Biogeochemical processes governing natural pyrite oxidation and release of acid metalliferous drainage

The oxidative dissolution of sulfide minerals (principally pyrite) is responsible for the majority of acid metalliferous drainage from mine sites, which represents a signi?cant environmental problem worldwide. Understanding the complex biogeochemical processes governing the natural pyrite oxidation is critical to not only solving this problem but also industrial bioleaching of sulfide minerals. To this end, we conducted a simulated experiment of natural pyrite oxidative dissolution. Microbial community analysis assessed by pyrosequencing revealed a distinct succession across the three stages: at the early stage, a newly proposed genus Tumebacillus using sodium thiosulfate and sulfite as sole electron donors, dominated the microbial community; at the mid stage, Alicyclobacillus (the fifth most abundant genus at the early stage) became the most dominant genus, while Tumebacillus was still ranked as the second most abundant genus; at the last stage, the microbial community was dominated by Ferroplasma (the tenth most abundant genus at the early stage). The geochemical and mineralogical analyses showed that the exchangeable heavy metals increased as the oxidation progressed and that some secondly sulfate minerals (including jarosite and magnesiocopiapite) were formed at the last stage of the oxidation. Moreover, we proposed a comprehensive model of biogeochemical processes governing oxidation of sulfide minerals.

硫化矿物（主要为黄铁矿）的氧化溶解是造成绝大多数含金属酸性矿山排水的核心原因，该问题已成为全球范围内亟待解决的重大环境难题。解析调控天然黄铁矿氧化的复杂生物地球化学过程，不仅是破解该环境问题的关键所在，同时对硫化矿物的工业生物浸出也具有重要的理论与应用价值。为此，我们开展了天然黄铁矿氧化溶解的模拟实验。通过焦磷酸测序（pyrosequencing）开展的微生物群落分析结果显示，实验过程中微生物群落在三个阶段呈现出显著的演替特征：实验早期，新提出的Tumebacillus属（Tumebacillus）以硫代硫酸钠和亚硫酸盐作为唯一电子供体，成为群落的优势菌群；实验中期，原本在早期丰度排名第五的环酸芽孢杆菌属（Alicyclobacillus）跃升为群落的主导菌群，而Tumebacillus属仍位列丰度第二；实验末期，铁原体属（Ferroplasma，早期丰度排名第十）主导了整个微生物群落。地球化学与矿物学分析表明，随着氧化进程的推进，体系中可交换态重金属含量逐步升高，且在氧化末期形成了包括黄钾铁矾（jarosite）和镁叶绿矾（magnesiocopiapite）在内的多种次生硫酸盐矿物。此外，我们提出了一套调控硫化矿物氧化过程的综合生物地球化学模型。