Evaluation of selenium bioavailability to in representative Chinese soils based on diffusive gradients in thin-films (DGT) and chemical extraction methods.

Selenium (Se) is an essential micronutrient for humans but is toxic when consumed in excess through the food chain, such as vegetables. Therefore, it is imperative to understand the relationship between the bioavailability of Se in soil and its uptake in edible parts of vegetables. This study investigated Se bioavailability of in six representative Chinese soils treated with different concentrations of exogenous selenate fertilizer (0-2 mg·kg) by comparing diffusive gradients in thin-films (DGT) and chemical extraction methods. The correlation coefficients between the Se uptake by and soil available Se determined by different extraction methods was as follows: DGT > KCl > Water > EDTA > KHPO > NaHCO extractions. In addition, soil properties were correlated between and soil Se concentrations determined by chemical extraction methods, while the DGT method was independent of soil properties. DGT was more suitable for the measurement of Se thresholds for Udic Ferrisols, Mollisols, Stagnic Anthrosols, Fluviogenic Loamy Paddy soil, Silty Loam soil, and Calcaric Regosols with values of 373.34, 648.68, 436.29, 589.84, 295.35, and 464.95 μg·L, respectively. Thus, DGT may be an effective method for the prediction and evaluation of Se bioavailability to in different soil types.