Mercury is a global contaminant that is released to the atmosphere, travels long distances, and impacts humans and wildlife through bioaccumulation of toxic methylmercury. Selenium, in contrast, is an essential micronutrient that plays an important role in modulating oxidative stress in all vertebrates. Mercury is known to interact with selenium biomolecules, but very little is known about these interactions and their implications.

Postdoc fellow Becca Frei was selected for the ASLO Eco-DAS (Ecological Dissertations in the Aquatic Sciences) symposia. Becca will be joining forces with other young scientists at this symposia that focuses on cross-disciplinary sciences in aquatic ecology. Congrats Becca! 

Undergraduate Emily Richter was awarded the 2025 Provost’s Undergraduate Research Fellowship. Her research is investigating how climate change and temperature increases will affect the rate at which methylmercury is formed. We're excited to see her work develop! 

A recently published study in Environmental Science & Technology by our group highlights that nearly 1/3 of the methylmercury measured in the Snake River originates from formation in riparian zones of the river. This study coupled measurements of hydrology, surface and pore water biogeochemistry, sediment biogeochemistry, and aquatic biota. Big congrats to the whole team and especially PhD Candidate Virginia Krause for the publication!

We welcome incoming PhD Student Julia Davidson, who was awarded the prestigious NSF Graduate Research Fellowship. She will be developing her research project to study how mercury is detoxified by selenium-containing proteins. 

We're excited to have Rebecca Frei join the group! She was awarded a 3-year postdoctoral fellowship by the National Park Foundation, and will be studying rivers and streams in Arctic Alaska impacted by permafrost thaw. 

A new study by our group and members of the National Park Service and U.S. Geological Survey (link) documents the widespread and sudden shifts in water quality in rivers in Alaska's Brooks Range. The study documents over 75 rivers and streams that have undergone recent changes in water chemistry, attributed to the weathering of sulfide minerals that releases sulfuric acid, iron, and a range of toxic trace metals.

In May 2024 Mark was awarded the prestigious NIEHS predoctoral fellowship that will provide training, networking and professional development opportunities, and 2 years of support for his graduate studies. 

Current Postdoctoral Fellowship (via the National Park Foundation): 

Application Link: https://www.nationalparks.org/science-parks-postdoctoral-fellowship

Title: The Resilience & Vulnerability of Arctic Rivers to Permafrost Thaw and Emergent Environmental Toxicity

Research Questions:

Our research was highlighted by the ESRF following a recent visit to beamline ID26! Enjoy the full article here. 

Reservoirs provide critical drinking water supply, flood control, and renewable energy.

Dissolved organic sulfur is an important component of waters, influencing the cycling of many elements. Our recent study published in the journal Environmental Science & Technology Letters documents how sunlight selectively photo-oxidizes reduced dissolved organic sulfur (DOS) to inorganic sulfate. The results have implications for the cycling of carbon, sulfur, and trace metals (e.g., mercury) in aquatic environments, and documents a reaction that may be relevant in the atmosphere.