Prediction of Zinc and Cadmium Phytoavailability Within a Contaminated Agricultural Site using DGT

Environmental Context. In some agricultural areas, soils are contaminated by trace elements. This contamination of cultivated soils may constitute a serious problem for human health through the accumulation of metals in the edible parts of crops. In order to assess the risk for human health associated with metal contamination of soil, we need to develop simple tools like Diffusive Gradients in Thin Films (DGT) for predicting crop metal accumulation. The present study focuses on an agricultural site contaminated with fallout from industrial dust and reveals that DGT could be a predictive tool of zinc accumulation in lettuce.

Abstract. Risk assessment of metal contamination in cultivated soils needs to address metal phytoavailability. The technique of diffusive gradients in thin films (DGT) has been shown to be a promising tool to assess metal phytoavailability in a wide range of soils. The present study has examined the ability of the DGT method to predict metal phytoavailability within a contaminated agricultural site. Lettuce (Lactuva sativa cv Appia) was grown in nine metal-contaminated soils differing mainly by their pH. Metal concentrations (Zn, Cd) in plant shoots were compared with total soil metal concentrations and free ion metal concentrations in soil pore waters, and effective concentrations, C_E, measured by DGT. Plant Zn concentrations were highly related to C_E, suggesting DGT can be a sensitive tool able to assess Zn phytoavailability within mildly contaminated agricultural soils. Plant Cd concentrations were less closely related to C_E, signifying that processes other than Cd re-supply from the solid phase may occur during soil–plant transfer of Cd.