【摘要】 为筛选出适宜镉砷污染土壤的复合钝化剂,采用D-最优混料设计方法,研究铁改性生物炭、酸改性海泡石和酸改性蛭石钝化土壤Cd和As的最优复配配方。结果表明:经FeCl3改性后的生物炭对As的吸附能力增加,对Cd的吸附能力降低;经酸改性后的海泡石和蛭石对Cd的吸附能力不变,对As的吸附能力增强。铁改性生物炭、酸改性海泡石和酸改性蛭石复配能有效降低土壤有效态Cd和As含量,活性态Cd主要向残渣态转化,活性态As主要向有机结合态和残渣态转化,Cd和As生物有效性降低。采用Design Expert统计软件分析数据,通过建立回归方程及多目标优化分析,获得复配钝化剂的配比为铁改性生物炭26.97%、酸改性海泡石23.49%和酸改性蛭石49.54%,经验证实验,施用优化配方后的土壤有效态Cd和As含量分别为0.97 mg·kg-1和0.26 mg·kg-1,与预测值接近。研究表明,铁改性生物炭、酸改性海泡石和酸改性蛭石复配能有效降低土壤Cd和As的生物有效性。更多还原

【Abstract】 To select suitable amendments for soil polluted with cadmium and arsenic, the D-optimal mixture design method was used to find an optimum formula of modified biochar, sepiolite, and vermiculite for cadmium and arsenic stabilization. Compared to biochar, the capacity of FeCl3-modified biochar to absorb As increased but decreased for Cd. Compared to sepiolite or vermiculite, the capacity of acidmodified sepiolite or vermiculite to absorb As increased but remained unchanged for Cd. FeCl3-modified biochar combined with acid-modified sepiolite and acid-modified vermiculite could effectively reduce the content of Cd and As available in soil. The available Cd was transformed into a residual form whereas the available As was transformed into organic matter and residual forms. The statistical software Design Expert was used to analyze the data and a regression model was established for the available Cd and As parameters. Based on a complete consideration of these parameters, an optimal amendment formulation was found consisting of 26.97% FeCl3-modified biochar, 23.49% acid-modified sepiolite, and 49.54% acid-modified vermiculite. When added amendments with the optimized formulation, the actual available Cd and As of soil were 0.97 mg·kg-1 and 0.26 mg·kg-1, respectively, which closely approximated their predicted counterparts. The results indicated that the combination of FeCl3-modified biochar and acid-modified sepiolite and vermiculite could effectively reduce the bioavailability of Cd and As in soil.更多还原