施用外源物对尾矿土壤种植胡枝子修复效应初探

采用土培试验在两种尾矿土壤(废弃地和尾矿渣土)上种植耐性不同的两个胡枝子品种,通过添加客土、锯末,调控有机肥或无机肥等外源物,分析不同处理条件下胡枝子生物量、植株和土体内重金属含量,以明确外源物对尾矿土壤的修复效应。结果表明,二色胡枝子生物量整体上显著高于截叶胡枝子生物量;在所有处理中,废弃地上同时添加客土和有机无机肥的处理是二色胡枝子生物量最高的处理。外源肥料添加提高了两个品种地上部和根部的生物量,客土添加可能对改善立地生存的理化条件有较大帮助作用,更能体现出肥料的效果。两种土壤上添加客土或肥料,均较为显著地减少了截叶胡枝子根部和地上部重金属的吸收,而二色胡枝子效果不明显。两种土壤上添加外源物、种植不同品种胡枝子可以降低部分处理土壤中重金属含量,但通过植物种植直接摄取土壤中重金属的量是相对较少的。总之,客土添加、肥料施入均较为明显地改善了废弃地和尾矿渣土两类土壤的立地条件,增加了两种胡枝子的生物量,一定程度上限制了植物对重金属的吸收,土壤改良的基础上优先选择耐性品种是提高植物修复效果的上佳方案。

Remediation Effects of Xenobiotic Applications on Mine Tailing Soils Planted with Lespedeza Species

Soil culture experiment was conducted with two kinds of mine tailing soils (wastelands and tailing residues land) planted two lespedeza species differing in Cd sensitivity in order to explore the remediation effects by adding xenobiotic substance (e.g., new soil, sawdust, organic fertilizer or inorganic fertilizer). The results showed that the biomass of Lespedeza bicolor was significantly higher than that of Lespedeza cuneata, while the treatment of applying new soil and organic inorganic fertilizer had the highest biomass of Lespedeza bicolor in all treatments. In addition, biomass of root and shoot were enhanced by xenobiotic application in both lespedezar species, which the addition of new soil improved the physical and chemical conditions of sites. When two mine tailing soils were applied with new soil or fertilizer, the heavy metal contents in roots or shoots of Lespedeza cuneata were significantly reduced, but little change occurred in Lespedeza bicolor. The contents of some heavy metals in two mine tailing soils can be reduced by applying exogenous or planting two lespedezal species, but the net uptake amount of heavy metals by plants are extremely low. In a word, the application of new soil and fertilizer obviously enhanced the site quality of two kinds of mine tailing soils, which increased the biomass of two Lespedeza species and decreased the uptake of heavy metals, so priority choose the tolerance plant species on the basis of soil amendment is the optimal way to improve the phytoremediation effect.