Nitrogen fixation rates

In temperate climates, nitrogen fixation rates were in the range of 0.1-7 mg N m day, as compared to 5-140 mg N m day in tropical climates. 

A wide range in nitrogen fixation rates is reported in wetlands and aquatic systems (Table 8.13 Buresh et al 1980 Howarth et al., 1988 Herbert, 1999). Rice paddies and coastal wetlands showed higher nitrogen fixation rates than freshwater wetlands, peat bogs, and lakes. 

Nitrogen Fixation Rates (Estimated Acetylene Reduction Assay) in Select Wetland Ecosystems 

Colne Point marsh. United Kingdom 16.4 Herbert (1999) 

Estimated Dinitrogen Fixation Rates in the Root Zone of Wetland Plants 

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Nielsen, L. B., Finster, K., Welsh, D. T., DoneUy, A., Herbert, R. A., de Wit, R., and Lomstein, B. A. (2001). Sulphate reduction and nitrogen fixation rates associated with roots, rhizomes and sediments from Zostera noltii and Spartina maritima meadows. Environ. Microbiol. 3, 63—71. 

Welsh, D. T., Bourgues, S., deWit, R., and Auby, I. (1997). Effect of plant photosynthesis, carbon sources and ammonium availability on nitrogen fixation rates in the rhizosphere of Zostera noltii. Aquatic Mkrob. Ecol. 12, 285-290. 

Grabowski, M. N. W., Church, M. J., and Karl, D. M. (2008). Nitrogen fixation rates and controls at Station ALOHA. Aquat. Microb. EcoL, (in press). 

Table 22.2 Nitrogen fixation rates in salt marshes...

Nitrogen fixation in the marine environment occurs in benthic (sediments and microbial mats) and pelagic environments, and in salt marsh soils (see Carpenter and Capone, Chapter 4, this volume). Since very diverse microorganisms that span the Bacteria and Archaea domains of life can fix nitrogen, it is often difficult to ascertain which organisms are responsible for observed nitrogen fixation rates. Our discussion of the application of molecular approaches to the study of marine nitrogen fixation is brief because it has been reviewed extensively elsewhere (Carpenter and Capone, Chapter 4, this volume Foster and O MuUan Chapter 27, this volume Scanlan and Post, Chapter 24, this volume Paerl and Zehr, 2000 Zehr and Ward, 2002 Zehr et al., 2003). 

Figure 33.13 Hood et al. (2004) model-estimated nitrogen fixation rate in the mixed layer as a frmction of season. The fields are synoptic, from the middle of the specified month. The rates are expressed in mmol N m day Reproduced with permission from Hood et al. (2004).

Oxygenation of the early atmosphere The influence of shelf area and nitrogen fixation rates... 

Kustka A. B., Sanudo-Wilhelmy S., Carpenter E. J., and Sunda W. G. (2003b) Iron requirements for dinitrogen and ammonium supported growth in cultures of Trichodesmium (IMS 101) comparison with nitrogen fixation rates and iron carbon ratios of field populations. Limnol. Oceanogr. 48, 1869-1884. 

FIGURE 15.8 Annual course of concentrations of DIN, PO4, and biomass (wet weight) of heterocystous cyanobacteria in the upper mixed layer, as well as nitrogen fixation rates in the euphotic zone at station 271 in 2001, (after Wasmund et al., 2005b, coiTected). 

Wasmund, N., Nausch, G., Schneider, B., Nagel, K., Voss, M., 2005b. Comparison of nitrogen fixation rates determined with different methods a study in the Baltic Proper. Marine Ecology Progress Series, 297, 23-31. 

Temperature Like any other biological reactions, nitrogen fixation rates are influenced by temperature with 2io values around 2. Contrasting differences were noted in nitrogen fixation... 

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