Iron ore mining requires the surrounding rock to be excavated, and the beneficiation process generates tailings. When used as construction aggregates, these materials can cause concrete to crack due to the presence of pyrite. Currently, there are no established technical methods to prevent damage caused by pyrite, which limits the resource recovery of such solid waste. In this study, we selected the surrounding rock and tailings to serve as coarse or fine aggregates for C50 concrete based on standard engineering mix proportions. We found that surface-exposed pyrite on aggregates oxidizes first to form ettringite, triggering expansion, with the expansion rate positively correlated with the surface-exposed pyrite content. The deformation process was quantitatively characterized using the Arrhenius equation and by analyzing the acceleration effect of temperature on expansion, yielding an apparent activation energy of 8.28-9.47 kJ/mol. Using a 0.04% expansion value as the failure criterion, the results indicate that at an annual average temperature of 20 °C, C50 concrete with surface-exposed pyrite introduced by concrete aggregates exceeding 20 kg/m3 will fail within its service life.

When iron sulfides are used as aggregate in concrete production, it easily oxidizes to form harmful substances such as sulfates. This results in acid corrosion and internal sulfate attack (ISA), significantly reducing concrete durability. To date, the quantification methods for iron sulfides in aggregates remain inaccurate, often neglecting pyrrhotite (a type of iron sulfide). No standardized methods or threshold values for the sulfide content in aggregates have been established, nor have technical guidelines for the application of sulfide-containing aggregates, limiting their use. This study proposes an on-site quantification procedure for determining the pyrite and pyrrhotite content in tailings using a selective chemical dissolution process. An orthogonal experiment was designed to determine the optimal dissolution conditions by considering four factors: particle size, reaction temperature, acid concentration, and reaction time. The pyrrhotite quantification method showed a relative standard deviation (RSD) of 3.60% (<5%) and a mean relative error of 3.19% (<5%), while the pyrite quantification method showed an RSD of 3.11% (<5%) with a mean relative error of 4.70% (<5%). The results were further optimized under engineering conditions to reduce costs and enable on-site quantification without relying on complex precision instruments. The quantitative results of pyrite in mineral samples were verified by the XRD internal standard method, and the error was less than 0.6%. This approach ensures the effective monitoring and management of sulfide content in concrete aggregates, promoting the practical application of sulfur-bearing aggregates.

To increase the utilization rate of superfine iron tailings (SIT), a novel coal fly ash (CFA)/SIT-based threedimensional printing geopolymers (CS-3DPG) were synthesized for high-value resource application of SIT. The optimal preparation parameters of CS-3DPG were sodium citrate of 0.4%, water-solid ratio of 38%, SiO2/Na2O molar ratio of 1 and alkali activator of 6%, with the compressive strength of 32.14 MPa. Besides, the yield stress and plastic viscosity (rheological properties) of CS-3DPG reached 284 Pa and 18.8 Pa & sdot;S, respectively. The sodium aluminum silicate hydrate (N-A-S-H) gels were identified as dominant hydration products by the selective chemical extractions. Microstructural analysis also successfully indicated that the retarder caused some CFA and SIT to be unreacted, resulting in the decrease of early compressive strength compared with CS-3DPG. Based on the full width at half-maximum (FWHM) values, kinetics of hydration and hydration kinetic contribution degree results, retarders effectually inhibited nucleation and growth (NG) and diffusion (D). The phase-boundary interaction (I) reaction played a major role after adding retarders. This work successfully reveals the early retarding mechanism of CS-3DPG, and provides the possibility of large-scale resource application of SIT-based 3DPG in 3D printing construction.

固定化微生物技术凭借处理效率高、投入成本低的优势在重金属废水处理领域应用颇为广泛，然而相关的重金属去除机理尚不明确。以从酸性矿山废水中筛出的耐酸曲霉Aspergillus sp. MF1作为研究对象，对其进行固定化处理，运用亚细胞分离技术以及五步提取法并通过SEM、FTIR表征初步揭示固定化Aspergillus sp. MF1去除Pb2+的机理。研究结果表明，在pH为3.5，初始Pb2+质量浓度为10 mg/L时，固定化Aspergillus sp. MF1对于Pb2+的去除率最高可达78.26%。固定化Aspergillus sp. MF1去除Pb2+的机理可归纳为两点，一是源于固定化Aspergillus sp. MF1载体的高比表面积、聚乙烯醇和海藻酸钠等材料表面活性基团对Pb2+的吸附，二是归于Aspergillus sp. MF1细胞壁对于Pb2+的螯合、吸附和离子交换作用，以及液泡和其他细胞器的隔室化作用。此外，固定化Aspergillus sp. MF1连续循环使用5次对Pb2+的去除率均能达到30%以上，且在去除过程中未发生破裂、细胞泄露等情况。

