Tuesday August 6, 2024
USGS via Maven’s Notebook —
The findings document increases in total mercury mobilization and conversion to the more toxic form, methylmercury. The scientists also found increased methylmercury bioaccumulation in some aquatic insect species. These increased levels of mercury in headwater streams can pose risks to downstream ecosystems and human health.
“These results indicate that, with increasing wildfire frequency and severity, we may expect to see increases in mercury transport, methylation, and bioaccumulation in headwater streams and potentially downstream lakes and reservoirs,” said Austin Baldwin, USGS research hydrologist who led the study.
USGS scientists sampled soils, water, sediment, instream leaf litter, streambed algae, and aquatic invertebrates in 36 headwater-stream watersheds in Washington, Oregon, and Idaho one year after they had been burned by wildfire. For comparison, they also collected samples from 21 similar but unburned watersheds.