Biogeochemical mapping, Chapter

Using similar data the biogeochemical mapping of North Eurasia was carried out (see Chapter 2, Figure 4). 

The spatial heterogeneity of selenium content in rocks, various soils, and especially the peculiarities of its translocation from soils to plants, lead to the formation of so-called selenium biogeochemical provinces (see Chapter 7 Biogeochemical mapping ). These provinces are characterized by a deficient or excessive concentration of this trace metal in all links of biogeochemical food webs. Selenium deficiency in fodder crops is related to the less than 30 ppm content of this element (Table 8). This leads to myopatia (white colored animal tissues), necrotic degeneration of kidney, exude diathesis. The addition of sodium selenite is used for prevention of these diseases. 

The proportion of areas with different precipitation rates varies from continent to continent. For instance, different Arid ecosystems, from Dry Savanna to Extra-Dry Desert, are predominant in India and Australia. To a lesser degree these ecosystems occur in Central and South America (see Chapter 7 Biogeochemical Mapping ). In an equatorial belt of Africa, the distribution of areas with different precipitation is shown in Table 32. 

Tropical ecosystems and finally on the biogeochemical mapping of the whole tropical area (see Chapter 7). 

Application ofGIS techniques for calculation and mapping of critical loads Critical loads ofpollutants at an ecosystem can be calculated on the basis of the Steady-State Mass Balance (SSMB) biogeochemical model (see Chapter 10). All equations of this model include a quantitative estimation of the greatest possible number of... 

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