Acidophilic/acid-resistant algae exhibit innate survival advantages in acid mine drainage (AMD), but their response remains poorly understood. In this study, the detoxification and removal of Graesiella sp. MA1 isolated from AMD to the heavy metals of Cu 2 + and Mn 2 + at pH 3.5 was evaluated. The physiological response mechanism of the algae to these two heavy metals was analyzed by measuring the changes of algal biomass, photosynthetic pigments, malondialdehyde (MDA), reduced glutathione (GSH) and sulfhydryl (-SH) contents, as well as the specific activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX). The main functional groups bound to heavy metals in microalgae were analyzed using FITR and XPS spectra. Results indicate metalinduced growth and photosynthesis impacts, with MDA rising alongside metal concentrations. However, Graesiella sp. MA1 exhibited a certain degree of removal ability toward Cu 2 + and Mn 2 + , and increased the pH of the medium from 3.5 to 5.12-5.73 and 9.07 (control group), indicating the potential ability to regulate the environmental pH. Additionally, this strain alleviated the toxic effects of heavy metals by regulating the level of SOD, APX, GSH, and -SH in the antioxidant system. FTIR and XPS analysis reveal that the functional groups, such as carboxyl, amide I and amide II, which related to proteins and polysaccharides on the microalgal surface, combined with Cu 2 + and Mn 2 + for extracellular removal. Clarifying the detoxification and removal process of heavy metals from acid-tolerant microalgae will help us to better use microalgae to repair AMD in situ.

Acid mine drainage (AMD), a common environmental problem around the world, is characterized by low pH, high concentrations of heavy metals and sulfate. AMD treatment technology based on stimulating in-situ microorganisms has received widespread attention, but lack of organic matter is a limiting factor that restricts the remediation by heterotrophic microorganisms such as sulfate-reducing bacteria (SRB). In this study, a pilot scale reactor was set up next to an acid reservoir to evaluate the effect of livestock wastes on the in-situ bioremediation of AMD, focusing on performance assessment, heavy metal removal efficacy, and the evolution of the microbial community. Results indicated that the pH of AMD rises rapidly from 3.23 to 4.11, and metals (e.g., Fe, Cu, and Zn) rapidly got removed in Stage I. However, AMD experienced significant stratification in Stage II (biogas slurry supplemented). The pH of surface layer (0.5 m below the surface) gradually dropped to 3.67, and the bottom layer (2.3 m below the surface) remained around 4.1, and the metal removal efficiencies further improved. Microbial communities were dominated by Fe-OB and Fe-RB in surface layer, while SRB dominated in bottom layer. The addition of biogas slurry significantly increased the relative abundance of functional microbe in bioremediation. The growth of SRB in the bottom of the reactor made an important contribution to heavy metal removal. Heavy metals were mainly removed through the formation of insoluble hydroxide and sulfide precipitation and co-precipitation. This study innovatively integrates low-cost, locally sourced livestock waste as nutrient supplements into AMD bioremediation processes, and demonstrated the potential for integrating AMD treatment with livestock waste management, addressing both the nutrient needs for AMD processing and the challenge of livestock waste disposal. The findings contribute to the development of cost-effective and ecofriendly strategies for AMD management while advancing the understanding of microbial mechanisms of insitu bioremediation.

Fe-doped g-C3N4 has been proven to have the potential of visible light photocatalysis, but its catalytic activity of peroxymonosulfate (PMS) is neglected. Herein, the complex advanced oxidation processes of Fe-g-C3N4 mediated PMS and visible light photocatalysis was developed, named as Vis/Fe-g-C3N4/PMS system, whose effects and synergistic mechanism for decomposing Rhodamine B (RhB) was evaluated. The coupling of sulfate radicals and photocatalysis for RhB degradation showed that the synergistic efficiency (ηSyn) and factor (Sc) were 20.1

