田间施用锌肥对小麦籽粒镉累积的影响及施用风险

Effect of Zinc Fertilizer Application on Cadmium Accumulation in Wheat Grain and Its Application Risk

锌(Zn)和镉(Cd)的交互作用是近年来小麦Cd污染防治的重要研究方向.以华北地区典型小麦田为研究对象,通过田间试验,探究Zn肥对土壤-小麦系统Cd污染的控制效果和施用风险.结果表明,低用量Zn处理下,济源和开封两地小麦籽粒Cd含量均呈下降趋势,与对照相比下降幅度分别为33.4%和25.3%.高用量Zn处理下,两地小麦籽粒Cd含量不降反升,与低用量Zn处理下小麦籽粒Cd含量相比增幅为22.4%和34.2%.施Zn后两地土壤Zn总量和有效态含量均有显著升高,且造成了土壤Cd的部分活化.典型相关分析(CCA)显示,当土壤ω(Zn)小于200 mg·kg^(-1)时,土壤Zn是土壤-小麦系统Cd富集的主要影响因子,而当土壤ω(Zn)大于200 mg·kg^(-1)时,土壤Cd的活化是影响小麦籽粒Cd富集的主要原因.回归分析显示土壤Cd/Zn降至0.008 9时(低用量Zn),Zn和Cd表现出拮抗效应,土壤Cd/Zn降至0.007 8时(高用量Zn),Zn和Cd表现出协同效应.针对区域Cd污染特征,调整Zn肥用量可以提高污染防治效率并避免加剧Cd污染危害.

The interaction of zinc(Zn) and cadmium(Cd) is an important research direction in the prevention and control of Cd pollution of wheat in recent years.In this study,a typical wheat field in North China was selected as the object to explore the control effect and application risk of Zn fertilizer on Cd pollution in a soil-wheat system through field experiments.The results showed that under the treatment of a low dosage of Zn,the Cd concentrations in wheat grains in Jiyuan City and Kaifeng City decreased by 33.4% and 25.3% compared with those in the control,respectively.By contrast,Cd concentrations in wheat grains treated with a high dosage of Zn increased by 22.4% and 34.2% compared with that of the low-dosage Zn treatment.After the application of Zn,the total amount and available Zn concentrations increased significantly,and Cd was partially activated in these two locations.Canonical correlation analysis(CCA) showed that when the Zn concentrations in the soils were less than 200 mg·kg^(-1),soil Zn was the main factor affecting Cd accumulation in the soil-wheat system,whereas when Zn concentrations in soils were greater than 200 mg·kg^(-1),the activation of soil Cd was the main factor affecting Cd accumulation in wheat grains.Regression analysis showed that when the soil Cd/Zn ratio decreased to 0.008 9(low dosage of Zn),Zn and Cd showed an antagonistic effect,whereas when the soil Cd/Zn ratio decreased to 0.007 8(high dosage of Zn),Zn and Cd showed a synergistic effect.According to the characteristics of regional Cd pollution,adjusting the amount of Zn fertilizer can improve the efficiency of pollution control and avoid aggravating the harm of Cd pollution.