甘肃陇南锑矿区污染及微生物群落结构特征

锑（Sb）是有色金属矿山开采和加工中对环境造成严重威胁的重点污染物,与砷（As）的硫化物和氧化物共存. 微生物对土壤中重金属的迁移转化及修复具有重要意义. 目前,锑矿不同功能分区（采矿区和冶炼区）中重金属有效态对土壤微生物群落结构的生态效应仍知之甚少. 为掌握不同功能分区中重金属污染特征及重金属有效态与土壤微生物群落之间的相互作用关系,采用Wenzel连续提取法和16S rDNA 高通量测序技术测定了Sb和As的化学形态及微生物信息. 结果表明,Wenzel连续提取后Sb和As的化学形态分布占比大小为：无定型铁铝氧化物结合态（F3）>晶质铁铝氧化物结合态（F4）>残渣态（F5）>专性吸附态（F2）>非专性吸附态（F1）. 潜在生态风险指数（RI）和地累积指数（I_geo）显示,Sb污染程度大小为：冶炼区>采矿区>对照区,冶炼区为严重污染,采矿区为中度至重度污染；As污染程度大小为：采矿区>冶炼区>对照区,采矿区和冶炼区均为中度至重度污染. 16S rDNA 高通量测序显示：Proteobacteria是采矿区与冶炼区中相对丰度最高的门, Kaistobacter、Pseudomonas、Sphingomonas和Lysobacter是采矿区与冶炼区中相对丰度最高的属；Geobacter和Luteolibacter在采矿区有较高的LDA得分,Thiobacillus在冶炼区具有较高的LDA得分. Spearman相关性、方差分解（VPA）和随机森林预测（RF）表明,Sb、As、有效态锑[Sb（Bio）]和有效态砷[As（Bio）]是影响锑矿不同功能分区中微生物群落结构的主要因子；冗余分析（RDA）显示,对属水平微生物群落结构的影响大小为：As（Bio）>Sb（Bio）>Sb>As,Sb及Sb（Bio）和Nitrospira呈现显著负相关关系,和Thiobacillus呈现显著正相关关系（P<0.05）. 通过深入研究重金属污染特征及重金属有效态对微生物群落结构的生态效应,可为锑矿区生态修复和生态环境管理提供参考.

Characteristics of Pollution and Microbial Community Structure in the Antimony Mining Area of Longnan, Gansu Province

Antimony （Sb） is a major pollutant that poses a serious threat to the environment in the mining and processing of nonferrous metals, coexisting with sulfide and oxide of arsenic （As）. Microorganisms play an important role in the migration, transformation, and repair of metals in soil. The ecological effects of bioavailable Sb and As on the microbial community in antimony mining areas（mining and smelting areas）are still poorly understood. The Wenzel method and high-throughput 16S rDNA amplicon were used to characterize soil pollution characteristics in different functional areas, and the relationship between the bacterial community and bioavailable concentrations have been investigated comprehensively. The results showed that： Chemical speciation of Sb and As were amorphous, and poorly crystalline hydrous oxides of Fe and Al （F3） > well-crystallized hydrous oxides of Fe and Al （F4） > residual phases （F5） > specifically adsorbed （F2） > non-specifically adsorbed （F1）. According to the estimation of the potential ecological risk index （RI） and geo-accumulation index （I_geo）, the Sb pollution degree was： smelting area > mining area > contrast area, in which the smelting area showed serious pollution, and the mining area showed moderate to severe pollution. The As pollution degree was： mining area > smelting area > contrast area, in which the mining area and smelting area showed moderate to severe pollution. High-throughput 16S rDNA amplicon showed that Proteobacteria was the most abundant phylum in mining and smelting areas； Kaistobacter, Pseudomonas, Sphingomonas, and Lysobacter were the most abundant microbial genera； Geobacter and Luteolibacter had a high LDA score in mining areas； and Thiobacillus had a high LDA score in antimony-contaminated areas. Spearman correlation analysis, variation partitioning analysis （VPA）, and random forest （RF） analysis showed that Sb, As, bioavailable antimony [Sb （Bio）], and bioavailable arsenic [As （Bio）]were the main factors affecting the microbial community structure in different functional areas of antimony ore. Redundancy analysis （RDA） indicated that Sb and its bioavailable concentrations showed uniformly negative associations with the relative abundance of bacteria Nitrospirae and showed a significant positive correlation with Thiobacillus （P<0.05）. The in-depth research on the ecological effects of bioavailable Sb and As on the bacterial community provides references and new perspectives for environmental monitoring and management.