铁基生物炭钝化Cd大田试验研究

Cadmium Immobilization by Iron-based Biochar:A Field Study

近年来,稻田Cd污染引起的环境及健康问题日益突出。应用钝化技术对土壤中有效性Cd进行钝化对稻田生态系统中Cd的生物地球化学循环具有重要的理论和实际意义。在广东省韶关市仁化县董塘镇红星村一受Cd污染的稻田上,设置大田试验,研究铁基生物炭对Cd在大田土壤-水稻系统迁移的影响以及对作物产量的影响。试验共设6个处理:(1)空白对照;(2)每一季水稻插秧前,一次性施加1500 kg·hm^(-2)的普通生物炭;(3)每一季水稻插秧前,一次性施加75 kg·hm^(-2)的零价铁(Fe0);(4)每一季水稻插秧前,一次性施加1500 kg·hm^(-2)、ω(Fe)=1%的铁基生物炭(ω(Fe)=1%in Fe-Biochar);(5)每一季水稻插秧前,一次性施加1500 kg·hm^(-2)、ω(Fe)=3%的铁基生物炭(ω(Fe)=3%in Fe-Biochar);(6)每一季水稻插秧前,一次性施加1500 kg·hm^(-2)、ω(Fe)=5%的铁基生物炭(ω(Fe)=5%in Fe-Biochar)。结果表明:(1)施用生物炭、铁粉和铁基生物炭土壤钝化调理剂可以增加水稻产量,显著降低籽粒重金属Cd含量;(2)施用铁基生物炭可以显著增加水稻根表铁膜Fe含量,同时显著增加水稻根表铁膜固定的Cd量,抑制重金属Cd向籽粒的运输累积。综合考虑施用成本和钝化效果,对于Cd污染稻田,建议施用1500 kg·hm^(-2)、ω(Fe)=3%的铁基生物炭材料。

The environmental health problems induced by cadmium(Cd)pollution in paddy soil become more and more serious.Immobilization of available Cd in soil has important theoretical and practical significance to the biogeochemical cycles of Cd in paddy ecosystem.To study the impact of iron-based biochar on Cd migration and crop yield in the soil-rice system,a field experiment was performed on Cd contaminated paddy soil in Dongtang Town,Renhua County,Shaoguan City,Guangdong Province.Six treatment groups were set up in the experiment:(1)Control group;(2)Amendment with 1500 kg·hm−2 common biochar before rice transplanting in every season;(3)Amendment with 75 kg·hm^(−2) zero-valent iron(Fe0);(4)Amendment with 1500 kg·hm−2 iron-based biochar(ω(Fe)=1%in Fe-Biochar);(5)Amendment with 1500 kg·hm^(−2) iron-based biochar(ω(Fe)=3%in Fe-Biochar);And(6)amendment with 1500 kg·hm^(−2) iron-based biochar(ω(Fe)=5%in Fe-Biochar).The results indicated that all the soil amendments including biochar,zero-valent iron,and iron-based biochar increased the rice yield and reduced Cd content in grain.In addition,iron-based biochar amendment significantly increased the Fe content on root iron plaque of the rice,which further enhanced the Cd fixation by the root iron plaque and inhibited the transport of Cd to grains.Considering the cost and passivation performance,1500 kg·hm^(−2) iron-based biochar(ω(Fe)=3%)was recommended to amend Cd contaminated paddy soil.