Denitrification dissimilatory nitrate reduction

Coupling of nitrification, denitrification, dissimilatory nitrate reduction to ammonium, and anammox... 

FIGURE 8.48 Effect of sediment depth on partitioning of nitrate reductive processes of denitrification, dissimilatory nitrate reduction to ammonia (DNRA), and assimilatory nitrate reduction (ANR). Each value represents the mean of six relications (D Angelo and Reddy, 1993). 

Figure 3. The general nitrogen model for illustrating the bio geochemical cycling in Forest ecosystems. Explanations for the fluxes 1, ammonia volatilization 2, forest fertilization 3, N2-fixation 4, denitrification 5, nitrate respiration 6, nitrification 7, immobilization 8, mineralization 9, assimilatory and dissimilatory nitrate reduction to ammonium 10, leaching 11, plant uptake 12, deposition N input 13, residue composition, exudation 14, soil erosion 15, ammonium fixation and release by clay minerals 16, biomass combustion 17, forest harvesting 18, litterfall (Bashkin, 2002).

Tiedje, ]. M. (1988). Ecology of denitrification and dissimilatory nitrate reduction to ammonia. In Biology of Anaerobic Microorganisms (A. J. B. Zehnder, ed.). pp. 179-244. Wiley, New York. 

An, S., and Gardner, W.S. (2002) Dissimilatory nitrate reduction to ammonium (DNRA) as a nitrogen link, versus denitrification as a sink in a shallow estuary (Laguna Madre/Baffin Bay, Texas). Mar. Ecol. Prog. Ser. 237, 41-50. 

Christensen, P. B., Rysgaard, S., Sloth, N. P., Dalsgaard, T., and Schwaerter, S. (2000). Sediment mineralization, nutrient fluxes, denitrification and dissimilatory nitrate reduction to ammonium in an estuarine ord with sea cage trout farms. Aquat. Microb. Ecol. 21(1), 73—84. 

Figure 16.2 The redox intermediate, nitrite (N02 ), occupies a central position in the marine N-cycle. Shown are the various processes that are either sources or sinks for N02. Abbreviations include (clockwise from top) ANR = assimilatory nitrate reduction, Nit = nitrification, photolysis = UV-driven photocatalysis, DNR/DN = dissimilatory nitrate reduction/denitrification, ANR and Nit = as above, Anammox = Anaerobic ammonium oxidation.

KeUy-Gerreyn, B. A., Trimmer, M., and Hydes, D. J. (2001). A diagenetic model discriminating denitrification and dissimilatory nitrate reduction to ammonium in a temperate estuarine sediment. Mar. Ecol. Prog. Ser. 220, 33-46. 

Figure 21.1 Microbial nitrogen cycling processes in sedimentary environments on a coral reef (A) nitrogen fixation (B) ammonification (C) nitrification (D) dissimilatory nitrate reduction and denitrification (E) assimilatory nitrite/nitrate reduction (F) ammonium immobilization and assimilation. Adapted from D Elia and Wiebe (1990). Anammox (the anaerobic oxidation of NH4" with NO2 yielding N2 ) is not represented, as it has not yet been shown to occur on coral reefs, but may be found to be important in reef sediments.

There are two pathways of dissimilatory nitrate reduction, generally thought to be mediated by anaerobic, or facultatively anaerobic bacteria, using NOs" as a terminal electron acceptor in respiration (Fig. 21.ID and F) (see Chapter 6, Devol, this volume). One pathway leads to production of ammonium, and may act as an internal cychng loop within the system (D Elia and Wiebe, 1990). The other pathway, denitrification, ends in production of N2O and/or N2 gas, which can then be lost from the system to the atmosphere. 

Figure 12 Major reduction-oxidation reactions involving nitrogen. The reactions are numbered as follows (1) mineralization, (2) ammonium assimilation, (3) nitrification, (4) assimilatory or dissimilatory nitrate reduction, (5) ammonium oxidation, (6) nitrite oxidation, (7) assimilatory or dissimilatory nitrate reduction, (8) assimilatory or dissimilatory nitrite reduction, (9) denitrification, (10) chemodenitrification, (11) anaerobic ammonium oxidation, and (12) dinitrogen fixation (after Capone, 1991) (reproduced by permission of ASM Press from Microbial Production and Consumption of Greenhouse Gases Methane, Nitrogen Oxides, and Halomethanes, 1991).

Fazzolari E., Nicolardot B., and Germon J. C. (1998) Simultaneous effects of increasing levels of glucose and oxygen partial pressures on denitrification and dissimilatory nitrate reduction to ammonium in repacked soil cores. Euro. J. Soil Biol. 34, 47-52. 

Hattori, A. (1983) Denitrification and dissimilatory nitrate reduction, in Nitrogen in the Marine Environment (eds E.J. Carpenter and D. Capone), Academic, New York, pp. 191-232. 

FIGURE 8.5 Oxidation and reduction reactions of nitrogen in wetlands. Numbers 1-7 refer to pathways of nitrogen reactions. 1 = ammonification 2 = immobilization 3 = nitrification 4 = denitrification 5 = dissimilatory nitrate reduction to ammonia 6 = dinitrogen fixation and 7 = ammonia volatilization. 

Tiedje, J. M. 1988. Ecology of denitrification and dissimilatory nitrate reduction to ammonia. In A. J. B. 

Denitrification (often referred to as dissimilatory nitrate reduction) is the microbial reduction of NO3" to N2. The reaction steps require an organic carbon as electron donor (CH2O generically used) and are shown below ... 

Denitrification, a dissimilatory pathway of nitrate reduction (see Section 3.3 also) into nitrogen oxides, N2O, and dinitrogen, N2, is performed by a wide variety of microorganisms in the forest ecosystems. Measurable rates of N20 production have been observed in many forest soils. The values from 2.1 to 4.0 kg/ha/yr are typical for forest soils in various places of Boreal and Sub-Boreal Forest ecosystems. All in situ studies (field monitoring) of denitrification in forest soils have shown large spatial and temporal variability in response to varying soils characteristics such as acidity, temperature, moisture, oxygen, ambient nitrate and available carbon. 

---