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.