土壤调理剂联合芽孢杆菌施用对水稻吸收镉砷的影响

Effects of Soil Amendment Combined with Bacillus subtilis Application on Cadmium and Arsenic Uptake by Rice

矿区农田重金属污染严重影响生态环境质量和农产品安全,重金属污染治理修复研究是矿区农田土壤安全利用的前提.为探究不同土壤调理剂联合芽孢杆菌施用对矿区土壤镉(Cd)和砷(As)的修复效果,采用田间小区试验的方法,设置对照处理(CK)、单一/复合施用芽孢杆菌(J)以及两种土壤调理剂(氧化钙镁肥,D1;硅钙镁钾肥,D2)共8个处理(CK、J、D1、D2、J+D1、J+D2、D1+D2和J+D1+D2),分析不同处理对土壤化学性质、土壤有效态Cd和As含量、水稻产量以及水稻各部分Cd和As含量的影响.结果表明:①除菌剂外,单一/复合施用两种土壤调理剂能提高土壤pH,对比CK处理,其余处理组均能提高阳离子交换量(CEC)、有效磷(AvP)含量和有效硅(Si)含量.②单一/复合施用土壤调理剂和菌剂均同时降低了土壤有效态Cd和As含量,二者降幅分别为5.46%~47.53%和5.32%~25.49%,同时有效态Cd和As含量的降幅以D1+D2处理最大,D2处理次之,菌剂(J)单独施用的降幅最小.③D2、J+D1、J+D2、D1+D2和J+D1+D2这5种处理均能显著降低糙米和精米中Cd的含量,J处理和J+D1+D2处理均能显著降低精米As含量,达到《食品安全国家标准食品中污染物限量》(GB 2762−2022)中的食品安全生产标准.④试验材料主要通过改变土壤pH、CEC和有效Si含量来影响土壤Cd和As的生物有效性,以及水稻对Cd和As的吸收和转运.研究显示,硅钙镁钾肥(D2处理)无论单施还是联合施用均能显著降低糙米Cd含量,达到《食品安全国家标准食品中污染物限量》(GB 2762−2022)中的食品安全标准,但其对糙米As含量无显著影响,因此硅钙镁钾肥可为单一Cd污染土壤的水稻安全生产提供有效的解决途径.

Heavy metal pollution in farmland in mining areas seriously affects the ecological and environmental quality and the safety of agricultural products.Conducting research on the remediation and restoration of farmland soil contaminated with cadmium(Cd)and arsenic(As)has become a prerequisite for the safe utilization of farmland soil in these areas.In order to explore the remediation effects of different soil amendments in combination with Bacillus subtilis on the remediation of Cd and As in mining areas,a field plot experiment was conducted,including CK treatment and single or combined application of Bacillus subtilis(J)and two soil amendment(oxycalcium�magnesium amendment,D1;Si-Ca-Mg-K amendment,D2),with a total of 8 treatments(CK,J,D1,D2,J+D1,D1+D2,D1+D2,and J+D2).The effects of different treatments on soil chemical properties,soil available Cd and As content,rice yield,and Cd and As content in various parts of rice were studied.The results showed that:(1)Apart from Bacillus subtilis,single or combined application of two soil amendments could increase the soil pH.Single or combined application of soil amendment with the Bacillus subtilis could increase the cation exchange capacity(CEC)and available phosphorus(AvP)and available silicon.(2)Single or combined application of soil amendment and Bacillus could reduce the available Cd and As contents in soil from 5.46%to 47.53%and from 5.32%to 25.49%,respectively.The greatest reduction in available Cd and As was achieved by the D1+D2 treatment,followed by the D2 treatment,while the Bacillus(J)alone had the least effect.(3)Single application of D2 treatment or combined application of soil amendment with Bacillus(J+D1,J+D2,D1+D2 and J+D1+D2)could significantly reduce the Cd content in brown rice and polished rice.Single application of Bacillus(J)and the combined application of all three materials(J+D1+D2)could significantly reduce the As content in polished rice,reaching the food safety production standard in the National Standard for Food Safety Limit of Pollutants in Food(GB 2762-2022).(4)The remediation test materials in the experiments mainly affected the availability of soil Cd/As and the absorption and transportation of Cd and As in rice by changing the soil pH,CEC and available silicon content.The results of research show that both single and combined application of Si-Ca-Mg-K amendment(D2)can significantly reduce the Cd content in brown rice and meet the national food safety standards.However,it has no significant impact on the As content in brown rice,reaching the food safety standard in the National Standard for Food Safety Limit of Pollutants in Food(GB 2762-2022).Therefore,Si-Ca-Mg-K amendment can provide an effective solution for the safe production of rice in soil polluted by a single Cd.