金属矿区硫素生物地球化学循环过程中的关键问题

During the mining process of metal sulfides minerals, large volumes of AMD containing high concentration of heavy metals and sulphate are generated and discharged to surrounding environments.Through transport in river, sulphate ion is spread to sediment and soil, causing serious problem to nearby ecosystems. In this project, the principal mechanisms of formation, migration, transformation and biogeochemistry of sulfate will be studied. Details are listed as follows: (1) investigating the mechanism of sulfate formation, including i) characterization of different valences and speciation of sulfur in the process of sulfide oxidation; ii) the formation, composition and oxidation of sulfur layers on the surface of sulfide minerals; iii) quanlitative and quantitative analysis of microbial community in the mine tailings using cultivation (MPN,SYBER-green stained,etc.) and molecular biological (PCR-DGGE,Q-PCR,CARD-FISH,meganomics,etc.) methods; iv) isolation and identification of typical sulfur-oxidizing bacteria from the mine tailings; v) comparative study of sulfur oxidation in the presence and absence of sulfur-oxidizing bacteria; (2) Studying the migration and transformation of sulfate in the surface water, suspended particles and sediments, including i) the analysis of the sulfate concentration in diffent seasons (flooding and drought, winter and summer);ii) the horizontal and vertical distribution of microbial community, sulfate reducing bacteria and sulfur speciation in the sediment; iii) the effect of various minerals and complexes of humid acid-minerals on the adsorption and migration of sulfate;iv) the effect of geochemical parameters (Eh, pH, metal ions, etc.) on the biogeochemical process of sulfate-reduing bacteria in sediment;(3) demonstrating the mechanism of sulfate reduction and microbial communities in the long-term AMD irrigated soil, including i)the effect of long-term irrigated AMD on the microbial community of farm soil;ii) the analysis of sulfur speciation in the rhizosphere of farm soil; iii) the relationship betwwen sulfate reduction and microbial metabolic pathway of sulfate-reducing bacteria. In addition, typical sulfur-oxidizing bacteria (SOB) and sulfate-reducing bacteria (SRB) will be isolated from the sulfides minerals tailing, sediment and soil, respectively. They will be further used to study the mechanism the formation and transformation of sulfate in metal mining area using molecular biological methods.The results of this study will help elucidate mechanisms underlying the sulfur biogeochemical processes, assess environmental impacts of sulfate, and provide scientific support for remedy of sulfate-polluted areas.

金属硫化物矿山在开采过程中会产生大量的酸性矿山废水（AMD），其中所含的硫酸根离子浓度极高，通过水体迁移进入到河流、沉积物及土壤环境后，给周边生态环境带来严重影响。本项目拟以矿山尾矿中常见金属硫化物矿物为对象，重点研究矿物氧化过程中硫膜形成和进一步氧化机理；研究硫酸根在矿区水体、悬浮物、水-沉积物界面和沉积物中的迁移和转化规律，在沉积物中硫形态变化与还原机理；研究AMD长期灌溉水稻土中微生物功能菌群演替特征和硫酸根离子生物还原过程驱动因素，包括SRB群落对水稻土环境地球理化因子变化的响应（SRB菌群组成、多样性和丰度的演替），硫酸根离子还原速率差异等；应用宏基因组学和稳定同位素探针研究矿区典型硫氧化菌和硫酸盐还原菌在硫酸根形成和转化中的微观机理。通过上述研究弄清楚硫素在矿区的生物地球化学过程主要关键问题,加深对硫酸根离子环境影响的认识，为硫酸根离子的污染治理提供理论支撑。

金属硫化物矿山在开采过程中会产生大量的酸性矿山废水（AMD），其中所含的硫酸根离子浓度极高，给周边生态环境带来严重影响。本项目以典型的多金属硫化物矿山广东大宝山为对象，对矿山尾矿氧化过程中硫素氧化及其在不同环境介质中迁移转化的生物地球化学过程的关键问题进行研究。结果表明，金属硫化物矿物黄铁矿化学和生化氧化过程形成硫膜及一系列硫氧化中间产物，SnO62-为微生物氧化主要中间产物，经水解产生SO42-和单质硫，以及伴随产生铁硫酸盐次生矿物；基于转录组学阐明硫氧化菌A. ferriphilus SCUT-1的无机硫氧化模型和参与亚铁氧化的相关基因；受酸性矿山废水（AMD）污染的富含SO42-域中水体、悬浮物和沉积物等不同环境介质中SO42-的形态各异，河水中硫最主要的存在形态是SO42-，其次是FeSO4+和HSO4-；横石河沉积物中的硫仍以可交换态硫（ExS）为主， SO42-与Fe(III)及重金属共沉淀形成含铁羟基硫酸盐矿物、含铁羟基（硫酸盐）次生矿物，对SO42-以及重金属的吸附和再分配行为具有重要影响；沉积物中硫酸盐还原功能菌诱导沉积物中富硫次生矿物（施氏矿物和黄钾铁钒）溶解转化是SO42-释放的关键过程；AMD灌溉水污染水稻土系统中还原态无机硫和碳键硫主要分布在表层土壤，吸附态硫主要在20~30cm深度，酯键硫在每一层都有较高含量630~1065 mg/kg硫；发现AMD灌溉稻田土壤中Acidobacteria的相对丰度较高，SRB的优势菌属是Desulfobacca，明晰了矿区AMD污染水稻土中SO42-迁移转化过程及微生物功能菌群的作用机制，为矿区硫酸根和重金属污染的治理提供理论支撑。