Abstract

A sequential extraction procedure was used to fractionate Pb and Zn in highly contaminated soils in New South Wales into the conceptual metal pools; exchangeable; carbonate bound; bound organically; bound in Fe-Mn oxides; and residual. The fractionation of Pb and Zn were different with the results indicating that the majority of Pb (61.83 ± 21.59 %) is associated with the carbonate bound pool, and the majority of Zn (36.82 ± 36.03) is associated with the Fe-Mn oxide bound fraction. These pools and basic soil properties such as pH organic carbon and clay content were related to the amounts of Pb and Zn taken up by Canola (Brassica napola) in a pot trial grown on the same soils. From these correlations, simple one variable linear and multiple stepwise models with log normalised data were developed to predict the Pb and Zn concentrations within the Canola plants in a controlled environment. These were then used to predict metal contents in plants that are grown in the “natural” environment. These models were highly successful in predicting metal uptake in Canola in a controlled environment (R² =0.93), and moderately successful in predicting natural plant Pb concentrations (R²= 0.64). Zinc on other hand was highly predictable in Canola in a controlled environment (R² =0.93) but could not be not significantly modelled under natural conditions.