EESA10H3 Lecture Notes - Lecture 5: Heavy Metals, Bioavailability, Ionic Bonding
8 Mar 2019
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Heavy metals: naturally occurring, extracted from the earth, in ore, wide environmental dispersion, tendency to accumulate in select tissues, toxic in low concentrations, e. g. lead, mercury, copper, nickel, etc. Classification of metals: class a, k, na, mg, ca, macronutrients (essential for biological processes, tend to form ionic bond. Low toxicity: class b, hg, pb, ti, non-essential elements, tend to form covalent bond, very toxic (form soluble organometallics, borderline, cr, cu, as, co, ni, zn, mn, fe, almost all micronutrients. Blocking essential functional groups in proteins or enzymes; proteins can not carry anything. Modifying the active conformation of biomolecules (class b) Resistance species develop mechanisms not to uptake metal (e. g. pb) Tolerance capacity of a species to withstand high level of metals. Internal detoxifying mechanisms: binding to non-sensitive compound structures, metabolic transformations to less toxic forms (methylation of as in marine biota, can develop multiple tolerance cu, pb, zn, cd.
