Combining multisurface model and Gouy-Chapman-Stern model to predict cadmium uptake by cabbage (Brassica Chinensis L.) in soils

Cadmium is an extremely toxic substance known to cause serious health problems. The uptake of Cd in plants is critically affected by dissolved Cd in soil porewater, controlled by soil physicochemical properties. Rhizoavailability of Cd is assumed, as the Cd fraction is found on the plasma membrane of surface root cells. Based on the theory of Cd transformation in soil-crop systems, we established a novel combined mechanistic model related to soil, soil solutions, and crops. The combined model comprises a multisurface model (MSMs; solid adsorbent and porewater) and the Gouy-Chapman-Stern model (GCS; porewater and root surface). The results suggested that in mildly contaminated soil samples, optimum prediction was achieved when DTPA-extractable Cd was used as input variable (R2 = 0.723). Our approach was superior to single-step model calculation (MSMs: R2 = 0.613; GCS: R2 = 0.629) and prediction based on extractable soil Cd (R2 = 0.281). Introducing DTPA extraction expanded the range of model applications at different soil pHs. Our proposed mechanism model was based on soil physicochemical properties for Cd migration from soil to cabbage. Our model showed promise in predicting Cd bioavailability in soil with a wide pH range and evaluating soil risk near the standard Cd safety level.

Automated summary

The research showed that optimal prediction was achieved in mildly contaminated soil samples when using DTPA-extractable Cd as the input variable. Introducing DTPA extraction expanded the range of model applications at different soil pH levels.