茶园土壤中铅形态分布与茶叶中铅质量分数关系的研究

RELATIONSHIP BETWEEN Pb CONTENT IN TEA LEAVES AND Pb SPECIES DISTRIBUTION IN TEA GARDEN SOILS

基于茶园土壤中0～100 cm剖面不同层位各种形态铅及茶叶样品中总铅质量分数（w）的测定分析结果,定量分析了各种形态铅在不同土壤层位中的w及其分布特点,同时利用灰色关联度分析方法,估算了土壤剖面不同层位中5个形态铅即可交换态（EXE）、碳酸盐结合态（CA）、铁锰氧化物结合态（OX）、有机结合态（OM）和残渣态（REX）的w与茶叶中总铅w的相关性.研究结果显示：茶园土壤中不同形态铅w在所测剖面范围内的平均值由大到小排序为：w（REX）〉w（OX）〉w（OM）〉w（CA）〉w（EXE）;同一剖面内铅的分布特点为：w（EXE）,w（OM）,w（REX）为表层高于底层,w（CA）和w（OX）则是底层高于表层;各形态铅所占总铅的比例,随其在土壤剖面各层中w值的变化而变化,其中EXE铅在各土壤层中所占比例最小,REX铅所占比例最大（除底层外）;灰色关联度分析结果显示,茶叶中的铅w与不同形态铅在土壤各层中的w均呈正相关,但关联度最大的是EXE铅,其次为OM铅,且以表层土壤中的铅对茶叶中铅的w影响最大.

On the basis of Pb content at different layers of soil in tea garden from 0 to 100 cm, and total Pb content in tea leaves, the content and distribution of Pb in different forms in various soil layers, and correlation between Pb content in different forms in soil and total Pb content in tea leaves were investigated by using grey scale correlation analysis. Results show that in the studied soil profile, averaged Pb content in different forms was： residual lead〉 oxide lead〉 organic combined lead〉 carbonate lead〉 exchangeable lead. Pb distribution characteristics in the same profile was. exchangeable lead, organic combined lead and residual lead had higher content in the surface layer than that in the substrate, while the content of carbonate lead and oxide lead were higher in the bottom layer. The proportion of different forms of Pb varies along with their content in different layers. Therefore, the content of exchangeable lead had the lowest proportion in various layers while that for residual lead had the highest proportion （except in substratum）. Grey scale correlation analysis revealed that Pb content in tea leaves had positive correlation with Pb content in each soil profiles, exchangeable lead showed maximum correlation while organic combined lead showed the second, especially Pb content in surface layer of soil has the greatest effect on Pb content in tea leaves.