Biogeochemical mapping

III, 27). This system is very important for biogeochemical mapping but until now it has not been understood quantitatively. 

Field monitoring and experimental simulation allow the researcher to study the variability of different links of biogeochemical food webs and to carry out the biogeochemical mapping of biosphere in accordance with above-mentioned classification regions of biosphere, sub-regions of biosphere and biogeochemical provinces. 

BIOGEOCHEMICAL MAPPING FOR ENVIRONMENTAL RISK ASSESSMENT IN CONTINENTAL, REGIONAL AND LOCAL SCALES... 

Application of the above-mentioned approaches to biogeochemical mapping will be highlighted below on the examples from North Eurasia. 

On a basis of data, presented in Table 4, a biogeochemical map of Northern Eurasia (the former USSR area) has been created (Figure 4). 

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

Similar biogeochemical studies of cancer development have been carried out in the biosphere of the Middle Volga silicon sub-region (Kovalsky and Suslikov, 1980 Ermakov, 1993). The biogeochemical map of this sub-region is shown in Figure 2. 

The following biogeochemical mapping of Se content in China s ecosystems has been suggested. 

Ermakov, V. V. (1993). Biogeochemical mapping of continents. In V. N. Bashkin, E. V. Evstafieva, V. V. Snakin, et al. Biogeochemical Fundamentals ofEcological Standardization, Nauka Publishing House, Moscow, pp. 5-24. 

Collins, W., Chang, S.H., Raines, G., Canney, F. and Ashley, R., 1983. Airborne biogeochemical mapping of hidden mineral deposits. Econ. Geol., 78 737-743. 

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). 

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