Acidic pit lakes (APLs) emerge as reservoirs of acid mine drainage in flooded open-pit mines, representing extreme ecosystems and environmental challenges worldwide. The bioremediation of these oligotrophic waters necessitates the addition of organic matter, but the biogeochemical response of APLs to exogenous organic matter remains inadequately comprehended. This study delves into the biogeochemical impacts and remediation effects of digestate-derived organic matter within an APL, employing a multi-omics approach encompassing geochemical analyses, amplicon and metagenome sequencing, and ultra-high resolution mass spectrometry. The results indicated that digestate addition first stimulated fungal proliferation, particularly Ascomycetes and Basidiomycetes, which generated organic acids through lignocellulosic hydrolysis and fermentation. These simple compounds further supported heterotrophic growth, including Acidiphilium, Acidithrix, and Clostridium, thereby facilitating nitrate, iron, and sulfate reduction linked with acidity consumption. Nutrients derived from digestate also promoted the macroscopic development of acidophilic algae. Notably, the increased sulfate reduction-related genes primarily originated from assimilatory metabolism, thus connecting sulfate decrease to organosulfur increase. Assimilatory and dissimilatory sulfate reduction collectively contributed to sulfate removal and metal fixation. These findings yield multi-omics insights into APL biogeochemical responses to organic matter addition, enhancing the understanding of carbon-centered biogeochemical cycling in extreme ecosystems and guiding organic amendment-based bioremediation in oligotrophic polluted environments.

The alkaline sludge produced by the neutralization treatment of acid mine drainage (AMD) is not only large and difficult to treat, but also prone to secondary pollution. The cost of conventional sludge treatment technology is high, so there is an urgent need to develop new methods. The process of neutralizing AMD is similar to the co-precipitation reaction of LDHs, so the cost of recovering LDHs from AMD is lower, but the application performance of LDHs is limited by the stacking of laminates. In this paper, the structure of LDHs was optimized by adding biochar (BC) during the neutralization process of AMD. After adding 40 % BC, the crystal planes of alkaline sludge based LDHs (AS-LDHs) became more parallel, and the adsorption properties of Cd and Cu were increased by 2.7 and 1.95 times, with the maximum adsorption amounts of 901.5 and 231.3 mg/g, respectively. The relevant removal mechanism was investigated in depth at the electronic scale by experiments combined with DFT calculations. Since AS-LDHs have the advantages of good acid stability, low zero-point charge and strong adsorption and regeneration capacity, this method has a broad application prospect.

针对含锰(Mn2+)废水处理与城市污水处理厂污泥的安全处理处置问题,文章将合肥市某污水处理厂污泥在CO2气氛和550℃条件下进行热解,并用3 mol/L KOH进行改性,制备得到复合改性污泥生物炭(composite modified sludge biochar,CMSB),并将其用于含Mn2+废水处理.实验结果表明,CMSB在pH=4、投加量为1.0 g/L时,对Mn2+的吸附量可达37.63 mg/g.CMSB对Mn2+的吸附行为可以很好地通过准二级动力学模型和Langmuir等温线模型拟合,热力学分析结果表明吸附过程是自发、吸热、熵增的,主要吸附机制包括含氧官能团络合、π键作用、静电吸引及阳离子交换.研究结果可为城市污水处理厂污泥的安全处置和含Mn2+废水处理提供技术支持和理论基础.

The stratified acidic pit lake formed by the confluence of acid mine drainage has a unique ecological niche and is a model system for extreme microbial studies. Eukaryotes are a component of the AMD community, with the main members including microalgae, fungi, and a small number of protozoa. In this study, we analyzed the structural traits and interactions of eukaryotes (primarily fungi and microalgae) in acidic pit lakes subjected to environmental gradients. Based on the findings, microalgae and fungi were found to dominate different water layers. Specifically, Chlorophyta showed dominance in the well-lit aerobic surface layer, whereas Basidiomycota was more abundant in the dark anoxic lower layer. Co-occurrence network analysis showed that reciprocal relationships between fungi and microalgae were prevalent in extremely acidic environments. Highly connected taxa within this network were Chlamydomonadaceae, Sporidiobolaceae, Filobasidiaceae, and unclassified Eukaryotes. Redundancy analysis (RDA) and random forest models revealed that Chlorophyta and Basidiomycota responded strongly to environmental gradients. Further analysis indicated that eukaryotic community structure was mainly determined by nutrient and metal concentrations. This study investigates the potential symbiosis between fungi and microalgae in the acidic pit lake, providing valuable insights for future eukaryotic biodiversity studies on AMD remediation.

