薄膜扩散梯度技术评价土壤砷生物有效性研究

Assessment of Diffusion Gradients in Thin Films Technique for Measurement of the Arsenic Bioavailability in Soils

【目的】探讨薄膜扩散梯度技术(Diffusive Gradients in Thin Films Technique,DGT)在表征土壤砷生物有效性方面的准确性与优势,为正确评价土壤砷污染风险提供新技术。【方法】采用盆栽试验研究DGT方法测定土壤砷有效浓度(CE)、土壤孔隙水中砷含量、NaHCO3提取态砷含量、NH4Cl提取态砷含量及土壤总砷含量与油菜体内吸收砷量之间的关系,并初步尝试利用DGT测定结果和DIFS(DGT Induced Fluxes in Sediments andSoils)模型对土壤中砷的迁移过程进行模拟。【结果】DGT测定土壤砷有效浓度(CE)与植物吸收砷量之间均存在极显著相关关系,决定系数(R2)为0.990,DIFS模型模拟结果表明砷生物有效性高的土壤,具有较高的解析速率(kb)和较短的特征响应时间(Tc)。【结论】DGT能较准确地表征土壤砷生物有效性,并可根据DIFS模型计算出土壤中砷迁移动力学参数,有助于进一步阐释土壤中砷的生物有效性。

【Objective】This study was conducted to evaluate the feasibility and accuracy of bioavailable arsenic（As） measurement in soils using DGT（Diffusive Gradients in Thin Films Technique） and in further to shed light on the risk evaluation of As-contaminated soils.【Method】 A pot experiment was used to study the relationship between rape As in rape（Brassica campestris） and the effective concentration（CE） by DGT,soil solution As,NaHCO3-extracted As,NH4Cl-extracted As,and total soil As.Furthermore,the kinetic process of As transporting in soils was simulated using DIFS（DGT Induced Fluxes in Sediments and Soils） model and DGT data.【Result】A significant correlation between As contants in rape（B.campestris） and CE in soils was obtained with the coefficient determination（R2） of 0.990,and the results of DIFS model indicated that the shorter response time（Tc） and a higher desorption rate constants（kb） were both observed in the soils with a greater As bioavailibility.【Conclusion】 DGT was a reliable and an effective method for pre-concentration of bioavailable As and helped to elucidate the bioavailable process of As in soils on conjugation with the resupply parameters from DIFS model.