贵阳市郊菜园土-辣椒体系中重金属的迁移特征

Characteristics of Heavy Metal Transportation in Vegetables Soil and Capsicum(Capsicum frutescens Lvarlongum Bailey) System in Guiyang,Southwest China

选择贵阳市郊二戈寨、马铃乡和永乐乡的辣椒地,研究重金属在菜园土-辣椒体系中的迁移过程。结果表明,二戈寨、马铃乡和永乐乡3处采样地点菜园土中存在不同程度的重金属污染,综合污染指数分别为1.17、1.23和2.18,主要污染元素为Zn、Cu、Cd。但辣椒果实中仅有Cd超标。在土壤-辣椒体系各界面间,重金属元素迁移能力大小顺序发生了变化：在土壤-根部间为Cd Cu〉Zn〉Pb,在根部-茎叶间为Zn〉Cd〉Pb〉Cu,在茎叶-果实间为Cu Zn〉Cd〉Pb。对于Cu、Pb和Zn元素来说,辣椒根-土界面是重金属进入辣椒果实的主要障碍,其生物富集系数BCF值（蔬菜根中重金属含量/土壤中重金属含量）分别在0.21-0.44、0.04-0.24和0.033-0.08之间,而Cd的BCF值却达1.06-4.23,表现为富集作用。Cd的迁移系数TF1值（蔬菜茎叶中重金属含量/根部重金属含量）表明,其在根部-茎叶间的迁移几乎不受阻碍,但在果实-茎叶界面再次受阻,其TF2值（蔬菜果实中重金属含量/茎叶中重金属含量）在0.42-0.51之间。

Samples of whole capsicum （ Capsicum frutescens L. var. longum Bailey） plants and root soils were collected from capsicum fields in three villages in the suburbs of Guiyang, Southwest China to study characteristics of heavy metal transportation in the soil-apsicum system. Results show that the fields were polluted with heavy metals to a varying degree, with integrated pollution index being 1.17, 1.23 and 2. 18, respectively. Zn, Cd and Cu were the major pollutants. However, in the capsicum fruit only Cd was overproof. Transportation ability of the measured heavy metals follows a decreasing order of Cd〉〉Cu 〉Zn 〉 Pb in the soil/root interface, Zn 〉 Cd 〉 Pb 〉 Cu in the stem/root interface, and Cu〉〉 Zn 〉 Cd 〉 Pb in the fruit/stem interface. And the soil/root interface was the main barrier for Cu, Pb and Zn to enter into capsicum fruit, and their bio-concentration factor （BCF） was in the range of 0.21 - 0.44, 0.04 - 0. 24, and 0. 033 - 0. 08, respectively. However, Cd accumulated in the root, with its BCF being in range of 1.06 - 4.23. Its translocation factors （ TF1 ） demonstrated that there was almost no hindrance for it in the root/stem interface, but its TF2 being in the range of 0.42 and 0.51 revealed that its translocation was impeded in the stem/fruit interface.