Heavy Metals, Major Metals, Trace Elements

MARCOVECCHIO, J.E.; BOTTÉ, S.E.; DOMINI, CLAUDIA; FREIJE, R.H.

Handbook of Water Analysis

CRC Press Taylor & Francis Group

Lugar: Boca Ratón; Año: 2013; p. 385 - 434

The term heavy metal includes both essential and nonessential trace metals, which may be toxic to the organisms depending on their own properties, availability (chemical speciation), and concentration levels. Heavy metals (Ag, As, Cd, Cu, Cr, Hg, Ni, Pb, Zn) can be present in the aquatic system in both dissolved forms (which can cause toxic effects on a wide diversity of organisms, including vertebrates) and particulated ones (including adsorbed on sediments, suspended particulate matter or colloids, in transitional complexes, and Fe/Mn hydroxides nets, linked to organic matter and carbonates, etc). The dynamics which regulates the transference of heavy metals between the dissolved and the particulated phases (in both senses) depends on the pH and oxide-reduction potential of the system. Also these parameters regulate the chemical speciation of heavy metals within the system. It has been largely recognized that heavy metal concentrations are much higher in urban or industrial areas than in wild ones [1?3]. Consequently the possibility of incorporation of heavy metals into drinking water or trophic webs exits, and so the potentially generation of deleterious effects on human populations [4?6]. Moreover the toxicity of heavy metals can be significantly increased due to synergistic effects within natural systems. In addition, and considering the average long-life of these elements, their persistence and potential transformation to more toxic compounds must be addressed.