ABSTRACT
In the literature the term “heavy metal” is used with a very broad and misleading meaning but in a strictsenseitincludesagroupofmetalswithdensityhigherthan5.0gcm−3 and an atomic weight above20.Actually,thereisastrongtendencytoclassifymetalsaccordingtotheirpropensityto interactwithbiologicalligands,whichlargelydenestheirtoxicity.Thischapterspeaksofheavy metals as metals and metalloids that are toxic to plants.
