Role of gas exchange in the inorganic carbon, oxygen, and /sup 222/Rn budgets of the Amazon River

Journal Article · Thu Jan 01 00:00:00 EST 1987 · Limnol. Oceanogr.; (United States)

DOI:https://doi.org/10.4319/lo.1987.32.1.0235· OSTI ID:6741139

Devol, A H; Quay, P D; Richey, J E; Martinelli, L A

Dissolved oxygen, /sup 222/Rn, pCO/sub 2/, alkalinity, respiration rate, and discharge have been measured at eight mainstem and seven tributary stations during February-March 1984 in a 1700-km stretch of the Amazon River between Vargem Grande and Obidos in Brazil. Air-water gas exchange rates were estimated two ways: measurements of the flux of /sup 222/Rn int floating domes yielded an average boundary layer thickness of 78..mu..m, and oxygen mass balance calculations resulted in an average of 38..mu..m. Given a boundary layer thickness on the order of 50..mu..m, CO/sub 2/ loss to the atmosphere in the entire reach would have been 37.4 kmol s/sup -1/, which is about equal to the total tributary dissolved inorganic carbon (DIC) input and is about half of the total fluvial DIC input to the section. Thus, CO/sub 2/ evasion is a major component of Amazon River DIC balance. Because gas exchange within the section was rapid relative to water travel time through the section, a quasi-steady state was maintained between respiratory input and evasion of CO/sub 2/. Dissolved /sup 222/Rn activities in the mainstem varied from 3.5 to 8.3 dpm liter/sup -1/ and were always highly supersaturated with respect to the atmosphere. Dissolved radon was also not supported by decay of /sup 222/Ra in the mainstem. A /sup 222/Rn mass balance indicated that direct groundwater input into this stretch of the Amazon mainstem probably accounted for no more than 1% of water discharge.

• Research Organization: Univ. of Washington, Seattle
• OSTI ID: 6741139
• Journal Information: Limnol. Oceanogr.; (United States), Vol. 32:1
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AMAZON RIVER
WATER CHEMISTRY
RADON 222
MASS BALANCE
AIR
BOUNDARY LAYERS
CARBON CYCLE
CARBON DIOXIDE
OXYGEN
RESPIRATION
WATER
ALPHA DECAY RADIOISOTOPES
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMISTRY
DAYS LIVING RADIOISOTOPES
ELEMENTS
EVEN-EVEN NUCLEI
FLUIDS
GASES
HEAVY NUCLEI
HYDROGEN COMPOUNDS
ISOTOPES
LAYERS
NONMETALS
NUCLEI
OXIDES
OXYGEN COMPOUNDS
RADIOISOTOPES
RADON ISOTOPES
RIVERS
STREAMS
SURFACE WATERS
520100* - Environment
Aquatic- Basic Studies- (-1989)