HR: 15:25h
AN: GC53B-08    [Abstracts]
TI: Impact of Seasonal Shifts in Stream Flow on Long-Term Trends in Dissolved Organic Carbon
AU: * Eimers, C
EM: ceimers@trentu.ca
AF: Trent University, Department of Geography, Peterborough, ON K9J7B8, Canada
AU: Buttle, J
EM: jbuttle@trentu.ca
AF: Trent University, Department of Geography, Peterborough, ON K9J7B8, Canada
AU: Watmough, S
EM: swatmough@trentu.ca
AF: Trent University, Environmental Sciences Program, Peterborough, ON K9J7B8, Canada
AB: Long-term monitoring (20+ year) of dissolved organic carbon (DOC) concentrations and discharge in small headwater streams in south-central Ontario, Canada has revealed unexpected relationships between seasonal stream flow and trends in DOC concentration. In catchments containing wetlands, DOC concentrations are high (> 6 mg L-1), and there is a strong negative relationship between daily stream flow and DOC concentration, with annual DOC minima occurring at the height of spring snow melt. In contrast, DOC concentrations in upland- dominated catchments are low (< 4 mg L-1) and show relatively little intra- or inter-annual variation. Variations in the total amount of spring stream flow (March-April-May) correlate negatively with annual average DOC concentrations in wetland-influenced catchments. Similar to other parts of the world, significant increases in DOC concentration (1980 – 2001) have been observed at these small wetland-influenced catchments; however, for the most part, positive trends are driven by relatively high DOC concentrations in the latter years of record, which also had lower than average spring flow. These results highlight the importance of record length for determining trend magnitude and direction and the value of long-term monitoring records for identifying potentially subtle relationships between hydroclimatic shifts and water quality.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 0434 Data sets
DE: 1804 Catchment
DE: 1806 Chemistry of fresh water
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting