藻源性缺氧湖区沉积物-水界面还原态硫形成过程及机制研究

Algae-induced hypoxia is one of the most serious risks in eutrophic shallow lakes. Transportation and transformation of reduced sulfur in water column is directly related to the formation and recover of lake black bloom disaster. This research focus on the behavior of reduced sulfur at sediment water interface in algae-induced lake hypoxia. Sediment water interface micro-sensors, δ34S stable isotope analysis, synchrotron radiation-X ray analysis of the near edge structure analysis etc. are employed to detect the formation of reduced sulfur. During the hypoxia period, the accumulation characteristics, the transportation dynamics, the material resource, and the affecting factors of reduced sulfur at sediment water interface are fully studied. The research results will contribute to the formation mechanism of reduced sulfur at sediment water interface and will provide new viewpoints and methods to the sulfur cycle in hypoxic lake environment.

浅水湖泊藻源性缺氧是水体富营养化加剧的危害之一，缺氧过程水环境还原态硫的迁移转化直接影响湖泊黑臭次生灾害的暴发与恢复。本项目以藻源性缺氧湖泊沉积物-水界面溶解性还原态硫为研究对象，利用沉积物-水微界面探测、δ34S稳定同位素分析、还原态硫化学精细结构解译等技术，重点研究水体缺氧过程沉积物-水界面还原态硫积累、迁移的动力学规律，解析水土界面还原态硫的形成过程及物质供应来源，并分辨影响还原态硫积累的主要驱动因子。通过上述研究，试图建立缺氧过程沉积物-水界面还原态硫形成机制，为缺氧水体水环境变化及水环境硫素迁移转化研究提供新的观点和方法。

本项目以浅水湖泊藻源性缺氧沉积物-水界面为研究对象，对该体系中还原态硫素迁移转化特征规律进行全过程研究。在野外调研和室内模拟研究相结合的基础上，借助微界面分析、微生物分析等技术手段开展综合研究。研究结果表明：典型缺氧易发湖区沉积物间隙水SO42-呈现明显的季节性变化及夏季亏损现象，表层沉积物酸可挥发性硫化物及还原态硫含量在藻类暴发季节明显增加。水体缺氧过程中，受氧化还原场变化及电子受体顺位影响，上覆水ΣS2-出现典型的随缺氧程度加深而迅速积累的特征，沉积物-水界面ΣS2-产率显著加快，水相和土相中S素出现从SO42-向ΣS2-转化的趋势。水土界面ΣS2-迁移规律分析表明，沉积物-水界面是S素从高价态向终端还原态转化的源场所和主要转化地，是浅水湖泊缺氧灾变成黑臭水体“湖泛”的发生场所。还原态硫素ΣS2-的生成和积累，是控制湖泛形成的直接限制因子。水土界面DO的缺失及pH-EH场向还原态的转化是沉积物-水界面还原态硫形成的最主要影响因素，SRB的大量增殖及生长代谢是沉积物-水微界面ΣS2-得以积累的直接驱动。