Chengdu Medical College, Chengdu 610500, Sichuan, PR China.
Chengdu Medical College, Chengdu 610500, Sichuan, PR China.
Sci Total Environ. 2018 Dec 10;644:1602-1611. doi: 10.1016/j.scitotenv.2018.06.380. Epub 2018 Jul 23.
Artificial soil on railway rock-cut slopes may be considerably contaminated with cadmium (Cd) and lead (Pb), which may migrate to nearby croplands and pose substantial risks to human and animal health. We investigate the influence of three types of revegetation modes - herbs (HS); herbs and shrubs (HSS); and herbs, shrubs, and trees (HSTS) - on the transportation of these heavy metals in soils. Six representative rock-cut slopes were chosen, and the vegetation, pollutant concentration, phytostabilization, and simulated rainfall were investigated. The results indicated that Cd posed a considerable ecological risk, while Pb posed a low ecological risk in the artificial soil. The erosion of artificial soil on the slopes played a primary role in the migration of Cd and Pb, because 87-91% of Cd and 85-89% of Pb was lost in sediments. Revegetation modes significantly affected the transportation of Cd and Pb. HSTS controlled a lot of Cd in their dominant plants among the three revegetation modes. HSTS not only decreased enrichment factor (EF) and ecological risk (E) values of Cd in the soils, but also decreased runoff, sediment and cumulative migrated Cd and Pb. The relationships among multi-factors were analyzed by stepwise mediation effect test and the results indicated that root weight density, aboveground biomass and immobilization of dominant plants for Cd and Pb were important direct factors which influenced the transportation of Cd and Pb. Overall, HSTS has proven to be beneficial in controlling the migration of Cd and Pb to croplands near the slopes and reducing their environmental risk. These results can offer a tested and implementable solution for mitigating the risks posed by these pollutants around the quickly expanding railways in the study region.
铁路岩质边坡上的人工土壤可能受到大量镉（Cd）和铅（Pb）的污染，这些重金属可能迁移到附近的农田，对人类和动物健康构成重大风险。我们研究了三种植被恢复模式——草本植物（HS）、草本植物和灌木（HSS）以及草本植物、灌木和树木（HSTS）——对土壤中这些重金属迁移的影响。选择了六个有代表性的岩质边坡，调查了植被、污染物浓度、植物稳定化和模拟降雨。结果表明，Cd 对人工土壤构成了相当大的生态风险，而 Pb 则构成了低生态风险。边坡人工土壤的侵蚀对 Cd 和 Pb 的迁移起着主要作用，因为 87-91%的 Cd 和 85-89%的 Pb 流失在沉积物中。植被恢复模式显著影响了 Cd 和 Pb 的迁移。在三种植被恢复模式中，HSTS 控制了其优势植物中大量的 Cd。HSTS 不仅降低了土壤中 Cd 的富集因子（EF）和生态风险（E）值，而且减少了径流量、泥沙和累积迁移的 Cd 和 Pb。通过逐步中介效应检验分析了多因素之间的关系，结果表明，优势植物的根重密度、地上生物量和对 Cd 和 Pb 的固定是影响 Cd 和 Pb 迁移的重要直接因素。总体而言，HSTS 已被证明有利于控制 Cd 和 Pb 向边坡附近农田的迁移，降低其环境风险。这些结果为在研究区域快速扩张的铁路周围减轻这些污染物带来的风险提供了一种经过测试和可实施的解决方案。
