Nitrogen cycle schematic

Figure 1.3. Schematic illustration of the structure of the nitrogen cycle in various environments. From Matson et al. (2002), Krapivin and Varotsos (2007).

Figure 1.8 Schematic illustration of the nitrogen cycling paradigm in the euphotic zone. Adapted from Sarmiento and Gruher (2006).

Figure 1.15 Schematic budget of the global nitrogen cycle in preindustrial times (black) and how it changed as a result of human intervention (red). Fluxes are in units of Tg N year and inventories (bold italics) inTg N. The flux estimates are based on Gruber and Galloway (2008).

Figure l.l6 Schematic representation of feedbacks within the marine nitrogen cycle. The inner light grey ellipse shows the two nitrogen cycle internal feedback loops that tend to be stabilizing. These two feedback are proposed to be mainly controlled by the NO to (N P) ratio in sur-... 

Figure 29.2 Schematic overview of the marine nitrogen cycle. A Important species, their oxidation state (vertical axis), and major biological transformations of nitrogen (arrows). B Typical values of the isotopic enrichment factor (e) are shown for reactions that have been characterized isotopically. Estimates of 6 were drawn from the available literature on N2-fixation and the of diazotrophs (Carpenter et al, 1997 Delwiche and Steyn, 1970 Hoering and Ford, 1960 Macko et al., 1987 Montoya et ah, 2002), denitrification (Barford et ah, 1999 Cline and Kaplan, 1975 Delwiche and Steyn, 1970 Mariotti et ah, 1981,1982 McCready et ah, 1983 Miyake and Wada, 1971 Voss et ah, 2001 Wada, 1980 ), nitrification (Delwiche and Steyn, 1970 Mariotti et ah, 1981 Miyake and Wada, 1971 Ybshida, 1988), N03 uptake (Montoya and McCarthy, 1995 Needoba et ah, 2003 Needoba and Harrison, 2004 Pennock et ah, 1996,1998 Wada and Hattori, 1978 Waser et ah, 1998a, 1998b ), NO2 uptake (Wada and Hattori, 1978 Wada, 1980), NH4 uptake (Cifuentes et ah, 1989 Montoya et ah, 1991 Pennock et ah, 1988 Wada, 1980 Wada and Hattori, 1978), and zooplankton excretion (Checkley and Miller, 1989).

FIGURE 1. Schematic view of biogeochemical nitrogen cycle 1, nitrogen fixation 2, mineralization 3, immobilization 4, nitrification 5, nitrate assimilation 6, dissimilatory nitrogen reduction 7, denitrification (Rosswall, 1982). 

A schematic view of the biogeochemical nitrogen cycle (Rosswall, 1982) is presented in Figure 1. Of special interest in the context of this discussion are reactions 1, 2, 3, and 4 which involve nitrogen associated with organic matter. These reactions are ... 

Figure 5.4 Schematic showing the key nitrogen cycle processes in intertidal sediments.

General Characterization of Nitrogen Biogeochemical Cycling Processes Let us consider the various ways that N is processed by the biosphere. These ways are important for both terrestrial and oceanic nitrogen cycles. They are shown schematically in Figure 19. 

Figure 7.12. Schematic description of the nitrogen cycle, placed on a redox scale.

Simplified Schematic for the Microbial Processes of the Nitrogen Cycle... 

Fig. 6.9 Schematic nitrogen cycle (modified after Shapleigh 2000).

The cyclic transformation of nitrogenous compounds is of great importance in the total turnover of this element in the biosphere. The main features of the biological nitrogen cycle are illustrated schematically in Fig. 4.16. Plants and algae assimilate nitrogen as either nitrate or ammonia to form... 

The main features of the nitrogen cycle are illustrated schematically in Fig. 4.9. The nitrogen cycle is of huge importance for soil fertility. 

Figure 1 Schematic representation of the various transformations from one form of nitrogen to another that compose the marine nitrogen cycle. Shown at the bottom is the oxidation state of nitrogen for each of the components. Most transformations are microbiological and most involve nitrogen reduction or oxidation. (Adapted from Capone, ch. 14 of Rogers and Whitman (1991).)...

Fig. 13.10 (a) Tapered optical fiber. p0 is the initial diameter, inset schematic cross section of the device p is the waist diameter, L0 is the length of the waist, t is the maximum thickness of the palladium film (shadowed area) and X is radiation wavelength, (b) Time response of the sensor to periodic cycles from a pure nitrogen atmosphere to a mixture of 3.9% hydrogen in nitrogen, (c) Time response of a sensor when it was exposed to different hydrogen concentrations, (d) Transmission versus hydrogen concentration sensor parameters p 1,300 nm, L 2 mm, and t 4 nm. Reprinted from Ref. 15 with permission. 2008 Optical Society of America... 

Figure 10.1 Schematic of nitrogen sources and cycling in estuaries. These sources range from a diverse group of both diffuse non-point agricultural, urban, and rural point sources (e.g., wastewater, industrial discharges, stormwater, and overflow discharges) across a broad spectrum of watersheds (e.g., urban, agricultural, upland and lowland forests). (Modified from Paerl et al., 2002.)...

This net transformation, however, encompasses a more complex mechanism that can be visualized in the generic catalytic cycle shown schematically in Fig. 5.2. Compounds I and II, the critical catalytic intermediates, are readily distinguished from the resting ferric state of the protein by their UV-visible absorption spectra (Table 5.1) [1-4]. Although the exact positions of the maxima show small variations, the spectroscopic properties of HRP are representative of those of all the peroxidases in which the heme iron atom is coordinated to a histidine nitrogen atom. The individual stages of the catalytic cycle are considered below. 

Figure 7.95 shows a schematic of a typical combined-cycle power plant. High temperatures produced by GTs cause nitrogen and oxygen in the combustion air to combine to form nitrogen oxide gases NO. The NO levels of around 200 ppm were produced in each GT train. 

Figure 11 Schematic representation of the biogeochemical cycle of nitrogen, indicating the approximate magnitude of fluxes and reservoirs (After O Neill. )...

Schematic diagrams of the apparatus, designed in our lab at< y, are shown in Fig. 1. Polymer flakes are placed, with a balls of about 5 mm dieter, in a glass an oule A about 4 cm in diameter and 7 cm in length. To the other end of the ampoule an ESR sample tube B is attached. Through connector C, the ampoule can be connected to a vacuum system and then evacuated to 10 mm Hg. After evacuation the connector is sealed off and the ampoule is removed from the vacuum system. The evacuated ampoule is now placed on a vibrator, wWch moves vertically at about 4 cycle per second. The procedure can be carried out in a Dewar flask containing coolant, such as liquid nitrogen, to fix the temperature. After some hours of this vibration, the crushed flakes are transferred to the ESR sample tube without raising the temperature of the sample. Ihen, sample tube containing the fractured flakes is placed in an ESR cavity at controlled temperature. The ball-mill apparatus permitted polymeric materials to be crushed in vacuum at low temperature and the ESR spectrum to be observed without contamination of oxygen.

Figure 35-6 Simplified schematic views of the oceanic nitrogen and oxygen cycles. Nj and Oaa are the deep ocean dissolved inorganic nitrogen and dissolved oxygen concentrations respectively, Npre attd 02pre preformed nitrogen and oxygen concentrations, and Nj, , and Oabio re the...

FIGURE 17.19 Schematic showing interactions among carbon, nitrogen, and phosphorus cycling in soil and water column. 

---