Nitrogen pools

Lundquist EJ, Jackson LE, Scow KM, Hsu C (1999) Changes in microbial biomass and community composition, and soil carbon and nitrogen pools after incorporation of rye into three California agricultural soils. Soil Biol Biochem... 

The oxidation munber of nitrogen in all organic compoimds is -III. Most of the dissolved nitrogen in seawater is in the form of DON except in the deep ocean where nitrate concentrations are very high. The mean smfece water DON concentration is 6 2 p,M N and in deep waters it is 4 2 p,M N. PON generally represents only a small fraction of the fixed nitrogen pool. 

DON, dissolved organic nitrogen The fraction of the organic nitrogen pool in seawater that is dissolved. 

PON, particulate organic nitrogen The fraction of the organic nitrogen pool that is not dissolved in seawater. In practical terms, this includes aU organic nitrogen compormds that do not pass through a filter with a 0.45-micron pore size. 

Friedel, J.K., Gabel, D. and Stahr, K. 2001. Nitrogen pools and turnover in arable soils under different durations of organic farming II Source-and-sink function of the soil microbial biomass or competition with growing plants Journal of Plant Nutrition and Soil Science-Zeitschriftfur Pflanzenernahrung und Bodenkunde 164 421-429. 

We will look first at the reactions by which organic nitrogen compounds are formed from inorganic compounds, then at the reactions of the nitrogen pool. After that we will examine the specific reactions of synthesis and catabolism of individual nitrogenous compounds. 

Labeling of the phytoplankton nitrogen pool in this linear fashion was contrary to the expected result. The solid line in Figure 4 shows the expected asymptotic increase in 15N that was calculated by using the DIN concentrations in the epilimnion, the addition rate of 15NH4, and the assumption of a 1-week nitrogen-turnover time (87) in the phytoplankton. A similar asymptotic increase in 15N content of phytoplankton, with the phytoplankton reaching isotopic equilibrium in 1 week, was measured in an isotope-addition experiment done in limnocorrals in nearby Toolik Lake (Kipphut, G. W. Whalen, S. C. unpublished data). 

Wang L, Schjoerring JK (2012) Seasonal variation in nitrogen pools and 15N/13C natural abundances in different tissues of grassland plants. Biogeosciences 9 1583-1595... 

Fig. 4. Compartmental model describing the cycling of nitrogen in a planktonic community in the mixed layer of a water column. Flow pathways are represented by arrows and numbers which correspond to mathematical expressions described in Table 2. The nitrogen pool represents all abiotic nitrogen (nitrate, ammonia and urea), and other compartments represent bacteria, zooflagellates, larger protozoa, and micro-mesozooplankton, giving off waste products (F+U). Arrows (13) and (14) depict sedimentation of zooplankton faeces and phytoplankton cells, respectively (After Moloney et al., 1985).

Values assigned to each of the 22 constants in the 19 expressions used in the simulation model, and the relevant sources. The flow pathways are represented as donor -> recipient compartments. N = nitrogen pool P = phytoplankton B = bacteria F = zooflagellates L = large protozoa Z = micro-mesozooplankton (F+U) = faeces and urine (nitrogen pool). All units expressed in terms of mg, m2 and/or d. 

The nitrogen released serves as input to the abiotic nitrogen pool as shown in Fig. 4. In addition, a small starvation rate of 5 % of the standing stock per day was assumed to be excreted in the absence of food. 

Fig. 5. Simulation results showing the development and decay of a phytoplankton bloom and the changes in the standing stocks of the associated heterotrophic compartments with increasing daily rates of sedimentation out of the mixed layer. (A) no sedimentation, (B) 10% sedimentation, (C) 20% sedimentation, (D) 30% sedimentation. Axes give nitrogen standing stocks (mg.N.m-2 integrated over 60 m depth) and the nitrogen pool concentration (pg.at.l- ) (After Moloney et al., 1985).

Bertilsson, S., R. Stepanauskas, R. C. Hansson, W. Graneli, J. Wikner, and L. Tranvik. 1999. Photochemically induced changes in bioavailable carbon and nitrogen pools in a boreal watershed. Aquatic Microbial Ecology 19 47-56. 

Carlsson, P., A. Z. Segatto, and E. Graneli. 1993. Nitrogen bound to humic matter of terrestrial origin — a nitrogen pool for coastal phytoplankton. Marine Ecology Progress Series 97 105-116. 

Figure 10.7 Average composition of nitrogen pools (excluding dissolved N2) in estuarine waters DON = dissolved organic nitrogen PON = particulate organic nitrogen. (Modified from Berman and Bronk, 2003.)...

Table 7.1. Typical data for boreal and temperate forest floor nitrogen pools...

Despite the inertness of N2, the atmospheric N2 pool is available for biological productivity by N2 fixation (N2 —> NH ), which takes place in both the oceanic and the terrestrial environments. Further details about oceanic N2 fixation can be found in Chapter 4. The release of nitrogen as N2 from the fixed inorganic nitrogen pool (i.e. N03, N02 and NH ) is mediated by two microbial processes ... 

Meador, T. B., Aluwihare, L. I., and Mahaffey, C. (2007). Isotopic heterogeneity and cycling of components of the dissolved organic nitrogen pool in the oligotrophic ocean. Limnology and Oceanography 52(3), 934—947. 

Kaspar, H. F. (1983). Denitrification, nitrate reduction to ammonium, and inorganic nitrogen pools in intertidal sediments. Mar. Biol. 15, 133-140. 

McGlathery, K. J., Pedersen, M. F., and Borum, J. (1996). Changes in intracellular nitrogen pools and feedback controls on nitrogen uptake in Chaetomorpha linum (Chlorophyta). J. Phycol. 32,... 

Slawyk, G., Raimbault, P., and Garcia, N. (1998). Measuring gross uptake of N-labeled nitrogen by marine phytoplankton without particulate matter collection Evidence for low N losses to the dissolved organic nitrogen pool. Limnol. Oceanogr. 43(7), 1734-1739. 

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