三种黏土矿物对蚕豆生长和重金属含量的影响

以云南会泽铅锌矿周边污染农田土壤为供试土壤,施加沸石、钠基膨润土、硅藻土3种黏土矿物,开展室内种植蚕豆的盆栽试验,研究黏土矿物对蚕豆光合生理、生物量、矿质营养、重金属含量和累积量的影响。结果表明:3种黏土矿物显著增强蚕豆叶片的光合作用,增加植株的生物量,其中钠基膨润土处理的增幅最大,为21.7%。黏土矿物降低土壤速效氮、磷、钾的含量,降幅为12%～48%,改变蚕豆植株氮、磷、钾的含量,其中,硅藻土显著增加蚕豆植株磷、钾和根系氮的含量,增幅为23%～83%,钠基膨润土降低蚕豆地上部氮、磷、钾的含量。3种黏土矿物均显著降低土壤有效态铅和铜的含量,降幅为14%～28%,减少蚕豆植株的锌含量、根系铅和铜的含量;沸石还显著降低土壤有效态镉、蚕豆植株镉和地上部铅的含量。相关分析发现,土壤有效态镉与蚕豆地上部镉、有效态铜与根系铜、有效态锌与植株锌的含量呈极显著或显著正相关。研究表明黏土矿物能降低污染土壤重金属的生物有效性,减少蚕豆植株的重金属含量,改善光合作用和提高生物量。

Effects of three clay minerals on the growth and heavy metal content in Vicia faba

Polluted soils from farmland around a lead-zinc mine in Huize County, Yunnan Province,were sampled and used in the present pot experiment. Three clay minerals (zeolite, sodium bentonite, and diatomite) were added to the polluted soils, which were used to grow Vicia faba in a greenhouse. The effects of these clay minerals on the photosynthesis, biomass, mineral nutrition, and content and accumulation of heavy metals in Vicia faba were investigated. The results showed the following:Photosynthesis in the leaves was enhanced significantly and biomass of Vicia faba increased with the three treatments; the biomass increased by 21.7% for the sodium bentonite addition. The available nitrogen (N), phosphorus (P), and potassium (K) content in the soils were reduced by 12%~48% with the clay minerals treatments. The N, P, and K content in the roots of the Vicia faba increased by 23%~83% with the addition of diatomite,but decreased in the shoots of the plants with the addition of sodium bentonite. The content of available lead (Pb) and copper (Cu) in the soils decreased significantly with the addition of the three clay minerals.The zinc (Zn) content in the plants and the Pb and Cu content in the roots decreased. In addition, the content of available cadmium (Cd) in the soils and in the plants, and the Pb content in the shoots of the Vicia faba, fell significantly with the addition of zeolite. Significant positive correlations were observed between the content of available Cd in soils and Cd content in shoots; the content of available Cu in soil and Cu content in roots; and the content of available Zn in soil and Zn content in the plants. The results indicate that clay minerals could decrease the bioavailability of heavy metals in polluted soils, reduce the heavy metal content in plants, and improve the photosynthesis and biomass of Vicia faba.