ABSTRACT
This chapter discusses background concentrations of heavy metals in Australian and New Zealand soils and crops, sources of contamination, their environmental impact, some amelioration strategies especially in relation to farm management practices, and regulatory controls. Background values are often used to determine if a soil has become enriched with an undesirable substance; such soils with values exceeding the local normal background values are then deemed “contaminated.” The global perspective of increasing accumulation of heavy metals should stimulate our efforts to control emissions and disposal, and to rehabilitate contaminated land. The main anthropogenic sources of emission for heavy metals are from smelters and urban sources such as coal and refuse combustion. The heavy metal content of the processed sewage becomes trapped in the solid phase of sewage sludge during treatment; the liquid effluents are relatively metal free.
