Green solution for lead pollution: phytoremediation with <i>Festuca rubra</i> and brushite-aluminosilicate geopolymer material

Aluminosilicate materials are known for their high removal efficiency of lead (Pb) ions from aqueous solutions, whereas in Pb-contaminated soils they can immobilise lead ions and improve soil quality, contributing to more efficient remediation. Brushite-aluminosilicate geopolymer materials synthesised from an abandoned, raw kaolinite clay with the addition of 2, 4, and 6 wt% of brushite, were tested for their efficiency in removing Pb ions with <i>Festuca rubra</i>, which is known to tolerate its high concentration in soil. The highest efficiency for Pb immobilisation in the soil was observed with the addition of brushite-metakaolin-based geopolymer GPB2% and GPB6%, whereas physiological and biochemical parameters indicate a reduction in metal stress with increasing brushite content, as the concentrations of proline, total phenolic content and antioxidant activity in the shoots of the plants to which GPB6% was added were even lower than in some samples grown on uncontaminated soil. Moreover, in this sample the highest concentrations of photosynthetic pigments were found. This study suggests that the brushite-metakaolin geopolymer material improves the potential of <i>F. rubra</i> in remediation, whereas its stability and harmlessness to the environment, further recommend its use in the field.铝硅酸盐材料因其对水溶液中铅（Pb）离子的高去除效率而广为人知，而在铅污染土壤中，它们可固定铅离子并改善土壤质量，从而助力更高效的修复。以废弃原生高岭土为原料，添加2、4和6 wt%透钙磷石合成的透钙磷石-铝硅酸盐地质聚合物材料，与耐受土壤中高浓度铅的<i>Festuca rubra</i>（紫羊茅）协同测试其去除铅离子的效率。土壤中铅固定效率最高的是添加透钙磷石-偏高岭土基地质聚合物GPB2%和GPB6%的处理组；而随着透钙磷石含量增加，植物的生理生化参数显示金属胁迫有所减轻——添加GPB6%的植物地上部分中脯氨酸浓度、总酚含量及抗氧化活性甚至低于未污染土壤中生长的部分样本。此外，该样本中检测到最高浓度的光合色素。本研究表明，透钙磷石-偏高岭土地质聚合物材料可提升<i>F. rubra</i>的修复潜力，且其环境稳定性与无害性进一步支持其田间应用。