July Slugs & Steins

Mercury in Coastal Fog – Evidence for Bioaccumulation in Food Webs
Professor Peter Weiss-Penzias
Monday, July 13, 2020
6:30-8:00 p.m. 

Mercury is a naturally occurring element that is released to the atmosphere by human activities - approximately 4000 metric tons each year. Coal combustion, gold mining, and other industrial processes are the main culprits. Mercury is dangerous for humans and wildlife because it is a neurotoxin that can bioaccumulate in food webs to reach levels that exceed dietary thresholds. Normally, this is a problem in aquatic systems where methylmercury is produced by bacteria and there are many levels in the food web (big fish eats the little fish). However, coastal fog like the kind we have in California acts as a sponge for methylmercury emissions from the ocean, and when this fog moves onshore and wets the forest with droplets, methylmercury from the ocean can enter the food web on land. My research on mountain lions in the Santa Cruz area showed that they had mercury concentrations that approached toxicological thresholds, with levels that were three times greater in their fur and whiskers compared with mountain lions from the Sierra Nevada Mountains. Deer in the Santa Cruz Mountains, which are the main food source of mountain lions, also contained higher concentrations of mercury compared to deer in the Sierra Nevada. Lichen, the symbiotic organism that lives on trees, also showed similar enhancements in mercury, which strongly suggested an atmospheric source (i.e. fog) since lichen lack roots and only absorb materials from the air. Thus, although fog makes up a small portion of the water inputs to the Central Coast, it may play an outsized role in cycling mercury from the ocean to the land. 

Peter Weiss-Penzias has a Ph.D. from the University of Washington in Chemistry (1995) and has worked as an Associate Researcher in the Department of Microbiology and Environmental Toxicology at UC Santa Cruz since 2009. He is an internationally known researcher of mercury biogeochemistry with over 2500 citations according to his Google Scholar profile. Last year he launched a crowd-funding campaign titled "Mercury is our fog - so what about our food" and raised enough money to fund an undergraduate research scholarship for the collection and testing of foods from local farms in the fog-belt. In 2019 he won the Clean Air Award from the Monterey Bay Air Resources District for his efforts to understand air pollution. Peter also performs original music as the Singing Scientist to educate people about the environment. You can find his music on Spotify and YouTube. 

image-1.png

UC Santa Cruz Professor Peter Weiss-Penzias