改性纳米碳黑隔层对络合剂存在下草坪堆肥基质重金属淋溶的影响

Effects of modified nano-carbon black barriers on the leaching of heavy metals mobilized by chelators in turfgrass compost medium

为了减少草坪堆肥基质中重金属淋溶对下层土壤的污染,以改性纳米碳黑作为防渗隔层材料,研究隔层设置对高羊茅富集重金属的效率及重金属淋溶作用的影响.结果表明,纳米碳黑隔层处理组中,高羊茅地上生物量减少,地上部重金属富集量明显增加.HNO_3改性纳米碳黑隔层处理组中,高羊茅地上部对重金属Cd、Zn、Cu的富集量增加显著;H_2SO_4改性纳米碳黑隔层处理组中,高羊茅对重金属Pb的富集量增加显著;KMnO_4改性纳米碳黑隔层处理组中,高羊茅对Cr、Pb的富集量显著增加.隔层处理对施用络合剂后草坪堆肥基质重金属向下淋溶迁移起到了显著的阻碍作用.HNO_3和KMnO_4改性纳米碳黑隔层处理组中,渗滤液中Cd、Cr、Pb、Zn的含量显著减少,KMnO_4改性纳米碳黑隔层对Cu的阻隔作用尤其显著.因此,在络合剂强化植物修复基质的重金属污染时,设置改性纳米碳黑隔层可促进植物对重金属的富集并有效阻隔被络合剂活化的重金属向下层土壤的淋溶迁移.

To reduce the soil pollution caused by the leaching of heavy metals in turfgrass compost medium, the modified nano-carbon black （ CB ） barriers were adopted as interlayer materials to investigate the effects of CB barriers on the enrich- ment efficiency of heavy metals by Festuca arundinacea Schreb. and the leaching of heavy metals. The results showed that the above-ground biomass of F. arundinacea decreased and the uptakes of heavy metals in shoots increased in the presence of modified nano-CB barriers. The uptakes of Cd, Zn, Cu in plant shoots significantly increased in the presence of HNO_3 modi- fied nano-CB barrier. The uptake of Pb significantly increased in the treatment of H_2SO_4 modified nano-CB barrier. KMnO_4 modified nano-CB barrier significantly enhanced the uptakes of Cr, Pb, Zn in plant shoots. At the same time, permeable barriers with different materials significantly hindered the migration downward of heavy metals. HNO_3 and KMnO_4 modified nano-CB barriers significantly reduced the amounts of Cd, Cr, Pb, Zn in the leachates, and the latter greatly lowered the leaching of Cu. In conclusion, the set of modified nano-CB barrier can effectively enhance the enrichment of heavy metals by plants and lower the risk of migration downward of heavy metals mobilized in chelator-assisted phytoremediation of heavy metal contaminated medium.