https://doi.org/10.16030/j.cnki.issn.1000-3665.202410014

Pi Kunfu; Wang Yanxin; LIU Juewen; Yang Yanan; PHILIPPE Van Cappellen (2025) Speciation and migration mechanism of trace mercury in groundwater, Hydrogeology and Engineering Geology. 2025, 52 (02)., https://doi.org/10.16030/j.cnki.issn.1000-3665.202410014

Accurately measuring the concentration changes of different forms of mercury (Hg) in groundwater is crucial for understanding the migration and transformation mechanisms of mercury and its potential risks to aquatic ecosystem security. However, this fundamental research currently faces challenges, with the bottleneck being the lack of a detection technology that combines high sensitivity, high reliability, and rapid on-site deployment to achieve precise monitoring of trace amounts of Hg(II) in groundwater. Therefore, this article introduces novel detection methods based on deoxyribonucleic acid (DNA) sensing materials and explores the feasibility and advantages of two biosensing methods: one is the direct detection of Hg(II) in groundwater using DNA-functionalized hydrogels; the other is the construction of a DNA-DGT sensor by combining thin-film diffusion gradient technology (DGT) with DNA sensing elements to achieve real-time sampling and detection of Hg(II). Testing of groundwater from the Rio Grande River basin in Canada, which exhibits diverse hydrogeochemical characteristics, revealed that DNA-functionalized hydrogels can rapidly detect dissolved Hg(II), but are not suitable for low concentrations (<1.60 ?g/L). In contrast, DNA-DGT sensors can capture ultra-trace Hg(II) speciation at varying concentrations depending on the testing duration. Further quantitative analysis of Hg(II) speciation in groundwater, combining DNA-DGT sensor detection with hydrogeochemical calculations, showed that temperature, pH, Cl-, and dissolved organic matter (DOM) significantly influence the speciation, diffusion efficiency, and migration capacity of trace Hg(II). Combined with hydrogeochemical simulation analysis, DNA-DGT measurements revealed a close correlation between Hg(II) migration and transformation processes and the sulfur redox cycle in groundwater. This study emphasizes the importance of using highly sensitive, easily deployable biosensing methods to monitor low concentrations of Hg(II) for understanding the migration and transformation patterns of mercury in groundwater and its potential threat to safe water supply.

https://doi.org/10.16030/j.cnki.issn.1000-3665.202410014