The effect of soil moisture content on their availability of metals to DGT and plants

摘要

The supply of metals to both plants and a DGT (diffusive gradients in thin-films) device is affected by their concentrations in the soil solution, the pool of readily available metal in the solid phase and, via the diffusive transport, the porosity and tortuosity of the soil. A systematic set of experiments have been undertaken to investigate how the moisture content of three different soils affects the concentration of metal in the roots and shoots of wheat, lettuce and cress, the concentration in the extracted soil solution and the concentration interpreted from the DGT measurement. The moisture content only affected the concentrations measured by DGT and in soil solution for the redox sensitive metals Co, Mn and Fe. The dependency of metals in plants on moisture content generally reflected the DGT and soil solution measurements. Growing plants on the soil with lowest pH released metals to the porewater, but appeared to diminish the pool available to DGT from the solid phase.