不同土地利用方式下土壤养分和重金属元素垂直分布特征

Vertical distribution of soil nutrient and heavy metals in soil under different land use

为探讨不同土地利用方式下土壤养分和重金属元素垂直分布特征,对2种母质的自然土壤、耕作土壤、休耕土壤养分和重金属元素垂直分布状况进行了比较研究。结果表明:不同土地利用方式下土壤表层养分元素含量总体表现为休耕土壤>耕作土壤>自然土壤,土壤表层重金属含量总体表现为农田土壤(耕作土壤和休耕土壤)>自然土壤,耕作土壤与休耕土壤差异较小,土壤淀积层到母质层养分和重金属元素差异逐渐减小;土壤养分元素和Cu、Zn、Pb、Cd随土层深度的增加而减小,而Cr表现出相反的趋势;农田土壤耕作层有效钾含量最高可达215.6 mg·kg^(-1);耕作层Cd含量最高可达0.74 mg·kg^(-1)。3种土地利用方式中,休耕土壤养分和重金属含量相对较高,建议在休耕期间种植伴矿景天等重金属高积累植物进行植物修复。

To study the vertical distribution characteristics of nutrients and heavy metals in soil under different land use types, three land use types（natural soil, cultivated soil and fallow soil） were selected. The results indicated that the soil nutrients in topsoil followed a sequence of fallow soil, cultivated soil and natural soil under the three land use types, however, the concentration of heavy metal in farmland（cultivated soil and fallow soil） topsoil was higher than that of natural soil. The concentration of heavy metal in cultivated soil and fallow soil had no significant difference.From deposition layer to parent material layer, the concentration of nutrients and heavy metals in topsoil decreased significantly. The significant of soil nutrients and Cu, Zn, Pb, Cd decreased with the increase of soil depth, however,the concentration of Cr showed the opposite trend. The maximum concentration of available potassium in farmland soil was 215.6 mg·kg^-1, and the maximum concentration of Cd in tillage layer was 0.74 mg·kg^-1. Among the three land use types, the concentration of heavy metals in topsoil of fallow soil was the highest, hyperaccumulator（such as Sedum plumbizincicola） was suggested to be cultivated for soil remediation during the fallow period.