Mercury in Wetlands, Adirondack Region of New York State
Abstract
Wetlands play a prominent role in the cycling of mercury by harboring bacteria that transform mercury into methyl mercury, a neurotoxin, and by having high concentrations of dissolved organic carbon (DOC) that interact with mercury transport. We are measuring total mercury and methyl mercury in vegetation, soil, surface water, and ground water in the Sunday Lake watershed, in which wetlands cover 274 ha of the 1340-ha watershed area. Three wetland types occur: (1) riparian wetlands adjacent to low-order streams that drain the upland forested watershed; (2) peat-forming wetlands dominated by Carex sedges; and, (3) low shrub, Sphagnum (bog moss) dominated peatlands. Total mercury concentrations in wetland ground waters were greater in the riparian wetland (10.6 ng/L) and in sites with shallow peat than deep peat, suggesting water moves more readily around the peat than through it. The highest rates of microbial activity occurred in the top 10-cm of the sedge-derived peat, presumably being fueled by the freshest organic matter, although there was no relationship between microbial activity and DOC. Microbial sulfate reduction, which can methylate inorganic mercury, occurred in sites closest to low-order streams, presumably being fueled by sulfate brought into wetlands in surface water. Sites located away from the stream had microbial methane production, where demethylation might be occurring. Overall the wetlands are the primary source of methyl mercury within the watershed, and we are measuring water flow pathways and microbial processes to learn more about wetland controls of mercury cycling in watersheds.
- Publication:
-
AGU Spring Meeting Abstracts
- Pub Date:
- May 2001
- Bibcode:
- 2001AGUSM...B42B08Y
- Keywords:
-
- 4805 Biogeochemical cycles (1615)