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Differences in metal uptake between plant species and soil types were compared to assess the safe use of mildly contaminated soils for the growth of edible food crops. Accumulation of metals in five plant species grown in each of three field soils and a commercial soil were evaluated in a controlled environment room. Metal bioavailability varied more with plant species than with type of soil. Among a number of physical and chemical soil properties that were determined, high metal content and low percent organic matter were the best predictors of increased metal bioavailability. Contamination levels of metals measured in soil and vegetable samples were used to calculate bioconcentration factors and hazard quotients. The results indicated significant differences between plant species. The most metal-accumulating species was carrot and the most mobile element was cadmium. Some hazard quotients exceeded the threshold value of 1, even in soils considered uncontaminated by current guidelines. Overall, these results reinforce the need to include soil characteristics when setting threshold guidelines for metal content of agricultural soils and indicate the need for species-specific planting guidelines.
The final publication is available here: http://dx.doi.org/10.1139/B09-019