Comparison of DGT with traditional methods for assessing cadmium bioavailability to Brassica chinensis in different soils

There is no universally accepted method for evaluating cadmium (Cd) bioavailability in soil. The diffusive gradient in thin films (DGT) technique is a promising tool, but there is considerable debate about its suitability. The ability of this technique to estimate Cd bioavailability in soils was compared with the abilities of other traditional chemical extraction techniques (soil solution, ethylene diamine tetraacetic acid (EDTA), acetic acid (HAc), calcium chloride (CaCl2), and pseudo-total Cd methods) based on a greenhouse experiment using pakchoi (Brassica chinensis) grown in 15 soils from different provinces of China. In addition, we assessed whether these methods were independent of the soil properties. Correlations between the plant and soil Cd concentrations measured with the traditional extraction techniques were dependent on the pH and organic carbon (OC) content, indicating that these methods are influenced by the soil properties. In contrast, the DGT measurements were independent of the soil properties and showed a higher correlation coefficient compared to that of the traditional techniques. Hence, the DGT technique is better and should be preferable for assessing Cd biological effectiveness in different soil types.