Acidic pit lakes represent hydrological features resulting from the accumulation of acid mine drainage in mining operations. Long-term monitoring is essential for these extreme and contaminated environments, yet tracking investigations integrating microbial geochemical dynamics in acidic pit lakes have been lacking thus far. This study integrated historical data with field sampling to track decadal biogeochemical changes in an acidic pit lake. With limited artificial disturbance, significant and sustained biogeochemical changes were observed over the past decade. Surface water pH slowly increased from 2.8 to a maximum of 3.6, with a corresponding increase in bottom water pH to around 3.9, despite the accumulation of externally imported sulfate and metals. Elevated nutrient levels stimulated the macroscopic growth of Chlorophyta, resulting in a shift from reddish-brown to green water with floating algal bodies. Furthermore, microalgae-fixed organic carbon promoted the transition from the initial chemolithotrophy-based population dominated by Acidiphilium and Ferrovum to a heterotrophic community. The increase in heterotrophic iron- and sulfate-reducers may cause an elevation in ferrous levels and a decline in copper concentrations. However, most metals were not removed from the water column, potentially due to insufficient biosulfidogenesis or sulfide reoxidation. These findings offer novel insights into microbial succession in extreme ecosystem evolution and contribute to the management and remediation of acidic pit lakes.

与传统的废水中去除Mn2+方法相比,生物修复具有更高的环境和经济效益.从安徽某铁硫矿山的酸性废水坑湖中分离纯化得到一株新型藻株——Parachlorella kessleri MP1,研究了其在不同pH值、Mn2+浓度条件下的生长过程、培养基pH值变化和除锰效率,并分别通过测定细胞内外去除Mn2+量、谷胱甘肽(GSH)含量、巯基含量以及傅里叶变化红外光谱(Fourier transform infrared spectroscopy,FTIR)分析初步探讨了除锰机制.结果表明,Parachlorella kessleri MP1 可耐受pH值为 3.5 的酸性环境,且对Mn2+具有良好去除效果.当Mn2+初始浓度分别为5、15 和30 mg/L时,pH=3.5 和pH=7.0 初始条件下可分别实现 35.86%、30.82%、27.54%和 93.73%、74.11%、52.22%的去除率.此外,该藻株具有产碱作用,pH=3.5 试验组反应结束时pH值达到了 9.04.所测胞外去除Mn2+量远大于胞内去除,胞内GSH和巯基含量有所增加,FTIR分析得知细胞表面—NH2、—OH、—COOH和C—O等官能团参与了除锰过程.因此,微藻除锰过程中胞外去除发挥主要作用.

Biological processes based on the oxidation of Mn(II) are extensively favored. However, this is always limited by the low pH of wastewater. The biological removal of Mn(II) from acidic wastewater through immobilization technology is a promising approach owing to its high efficiency and low cost. However, the mechanism underlying Mn(II) removal by fungi remains unclear. In this study, a strain of acid-tolerant Aspergillus sp. MF1 screened from acid mine drainage (AMD), was used for immobilization. The results showed that polyvinyl alcohol (PVA), sodium alginate (SA), and zeolite were the best carrier materials, and the contents of CaCl2, PVA, SA, zeolite, and spore suspension were 4%, 6%, 2%, 4%, and 15%, respectively. The maximum Mn(II) removal efficiency achieved was 77.21%. Additionally, the analysis of subcellular distribution and chemical morphology demonstrated that Mn(II) removal was attributed to intracellular enrichment. The microspheres were reused for three cycles, and the removal efficiency of Mn(II) was guaranteed to exceed 60%. In summary, the immobilized Aspergillus sp. MF1 has stronger acid resistance and more effective treatment efficiency under high concentrations of Mn(II) compared to traditional biological processes, illustrating the excellent application prospects for Mn(II)-containing acidic wastewater.

