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The Estuarine Axis of Evil: How Tidal Wetlands Toxify Mercury From the Air and Spit It Out Into Coastal Waters

October 21, 2016 @ 11:00 am - 12:00 pm

School of Marine Sciences and Dept. of Wildlife, Fisheries and Conservation Biology

Joint Seminar

October 21, 2016

11:00 a.m. ~ Senator George Mitchell Center

Dr. Brian Bergamaschi

USGS – Sacramento Field Office

The Estuarine Axis of Evil: How Tidal Wetlands Toxify Mercury From the Air and Spit It Out Into Coastal Waters

Elevated mercury levels have been widely reported in wading birds, raptors, alligators, sport fish and other animal species in the South Florida’s coastal and inland waters, and in sport fish and birds in San Francisco Bay. In the case of South Florida, the source of the mercury entering the food web is unknown because there are no nearby geological sources. In the case of San Francisco Bay, although there is a great deal of mercury in aquatic environments due to legacy of gold mining, the process by which mercury is altered into methyl mercury (MeHg) — the organic form that can bio -accumulate — is not understood. Tidal wetlands in estuaries contain the “biogeochemical axis of evil”: a witch’s brew of sulfate, mercury, and easily-degradable organic material that leads to formation of MeHg right where tidal exchange can transport it into the estuary. We developed methods to characterize the flux of MeHg from tidal wetlands and found that both tidal wetlands produce and export the highest amount of MeHg ever reported from wetlands, indicating that tidal wetlands can be significant sources to estuarine foodwebs. Further, our results show that the source of mercury being methylated can be atmospheric, suggesting that remediation efforts focused on source control may not achieve desired results in these settings. In collaboration with JA Fleck, kR Fujii, B Downiing, DP Krabbenhoft, GR Aiken, and many others.

Polycom availability with Darling Marine Center, Gulf of Maine Research Institute, and Bigelow Laboratories

Hosts: Lee Karp-Boss (, Aly McKnight (

The University of Maine does not discriminate on the grounds of race, color, religion, sex, sexual orientation, including transgender status and gender expression, national origin, citizenship status, age, disability, genetic information or veteran’s status in employment, education, and all other programs and activities. The following person has been designated to handle inquiries regarding non-discrimination policies: Director, Office of Equal Opportunity, 101 North Stevens Hall, 581-1226. If you are a person with a disability and need an accommodation to participate in this program, please call Dr. Susan Brawley , as early as possible, at 207.581.2973 or Dr. Lee Karp-Boss at 207-581.4305 to discuss your needs.


October 21, 2016
11:00 am - 12:00 pm
Event Category:


Senator George J. Mitchell Center
Norman Smith Hall, University of Maine
Orono, ME 04469 United States
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