HR: 15:10h
AN: B53A-07    [Abstracts]
TI: Dissolved Organic Carbon Export From the Penobscot River Basin to the Gulf of Maine
AU: * Huntington, T G
EM: thunting@usgs.gov
AF: U. S. Geological Survey, 196 Whitten Rd., Augusta, ME 04330 United States
AU: Aiken, G R
EM: graiken@usgs.gov
AF: U. S. Geological Survey, 3215 Marine St., Boulder, CO 80303 United States
AB: Recent and historical water quality data collected from the Penobscot River in central Maine were analyzed to estimate the flux of dissolved organic carbon (DOC). Historical data collected by the U.S. Geologic Survey during 1973 to 1981 as part of the National Stream Quality Accounting Network (NASQAN) and recently collected data during 2004 and 2005 supported by NASA provide a framework for preliminary estimates of seasonal and interannual variability in DOC export. Monthly average concentrations were computed from samples collected during all seasons. Flux estimates were calculated using monthly average concentrations and average daily discharge. For snowmelt and storms measured during 2004 to 2005 DOC increased with increasing discharge, but the increase was distinctly muted during the snowmelt-dominated high spring flow compared with summer and fall storms. DOC export was highest during the spring snowmelt season in spite of relatively low concentrations, compared with late summer and fall because of the substantially higher spring discharge. DOC export tends to be lowest during July through August and increases progressively to moderately high levels during the fall. Export of DOC during the winter months is intermediate between summer and fall levels. Estimated DOC export varied substantially among years ranging from 4.0 t/sq km/yr during the driest year to 7.8 t/sq km/yr during the wettest year. Average annual DOC export per unit area for all years was 5.7 t/sq km/yr. Under wetter conditions flowpaths are thought to include more organic matter-rich surface soils. DOC export from the Penobscot River is substantially higher than estimated for most larger rivers in North America and smaller rivers draining to the Atlantic Ocean along the east coast of the United States. Preliminary evidence from analysis of DOC concentrations in tributaries to the Penobscot River indicates that wetland area and reservoir volume exert substantial control over DOC export in this basin
DE: 3322 Land/atmosphere interactions (1218, 1631, 1843)
DE: 4808 Chemical tracers
SC: Biogeosciences [B]
MN: Fall Meeting 2005