The growth and metabolism of microorganisms are often affected by salinity, so screening the salt-tolerant strains is of great significance for the biological treatment of saline wastewater. In this paper, Shewanella aquimarina XMS-1, a marine strain with salt tolerant metal reduction function (DMRB), was selected as the research object to explore the effects of salinity on the reduction process of Fe3+ and the changes of extracellular polymers. The Fe3+ reduction ability of XMS-1 and the extracellular polymer (EPS) content under different salinity were investigated. Furthermore, Three dimensional fluorescence excitation-emission ( 3D-EEM) Raman spectra ( Raman) Fourier transform infrared spectroscopy ( FTIR) and Twodimensional correlation spectroscopy (2D-COS) were used to analyze the changes in extracellular polymers during the reduction of Fe3+ by XMS-1. The results show that protein is the main substance in XMS-1 EPS, accounting for more than 80% of EPS content, and polysaccharide content is relatively small. 3% salinity conditions promote EPS production. XMS-1 will secrete more EPS in the high salt environment to protect cells from normal physiological activities. The reduction process of Fe3+ is accelerated at the salinity of 1%, but is inhibited when the salinity is higher than 5%0. Too high salinity would inhibit the growth of XMS-1, resulting in the decrease of the Fe3+ reduction rate. The reduction rate of Fe3+ was increased by 2. 18 times and reached 44. 1% at the salinity of 3%. FTIR and Raman spectra showed that XMS-1 EPS contained metal ion redox functional groups such as carboxyl, hydroxyl, amino and carbonyl. The peaks of protein amides and polysaccharides in EPS were enhanced at 3% salinity, and the representative peaks of protein amides changed significantly. The O- and N- groups were effective redox groups in Fe3+ reduction. In addition, the Three-dimensional fluorescence results showed that after the Fe3+ reduction process, the intensities of the two fluorescent components of tryptophan and tyrosine in EPS decreased. Combined with the analysis of 2D-COS spectral results, it was found that tryptophan-like proteins changed significantly during the reduction of Fe3+, indicating that the two fluorescent components were involved in the reduction process of Fe3+, and tryptophan-like proteins played a stronger role in the reduction process. This study enriched the understanding of the extracellular electron transfer process of EPS in halophilic bacteria, and highlighted the significance of EPS in iron redox transformation in natural environment.

[目的]探究酸性矿山废水(acidmine drainage,AMD)坑湖中细菌群落沿垂向不同水深的分布规律及与环境因子之间的相互作用.[方法]采用16S rRNA基因高通量测序技术,对安徽省某AMD坑湖中6条采样垂线不同水深深度的细菌群落进行调查,同时测定水质理化指标,使用统计学软件分析细菌和地化参数间的联系.[结果]AMD坑湖中水质特征及细菌群落结构出现明显分层现象,自上而下溶解氧降低而pH和多种金属离子浓度增加,微生物群落结构发生变化,多样性和部分物种的丰度增大.细菌群落组成上,表层水域以Proteobacteria(Alpha、Gammaproteobacteria)和 Acidobacteria 占据主导地位;中下层水域则由 Firmicutes、Acidobacteria、Actinobacteria、Gammaproteobacteria 和 Patescibacteria等共同主导.统计分析结果表明,TN、DO、ORP、pH、Fe、Mn、Al和Zn与嗜酸细菌丰度显著相关,是细菌空间分布的主要限制因素.[结论]AMD坑湖中水质理化特征和细菌群落分布在垂向空间上存在显著差异,群落的垂向分层特征是由多种环境因子共同作用下的结果.本研究对深入了解AMD的微生物分布规律及对AMD的原位生物修复和治理具有参考价值.

Acid mine drainage (AMD) is characterized by high acidity and high-concentration metals and sulfate, representing an extreme environment to life as well as environmental challenge worldwide. Microorganisms thriving in AMD habitats have evolved with distinct mechanisms in response to multiple stresses. Compared with microbial prokaryotes, our understanding regarding eukaryotic occurrence and role in AMD habitats remain limited. Here we examined microbial diversity and co-occurrence pattern within all domains of life in five lakes with varying degrees of AMD contamination ranging from extremely acidic to neutral. We demonstrated that AMD pollution reduced both eukaryotic and prokaryotic diversity in the lakes. In lakes with serious AMD pollution, chemoautotrophs including Ferrovum, Acidithiobacillus, and Leptospirillum showed significantly higher abundance, whereas with the macroscopic growths of photosynthetic microalgae (e.g., Coccomyxa and Chlamydomonas), heterotrophic or mixotrophic prokaryotes (e.g., Acidiphilium, Thiomonas, and Alicyclobacillus) increased in less polluted lakes. In the further improved ecosystems, Ochromonas, Rotifer, Ciliophora and other microeukaryotes appeared. Combined with a public dataset focusing on the microbes along an AMD-contaminated stream, we further demonstrated that acidity-dominated environmental selection served as the primary driver of both eukaryotic and prokaryotic community assemblies, and to a greater extent for eukaryotes. Furthermore, specific prokaryotic and eukaryotic taxa (e.g., Proteobacteria and Chlorophyta) exhibited wide taxonomic and functional associations in these AMD-polluted waters. These findings expand our knowledge on the eukaryotic diversity in AMD habitats, and provide insights into the ecological processes underlying microbial communities in response to AMD contamination.

