Environmental problems – An overview - Environmental Deterioration and Contamination: Problems and their Management - page 19

Figure 1.13 Global sulfur budget: reserves and fluxes.

by the biota is in the form of N 2 (nitrogen-fixing plants and microorganisms) or NO 3
(plants); output into the air as NH 3 ,asN 2 OorN 2 (denitrification products).
Anthropogenic surplus comes from incineration. Fertilizers result in a more or less
balanced surplus in the N-fluxes.
C and N have significant cycling in dissolved and biologically immobilized forms
in waters and soils, providing N source for the biosynthesis in those plants that do not
fix nitrogen and the food chain upstream. The C and N cycling processes within the
soil have already been introduced in Figure 1.10.
Sulfur cycling between atmosphere, lithosphere, and biosphere shows an inter-
esting pattern given that the anthropogenic surplus in both gas (incineration) and
dissolved forms (sulfuric acid leachate from mines) has a considerable weight.
The balance is kept in the atmosphere by the sulfur-containing acidic precipitation.
In the deeper or anoxic soils and waters, the balance is achieved by the sedimentation
of the immobile sulfide form.
Regulating services of the ecosystem:

- Regulating element cycling;

- Regulation of air quality;

- Regulation of water flows and water quality;