Abstract:

The pressing issue of vanadium (V) pollution in Chinese soils requires immediate attention, and combined plant and microbial remediation has been found to play a crucial role in the remediation of V-polluted soils. Microbial agents, such as arbuscular mycorrhizal fungi (AMF), which are ubiquitous in nature and form arbuscular mycorrhiza (AM) in most plants, have been used to remediate heavy metal pollution. However, the effectiveness and underlying mechanisms of AMF in mitigating V-polluted soil remain unclear. This study aimed to elucidate the patterns and underlying mechanisms of AMF remediation in V-polluted soils. In this study, dog tail grass (Setaria viridis) was used as a test plant and Rhizophagus irregularis served as the selected AMF strain. The experimental design included AMF-inoculated (+AMF) and non-inoculated (−AMF) groups, and pot experiments were conducted at three different levels of V pollution: mild (150 mg·kg⁻¹), moderate (500 mg·kg⁻¹), and severe (1000 mg·kg⁻¹). The results showed that the soil V concentrations in the +AMF groups were significantly lower than those in the −AMF groups in all three cases, with mycorrhizal effects of 12, 11, and 32%, respectively. This may be because AM significantly reduced the concentration of bioavailable vanadium, albeit with varying effects. Specifically, the order of the AM effects, from highest to lowest, was moderate pollution (59%), severe pollution (48%), and mild pollution (13%). AM significantly increased the biomass and V content of the plants and decreased the plant V concentration. In addition, AM improved the physical and chemical properties of the soil by increasing the weight mean diameter, mass geometric diameter, and total organic carbon concentrations, but also by decreasing the soil pH. The presence of AM increased the concentration of glomalin-related soil protein (GRSP), with the strongest AM effect observed for easily extractable GRSP, reaching 150%. Notably, AM led to an increase in the specific surface area of GRSP and a corresponding increase in the V concentration of GRSP, which reached a maximum of 1.2 mg·g⁻¹ under heavy V loading in the +AMF groups. This value was 1.9 times higher than that of the corresponding soil V concentration, indicating the effective sequestration of V in the soil by GRSP within the matrix. These results highlight the significant potential of AM for the remediation of V-polluted soils, with GRSP emerging as a central component of this remediation process.

Key words: arbuscular mycorrhizal fungi, soil polluted with vanadium, glomalin-related soil protein, plant-microorganism combined remediation

摘要： 丛枝菌根真菌（arbuscular mycorrhizal fungi，AMF）作为一种广泛存在的微生物，已被用于其他重金属修复，但其对于钒污染土壤的修复效果及机理尚不清晰。为探究丛枝菌根修复钒污染土壤规律以及作用机制，以狗尾草（Setaria viridis）为供试植物，选取异形根孢囊霉（Rhizophagus irregularis）为供试AMF菌株，通过接种AMF（+AMF）与不接种AMF（−AMF）的方式形成处理和对照，在轻度（150 mg·kg⁻¹）、中度（500 mg·kg⁻¹）和重度（1000 mg·kg⁻¹）钒污染条件下，进行盆栽试验。结果表明，轻度、中度和重度钒污染土壤中，+AMF组土壤钒质量分数显著低于−AMF组，菌根效应分别为12%、11%和32%；丛枝菌根显著降低了有效态钒质量分数，但菌根效应不同，菌根效应表现为中度（59%）≈重度（48%）>轻度（13%）。丛枝菌根显著提高植物生物量和钒含量，降低了植物钒质量分数。丛枝菌根改善了土壤物理化学结构，增大了土壤团聚体的平均质量直径和平均几何直径，同时提高了土壤总有机碳质量分数，降低了土壤pH；丛枝菌根增加了球囊霉素相关土壤蛋白（glomalin-related soil protein，GRSP）质量分数，其中易提取GRSP菌根效应最大，为150%。丛枝菌根增加了GRSP比表面积，提高了GRSP钒质量分数，最大可达1.2 mg·g⁻¹（+AMF组重度钒污染条件下），为对应土壤钒质量分数的1.9倍，说明基质中的GRSP能够有效螯合土壤中的钒。该研究表明，丛枝菌根在修复钒污染土壤方面具有重要潜力，且GRSP在修复过程中发挥重要作用。

关键词: 丛枝菌根真菌, 土壤钒污染, 球囊霉素相关土壤蛋白, 植物微生物联合修复