Nitrogen fixation and dissimilatory nitrate reduction to ammonium (DNRA) support nitrogen dynamics in Texas estuaries

Gardner, Wayne S.; McCarthy, Mark J.; An, Shuqing; Sobolev, Dmitri; Sell, Karen S.; Brock, David A.

doi:10.4319/lo.2006.51.1_part_2.0558

Cited by 272 publications

(193 citation statements)

References 40 publications

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“…We found a small, statistically insignificant 17 decrease in ammonium fluxes with increasing salinity. To account for differences in 18 sediment type, nutrient loading and organic matter supply to the sediment between these 19 systems, we also compared the ratio of ammonium efflux to total nitrogen flux and found 20 an increase with increasing salinities, in agreement with the results from Texas estuaries 21 (Gardner et al 2006). However, the differences in median are not statistically significant, 22 hence, no general conclusions about the relationship between ammonium fluxes and 1 salinity can be drawn.…”

supporting

confidence: 74%

Modeling denitrification in aquatic sediments

et al. 2008

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1 Sediment denitrification is a major pathway of fixed nitrogen loss from aquatic systems. 2 Due to technical difficulties in measuring this process and its spatial and temporal 3 variability, estimates of local, regional and global denitrification have to rely on a 4 combination of measurements and models. Here we review approaches to describing 5 denitrification in aquatic sediments, ranging from mechanistic diagenetic models to 6 empirical parameterizations of nitrogen fluxes across the sediment-water interface. We 7 also present a compilation of denitrification measurements and ancillary data for different 8 aquatic systems, ranging from freshwater to marine. Based on this data compilation we 9 reevaluate published parameterizations of denitrification. We recommend that future 10 models of denitrification use (1) a combination of mechanistic diagenetic models and 11 measurements where bottom waters are temporally hypoxic or anoxic, and (2)

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confidence: 74%

Modeling denitrification in aquatic sediments

et al. 2008

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“…DNRA is favored in organic rich-low NO 3 -systems (Burgin and Hamilton 2007). This process has been reported in fresh water sediments but has mostly been considered a minor pathway for NO 3 -removal (Gardner et al 2006;Erler et al 2008). To the best of our knowledge, DNRA has not been investigated in the SJR and Zamora et al (2012) suggested anaerobic mineralization is a key process for explaining high NH 4 ?…”

Section: Discussionmentioning

confidence: 99%

Nitrous oxide fluxes and dissolved N gases (N2 and N2O) within riparian zones along the agriculturally impacted San Joaquin River

Hinshaw

Dahlgren

2016

Nutr Cycl Agroecosyst

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TitleNitrous oxide fluxes and dissolved N gases (N2 and N2O) within riparian zones along the agriculturally impacted San Joaquin River ? and NO 3 -, while benthic N 2 O fluxes were regulated by variations in dissolved oxygen and river flow. Higher fluxes in the riparian soils in 2011 were attributed to several months of flooding that significantly impacted groundwater tables and nutrient availability. Dissolved N 2 O from groundwater within the riparian zones was not found to be a significant factor contributing to atmospheric fluxes. These results suggest that riparian zones within the agriculturally impacted San Joaquin River were a significant source of N 2 O when elevated NO 3 -was present. Different controlling factors for fluxes within benthic sediments suggested that riparian vegetation did not play a role in NO 3 -concentrations or fluxes within the surface water.

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“…Continuous flow experiments with intact sediment cores were used to determine the fluxes of nutrients and dissolved gases (Lavrentyev et al 2000, Gardner et al 2006, McCarthy et al 2007. Three intact sediment cores (6.4 cm diameter and approx 17 cm high) and overlying water (;400 ml per core) were collected by hand from each habitat two hours prior to low tide in February, May, July, and October of 2007.…”

Section: Sediment N Fluxes and N Transformationsmentioning

confidence: 99%

Habitat-specific distinctions in estuarine denitrification affect both ecosystem function and services

2011

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Abstract. Resource limitation controls the base of food webs in many aquatic ecosystems. In coastal ecosystems, nitrogen (N) has been found to be the predominant limiting factor for primary producers. Due to the important role nitrogen plays in determining ecosystem function, understanding the processes that modulate its availability is critical. Shallow-water estuarine systems are highly heterogeneous. In temperate estuaries, multiple habitat types can exist in close proximity to one another, their distribution controlled primarily by physical energy, tidal elevation and geomorphology. Distinctions between these habitats such as rates of primary productivity and sediment characteristics likely affect material processing. We used membrane inlet mass spectrometry to measure changes in N 2 flux (referred to here as denitrification) in multiple shallow-water estuarine habitats through an annual cycle. We found significantly higher rates of denitrification (DNF) in structured habitats such as submerged aquatic vegetation, salt marshes and oyster reefs than in intertidal and subtidal flats. Seasonal patterns were also observed, with higher DNF rates occurring in the warmer seasons. Additionally, there was an interaction between habitat type and season that we attributed to the seasonal patterns of enhanced productivity in individual habitat types. There was a strong correlation between denitrification and sediment oxygen demand (SOD) in all habitats and all seasons, suggesting the potential to utilize SOD to predict DNF. Denitrification efficiency was also higher in the structured habitats than in the flats. Nitrogen removal by these habitats was found to be an important contributor to estuarine ecosystem function. The ecosystem service of DNF in each habitat was evaluated in US dollars using rates from a regional nutrient-offset market to determine the cost to replace N through management efforts. Habitat-specific values of N removal ranged from approximately three thousand U.S. dollars per acre per year in the submerged aquatic vegetation to approximately four hundred U.S. dollars per acre per year in the subtidal flat. Because of the link between habitat type and processes such as DNF, changes in habitat area and distribution will have consequences for both ecosystem function and the delivery of ecosystem services.

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Nitrogen fixation and dissimilatory nitrate reduction to ammonium (DNRA) support nitrogen dynamics in Texas estuaries

Cited by 272 publications

References 40 publications

Modeling denitrification in aquatic sediments

Modeling denitrification in aquatic sediments

Nitrous oxide fluxes and dissolved N gases (N2 and N2O) within riparian zones along the agriculturally impacted San Joaquin River

Habitat-specific distinctions in estuarine denitrification affect both ecosystem function and services

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