HR: 17:20h
AN: B24A-06 INVITED     [Abstracts]
TI: Quantifying Sources and Fluxes of Aquatic Carbon in U.S. Streams and Reservoirs Using Spatially Referenced Regression Models
AU: * Boyer, E W
EM: ewboyer@syr.edu
AF: University of California, Berkeley, Department of Environmental Science, Policy & Management, Berkeley, CA 94720 United States
AU: Smith, R A
EM: rsmith1@usgs.gov
AF: US Geological Survey, Water Resources Division, Reston, VA 20192 United States
AU: Alexander, R B
EM: ralex@usgs.gov
AF: US Geological Survey, Water Resources Division, Reston, VA 20192 United States
AU: Schwarz, G E
EM: gschwarz@usgs.gov
AF: US Geological Survey, Water Resources Division, Reston, VA 20192 United States
AB: Organic carbon (OC) is a critical water quality characteristic in riverine systems that is an important component of the aquatic carbon cycle and energy balance. Examples of processes controlled by OC interactions are complexation of trace metals; enhancement of the solubility of hydrophobic organic contaminants; formation of trihalomethanes in drinking water; and absorption of visible and UV radiation. Organic carbon also can have indirect effects on water quality by influencing internal processes of aquatic ecosystems (e.g. photosynthesis and autotrophic and heterotrophic activity). The importance of organic matter dynamics on water quality has been recognized, but challenges remain in quantitatively addressing OC processes over broad spatial scales in a hydrological context. In this study, we apply spatially referenced watershed models (SPARROW) to statistically estimate long-term mean-annual rates of dissolved- and total- organic carbon export in streams and reservoirs across the conterminous United States. We make use of a GIS framework for the analysis, describing sources, transport, and transformations of organic matter from spatial databases providing characterizations of climate, land use, primary productivity, topography, soils, and geology. This approach is useful because it illustrates spatial patterns of organic carbon fluxes in streamflow, highlighting hot spots (e.g., organic-rich environments in the southeastern coastal plain). Further, our simulations provide estimates of the relative contributions to streams from allochthonous and autochthonous sources. We quantify surface water fluxes of OC with estimates of uncertainty in relation to the overall US carbon budget; our simulations highlight that aquatic sources and sinks of OC may be a more significant component of regional carbon cycling than was previously thought. Further, we are using our simulations to explore the potential role of climate and other changes in the terrestrial environment on OC fluxes in aquatic systems.
DE: 1806 Chemistry of fresh water
DE: 1860 Runoff and streamflow
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting