Nitrogen abiotic processes

The global nitrogen cycle is often referred to as the nitrogen cycles, since we can view the overall process as the result of the interactions of various biological and abiotic processes. Each of these processes, to a first approximation, can be considered as a self-contained cycle. We have already considered the biological cycle from this perspective (Fig. 12-1), and now we will look at the other processes, the ammonia cycle, the cycle, and the fixation/denitrification cycle. 

Similarly to N, most S pools are found in organic form in forest floor and soil humus. However, unlike nitrogen, there are important abiotic processes, especially sulfate sorption processes, which play a critical role in regulating sulfate dynamics in forest ecosystems. An example of this type of exposure pathway was shown in the Habbard Brook whole-tree harvesting experiment, where the decrease in sulfate output from the watershed was attributed to sulfate adsorption, which was enhanced by soil acidification from nitrification (see above). 

The ocean as a source of trace gases is between biogenic and abiotic processes hence we consider the ocean here in a separate subchapter. Whereas the generation of sea-salt particles from the surface of seawater is a purely physical process (see Chapter 2.6.4.2), it has been identified as a considerable global source of different nitrogen, sulfur and carbon species (Table 2.33). These species are produced in the... 

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