广东大宝山多金属污染排土场耐性植物与改良剂稳定修复研究

通过在广东大宝山多金属污染排土场种植重金属耐性作物红麻、苎麻,辅以石灰+有机肥、石灰+生物炭的土壤改良,研究不同植物稳定修复模式下植物的生长状况、土壤pH与重金属含量、径流液产生与理化性质的变化情况.结果表明:改良剂处理有效促进红麻、苎麻生长,提高株高、根长和生物量,有助于排土场土壤的植被恢复.石灰与有机肥、生物炭的施加可以改善土壤酸性环境,将土壤pH由酸性显著提高至中性,降低土壤重金属生物有效性,且生物炭的作用更显著;随着红麻、苎麻稳定修复时间的增加,土壤重金属有效态含量呈一定程度下降趋势.植物的定植和土壤改良还可以减少地表径流的产生;提高径流液pH,但pH会随着修复时间的增加而下降;径流液中溶解态和悬浮态重金属含量均在植物稳定修复过程中得到降低,土壤中重金属污染物的扩散迁移得到有效控制.

Phytostabilization with tolerant plants and soil amendments of the tailings of the Dabaoshan polymetallic mine in Guangdong Province

In this study, the reclamation of the tailings of the Dabaoshan polymetallic mine located in Guangdong province was investigated. The phytostabilization using the planting of heavy metal tolerant plants Hibiscus cannabinus (kenaf) and Boehmeria nivea L. (ramie), supplemented by soil amendment with lime, organic fertilizers and biochar, was monitored through the determination of the growth characteristics of plants, the pH and heavy metal contents of soil, and the quantity and quality of the runoff. The results suggested that the application of soil amendments would significantly promote the growth of kenaf and ramie by increasing the plant height, the root length and the biomass yield. The use of soil amendments also increased the pH value of the soil from acid to neutral, and reduced the bioavailability of heavy metals in the soil. Among the different amendments, the utilization of biochar was more effective than organic fertilizers for decreasing the contents of extractable heavy metals. During the 6-month phytostablization field trial, the growth of kenaf and ramie also contributed to reduce the bioavailability of heavy metals in the polluted soils, but to a lesser extent. Besides, the planting of kenaf and ramie, as well as the use of soil amendments also decreased the production of surface runoff in the tailings. The pH of the runoff was increased but tended to decline during the phytostabilization trial. Furthermore, the amount of the dissolved and suspended heavy metals in the runoff were effectively reduced, limiting the solubilization and the migration of heavy metal pollutants in the tailings.