Sonke et al. 2023 — Global change and mercury biogeochemical cycling
This synthesis review examines how global change drivers — climate change, land use, ocean deoxygenation, altered precipitation patterns, and changing atmospheric emissions — affect the biogeochemical cycling of mercury (tHg) and methylmercury (MeHg) from emission through environmental cycling to human dietary exposure, primarily via fish consumption. The paper estimates the annual economic cost of mercury-related human health impacts at approximately $117 billion USD and projects future mercury concentrations in fish under different emission reduction scenarios.
Key numbers
Economic cost estimate: ~$117 billion USD per year in global economic losses attributable to mercury exposure, primarily through reduced IQ and cardiovascular disease from dietary MeHg.
Dietary exposure pathway: Fish consumption is identified as the primary route of human MeHg exposure globally; the paper quantifies the fraction of total methylmercury exposure accounted for by seafood vs. other dietary sources.
Climate change projections: warming and changing precipitation are projected to increase MeHg methylation rates in freshwater and coastal systems by increasing microbial activity and organic carbon export, potentially raising fish MeHg concentrations by 10–30% above current levels under 2°C warming scenarios.
Ocean deoxygenation: expansion of oxygen minimum zones increases anaerobic MeHg production in the water column, with projected increases in deep-ocean fish MeHg concentrations.
Legacy pollution: terrestrial mercury stores in permafrost and soils represent a future release reservoir under warming conditions that could offset emission reductions from the Minamata Convention.
Methods (brief)
Synthesis and review; no new primary measurements. Draws on published monitoring data from GEOTRACES, long-term freshwater fish monitoring programs, atmospheric deposition networks, and biogeochemical model projections. Economic valuation from USEPA and European Commission methodology. Uncertainty in projections is discussed explicitly.
Implications
Certification: The $117 billion annual cost framing and the fish-consumption pathway are directly relevant to HMT&C certification rationale for seafood and fish-based products. Climate-change projections suggest MeHg in fish will increase, not decrease, under current trajectories — strengthening the long-term value of certification programs.
Courses: Excellent overview lecture reference for global mercury context, Minamata Convention framing, and future exposure trajectory.
App: No per-ingredient concentration data. Relevant to exposure framing for seafood/fish product categories.
Microbiome: Not applicable directly; could link to gut-mercury-absorption mechanisms if a mercury-microbiome page is developed.