不同安全利用技术对琼北地区稻菜轮作系统镉削减的效果

Effects of different safe utilization technologies on cadmium reduction in rice-vegetable rotation system in northern Hainan,China

为探讨不同安全利用技术在海南镉污染耕地上的应用效果,以琼北地区轻中度镉污染稻菜轮作耕地为研究对象,比较了6种安全利用技术对辣椒和稻米中Cd积累的削减效果,以及9种钝化剂对稻米Cd积累的影响。结果表明,各项安全利用技术的降Cd效果由高到低依次为优化施肥+土壤调理+叶面阻控>土壤调理+叶面阻控>优化施肥+叶面阻控>土壤调理>叶面阻控>优化施肥,在辣椒和稻米上的降Cd率分别为61.6%~91.5%、49.4%~91.3%,6项安全利用措施下辣椒Cd暴露的膳食安全风险均可接受,但仅优化施肥+土壤调理+叶面阻控和土壤调理+叶面阻控处理下稻米Cd暴露的膳食安全风险在可接受范围内。施用9种钝化剂均可显著(P<0.05)降低稻米Cd含量,但降Cd率差别较大,变化范围在29.7%~77.0%。其中,生物炭和磷复合钝化剂(生物炭+磷矿粉、生物炭+活化磷矿粉)、蚯蚓粪和铁磷复合钝化剂(蚯蚓粪+零价铁+磷矿粉)的施用效果最佳,稻米降Cd率在68%以上。针对海南轻中度镉污染耕地,宜采用优化施肥+土壤调理+叶面阻控和土壤调理+叶面阻控的联合措施,其中土壤调理技术中的钝化剂推荐使用生物炭和磷复合钝化剂或蚯蚓粪和铁磷复合钝化剂。

In order to evaluate the effects of safe utilization technologies on Cd-contaminated farmland in Hainan,rice-vegetable rotation system in northern Hainan with light to moderate Cd pollution was selected as the study object.The effects of 6 safe utilization technologies on Cd reduction in pepper and rice,and the effects of 9 passivators on Cd accumulation in rice were compared.The results showed that the Cd reduction effects of various safe utilization technologies decreased in the order of optimal fertilization+soil conditioning+foliage resistance>soil conditioning+foliage resistance>optimal fertilization+foliage resistance>soil conditioning>foliage resistance>optimal fertilization,and the Cd reduction rates in pepper and rice were 61.6%-91.5%,49.4%-91.3%,respectively.All these technologies reduced health risk of Cd-intake by pepper to an acceptable range,but only optimal fertilization+soil conditioning+foliage resistance and soil conditioning+foliage resistance reduced the health risk of Cd-intake by rice to an acceptable range.Applying passivators could significantly(P<0.05)reduce Cd content in rice,but the Cd reduction rates varied from 29.7%to 77.0%.Among them,biochar and phosphorus combined passivator(biochar+phosphate rock powder,biochar+activated phosphate rock powder),vermicompost and iron phosphorus combined passivator(vermicompost+zero-valent iron+phosphate rock powder)had better effect,and the Cd reduction rate of rice was higher than 68%.In conclusion,optimal fertilization+soil conditioning+foliage resistance,soil conditioning+foliage resistance were feasible for the safe utilization of Cd-contaminated farmland in Hainan,and biochar and phosphorus combined passivator,and vermicompost and iron phosphorus combined passivator were recommended passivators for soil conditioning.