Heavy Metals, Major Metals, Trace Elements

JORGE MARCOVECCHIO; SANDRA BOTTE; CLAUDIA DOMINI; HUGO FREIJE,

Handbook of Water Analysis, 3rd edition

CRC Press, Taylor & Francis Group LCC

Lugar: Boca Raton, Florida; Año: 2013; p. 385 - 433

The contamination of natural waters is a worldwide distributed problem which deserves large attention not only due to its environmental hazardous effects but also for the risks involved to human health as well as economic damages it produces. Between the wide diversity of pollutants affecting water resources, heavy metals receive particular concern considering their strong toxicity even at low concentrations. The occurrence of heavy metals in water bodies can be of natural origin (i.e., eroded minerals within sediments, leaching of ore deposits, and vulcanism extruded products) or anthropogenic in nature (i.e., solid waste disposal, industrial or domestic effluents, harbor channels dredging). 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.