Abstract
In recent years, concern has been expressed in many quarters over the level of exposure of the general population to heavy metals in the environment. An important aspect of current research is the environmental chemistry of metals. The chemistry and the mode of introduction of pollutant metal into the environment are in general so different from those affecting natural deposits of metals that the classic geochemical knowledge of metal behaviour has proved largely inapplicable to the atmospheric and aqueous chemistry of pollutant metal. Hence new lines of research into the chemical identity (or 'speciation') and chemical pathways of heavy metals in the environment have flourished. Such information is extremely valuable since the metal speciation profoundly affects not only the chemical and physical behaviour, and hence mobility of the metal in the environment, but also the toxicity to man and other organisms.