EESA10H3 Lecture Notes - Lecture 5: Bioaccumulation, Methylmercury, Silt
Document Summary
Heavy metals: natu(cid:396)all(cid:455) o(cid:272)(cid:272)u(cid:396)(cid:396)i(cid:374)g, e(cid:454)t(cid:396)a(cid:272)ted f(cid:396)o(cid:373) the ea(cid:396)th, i(cid:374) o(cid:396)e, wide e(cid:374)(cid:448)i(cid:396)o(cid:374)(cid:373)e(cid:374)tal dispe(cid:396)sio(cid:374, te(cid:374)de(cid:374)(cid:272)(cid:455) to a(cid:272)(cid:272)u(cid:373)ulate i(cid:374) sele(cid:272)t tissues, to(cid:454)i(cid:272) i(cid:374) e(cid:448)e(cid:374) lo(cid:449) (cid:272)o(cid:374)(cid:272)e(cid:374)t(cid:396)atio(cid:374)s. Mechanism of toxicity: blocking essential functional groups such as proteins or enzymes, proteins can not carry anything, displace other metals (class b, borderline, modifying the active conformation of biomolecules (class b) Coping mechanisms: resistance species develop mechanisms not to uptake metal (example pb, tolerance the 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. Bioavailability of metals: pe(cid:272)ies of the (cid:373)etal - free ions (charged ions zn+2 are more bioavailable than zno , neut(cid:396)al spe(cid:272)ies (cid:373)a(cid:455) (cid:271)e (cid:271)ioa(cid:448)aila(cid:271)le, important in complexes, ph of solutio(cid:374, redo(cid:454) pote(cid:374)tial of solutio(cid:374) First discovered in minamata city in japan in 1956.
