Mercury methylation from mercury selenide particles in soils

Area of Science:

• Environmental Chemistry
• Geochemistry
• Environmental Science

Background:

• Monomethylmercury (MeHg) poses significant environmental and health risks.
• Selenium's role in inhibiting MeHg production is a promising mitigation strategy.
• The methylation potential of aged mercury selenide (HgSe) particles in soils remains poorly understood.

Purpose of the Study:

• To investigate the net MeHg production from different geochemical species of HgSe particles during aging in soils.
• To compare MeHg production from HgSe nanoparticles, microparticles, and inorganic mercury mixed with selenite.
• To assess the influence of soil properties on MeHg production from HgSe nanoparticles.

Main Methods:

• Three floodplain soils were amended with HgSe nanoparticles, HgSe microparticles, and inorganic mercury with selenite (Hg(II)+Se(IV)).
• Net MeHg production was measured for each treatment across different soil types.
• Soil organic matter content and microbial methylator communities were analyzed.

Main Results:

• Net MeHg production from HgSe nanoparticles was similar to or significantly lower than from Hg(II)+Se(IV).
• HgSe nanoparticles yielded significantly greater net MeHg production compared to HgSe microparticles across all soils.
• MeHg production from HgSe nanoparticles varied significantly with soil type, correlating with organic matter and microbial communities.

Conclusions:

• Geochemical intermediates of HgSe precipitation and soil properties are critical factors in MeHg production.
• HgSe nanoparticles represent a more significant source of MeHg than microparticles.
• Findings support the development of Se-based remediation strategies to minimize MeHg impacts.