HR: 0800h
AN: B11B-0391    [Abstracts]
TI: Salmon and Wetland Influences on Streamwater Mercury Fluxes in Southeastern Alaska
AU: * Nagorski, S A
EM: sonia.nagorski@uas.alaska.edu
AF: Environmental Science Program University of Alaska Southeast, 11120 Glacier Hwy, Juneau, AK 9980, United States
AU: Hood, E
EM: eran.hood@uas.alaska.edu
AF: Environmental Science Program University of Alaska Southeast, 11120 Glacier Hwy, Juneau, AK 9980, United States
AU: Krabbenhoft, D P
EM: dpkrabbe@usgs.gov
AF: U.S. Geological Survey, 8505 Research Way, Middleton, WI 53562, United States
AU: Edwards, R T
EM: rtedwards@fs.fed.us
AF: USDA Forest Service Juneau Forestry Sciences Lab Pacific Northwest Research Station, 2770 Sherwood Lane, Juneau, AK 99801, United States
AU: D'Amore, D V
EM: ddamore@fs.fed.us
AF: USDA Forest Service Juneau Forestry Sciences Lab Pacific Northwest Research Station, 2770 Sherwood Lane, Juneau, AK 99801, United States
AU: Aiken, G
EM: graiken@usgs.gov
AF: U.S. Geological Survey, 3215 Marine Street, Boulder, CO 80303, United States
AB: Limited data indicate that mercury contamination in southeast Alaska is of growing concern due to the combination of rising Hg atmospheric imports from Asia, contributions of marine-derived mercury from spawning salmon, and the abundance of wetlands covering the region. Wetlands are prevalent (comprising 29% of the land area of the Tongass National Forest) and DOC concentrations are high (10-30 mg/L) in many southeast Alaskan brownwater streams. We investigated the Hg distribution in three watersheds with the goals of 1) obtaining original data on the concentrations of total and methyl Hg in regional catchments; 2) examining the extent to which the extensive areas of coastal wetlands may be facilitating the methylation of Hg, and 3) evaluating the influence of spawning salmon on Hg and nutrient export in streamwater. We measured Hg, nutrients, and ancillary water quality parameters and characterized dissolved organic carbon using chromatographic and spectroscopic techniques in streams draining three watersheds with varying wetland coverage. We also sampled tributary streams within the watersheds that drained individual landscape units across a gradient of vegetation types including upland, bog, and forested wetland to evaluate their contributions to streamwater Hg loads. Each stream was sampled before (June), during (August), and after (October) salmon spawning. Our initial results indicate that concentrations of total Hg in both mainstem and tributary streams were highly correlated with concentrations of bulk DOC and the percentage of DOC composed of hydrophobic acids, both of which were elevated in wetland-dominated sites. These results suggest that wetland landscapes are contributing disproportionately to riverine mercury export in southeastern Alaska.
DE: 0432 Contaminant and organic biogeochemistry (0792)
DE: 0470 Nutrients and nutrient cycling (4845, 4850)
DE: 0478 Pollution: urban, regional and global (0345, 4251)
DE: 0496 Water quality
DE: 0497 Wetlands (1890)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting