基于梯度扩散薄膜(DGT)技术评估玉米农田土壤中铅的生物有效性及动力学过程OA北大核心CSTPCD

To verify the feasibility of diffusive gradients in thin-films(DGT)technique for accurately evaluating the bioavailability of lead(Pb)in maize farmland soils in the natural environment,and to explore the kinetic process of Pb in soils based on DGT technique,the extractable Pb concentrations in maize farmland soils in Fenghuang County,Hunan Province,China,were determined by the DGT technique,soil solution method,and single extraction methods.The linear regression analysis was then conducted between the extractable Pb concentrations and Pb concentrations in different parts of maize.The DGT technique combined with DGT induced fluxes in soils and sediments(DIFS)model was employed to simulate the kinetic process of Pb within the soils.The results revealed that the Pb concentrations for 35%soil samples were exceeded the background value of Pb in Hunan Province,while the Pb concentrations for all maize grain samples in the study area were below the standard value(GB 2762-2022).The migration and enrichment ability of Pb in different parts of maize was relatively low and Pb was mainly enriched in the roots,making it difficult to migrate to aboveground parts.The bioavailable Pb concentrations in soils determined by both DGT technique and soil solution were(1.32±2.49)µg·L-1 and(2.23±3.75)µg·L-1,respectively.The bioavailable Pb concentrations determined by diethylenetriaminepentaacetic acid(DTPA),acetic acid(HAc)and calcium chloride(CaCl2)single extraction methods in soils were(5.79±2.51)mg·kg-1,(0.81±0.49)mg·kg-1 and(0.05±0.13)mg·kg-1,respectively.DGT technique demonstrated better prediction for Pb concentrations in different maize parts compared to other methods,with the best prediction observed for Pb concentrations in maize leaves.The DIFS model simulation results indicated a relatively low supply capacity of Pb from the soil solid phase to the liquid phase for the most soil samples.However,the Pb release from the soil solid phase remained relatively stable,potentially posing ecological risks to the local environment.Overall,the DGT technique proved to be the best method for evaluating the bioavailability of Pb in maize farmland soils among all the methods,it can provide good prediction for Pb concentrations in leaves,but not good for Pb concentration in grains.DGT technique enabled to characterize the kinetic process of Pb within the soils when coupled with the DIFS model.This study provides scientific evidence for precise prevention and control of soil pollution.