深耕技术对土壤—苋菜系统中迁移与再分配的影响

Effects of Deep Tillage on Migration and Redistribution on Soil-Amaranth Systems

在浙江某铅(Pb)、砷(As)污染地进行了翻耕技术试验,研究了不同耕作深度对土壤-苋菜系统中重金属迁移和再分配的影响。结果表明:供试土壤中有效态Pb、As与耕作深度呈显著负相关,当耕作深度为40 cm时,与常规处理耕作深度20 cm时相比,有效态Pb含量下降16.84%,有效态As含量下降22.86%。随着耕作深度的增加,苋菜根、茎、叶中有效态Pb、As的含量有不同程度的下降,当耕作深度为40 cm时,与常规处理耕作深度20 cm时相比,苋菜根、茎、叶中Pb的含量分别下降了19.28%、42.30%、2.16%;苋菜根、茎、叶中As的含量下降了3.28%、3.70%、25.7%。不同耕作深度时,根对Pb、As的富集系数均明显大于茎、叶的富集系数,这说明苋菜根对Pb、As的富集起了最明显的作用。随着耕作深度的增加,苋菜茎对根中重金属Pb的转运系数下降,叶对茎中重金属As的转运系数下降,而叶对茎中Pb的转运系数有所上升,茎对根中As的转运系数基本保持。故深耕可以有效降低重金属Pb由根向茎中转移,As由茎向叶转移,降低重金属Pb、As在食用部分茎、叶中的积累。

The trial was launched in a heavy metal Pb and As polluted area in Zhejiang province. The effects of different tillage depths on heavy metal migration and redistribution on soil-amaranth system are studied. The results show that there was a significant negative correlation between available Pb and As and tillage depth. When the tillage depth was 40 cm, the content of available Pb decreased by 16.84%, and the content of available As decreased by 22.86%, compared with the tillage depth 20 cm. The content of available Pb and As in roots, stems and leaves of amaranth decreased with the increased of tillage depth. When the tillage depth was 40 cm, compared with the tillage depth 20 cm, the content of available Pb in roots, stems and leaves decreased by 19.28%, 42.30% and 2.16% respectively, and the contents of available As in roots, stems and leaves decreased by 3.28%, 3.70% and 25.7% respectively. The enrichment coefficients of Pb and As in roots were all significantly higher than those in stems and leaves at different tillage depth, which indicated that amaranth roots had the most obvious effect on Pb and As enrichment. With the increase of tillage depth, the transport coefficient of Pb from roots to stems decreased, and that of As from stems to leaves decreased, but that of Pb from stems to leaves increased, and that of As from roots to stems maintained. Deep tillage could effectively reduce the transfer of Pb from roots to stems and As from stems to leaves, which means deep tillage could reduce the accumulation of heavy metal Pb and As in edible part of stems and leaves.