茶园土壤-茶树-茶叶-茶汤中镉转移规律及安全性评价

为论证镉污染土壤种植茶树的安全性与可行性,通过盆钵茶园试验研究了湖南9个主栽茶树品种在不同镉含量土壤中对镉的吸收积累特性和茶汤中镉元素的浸出率。结果表明,在pH值4.1的土壤中,通过根系吸收的镉元素从根系到主干,再到侧枝枝干和茶树叶片的转运过程中,各器官的镉含量依次递减,茶树嫩芽(叶)中镉的富集系数仅0.13~0.24;茶树种植在土壤镉含量低于3.0 mg/kg的土壤中,茶叶没有出现镉超标现象;镉元素在茶汤中的平均浸出率为9.87%,利用膳食暴露风险评估模型对茶叶和茶汤中的镉含量进行风险评估,表明供试茶叶样品中的镉不会对人体健康产生威胁。

Transfer Rule and Safety Evaluation of Cadmium in Tea Garden Soil and Tea Tree and Tea Leaf and Tea Liquor

In order to demonstrate the safety and feasibility of planting tea trees in cadmium polluted soil,the absorption and accumulation characteristics of cadmium and the leaching rate of cadmium in tea liquor of nine main tea varieties in Hunan Province were studied by pot tea garden experiment.The results showed that:in the pH 4.1 soil,the cadmium absorbed by the roots decreased from the roots to the trunk,then to the lateral branches and leaves,and the cadmium concentration coefficient of tea shoots(leaves)was only 0.13~0.24,when tea trees were planted in the soil with the cadmium content lower than 3.0 mg/kg,the cadmium content of tea did not exceed the standard.The tea brewing experiment showed that the average leaching rate of cadmium in tea liquor was 9.87,and the risk assessment model of dietary exposure was used to assess the cadmium content in tea and tea liquor,which showed that the cadmium in tea samples did not pose a threat to human health.