Nutrient scenario

Fig.1 Generalized pelagic food web [ 13]. The old view of a simple food chain vertical line in this figure) with phytoplankton (mainly diatoms) at the base, herbivorous mesozoo-plankton (mainly copepods) at the second trophic level, and planktivorous fish has been extended to a pelagic food web including nanoplankton (<20 pm), picoplankton (<2 pm), and their protozoan feeders lower left). Herbivorous tunicates and jellyfish as primary carnivores also play a role, as do mixotrophic flagellates. The main pathway of energy flow depends on the nutrient scenarios [13]. DOC=dissolved organic carbon, HNF=heterotrophic nanoflageUates. From [13] with permission of Kluwer Academic Press...

The maximum temperature and duration of heating during fires are important variables that influence the soil nutrient status, as well as the survival of residual vegetation following fire (Table III). Deforestation results in the presence of large quantities of wood debris in close proximity to the soil surface. Fires in this scenario result in soil temperatures and magnitudes of heat flux far in excess of those which occur in fires in uncut forests (Shea, R. W. Oregon State University, unpublished data). 

This chapter aims to review current knowledge on the effects of wastewater treatment plant (WWTP) inputs (as major nutrient point sources) on stream nutrient dynamics, with major emphasis on nutrient loads and in-stream nutrient retention, and to discuss its implications within the context of actual and future scenarios of water scarcity conditions. Following this introduction, the second section of this chapter describes water quality problems associated with wastewater inputs from urban areas and how they are faced within the context of increasing urbanization across the world and its higher impact on water availability. In the third section, we... 

Caille F, Riera JL, Rodriguez-Labajos B, MiddeUcoop H, Rosell-Mele A (2007) Participatory scenario development for integrated assessment of nutrient flows in a Catalan river catchment. Hydrol Earth Syst Sci Discuss 4 1265-1299... 

Dalgaard et al. (1998) choose a scenario approach based on the empirical data by Halberg et al. (1995) of the nutrient cycles presented in Table 4-13. Daalgard et al. set up national scenarios for dairy farms converting to organic farming in order to quantify the national reduction of N-losses. The model calculations resulted in a 50% N-surplus reduction per hectare and a 25% N-surplus reduction per ton milk (Table 4-17). 

It is difficult to say what happens to these enhanced carbon fluxes today. In Figure 10.34, two opposing scenarios are presented for the oceans. In one case (Figure 10.34A), most of the excess carbon brought by rivers is respired and oxidized to CO2, and the excess organic carbon, supported by excess nutrient loading, is accumulated, primarily in nearshore environments. Also, all the... 

Table 7. Scenarios of nutrient demand and supply by agriculture in SSA in 2005 and 2025. Values in % refer to shares of the respective total amounts available in each country (as calculated using Tables 5 and 6). Production in 2025 was assumed to be sufficient to meet domestic demand. Land reclamation was expected to contribute 15% of the increase, the remainder resulting from yield increases.

Figure 4. Gross N and P balances in the DR Congo, Kenya and Mali for three nutrient demand and supply scenarios (defined in Table 7). All nutrients contained in applied materials are accounted for as inputs.

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