Last updated: August 29, 2025
Article
Freshwater Mercury Exposure Risk Just Got Easier to Anticipate
Elevated mercury levels are hard to predict. But a new model based on data from across the U.S. is up to the task.
By the editors of Park Science magazine
About this article
This article was originally published in the "Research Roundup" section of Park Science magazine, Volume 39, Number 2, Summer 2025 (August 29, 2025).
Image credit: Kotalik and others. 2025. Ecosystem Drivers of Freshwater Mercury Bioaccumulation Are Context-Dependent: Insights from Continental-Scale Modeling. Environmental Science & Technology. 59 (3): 1780-1789.
Too much mercury can lead to neurological and reproductive harm in animals and people. Mercury that enters aquatic food chains can accumulate to dangerous levels, especially in fish. But it’s not easy to predict where mercury levels may be high. That’s because the factors influencing mercury accumulation in food chains depend on the context. The same factor can have different effects depending on the environment. So scientists have had to measure mercury—typically via dragonflies—on a site-by-site basis.
A study in the January 2025 issue of Environmental Science & Technology describes a way to predict mercury concentrations without having to take new measurements. The authors used mercury measurements from 21,000 dragonflies collected throughout the U.S. from 2008 to 2021. They also gathered data on water chemistry, landscape characteristics, habitat type, and ecoregion for each collection site. The researchers then combined those data to train and test a continent-scale model.
The model predictions explain 85 percent of why mercury concentrations differ from place to place. They also shed light on which factors influence mercury concentrations most. And they confirm that context is key. For example, sites surrounded by wetlands typically have higher dragonfly mercury concentrations. But the aquatic habitat types and which ecoregions they occur in matter a lot too. The study authors envision many potential uses for their model. Crucially, it can identify areas likely to have mercury contamination.
Kotalik and others. 2025. Ecosystem Drivers of Freshwater Mercury Bioaccumulation Are Context-Dependent: Insights from Continental-Scale Modeling. Environmental Science & Technology. 59 (3): 1780-1789.