Prediction of Cd in vegetables and soil Cd threshold derivation based on transfer function.

Abstract

The construction of transfer function of cadmium (Cd) in the soil-vegetable system is important for risk management. This study investigated the Cd concentration in 745 paired soils and vegetable samples, aiming to determine the influences of major soil properties on uptake of Cd by vegetables, and to derive the soil Cd threshold for vegetable cultivation based on China foodstuff regulations. Results of species sensitivity distribution model showed that the Cd accumulation potential of leafy vegetables was greater than that of rootstalk vegetables. Stepwise multiple regression analysis showed soil total Cd, pH, and soil organic matter (SOM) were major factors contributing to Cd accumulation in vegetables. The derived transfer function explained 54.2% and 69.1% of the variance for the accumulation of Cd in leafy and rootstalk vegetables, respectively. The derived soil threshold increased with soil pH and SOM contents. The rootstalk vegetables were potentially hazardous when grown in strong acidic areas. For soils in the southern China with excessive acidic nature and low SOM contents, the soil Cd limits for vegetables cultivation might be over-estimated.