HR: 0800h
AN: H51D-1168    [Abstracts]
TI: Terrestrial-aquatic Interactions in SE Alaska: Seasonal Stream Response to DOM and Nutrient Inputs From Wetlands and Salmon
AU: * Edwards, R T
EM: rtedwards@fs.fed.us
AF: USDA Forest Service, PNW Research Station, 2770 Sherwood Lane, Suite 2A, Juneau, AK 99801 United States
AU: Hood, E
EM: eran.hood@uas.alaska.edu
AF: Environmental Science Program, University of Alaska Southeast, 11120 Glacier Hwy, Juneau, USA 99801 United States
AU: D'Amore, D V
EM: ddamore@fs.fed.us
AF: USDA Forest Service, PNW Research Station, 2770 Sherwood Lane, Suite 2A, Juneau, AK 99801 United States
AU: Lange, B J
EM: blange@fs.fed.us
AF: USDA Forest Service, PNW Research Station, 2770 Sherwood Lane, Suite 2A, Juneau, AK 99801 United States
AU: Lange, B J
EM: blange@fs.fed.us
AF: Environmental Science Program, University of Alaska Southeast, 11120 Glacier Hwy, Juneau, USA 99801 United States
AU: Fellman, J B
EM: jfellman@fs.fed.us
AF: USDA Forest Service, PNW Research Station, 2770 Sherwood Lane, Suite 2A, Juneau, AK 99801 United States
AB: Forested and peat-dominated wetlands comprise about 30% of the uplands in Southeastern Alaska. Inputs from these carbon-rich soils presumably have a large influence on the biogeochemistry of streams draining them, the most obvious being the presence of brownwater, high DOM streams in catchments dominated by peatlands. We measured N and DOM concentration and quality within wetland soil pore water and surface water in two stream types: a brownwater stream and a clearwater stream. Surface samples were taken in intermittent tributaries draining wetlands and the perennial streams receiving those inputs. Soil water samples were taken in dominant end member wetland types: forested wetlands, bogs and fens. Seasonal patterns of DOM and forms of nitrogen were tracked to correlate wetland source pool and surface channel patterns. Soil porewater concentrations ranged from 15 to 50 mg C L$^{-1}$. Wetland drainage channels ranged from 10 to 35 mg C L$^{-1}$ and were similar in wetlands draining into both stream types. DOC concentrations varied between 3 and 15 mg C L$^{-1}$ within the brownwater creek, and less than 1 to 5 mg C L$^{-1}$ in the clearwater creek. The close similarity of seasonal and storm-related DOM patterns in wetland drains and streams indicates that, during storm runoff periods, wetland inputs influence DOM within both stream types, but during low-flow periods wetland influences are strong only in the brownwater stream. Another important source of DOM to SE Alaskan streams is decaying salmon carcasses. The summer of 2004 was unusually dry with low flows in the study streams. When salmon were present, DOM exceeded 15-20 mg C L$^{-1}$. DOM quality increased during summer in both stream types. Soil porewater nitrogen concentrations were higher than surface waters. In spring $<$5% of total N in surface waters was in organic forms. During summer the organic fraction increased to 10-15% of total N in the clearwater stream, and up to 50% in the brownwater stream.
DE: 1806 Chemistry of fresh water
DE: 1871 Surface water quality
DE: 0330 Geochemical cycles
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting