重金属复合污染对茶叶重金属、主要生化成分含量及冲泡茶汤浸出率的影响研究

通过土壤盆栽实验,研究四种重金属As、Pb、Cr、Cd复合污染对茶叶重金属含量及主要生化成分含量的影响,同时研究了不同冲泡次数下茶汤中四种重金属的浸出率。结果表明:复合污染条件下,茶叶中重金属积累量显著高于对照,其高低顺序为Pb>Cr>Cd>As,其中,Cd在盆栽土壤中的添加量低于As,但在茶叶中的积累量高于Cd,表明Cd在茶树体内的迁移率高于As。复合污染茶叶中的氨基酸和咖啡碱含量均低于对照,酚氨比值高于对照,从而降低了茶叶品质。四种重金属元素在茶汤中的浸出量均随着冲泡次数的增加而减少,Cd、Cr、Pb和As的总浸出率分别为:18.0%~35.7%、14.8%~26.8%、15.4%~31.9%和13.7%~22.1%,Pb和Cd的浸出率大于Cr和As;四种重金属元素之间的络合作用,会影响重金属在茶叶中的累积量和茶汤中的浸出量。 

Effects of compound pollution of 4 heavy metals on components of heavy metals and main biochemical composition and diffusion rate in tea

Pot experiments were conducted to study the compound effects of As,Pb,Cr and Cd on the heavy mental content,the components of main biochemical composition and diffusion rate of different brewing times in tea when tea plants were grown in the soil.The results showed that under the conditions of compound pollution,the accumulation of heavy metals in tea,which the order of content was Pb > Cr > Cd > As,were significantly higher than the comparison( p < 0.05).Consistently,Cd had higher mobility rate compared with As,as indicated by Cd had lower added level but higher accumulation than As. Importantly,compound pollution declined the quality of tea,because amino acids and caffeine contents were lower than the comparison and the ratio of polyphenol and amino acids was higher than the comparison.Furthermore,the leaching amount of four kinds of heavy metals were reduced with the increase of brewing times and numbers of total leaching rate of Cd,Cr,Pb and As were 18.0% ~35.7%,14.8% ~26.8%,15.4% ~31.9% and 13.7% ~22.1%,respectively.In summary,the leaching rate of Pb and Cd,were higher than Cr and As,and the amount of heavy metals accumulated in tea and leached in water were also influenced by the complex effects among the four kinds of heavy metals.