铅锌尾矿渣改良下木本耐性植物的根际环境研究

Study on the rhizosphere environment of woody tolerant plants under improved conditions of lead-zinc tailings

近年来,木本植物因生物量大、根系发达等特点,被广泛应用于重金属尾矿修复。其中,夹竹桃、栾树、泡桐等品种在铅锌胁迫下,表现出较好的抗性和富集效果。但其对矿渣根际环境的具体影响尚有待明确。本研究取湖南省郴州市某铅锌矿区的矿渣为实验基质,以100%矿渣(CK组)和90%矿渣+5%蘑菇渣+5%碳酸钙(S0组)为对照组;S0组基础上分别种植夹竹桃、栾树、泡桐(S1组)为实验组。通过比较基质的理化性质、有效态Pb和Zn、挥发性有机物、微生物群落结构等指标差异,探究木本耐性植物在铅锌胁迫下的根际环境响应机制。研究结果表明:改良条件下,三种植物能通过基质pH、有机质含量、阳离子交换量、速效氮和有效磷等指标,调节矿渣基质酸碱平衡,从而提高基质持水保肥力。有效态Pb、Zn含量分别下降了16.29%~36.50%和24.50%~47.33%。此外,酯类和酚类等有机化合物种类丰度增加。变形菌门的相对丰度减少,拟杆菌门、放线菌门、慢生根瘤菌属相对丰度增加。综上,改良条件下种植木本植物,改变了基质的理化性质、有机物丰度种类、微生物群落结构,显著降低了矿渣Pb和Zn的生物有效性。

In recent years,woody plants have been widely utilized for the remediation of heavy metal tailings due to their large biomass and well-developed root systems.Among them,species like Nerium oleander,Koelreuteria paniculata,and Paulownia have demonstrated strong resistance and effective enrichment under lead and zinc stress.However,the precise impacts on the rhizosphere environment of slag remain unclear.This study employed slag from a lead-zinc mining region in Chenzhou City,Hunan Province,as the experimental substrate.Two control groups were established:100%slag(CK group)and 90%slag+5%mushroom residue+5%calcium carbonate(S0 group).Additionally,Nerium oleander,Koelreuteria paniculata,and Paulownia were cultivated on the basis of the S0 group(S1 group).The study aimed to discern differences in substrate physicochemical properties,forms of Pb and Zn,volatile organic compounds,microbial community structure,and related indicators to explore the response mechanism of woody tolerant plants in the rhizosphere under lead and zinc stress.The findings revealed the following outcomes:Under enhanced conditions,these three plant species adjusted the slag substrate’s acid-base balance and enhanced water and nutrient retention by regulating parameters such as substrate pH,organic matter content,cation exchange capacity,available nitrogen,and available phosphorus.As a result,the effective content of Pb and Zn decreased by 16.29%to 36.50%and 24.50%to 47.33%,respectively.Furthermore,there was an increase in the abundance of organic compounds such as esters and phenols.The relative abundance of Proteobacteria decreased,while the abundance of genera in Bacteroidea,Actinobacteria,and Bradyrhizobium increased.In conclusion,planting woody plants under enhanced conditions not only altered the physicochemical properties of the substrate and the abundance of organic matter but also affected the structure of the microbial community.This led to an improved slag environment and a reduced bioavailability of Pb and Zn.