Heavy metal migration in biogeochemical food webs

Heavy Metal Migration in Biogeochemical Food Webs 

Due to the complex influence of various geological and biological processes during Earth s long history, many heavy metals are irregularly distributed in the biosphere. 

This complex biogeochemical structure with non-optimal content of heavy metals and some micronutrients induces the development of various endemic diseases of humans and animals (Bashkin, 2002). The biogeochemical structure of the modern biosphere is discussed in more detail in Chapter 2. 

Metals from the 6th period in Mendeleev s table are potentially the most toxic (Os, Ir, Pt, Au, Hg, Tl, Pb), however small water solubility of their prevalent salts decreases sharply this toxic influence (Table 1). 

In the environment, metals are common as a chemical species, and as usual the metal-organic species are more toxic. For example, the inorganic lead and mercury species are less toxic for living organisms than the organic ones (methyl mercury, tetraethyl lead). However inorganic arsenic compounds are more toxic than organic 

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