Song Yunjing, Cheng Qian, Zhao Bing
The College of Landscape Architecture and Arts, Northwest A&F University, Yangling 712100, China.
The College of Landscape Architecture and Arts, Northwest A&F University, Yangling 712100, China.
Ecotoxicol Environ Saf. 2025 Jan 15;290:117551. doi: 10.1016/j.ecoenv.2024.117551. Epub 2024 Dec 17.
Cadmium (Cd) contaminants with high toxicity and mobility seriously threatens the ecological environment and human safety. Hydrangea macrophylla is a potential plant for Cd-contaminated soil remediation. Exogenous organic acids have been proven to effectively enhance the phytoremediation of soil contaminated with Cd. However, research on the effects of organic acids on Cd tolerance and accumulation of H. macrophylla remains scarce. In this study, a potted experiment was performed with H. macrophylla as the research object. The effects of acetic acid (AA), citric acid (CA), and malic acid (MA) with different concentrations (2.5, 5, and 10 mmol·kg) on the growth physiology, Cd absorption and accumulation of H. macrophylla and soil microecological environment under Cd stress were systematically studied. Results indicated that organic acids increased chlorophyll content and promoted the growth of H. macrophylla, the biomass of shoots and roots increased by 165.44 % , 161.50 % under 5 mmol·kg citric acid treatment. Furthermore, organic acids reduced the level of membrane lipid peroxidation in leaves, increased plant biomass and promoted root growth of H. macrophylla. By boosting superoxide dismutase (SOD), peroxidase (POD), and catalase activities (CAT), elevating levels of proline (Pro), non-protein thiol (NPT), glutathione (GSH) and phytochelatins (PCs), exogenous organic acids promoted the Cd tolerance of H. macrophylla. In particular, 5 mmol·kg CA had the best effect on improving the Cd tolerance of H. macrophylla. The roots of H. macrophylla accumulated a large amount of Cd, ranging from 365.04 to1111.67 μg·plant. Appropriate concentration of organic acids increased the total Cd accumulation by 1.12-2.07 times of H. macrophylla. The translocation factor (TF) increased by 97.91 %, 107.95 % under 5 mmol·kg CA and 10 mmol·kg MA treatments. Nevertheless, TF values were all less than 1. We posit that using H. macrophylla and organic acids could reduce the Cd bioavailability in the soil mainly through rhizosphere immobilization and plant absorption. Additionally, organic acids increased the soil pH, accompanied by changes in soil enzyme activities. 10 mmol·kgAA and MA reduced the available Cd concentration by 20.42 % and 31.65 %, respectively. Overall, exogenous organic acids can assist H. macrophylla in phytoremediation. 5 mmol·kg CA treatment was considered the best choice for the remediation of heavy Cd-contaminated soil by H. macrophylla.
镉（Cd）污染物具有高毒性和迁移性，严重威胁生态环境和人类安全。绣球花是一种用于镉污染土壤修复的潜在植物。已证明外源有机酸能有效增强镉污染土壤的植物修复效果。然而，关于有机酸对绣球花镉耐受性和积累影响的研究仍然很少。在本研究中，以绣球花为研究对象进行了盆栽试验。系统研究了不同浓度（2.5、5和10 mmol·kg）的乙酸（AA）、柠檬酸（CA）和苹果酸（MA）对镉胁迫下绣球花生长生理、镉吸收积累及土壤微生态环境的影响。结果表明，有机酸增加了叶绿素含量，促进了绣球花的生长，在5 mmol·kg柠檬酸处理下，地上部和根部生物量分别增加了165.44%、161.50%。此外，有机酸降低了叶片膜脂过氧化水平，增加了植物生物量，促进了绣球花根系生长。通过提高超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性，提高脯氨酸（Pro）、非蛋白硫醇（NPT）、谷胱甘肽（GSH）和植物螯合肽（PCs）水平，外源有机酸提高了绣球花对镉的耐受性。特别是，5 mmol·kg CA对提高绣球花镉耐受性的效果最佳。绣球花根系积累了大量镉，范围为365.04至1111.67 μg·株。适宜浓度的有机酸使绣球花总镉积累量增加了1.12 - 2.07倍。在5 mmol·kg CA和10 mmol·kg MA处理下，转运系数（TF）分别增加了97.91%、107.95%。然而，TF值均小于1。我们认为，利用绣球花和有机酸主要通过根际固定和植物吸收来降低土壤中镉的生物有效性。此外，有机酸提高了土壤pH值，同时伴随着土壤酶活性的变化。10 mmol·kg AA和MA分别使有效镉浓度降低了20.42%和31.65%。总体而言，外源有机酸可协助绣球花进行植物修复。5 mmol·kg CA处理被认为是绣球花修复重度镉污染土壤的最佳选择。
