Use of NOx- microsensors to estimate the activity of sediment nitrification and NOx- consumption along an estuarine salinity, nitrate, and light gradient

Kjær, Thomas; Revsbech, Niels Peter

doi:10.3354/ame026181

Cited by 38 publications

(38 citation statements)

References 51 publications

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“…As a result, denitrification was restricted to a sediment layer that was about 3 mm thick. The presence of such thin zones of denitrification has been reported previously for stream sediments (6), lake sediments (14,15,19), and estuarine sediments (4,20).…”

Section: Resultsmentioning

confidence: 82%

“…The integrated N 2 O production rates determined in the acetylene block core incubations, the direct nitrate flux determinations, and the reactive transport modeling results all point to the high capacity for nitrate removal by the intertidal estuarine sediments in the upper Scheldt Estuary (21). High rates of benthic denitrification supported by nitrate uptake from the water column, similar to those at Appels (37 to 60 nmol N cm Ϫ2 h Ϫ1 ), have been reported for nitrate-rich streams (ϳ120 nmol N cm Ϫ2 h Ϫ1 ) (7) and eutrophic estuaries in Denmark (40 to 140 nmol N cm Ϫ2 h Ϫ1 ) (4,20). The experimentally calibrated reactive transport model provides further insight into the role of the kinetic parameters and the overlying water chemistry in denitrification activity in the sediments (Table 2).…”

Section: Resultsmentioning

confidence: 92%

“…A number of methods have been developed to quantify denitrification and related nitrogen transformations in sediments; these methods include, among others, benthic flux measurement (17), isotope pairing techniques (32), and microprofiling using nitrous oxide (31) or nitrate microsensors (9,20). The available data show that there are large spatial and temporal variations in denitrification rates in nearshore sediments.…”

mentioning

confidence: 99%

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Vertical Distribution of Denitrification in an Estuarine Sediment: Integrating Sediment Flowthrough Reactor Experiments and Microprofiling via Reactive Transport Modeling

Laverman

Meile

Cappellen

et al. 2007

Appl Environ Microbiol

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Denitrifying activity in a sediment from the freshwater part of a polluted estuary in northwest Europe was quantified using two independent approaches. High-resolution N 2 O microprofiles were recorded in sediment cores to which acetylene was added to the overlying water and injected laterally into the sediment. The vertical distribution of the rate of denitrification supported by nitrate uptake from the overlying water was then derived from the time series N 2 O concentration profiles. The rates obtained for the core incubations were compared to the rates predicted by a forward reactive transport model, which included rate expression for denitrification calibrated with potential rate measurements obtained in flowthrough reactors containing undisturbed, 1-cmthick sediment slices. The two approaches yielded comparable rate profiles, with a near-surface, 2-to 3-mm narrow zone of denitrification and maximum in situ rates on the order of 200 to 300 nmol cm ؊3 h ؊1 . The maximum in situ rates were about twofold lower than the maximum potential rate for the 0-to 1-cm depth interval of the sediment, indicating that in situ denitrification was nitrate limited. The experimentally and model-derived rates of denitrification implied that there was nitrate uptake by the sediment at a rate that was on the order of 50 (؎ 10) nmol cm ؊2 h ؊1 , which agreed well with direct nitrate flux measurements for core incubations. Reactive transport model calculations showed that benthic uptake of nitrate at the site is particularly sensitive to the nitrate concentration in the overlying water and the maximum potential rate of denitrification in the sediment.Anthropogenic inputs of nitrogen are a major cause of eutrophication in aquatic environments (39). Denitrification, the bacterial dissimilatory reduction of nitrate to gaseous products, counteracts eutrophication by removing inorganic nitrogen and releasing it to the atmosphere and by decomposing organic matter (34). The emissions resulting from denitrification, however, include nitrous oxide, a powerful greenhouse gas (8). Because of its environmental importance, denitrification has been the subject of numerous studies (for reviews, see references 12, 16, and 34). Oxygen and nitrate concentrations, temperature, pH, and the availability of suitable electron donor substrates (mainly organic carbon compounds) are considered the key factors controlling the occurrence and rate of denitrification (6,22,38).In estuarine and coastal environments, the most intense denitrification often occurs in sediments, where reduced solute transport rates enable the establishment of anaerobic conditions. A number of methods have been developed to quantify denitrification and related nitrogen transformations in sediments; these methods include, among others, benthic flux measurement (17), isotope pairing techniques (32), and microprofiling using nitrous oxide (31) or nitrate microsensors (9,20). The available data show that there are large spatial and temporal variations in denitrification rates in nearsho...

