The Effect of Temperature, Oxygen, Salinity, and Nutrient Enrichment on Estuarine Denitrification Rates Measured with a Modified Nitrogen Gas Flux Technique

Nowicki, Barbara L.

doi:10.1006/ecss.1994.1009

Cited by 158 publications

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“…Denitrification was measured from replicate cores taken in May 1997 (Stns M6 and M8) and November 1997 (Stn M35) using the N2-gas flux technique of Nowicki (1994). Sediment cores (volume range 230 to 385 cm3, sediment-depth range 6 to 10 cm) were taken by pushing open-ended plastic bottles into the sediment surface and placing each core in a gas-tight glass chamber (height 23.5 cm; i.d.…”

Section: Enterprise Tam Giangmentioning

confidence: 99%

“…The control chambers were incubated under anaerobic conditions (100 % He gas and deoxygenated-water exchanges) in order to block nitrification and denitrification (Nowicki 1994). Water exchanges were made on Days 3 and 6.…”

Section: Enterprise Tam Giangmentioning

confidence: 99%

“…This background flux of N, (F,,) measured in the control chambers was subtracted from the total N2 flux (F,) measured in the experimental chambers to derive the rate of N, flux due to denitrification (Fdn), where F,, = F,-F,, (Nowicki 1994). Denitrification rates (pm01 N2 m-2 d-l) were calculated as the average rate of triplicate cores from each site, from 3 to 4 data points over the 9 d incubations.…”

Section: Enterprise Tam Giangmentioning

confidence: 99%

“…The gas was analyzed for N2 and O2 using an MTI Analytical Instruments P200 gas chromatograph under conditions specified by Nowicki (1994). Calibration standards were run with each set of samples using a gas mixture (3 % N2, 20% 02, 77% He) certified by BOC Gases Australia Ltd (Townsville, Australia).…”

Section: Enterprise Tam Giangmentioning

confidence: 99%

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Benthic decomposition rates and pathways in plantations of the mangrove Rhizophora apiculata in the Mekong delta, Vietnam

Alongi¹,

Tirendi²,

Trott³

et al. 2000

Mar. Ecol. Prog. Ser.

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Rates and pathways of organic matter decomposition were estimated in sediments of 6, 8 and 35 yr old Rhizophora apiculata plantations in the lower Mekong delta, Vietnam. Rates of total carbon oxidation ( T o , = average of CO, gas fluxes from exposed sediments + ZCO, fluxes from submerged sediments) were slowest in the 8 yr old forest (mean T o , = 17.1 mm01 C m-' d-'), with higher rates in the 6 yr old (mean To, = 48.1 mm01 C m-' d.') and 35 yr old forests (mean Tcox = 53.7 mm01 C m-2 d-'). In all 3 forests, sediments to a depth of 40 cm were acidic, with mostly positive redox potential: free sulfides and methane were not measurable in the pore water or across the sedirnenwwater-air interface. Oxic respiration was the malor decomposition pathway, ranging from 63 to 64% of Tcox in the 2 older forests to 94 % of Tcox in the 6 yr old stand. Budget calculations suggest that most of the O2 flux was associated with chemical oxidation in sediments of the 2 youngest forests. Sulfate reduction was the second most important diagenetic pathway (range 0.2 to 13.0 mm01 S m-' d-l) and, on average, total rates increased with increasing forest age. Manganese reduction appeared to be a minor decornposition pathway in all 3 stands (range 1.0 to 2.8 mm01 Mn m-' d-l), and iron reduction was measurable only in the 6 yr old forest (0.9 * 0.6 mm01 Fe m-' d-'). Denitrification was measurable only in the 35 yr old forest (2.2 i 0.5 mm01 N2 m-' d-l), but was the thud largest C oxidation pathway at this s~t e .Nitrogen fixation was most rapid in the 8 yr old forest (1425 i 468 pm01 NZ m-' d-l) and equivalent in the 6 yr old (245 + 127 pm01 N2 m-' d-l) and 35 yr old forests (444 * 92 pm01 NZ d-l). The molar carbon ratio of sediment respiration to forest net primary production (Rh,,,,JNPP) in the 6 and 35 yr old forests averaged 18 and 28 %, respectively. These comparatively low mineralization losses, coupled with the lack of measurable denitrification at 2 of the 3 plantations, imply that these R. apiculata plantations are highly efficient at sequestering labile carbon and nitrogen into plant biomass and sediment pools.

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Section: Enterprise Tam Giangmentioning

confidence: 99%

Section: Enterprise Tam Giangmentioning

confidence: 99%

Section: Enterprise Tam Giangmentioning

confidence: 99%

Section: Enterprise Tam Giangmentioning

confidence: 99%

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Benthic decomposition rates and pathways in plantations of the mangrove Rhizophora apiculata in the Mekong delta, Vietnam

Alongi¹,

Tirendi²,

Trott³

et al. 2000

Mar. Ecol. Prog. Ser.

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“…N2 fluxes can be measured in closed chambers with a low-N2 headspace, but initially, diffusive fluxes from porewater N2 pools in equilibrium with atmospheric N2 dominate over denitrification fluxes. Thus long incubations are required for sediment "off-gassing" before denitrification can be measured (Seitzinger et ai., 1980;Nowicki, 1994).…”

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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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Denitrification in the Marine Environment

Joye

2003

Encyclopedia of Environmental Microbiology

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The Effect of Temperature, Oxygen, Salinity, and Nutrient Enrichment on Estuarine Denitrification Rates Measured with a Modified Nitrogen Gas Flux Technique

Cited by 158 publications

References 0 publications

Benthic decomposition rates and pathways in plantations of the mangrove Rhizophora apiculata in the Mekong delta, Vietnam

Benthic decomposition rates and pathways in plantations of the mangrove Rhizophora apiculata in the Mekong delta, Vietnam

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

Denitrification in the Marine Environment

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