两种淹水模式下施用钝化材料对镉污染农田水稻安全生产的影响

Effects of Different Amendments on Cadmium Accumulation in Rice Safety in Cadmium-Contaminated Farmland Under Two Flooding Treatments

为实现镉(Cd)污染农田稻米安全生产,以中度Cd污染农田为研究对象,通过连续2 a的大田试验,对比分析了间歇性淹水和全生育期淹水2种淹水模式下,玉石粉、生物炭和粉煤灰这3种钝化材料施用后对土壤pH,有效Cd和稻米Cd含量的影响.结果表明:(1)单一淹水处理下,全生育期淹水和间歇性淹水处理均可提高土壤pH,土壤有效Cd降低率分别为3.81%~17.27%和2.25%~6.74%,全生育期淹水处理Cd降低效果优于间歇性淹水处理,但降幅在年际间差异明显;(2)2种淹水模式下,施用3种钝化材料均可进一步提高土壤pH,并促使土壤中可交换态Cd向残渣态Cd转变,但3种钝化材料在全生育期淹水模式下的钝化效果更好.间歇性淹水模式下,配施3种钝化材料使土壤pH提高0.19~2.20个单位,土壤有效Cd降低率为4.72%~22.68%,稻米Cd降低2.60%~75.75%,降幅在材料间差异显著,表现为:玉石粉>生物炭>粉煤灰;全生育期淹水模式下,配施3种钝化材料使土壤有效Cd降低5.06%~36.63%,稻米Cd降低13.28%~77.01%,亦表现为:玉石粉>生物炭>粉煤灰;(3)2种淹水模式下,分别配施3种钝化材料,均可显著降低土壤有效Cd含量和稻米Cd含量,但其中仅以全生育期淹水配施玉石粉的组合处理能使本试验条件下的Cd中度污染农田达水稻安全生产标准.该组合处理模式下,连续2 a土壤有效Cd降低率分别达36.63%和25.16%,稻米ω(Cd)为0.058 mg·kg^(-1)(2019年)和0.170 mg·kg^(-1)(2020年),均低于国家水稻安全生产标准0.2 mg·kg^(-1),实现水稻安全生产.

Cadmium(Cd)accumulation in rice has become a serious public concern;thus,it is important to find an effective approach to reducing Cd accumulation in rice grains to ensure food safety.To investigate the effects of different amendments on Cd accumulation in rice in Cd-contaminated farmland under different flooding treatments,a field experiment with three amendments(jade powder,biochar,and fly ash)and two flooding treatments(intermittent flooding and flooding throughout the whole growth period)was conducted.The results showed that:①without amendment application,the soil pH significantly increased,whereas the soil available Cd concentration decreased by 3.81%-17.27%and 2.25%-6.74%with the treatments of flooding throughout the whole growth period and intermittent flooding,respectively.Additionally,the immobilizing efficiency of the treatment of flooding throughout the whole growth period was better than that of intermittent flooding;②under different flooding treatments,amendment application improved soil pH,resulting in a decrease in the soil available Cd concentration along with an increase in the residual Cd concentration.Under the treatment of intermittent flooding,the soil pH increased by 0.19-2.20 units,and the soil available Cd concentration and Cd concentration in rice grains decreased by 4.72%-22.68%and 2.60%-75.75%,respectively,with the application of different amendments.Under the treatment of flooding throughout the whole growth period,the application of different amendments decreased the soil available Cd concentration and Cd concentration in rice grains by 5.06%-36.63%and 13.28%-77.01%,respectively.The immobilizing efficiency in both flooding treatments was jade powder>biochar>fly ash.③Under different flooding treatments,the application of amendments significantly reduced the soil available Cd concentration and Cd concentration in rice grains.Among the three amendments,jade powder showed the best capacity of immobilizing efficiency with the treatment of flooding throughout the whole growth period;the soil Cd reduction rates were 36.63%and 25.16%,and the Cd concentrations in rice grains were 0.058 and 0.170 mg·kg^(-1) in 2019 and 2020,respectively.The Cd concentrations in rice grains were within the limitation of the National Food Hygienic Standard of China.Therefore,combining flooding throughout the whole growth period with jade powder can be considered as an ideal strategy for ensuring rice safety in Cd-contaminated farmland.