HR: 0830h
AN: H51C-1062    [PDF]
TI: Annual CO$_{2}$ Riverine Evasion From New Zealand
AU: * Scott, D "
EM: dtscott@usgs,gov
AF: Landcare Research, Private Bag 11052, Palmerston North, 5301 New Zealand
AU: * Scott, D "
EM: dtscott@usgs,gov
AF: U.S. Geological Survey, 430 National Center, Reston, VA 20192 United States
AB: Riverine dissolved organic carbon (DOC) export represents one fraction of the total carbon flux from the terrestrial environment to the coastal seas. Throughout transport, chemical and biological oxidation mechanisms remove DOC from the water column, producing CO$_{2}$ and other photochemical byproducts. The primary aim of this study was to estimate the annual CO$_{2}$ riverine evasion from New Zealand\'{ }s stream network using a combination of empirical measurements throughout the island nation, combined with diel experiments within a single basin and re-aeration estimates. From headwater streams to large rivers, surface-water CO$_{2}$ concentrations were supersaturated indicating that the river network releases CO$_{2}$ to the atmosphere. Diel measurements in subsurface porewaters showed that CO$_{2}$ concentrations were greater than surface-water concentrations due to both microbial DOC oxidation in the hyporheic zone and groundwater input of supersaturated CO$_{2}$ water. As expected, CO$_{2}$ concentrations are also a function of photosynthetic processes within the water column that consume CO$_{2}$ during daylight hours. Using our measurements and extrapolating to the national scale through a stream-order analysis, the annual CO$_{2}$ evasion estimates indicate that up to 30% of the riverine DOC export is consumed before reaching the sea.
DE: 1615 Biogeochemical processes (4805)
DE: 1806 Chemistry of fresh water
DE: 1845 Limnology
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: 2003 Fall Meeting