The suitability of 8 common soil extractants to predict plant uptake of
cadmium (Cd) from 10 New Zealand soils at low Cd concentrations was
investigated in a glasshouse experiment. In addition, a study of Cd uptake by
several vegetable, cereal, and pasture species in relation to different soil
types was undertaken. The concentrations of Cd extracted from soils varied
with each extractant: 0·05 acid ammonium acetate-EDTA (pH 4·65)
extracted the greatest concentration of Cd, whereas 0·01
CaCl2 extracted the least. Results indicate that for all
extractants tested, there were significant relationships between the
concentration of Cd extracted and the concentration of Cd in plant material;
however, the level of significance depended on the plant species and
individual soil extractant. When all plants were considered together, it was
found that 0·05 Ca(NO3)2
was the best predictor of plant Cd concentrations. Total Cd concentration was
found to be the most important soil parameter influencing plant Cd
concentrations. Plant Cd concentrations varied greatly among different plant
species. The greatest uptake was found in lettuce and to a lesser extent
carrot tops, and least in ryegrass, clover, and barley. All plants examined
were within the maximum residue limit (MRL) in New Zealand for the Cd content
of all foodstuffs intended for human consumption (i.e. 1 mg Cd/kg fresh
weight).
Comparative plant uptake and microbial degradation of trichloroethylene in the rhizospheres of five plant species-- implications for bioremediation of contaminated surface soils
