Research On The Diversity And Impact Factors Of Arbuscular Mycorrhizal Fungus In Typical Mercury Mining Area

Soil mercury pollution is a serious threat to soil ecological health,food safety,human and social security.Remediation of soil mercury pollution has become a hot topic of research.At present,the mercury pollution remediation technologies include physical remediation,chemical remediation,phytoremediation,microbial remediation and other bioremediation technologies.Bioremediation technology has attracted wide attention due to its advantages such as small side effects,low cost and good ecological friendliness.Arbuscular mycorrhizal fungi can form mycorrhizal symbiosis with most plant roots.Arbuscular mycorrhizal fungi can improve host plants' tolerance to heavy metal toxicity through direct and indirect effects,and affect plant growth and heavy metal absorption and transport,which provides a possibility for the application of arbuscular mycorrhizal fungi in soil mercury remediation.To fully understand the germplasm resources and diversity of arbuscular mycorrhizal fungi in mercury-contaminated areas is the premise and basis for the application of arbuscular mycorrhizal fungi in soil mercury pollution remediation,the exploration of arbuscular mycorrhizal fungi in mercury migration and transformation in soil-plant system,and the guarantee of food safety in mercury-contaminated areas.In this study,the dominant plant root soil of typical mercury mining areas in Tongren City,Guizhou Province was selected as the research object,and the molecular biological identification of arbuscular mycorrhizal fungi in the soil of mercury mining areas were carried out by means of high-throughput sequencing technology.The effects of soil properties,mercury content and morphology on arbuscular mycorrhizal fungi diversity in the mercury mining areas were studied by the determination of physical and chemical properties,mercury content and methyl mercury content of the root soil.In order to provide a basis for the selection of dominant arbuscular mycorrhizal fungi and dominant plants in mercury-contaminated soil,and to provide supporting materials for the study on the role of arbuscular mycorrhizal fungi in mercury in soil plant system.The main research results are as follows:(1)The physical and chemical properties of soil in Wanshan mercury mining area were analyzed.The results showed that the mercury content in the soil varied widely,ranging from 1.9 mg/kg to 353 mg/kg.Among them,the Dashuixi tailings and the Chongjiao ore path have high mercury content,with ranges and mean values of 30.6?353 mg/kg and 114 mg/kg,3.34?241 mg/kg and 100 mg/kg,respectively.The content of methyl mercury in soil is low,which is not significantly different from that of the control field in this study.The soil of Wanshan mercury mining area is alkaline as a whole.(2)The diversity of arbuscular mycorrhizal fungi is rich in Wanshan mercury mining area.Among them,Glomus is the dominant genus in Wanshan mercury mining area.Diversispora is the second dominant genus identified by molecular biology.Acaulospora and Archaeospora were detected in all fields except Gaolouping township.Glomus versiforme and Glomus lamellosum are dominant species of various fields respectively.(3)The results of Sobs index,Chao index,Shannon index and Simpson index all showed that the diversity of arbuscular mycorrhizal fungi in soil in the Meizixi tailings and Sanbaidun smeltery showed high diversity level.(4)Soil mercury content,available phosphorus and total potassium had significant correlation with Shannon index.Among them,Shannon index was significantly positively correlated with total mercury at lower soil mercury content level,and negatively correlated with total mercury at higher soil mercury content level.This may be due to the tolerance of arbuscular mycorrhizal fungi to heavy metal stress when soil mercury levels are low,as well as the "reciprocal rewards"mechanism between host plants and arbuscular mycorrhizal fungi.When the mercury content of soil is high,the excessive heavy metal concentration will be toxic to most arbuscular mycorrhizal fungi,and only arbuscular mycorrhizal fungi with strong tolerance can survive,thus reducing the diversity of arbuscular mycorrhizal fungi.The contents of available phosphorus(R2=0.132)and total potassium(R2=0.244)were negatively correlated with the diversity of arbuscular mycorrhizal fungi in soil.Soil total nitrogen,alkali-hydrolyzed nitrogen and available potassium were positively correlated with soil arbuscular mycorrhizal fungi diversity.Total phosphorus,organic carbon and pH were negatively correlated with the diversity of arbuscular mycorrhizal fungi.