曲靖烟区土壤pH与烟叶重金属含量的分布特点及关系分析

以曲靖烟区2010年1427份土壤样品和其相对应的1427份烤后烟叶样品为材料,分别对土壤pH值以及烟叶中的As、Hg、Pb、Cd和Cr 5种重金属含量的分布特征以及相互关系进行了分析。结果表明:(1)曲靖烟区土壤pH值的范围在4.28～8.37之间,其中处于最适烤烟生长土壤pH范围的样本数占总样本数的37.7%;不同土壤类型的pH值,以新积土的变异系数最大,黄壤土的变异系数最小。(2)Cd在5种重金属中的变异系数最大,5种重金属在烟叶内的含量均是下部叶>中部叶>上部叶。(3)As、Pb、Hg和Cd均与土壤pH存在明显的回归关系和相关性,不同部位间的烟叶重金属含量的变化随pH值的变化具有较高的一致性,随着土壤pH值的增大,烟叶中As、Hg和Cr的含量逐步降低,Pb和Cd在烟叶中的含量则逐步升高。

Distributive Characteristics and Relationship of Soil pH -value and Heavy Metal Content in Tobacco Leaves in Qujing Tobacco- planting Area

Taking 1427 soil samples and the corresponding 1427 flue - cured tobacco leaf samples from Qujing tobacco - planting area in the year 2010 as test materials, the distributive characteristics and relationships of soil pH - value and the contents of 5 heavy metal elements （As, Hg, Pb, Cd and Cr） in tobacco leaves were analyzed. The results indicated that： （1） The pH -value in the soil ranged from 4.28 to 8.37, and the soil samples with the pH - value which was within the most appropriate range for the growth of flue - cured tobacco accounted for 37.7% of the total soil samples. Among different types of soil, alluvial soil had the maximum coefficient of variation in pH - value ; while yellow loam had the smallest one. （2） The maximum coefficient of variation was found in Cd content among five heavy metal elements, and the contents of five heavy metal elements in tobacco leaves all had the following order： lower leaf 〉 middle leaf 〉 upper leaf. （3） The contents of As, Pb, Hg and Cd in tobacco leaves all had obvious regressive relationship and correlation with the soil pH - value. The changes in the content of heavy metals in different parts of tobacco leaves were highly consistent with the changes in soil pH - value. Along with the increase in soil pH - value, the contents of As, Hg and Cr in tobacco leaves gradually decreased, and that of Pb and Cd gradually increased.