Sigel A., Sigel H., Sigel R.K.O. (Eds.) Cadmium: From Toxicity to Essentiality

Dordrecht: Springer Science + Business Media, 2013. — 589 p. — (Metal Ions in Life Sciences 11).Chapter 1, devoted to the bioinorganic chemistry of cadmium(II), sets the scene for Volume 11, which covers the whole range from toxicity to essentiality of this element.
Of biological relevance is its high affinity for sulfur sites, which means, e.g., that in metallothionein with ZnS4 units, Cd2+ concentrations need to be only one thousandth of those of Zn2+ for an effective competition. Indeed, Cd2+ is toxic to almost all forms of life and therefore the understanding of its biogeochemical cycling and release into the environment is of high relevance as is pointed out in Chapter 2.
Cadmium is released to the environment through natural and anthropogenic sources.
In Chapter 3 an effort is made to quantify the speciation of cadmium in the atmosphere, in marine and fresh waters as well as in soils and sediments.
The behavior of cadmium is assessed by modeling its reactivity towards the main classes of ligands usually present in natural systems, like chloride, carbonate, sulfate, carboxylates, amines, amino acids, phosph(on)ates or thiols.
Chapters 4-16 describes physical analytical methods for cadmium, complex formation of Cd2+ in aqueous solution and chemistry of proteins containing Cd2+, as well the toxicity of Cd2+ for plants.
The only known biological function of Cd2+ is to serve as a metal ion cofactor in cadmium-carbonic anhydrase (CDCA) in diatoms.
The expression of CDCA is regulated by the availabilities of Cd2+ and Zn2+; both Zn2+ and Cd2+ can be used as the metal ion cofactor and be exchanged for each other in certain marine phytoplankton species.