Nitrogen volatile fluxes

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).

Zimmer MM, Fischer TP, Hilton DR, Alvaredo GE, Sharp ZD, Walker JA (2004) Nitrogen systematics and gas fluxes of subduction zones insights from Costa Rica arc volatiles. Geochem Geophys Geosys 5 Q05J11, doi 10.1029/2003GC000651... 

The amount of nitrogen in the upper mantle is therefore 1.6 X 10 ° g, which is only 3% that in the crust and atmosphere. The MORE flux is equivalent to a flux of 5.0 X 10 °molyr or 9% of the surface N2 over 4.5 Ga. Note that Javoy (1998) argued that nitrogen is relatively compatible, with an upper-mantle concentration of up to 40 ppm (Cartigny et ai, 2001). However, this is from mass balance calculations based upon model assumptions that volatiles in the upper mantle and on the surface are a mixture of enstatite chondrites and a late veneer of Cl chondrites, and such a model has not been widely adopted. 

Thus, the following links of nitrogen biogeochemical cycle were accounted for mass balance calculations in Northern-East Asia and the whole East Asian domain input — deposition, fertilizers, biological N fixation, import of food and products, riverine fluxes and output — crop uptake, denitrification, volatilization, runoff, sedimentation and sea water exchange. All calculations were condncted for 1994-1997 and the mean values were used. 

Figures 15.2 and 15.3 compare the various mass flux equations with experimental data for the evaporation of low volatility species. Figure 15.2 shows the data for dibutyl sebacate (DBS) droplets evaporating in nitrogen obtained by Davis and Ray...

Even if the typical volatilization loss from the tops of plants would be just 10 kg N/ha, the world s croplands would lose no less than 15 Mt N annually, a flux similar to NO3-N losses due to leaching. Because we do not know to what extent the gaseous nitrogen losses from the tops of plants may have been captured by previously outlined estimates of gaseous (NH3 and NO) fluxes, I will assume that just 10 (5-15) Mt N/year are lost in this way. 

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