Evaluating the role of re-adsorption of dissolved Hg2+ during cinnabar dissolution using isotope tracer technique

• Published in: Journal of hazardous materials Vol. 317; no. C; pp. 466 - 475
• Main Authors: Jiang, Ping, Li, Yanbin, Liu, Guangliang, Yang, Guidi, Lagos, Leonel, Yin, Yongguang, Gu, Baohua, Jiang, Guibin, Cai, Yong
• Format: Journal Article
• Language: English
• Published: United States Elsevier B.V 05.11.2016; Elsevier
• Subjects: 07 ISOTOPE AND RADIATION SOURCES; Cinnabar dissolution; Hg re-adsorption on cinnabar surface; Isotope dilution; isotope labeling; Isotope tracer technique; isotopes; mercury; oxygen; Redox condition; Isotope dilution; Cinnabar dissolution; Redox condition; Hg re-adsorption on cinnabar surface; Isotope tracer technique
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2016.05.084

[Display omitted] •Develop a new method to study Hg re-adsorption in cinnabar.•Both isotope dilution and tracer techniques were adopted.•The presence of O2 can significantly enhance the dissolution of cinnabar.•Prove the necessity of including re-adsorption in estimating cinnabar dissolution. Cinnabar dissolution is an important factor controlling mercury (Hg) cycling. Recent studies have suggested the co-occurrence of re-adsorption of the released Hg during the course of cinnabar dissolution. However, there is a lack of feasible techniques that can quantitatively assess the amount of Hg re-adsorbed on cinnabar when investigating cinnabar dissolution. In this study, a new method, based on isotope tracing and dilution techniques, was developed to study the role of Hg re-adsorption in cinnabar dissolution. The developed method includes two key components: (1) accurate measurement of both released and spiked Hg in aqueous phase and (2) estimation of re-adsorbed Hg on cinnabar surface via the reduction in spiked 202Hg2+. By adopting the developed method, it was found that the released Hg for trials purged with oxygen could reach several hundred μgL−1, while no significant cinnabar dissolution was detected under anaerobic condition. Cinnabar dissolution rate when considering Hg re-adsorption was approximately 2 times the value calculated solely with the Hg detected in the aqueous phase. These results suggest that ignoring the Hg re-adsorption process can significantly underestimate the importance of cinnabar dissolution, highlighting the necessity of applying the developed method in future cinnabar dissolution studies.