A research team led by Prof. Ruoyu Sun from the Isotope Frontier Science Research Center, School of Earth System Science, Tianjin University, has established a two-stage purge-and-trap method to separate inorganic mercury (IHg) and methylmercury (MeHg) in biotic samples, enabling direct, independent isotopic measurement of the two mercury species.
Taking the Bohai coastal marine food web as the study area, the team systematically analyzed seasonal and habitat-driven variations in concentrations and isotopic compositions of different mercury forms. Key findings show that mercury accumulation in marine organisms is more determined by the proportion of marine-sourced organic matter in their diet than trophic level. Distinct Δ¹⁹⁹Hg/Δ²⁰¹Hg slopes quantitatively confirm that 36±23% of IHg in summer surface-dwelling organisms comes from in-vivo MeHg demethylation, and that MeHg bioaccumulated in Bohai nearshore surface organisms is primarily produced via sediment methylation, rather than in-situ methylation in seawater.
This study addresses the long-standing limitation that previous mercury isotope research could not directly measure IHg isotopes in biota, offering new insights for coastal mercury exposure assessment and marine mercury cycling modeling under the Minamata Convention implementation context. The two related achievements have been published in top international journals Environmental Science & Technology and Journal of Analytical Atomic Spectrometry. Dr. Li Songjing, postdoctoral researcher at SESS, is the first author of both papers, and Prof. Sun Ruoyu serves as the corresponding author. This research was supported by the National Natural Science Foundation of China (Grants No. 42421003, 42173011, 42373011) and the Tianjin Distinguished Young Scientists Fund (Grant No. 23JCJQJC00280).
The articles:
Songjing Li(李松旌), Ruoyu Sun*(孙若愚), Xiaowei Chen(陈筱玮), Zhao Wang(王钊), Chao Zhang(张超), Pengfei Li(李鹏飞), Yi Liu(刘羿), Wang Zheng(郑旺), and Jiubin Chen(陈玖斌). 2026. Seasonal and Habitat-Specific Mercury Cycling in Coastal Biota Revealed by Species-Specific Isotopes. Environ. Sci. Technol.
https://doi.org/10.1021/acs.est.5c18280
Songjing Li(李松旌), Ruoyu Sun*(孙若愚), Xiaowei Chen(陈筱玮), Wei Zhang(张微), Mei Meng(孟梅), Yi Liu(刘羿), Wang Zheng(郑旺), and Jiubin Chen(陈玖斌). 2025. A dual-stage purge–trap protocol to separate species-specific mercury from marine biota for precise isotopic analysis. J. Anal. At. Spectrom., 40(3), 727–737.
https://doi.org/10.1039/D4JA00341A
