红铊矿微生物风化过程中铊形态组成变化特征研究

Thallium(Tl) is an extremely toxic heavy metal, which has two oxidation states known as monovalent Tl(I) and trivalent Tl(III). Transformations among different speciation of Tl have led to different environmental impact to the environment. Thallium has been added to the shortlist of heavy metals that are under governance controlled by ‘The Integrated Control of Heavy Metal Pollution of 12th Five-Year Plan’. The weathering of Tl-containing sulphide minerals is one of the most Tl contamination sources, which continuously emits Tl to the surface environment, while microbial activity play an important role in controlling the weathering process. Up to date, however, little is known on the transformation of Tl during microbial weathering of thallium-containing sulphides. Hence, the proposed project aims to study the transformation of Tl during the microbial weathering of Lorandite, which may further provide insights to the transportation of Tl from the sulphide minerals to the surface environment. The results of this study will not only increase our understanding on the biogeochemical cycling of Tl in the surface environment, but will also provide a guideline for future thallium pollution prevention.

铊（Tl）是一种毒害重金属元素，在自然界存在Tl(I)和Tl(III)两种价态，二者在环境体系中的相互转化过程会产生不同的环境效应，国家《重金属污染综合防治“十二五“规划》将其列为重点防控的重金属污染物之一。含铊硫化物风化是表生环境中铊污染持续的和最重要的来源，微生物活动会对其风化过程产生重要影响。但迄今对含铊硫化物矿物微生物风化过程中铊形态转化特征还缺少清晰认识。因此，本项目以含铊硫化物矿物红铊矿为研究对象，以微生物作用下红铊矿风化过程中铊形态转化特征为研究目标，开展红铊矿微生物风化溶解过程、风化产物成分及其形貌特征研究，查明红铊矿微生物风化过程中铊释放规律及铊形态转化特征，揭示含铊硫化物风化过程中铊进入表生环境的地球化学行为特征，项目研究成果有望丰富和深化对表生环境中铊生物地球化学循环规律的认识，还可为含铊硫化物铊污染防治提供理论指导。

含铊硫化物风化是表生环境中铊污染持续的和最重要的来源，微生物活动会对其风化过程产生重要影响。但迄今对含铊硫化物矿物微生物风化过程中铊形态转化特征还缺少清晰认识。本项目以典型Tl-Hg-As矿冶区含铊硫化物废弃矿物等为研究对象，开展含铊硫化物废弃矿物元素赋存、微生物群落分布和微生物风化溶解铊形态转化特征研究，研究结果表明：（1）含铊硫化物废弃矿物等呈现高Tl、As、S含量和低pH的特征，其风化释放进入表生环境污染风险较高；（2）含铊硫化物废弃矿物等铊的赋存形态基本存在以下规律：残渣态＞可还原态＞可氧化态＞可交换态＞水溶态。高S含量导致可氧化态铊占比升高；（3）S、Tl和As协同调控微生物物种丰度和生物多样性；（4）微生物通过产酸能力变化改变Tl释放-吸附特征；（5）微生物风化作用下进入环境中铊主要以Tl(I)形式存在，占比为67.1～91.8%，而部分以Tl（III）形式存在，占比范围为8.2～32.9%。综上所述，本研究成果不仅丰富和深化对表生环境中铊生物地球化学循环规律的认识，同时还为含铊硫化物铊污染防治提供理论指导。