土壤-烟草系统中铅的迁移特征及形态分布

Translocation and Fractions of Lead in Soil-Tobacco System

通过盆栽试验,以两烟草品种(云烟85和红花大金元)为对象,研究了重金属铅(Pb)在土壤-烟草系统中的迁移特征以及土壤与烟草各器官Pb化学形态分布特征。结果表明:与非根际土壤相比,根际土壤铁锰氧化物结合态Pb明显降低(降幅3.86%~22.33%),碳酸盐结合态、有机态和残渣态呈上升趋势。随着土壤Pb处理浓度的升高,两品种烟草生物量均显著降低,各器官Pb含量均显著上升,云烟85各器官Pb含量大小顺序为根】叶】茎,红花大金元为根】茎】叶。CK处理下两个品种烟草各器官Pb形态主要以氯化钠、醋酸和盐酸提取态为主(66.49%~72.40%),随着Pb处理浓度的升高,根部与叶部乙醇提取态Pb显著增加,这加剧了Pb的迁移性,红花大金元茎部Pb向盐酸提取态转化从而抑制Pb由茎部向叶部的转运。

The fractions and contents of lead(Pb)in soil-plant system would influence its mobility and plant toxicity. In a pot experiment, two varieties of tobacco(Yunyan 85 and Honghuadajinyuan)were used to study the distribution of different Pb chemical fractions in soil and tobacco organs. Compared with the non-rhizospheric soil, the percentages of iron and manganese-oxides-bound Pb decreased by 3.86% to 22.33%, wheras these of carbonate-bound, organic-bound and residual Pb all increased. Applying Pb significantly decreased biomass of the two tobacco varieties, while increased Pb concentrations in tobacco organs significantly. The Pb concentrations in tobacco organs were in order of root >leaf >stem for Yunyan 85, and root >stem >leaf for Honghuadajinyuan. In control treatment, Pb mainly existed as NaCl-extractable, HAc-extractable and HCl-extractable Pb, with sum of 66.49%~72.40%, but Pb addition significantly increased concentrations of ethanol-extractable Pb, which enhanced Pb mobility. Increased HCl-extractable Pb in the stem of Honghuadajinyuan might reduce Pb transference to the leaves.