. Direct measurements of Oz, COz, Nz, and inorganic N fluxes from the sediments of a salt marsh tidal creek were made in order to examine the interaction of denitrification with the carbon, oxygen, and N cycles. Organic carbon concentration and lability were the pnmary controls on metabolic rates. COz/N flux ratios averaged 6.1, indicating respiration driven by algal biomass. Allochthonous denitrification accounted for 39% of total sediment denitrification (2.7 mol N m-z yr-I). 46% of rem in eraIi zed ammonium was denitrified, while the contribution of autochthonous denitrification to Oz and COz fluxes was 18% and 10%, respectively. A 15N-ammonium tracer was used to study competition between plants and nitrifying bacteria for remineralized ammonium. In undisturbed sediments of Spartina alterniflora, plant uptake out-competed nitrificationdenitrification, with plant uptake accounting for 66% of remineralized ammonium during the growing season. Under N fertilization (15.5 mol m-z yr-I), both plant N uptake and denitrification increased, but denitrification dominated, accounting for 72% of the available N. When plant uptake was hydrologically suppressed, nitrificationdenitrification was stimulated by the excess N, shifting the competitive balance toward denitrification.7

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Increased sediment oxygen flux in lakes and reservoirs: The impact of hypolimnetic oxygenation

Bierlein

rezvani

Socolofsky

et al. 2017

Water Resources Research

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Hypolimnetic oxygenation is an increasingly common lake management strategy for mitigating hypoxia/anoxia and associated deleterious effects on water quality. A common effect of oxygenation is increased oxygen consumption in the hypolimnion and predicting the magnitude of this increase is the crux of effective oxygenation system design. Simultaneous measurements of sediment oxygen flux (J O2) and turbulence in the bottom boundary layer of two oxygenated lakes were used to investigate the impact of oxygenation on J O2. Oxygenation increased J O2 in both lakes by increasing the bulk oxygen concentration, which in turn steepens the diffusive gradient across the diffusive boundary layer. At high flow rates, the diffusive boundary layer thickness decreased as well. A transect along one of the lakes showed J O2 to be spatially quite variable, with near-field and far-field J O2 differing by a factor of 4. Using these in situ measurements, physical models of interfacial flux were compared to microprofile-derived J O2 to determine which models adequately predict J O2 in oxygenated lakes. Models based on friction velocity, turbulence dissipation rate, and the integral scale of turbulence agreed with microprofile-derived J O2 in both lakes. These models could potentially be used to predict oxygenation-induced oxygen flux and improve oxygenation system design methods for a broad range of reservoir systems.

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Influence of water circulation rate on in situ measurements of benthic community respiration

Cited by 116 publications

References 29 publications

Significance of euphotic sediments to oxygen and nutrient cycling in a temperate estuary

Significance of euphotic sediments to oxygen and nutrient cycling in a temperate estuary

The role of denitrification in the nitrogen cycle of New England salt marshes

Increased sediment oxygen flux in lakes and reservoirs: The impact of hypolimnetic oxygenation

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