ABSTRACT
Some metals are required for algal metabolism and physiology as macroele ments (K, Mg) or microelements (Co, Cu, Fe, Mn, Mo, Ni, V, Zn), and must be obtained from the external environment. However, the essential elements, such as Cu, Mn, Ni, and Zn, can be toxic at high concentrations. Other metals, such as Cd, Hb, Pb, have no known biological function and are always toxic. The term “ heavy metals,” used by ecologists, generally refers to the elements possessing a density greater than 6 g/cm3 and connotations of toxicity, e.g., Ag, As, Cd, Cu, Hg, Mn, Ni, Pb, and Zn (1). As reported in several reviews (2-8), all of these and related metals as well as metalloids may be accumulated in algae and have an impact on them.