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Section: Resultsmentioning

confidence: 82%

Section: Resultsmentioning

confidence: 92%

mentioning

confidence: 99%

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Vertical Distribution of Denitrification in an Estuarine Sediment: Integrating Sediment Flowthrough Reactor Experiments and Microprofiling via Reactive Transport Modeling

Laverman

Meile

Cappellen

et al. 2007

Appl Environ Microbiol

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“…The bulk nitrification rates estimated in this study are at the lower end of those normally observed in Danish shallow estuaries and coastal waters (Binnerup et al 1992, Jensen et al 1996, Hansen & Kristensen 1998, but within the range of 0 to 1.8 mmol m -2 d -1 measured by NO 3 -/NO 2 -sensors in another Danish fjord (Meyer et al 2001). Only a few studies have measured nitrification rates in association with burrow structures (see Mayer et al 1995 for review), and of these the majority report potential rates (slurry assays at high NH 4 + concentrations) as opposed to measured rates.…”

Section: Discussionmentioning

confidence: 85%

Microscale distribution of oxygen and nitrate in sediment inhabited by Nereis diversicolor: spatial patterns and estimated reaction rates

Nielsen

Gribsholt

Kristensen³

et al. 2004

Aquat. Microb. Ecol.

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Profiles of oxygen and nitrate were measured with microsensors in sediment surrounding burrow structures of the polychaete Nereis diversicolor in a shallow mudflat in Limfjorden, Denmark. Rates and spatial distribution of reactions involving oxygen and nitrate (oxygen consumption, nitrification and nitrate reduction) in the vicinity of burrow structures and surface sediment were calculated and identified from concentration profiles. The burrow walls of the natural N. diversicolor population increased the surface area of the sediment -water interface several-fold and introduced oxic microniches with high metabolic activity into otherwise anoxic sediment. Nitrification and nitrate reduction were spatially separated processes, with nitrification restricted to the 0.9 to 1.5 mm thick oxic zone and nitrate-reduction occurring as a strictly anaerobic process in the nitratecontaining layers next to the oxic zone. At a density of 2560 individuals m -2 , burrow walls of N. diversicolor account for 12 to 40% of bulk sediment oxygen uptake and 50 to 77% and 58 to 82% of bulk nitrification and nitrate reduction, respectively. Thus, burrow structures of macro-infauna are potentially a major sediment compartment involved in nitrogen cycling and may promote loss of bioavailable nitrogen from the sediment.

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“…The NO 2 Ϫ sensor was constructed like the NO x Ϫ biosensor except that the culture of bacteria used (Stenotrophomonas nitritireducens) was deficient in NO 3 Ϫ reductase (22). Concentrations of NO x Ϫ , NO 2 Ϫ , and O 2 in porewater were measured as three or more replicate profiles from at least two different cores, as described by Meyer et al (20). Profiles of NO 3 Ϫ were calculated by subtracting the averaged NO 2 Ϫ profile from the averaged NO x Ϫ profile.…”

Section: Methodsmentioning

confidence: 99%

Correlation between Anammox Activity and Microscale Distribution of Nitrite in a Subtropical Mangrove Sediment

Meyer¹,

Risgaard-Petersen²,

Allen

2005

Appl Environ Microbiol

195

144

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The distribution of anaerobic ammonium oxidation (anammox) in nature has been addressed by only a few environmental studies, and our understanding of how anammox bacteria compete for substrates in natural environments is therefore limited. In this study, we measure the potential anammox rates in sediment from four locations in a subtropical tidal river system. Porewater profiles of NO x ؊ (NO 2 ؊ plus NO 3 ؊ ) and NO 2 ؊were measured with microscale biosensors, and the availability of NO 2 ؊ was compared with the potential for anammox activity. The potential rate of anammox increased with increasing distance from the mouth of the river and correlated strongly with the production of nitrite in the sediment and with the average concentration or total pool of nitrite in the suboxic sediment layer. Nitrite accumulated both from nitrification and from NO x ؊ reduction, though NO x ؊ reduction was shown to have the greatest impact on the availability of nitrite in the suboxic sediment layer. This finding suggests that denitrification, though using NO 2 ؊ as a substrate, also provides a substrate for the anammox process, which has been suggested in previous studies where microscale NO 2 ؊ profiles were not measured.

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Use of NOx- microsensors to estimate the activity of sediment nitrification and NOx- consumption along an estuarine salinity, nitrate, and light gradient

Cited by 38 publications

References 51 publications

Vertical Distribution of Denitrification in an Estuarine Sediment: Integrating Sediment Flowthrough Reactor Experiments and Microprofiling via Reactive Transport Modeling

Vertical Distribution of Denitrification in an Estuarine Sediment: Integrating Sediment Flowthrough Reactor Experiments and Microprofiling via Reactive Transport Modeling

Microscale distribution of oxygen and nitrate in sediment inhabited by Nereis diversicolor: spatial patterns and estimated reaction rates

Correlation between Anammox Activity and Microscale Distribution of Nitrite in a Subtropical Mangrove Sediment

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