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Note: The abstract that appears on this page has been modified from the original text. The Greek letter "Sigma" as in SigmaCO2 has been spelled out in English in this version because the character cannot be displayed here in its native format.
ABSTRACT: Using a slurry technique, measurements of radon-222/radium-226 in San Francisco Bay sediments range from 0.3 to equilibrium. Radon deficiency generally decreases with increasing depth. A small deficiency may exist as deep as 40 cm in some cases. This deficiency is attributed primarily to irrigation of sediments by polychaete worms. If irrigation is modeled as an advective process, an irrigation rate of 3 cm·d-1 is calculated as a lower limit at a station in South Bay in August 1976. Using this model and nutrient measurements in interstitial waters, fluxes across the sediment-water interface for SigmaCO2, NH4+, PO4-3, and SiO2 are calculated to be 40, 4, 0.03, and 6 mmol·m-2·d-1 at this station. The flux of radon across the sediment-water interface is estimated to be 200±70 atoms·m-2·s-1 on the basis of integrated radon deficiencies and benthic flux chamber measurements. Simultaneous measurements of radon and wind speed in July 1977 suggest that flow-induced turbulence, rather than wind speed, is the primary factor controlling gas exchange across the air-water interface. From a radon mass balance, the mass transfer coefficient for radon across this interface is calculated to be 1.0±0.5 m·d-1. Using this information, a vertical mixing coefficient in the water column of South Bay is calculated to be greater than 1 x 10-2 cm·s-1, indicating the water column mixes more rapidly than once in 12 h. The volume transport of sand bedforms in Central Bay is estimated to be 8 x 106 m3·d-1.
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