含锰(Mn)重金属废水的处理是行业痛点与难点,近年来高效的生物脱锰技术得到广泛关注,但具有较高锰氧化效率菌株的报道仍然有限.本研究从酸性矿山废水中分离纯化出一株锰氧化细菌,并深入探究其微生物特性以及对Mn2+的去除作用.通过生理生化及16SrRNA序列分析鉴定该菌株为短芽孢杆菌,并命名为Brevibacillus brevis MM2.进一步通过单因素实验探究了环境因子和初始锰浓度对菌株MM2的生长和锰去除率的影响.结果表明,菌株MM2对Mn2+的最高耐受浓度可达1000mg·L-1,且在弱酸条件下(pH 6、pH 5)仍然显现出良好的生长趋势,具有较高的锰去除率(91.93％,pH=6).此外,菌株MM2在30～35℃,pH7,转速180r·min-1条件下生长趋势最好,当初始Mn2+浓度为100mg·L-1时,Mn2+的最高去除率为92.76％.最后,通过扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、X射线衍射(XRD)、傅里叶红外光谱仪(FTIR)对代谢固相产物分析表明,菌株MM2介导生成的生物氧化锰附着在菌株表面并以层状和颗粒状两种形态呈现,锰平均氧化度为3.55,其成分主要为无定形的Mn2O3和MnO2·综上所述,本研究分离纯化的菌株MM2不仅能在弱酸性条件下生长且对锰具有较高的耐受和去除能力,在含锰废水的处理中具有较好应用前景.

Chemical neutralization is extensively used in the treatment of acid mine drainage, and the removal of manganese (Mn) is the limiting process for meeting the discharge standards. The formation of Mn-containing precipitates is the main removal mechanism in the neutralization process. This study compared the formation of Mn-containing precipitates under aeration and mechanical stirring conditions, and the effect of aeration rates was also studied. In the aeration-stirring group, the precipitate was composed of hausmannite (Mn3O4), bixbyite (Mn2O3) and rhodochrosite (MnCO3). In addition, Mn(OH)2 was detected in the mechanically stirred group. The results show that the Mn3O4 content in the precipitate increased significantly under aeration conditions and reached a maximum value of 71.9% when the aeration rate was 66.90 L/min. Its content decreased to 54.0% when the aeration rate was increased to 133.80 L/min. The MnCO3 content increased with an increase in the aeration rate and reached a maximum value of 27.3% at an aeration rate of 133.80 L/min. The scanning electron microscopy images revealed that the generated lamellar rhodochrosite (MnCO3) could wrap MnOx and hinder the formation of Mn3O4. This was also verified by the Mn average oxidized state (MnAOS) of the groups. Based on the experimental and calculation results, MnO2 was formed under acidic conditions, and Mn3O4 and Mn2O3 appeared with an increase in the pH level. Meanwhile, the Mn (III) and Mn (IV) oxides are intermediates that were converted into low valance manganese oxides through autocatalysis.

Acid mine drainage (AMD) lakes are typical hydrologic features caused by open pit mining and represent extreme ecosystems and environmental challenges. Little is known about microbial distribution and community assembly in AMD lakes, especially in deep layers. Here, we investigated prokaryotic microbial diversity and community assembly along a depth profile in a stratified AMD lake using 16S rRNA gene sequencing combined with multivariate ecological and statistical methods. The water column in the AMD lake exhibited tight geochemical gradients, with more acidic surface water. Coupled with vertical hydrochemical variations, prokaryotic microbial community structure changed significantly, and was accompanied by increased diversity with depth. In the surface water, heterogeneous selection was the most important assembly process, whereas stochastic processes gained importance with depth. Meanwhile, microbial co-occurrences, especially positive interactions, were more frequent in the stressful surface water with reduced network modularity and keystone taxa. The pH was identified as the key driver of microbial diversity and community assembly along the vertical profile based on random forest analysis. Taken together, environmental effects dominated by acid stress drove the community assembly and species coexistence that underpinned the spatial scaling patterns of AMD microbiota in the lake. These findings demonstrate the distinct heterogeneity of local prokaryotic microbial community in AMD lake, and provide new insights into the mechanism to maintain microbial diversity in extreme acidic environments.