Simulated sea level rise in coastal peat oils stimulates mercury methylation

Bryce A. Cook; Benjamin D. Peterson; Jacob M. Ogorek; Sarah E. Janssen; Brett A. Poulin

doi:10.1021/acsearthspacechem.4c00124

Simulated sea level rise in coastal peat oils stimulates mercury methylation

ACS Earth and Space Chemistry

By: Bryce A. Cook, Benjamin D. Peterson, Jacob M. Ogorek, Sarah E. Janssen, and Brett A. Poulin

https://doi.org/10.1021/acsearthspacechem.4c00124

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Abstract

Coastal wetlands are vulnerable to sea level rise with unknown consequences for mercury (Hg) cycling, particularly the potential for exacerbating neurotoxic methylmercury (MeHg) production and bioaccumulation in food webs. Here, the effect of sea level rise on MeHg formation in the Florida Everglades was evaluated by incubating peat cores from a freshwater wetland for 0–20 days in the laboratory at five salinity conditions (0.16–6.0 parts-per-thousand; 0.20–454 mg L^–1 sulfate (SO₄^2–)) to simulate the onset of sea level rise within coastal margins. Isotopically enriched inorganic mercury (²⁰¹Hg(II)) was used to track MeHg formation and peat-porewater partitioning. In all five salinity treatments, porewaters became anoxic within 1 day and became progressively enriched in dissolved organic matter (DOM) of greater aromatic composition over the 20 days compared to ambient conditions. In the four highest salinity treatments, SO₄^2– concentrations decreased and sulfide concentrations increased over time due to microbial dissimilatory SO₄^2– reduction that was concurrent with ²⁰¹Hg(II) methylation. Importantly, elevated salinity resulted in a greater proportion of produced Me²⁰¹Hg observed in porewaters as opposed to bound to peat, interpreted to be due to the complexation of MeHg with aromatic DOM released from peat. The findings highlight the potential for enhanced production and mobilization of MeHg in coastal wetlands of the Florida Everglades due to the onset of saltwater intrusion.

Additional publication details
Publication type	Article
Publication Subtype	Journal Article
Title	Simulated sea level rise in coastal peat oils stimulates mercury methylation
Series title	ACS Earth and Space Chemistry
DOI	10.1021/acsearthspacechem.4c00124
Year Published	2024
Language	English
Publisher	American Chemical Society
Contributing office(s)	Upper Midwest Water Science Center
Description	13 p.
Country	United States
State	Florida
Other Geospatial	Everglades
Google Analytic Metrics	Metrics page