SREL Reprint #2655

Role of phosphorus in (Im)mobilization and bioavailability of heavy metals in the soil-plant system

Nanthi S. Bolan1, Domy C. Adriano2, and Ravi Naidu3

1Soil & Earth Science Group, Massey University, Palmerston North, New Zealand
2University of Georgia, Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802, USA
3CSIRO Land and Water, Adelaide, South Australia 5064

Introduction:
The term heavy metal in general includes elements (both metals and metalloids) with an atomic density greater than 6 g cm-3 [with the exception of arsenic (As), boron (B), and selenium (Se)]. This group includes both biologically essential [e.g., cobalt (Co), copper (Co), chromium (Cr), manganese (Mn), and zinc (Zn)] and nonessential [e.g., cadmium (Cd), lead (Pb), and mercury (Hg)] elements. The essential elements (for plant, animal, or human nutrition) are required in low concentrations and hence are known as trace elements or micronutrients. The nonessential metals are phytotoxic and/or zootoxic and are widely known as toxic elements (Adriano 2001). Both groups are toxic to plants, animals, and humans at exorbitant concentrations (Adriano 2001; Alloway 1990). Consequently, metals are extensively researched in the life, agricultural, and environmental sciences. Among the metals, Cd, Cr, Cu, Hg, Pb, and Zn have been intensively studied. Other metals, such as silver (Ag) and tin (Sn), are important especially in the mining environment and around industries that process ores containing these metals (Table 1).
Health authorities in many parts of the world are becoming increasingly concemed about the effects of heavy metals on environmental and human health and the potential implications to international trade. For example, Cd accumulating in the offal (mainly kidney and liver) of grazing animals not only makes it unsuitable for human consumption but also imperils the access of offal products to overseas markets (Bramley 1990; Roberts et al. 1994). Similarly, bioaccumulation of Cd in potato, wheat, and rice crops has serious implications for local and international commodity marketing. For these reasons, there is global urgency to ensure that the heavy metal content of foodstuffs produced complies with regulatory standards and compares well with those from other countries. Effective action in the long term will depend on gaining an understanding of the causes of heavy metal accumulation and a proper appreciation of these issues
for public health. . . .

SREL Reprint #2655

Bolan, N. S., D. C. Adriano and R. Naidu. 2003. Role of phosphorus in (Im)mobilization and bioavailability of heavy metals in the soil-plant system. Rev Environmental Contamination Toxicology 177:1-44.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).