Department of Crystallography, Mineralogy and Agricultural Chemistry, University of Seville, Campus Reina Mercedes, s/n., 41071, Seville, Spain.
Department of Integrated Sciences, University of Huelva, Campus El Carmen, s/n., 21071, Huelva, Spain.
Environ Geochem Health. 2023 Dec;45(12):9541-9557. doi: 10.1007/s10653-023-01523-w. Epub 2023 Mar 16.
Sulfidic mine wastes have the potential to generate acid mine drainage (AMD) and release acid leachates containing high levels of iron, sulfate and potentially toxic elements (PTEs). Soils receiving AMD discharges are generally devoid of vegetation. Only a few metal-tolerant plant species can survive under such adverse soil conditions. This work investigates two plant species, Nicotiana glauca and Euphorbia segetalis, that have successfully colonized an AMD-impacted wetland area in south-western Spain. The uptake of PTEs from the soil by roots and their transfer and accumulation in the above-ground biomass were quantified. Results showed that these pioneer plants grew in patches of neutral soil within the wasteland despite the high concentrations of PTEs in the rhizosphere soil (up to: 613 mg kg As, 18.7 mg kg Cd, 6370 mg kg Cu, 2210 mg kg Pb and 5250 mg kg Zn). The target organs of As, Cu and Pb accumulation were: root > leaf > stem in N. glauca, and root > stem > leaf in E. segetalis. Zinc and Cd showed a significant decrease in roots relative to aerial parts of N. glauca, and Co was preferentially partitioned in stems of N. glauca and leaves of E. segetalis. The soil-plant transfer coefficient values of PTEs in all parts of both plants were well below unity with the only exception of Cd in leaves of N. glauca (1.254), suggesting that roots acted as a barrier limiting the uptake of PTEs by plants. Interestingly, under the same soil conditions, N. glauca absorbed Cd in considerable proportions from soil and accumulated it in its leaves, while E. segetalis was not effective in transferring PTEs from roots shoots except for Co. In conclusion, soil pH and plant-related factors greatly influence the stabilization of PTE in the rhizospheric soil and produce inconsistencies in PTE phytoavailability. The findings of this study provide criteria to assist in natural remediation in other legacy contaminated sites worldwide.
硫化物矿山废物有可能产生酸性矿山排水 (AMD) 并释放含有高浓度铁、硫酸盐和潜在有毒元素 (PTE) 的酸性浸出液。接收 AMD 排放的土壤通常缺乏植被。只有少数几种耐金属的植物物种可以在这种不利的土壤条件下存活。这项工作研究了两种植物，Nicotiana glauca 和 Euphorbia segetalis，它们已成功地在西班牙西南部受 AMD 影响的湿地地区定殖。定量了根部从土壤中吸收 PTE 及其在地上生物量中的迁移和积累。结果表明，尽管根际土壤中 PTE 浓度很高（高达：613mgkgAs、18.7mgkgCd、6370mgkgCu、2210mgkgPb 和 5250mgkgZn），但这些先锋植物仍在荒地的中性土壤斑块中生长。As、Cu 和 Pb 积累的靶器官为：根 > 叶 > 茎在 N. glauca 中，根 > 茎 > 叶在 E. segetalis 中。Zn 和 Cd 相对于 N. glauca 的地上部分，根部显著减少，Co 优先分配在 N. glauca 的茎和 E. segetalis 的叶中。两种植物所有部位的 PTE 土壤-植物转移系数值均远低于 1，唯一的例外是 N. glauca 叶片中的 Cd（1.254），这表明根部充当了限制植物吸收 PTE 的屏障。有趣的是，在相同的土壤条件下，N. glauca 从土壤中吸收大量的 Cd 并将其积累在叶片中，而 E. segetalis 除 Co 外，根部向地上部分转移 PTE 的效率不高。总之，土壤 pH 和与植物相关的因素极大地影响了 PTE 在根际土壤中的稳定性，并导致 PTE 植物有效性的不一致。这项研究的结果为协助全球其他遗留污染场地的自然修复提供了标准。
