Gas exchange rates across the sediment-water and air-water interfaces in south San Francisco Bay

Journal of Geophysical Research C: Oceans
By:  and 

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Abstract

Radon 222 concentrations in the water and sedimentary columns and radon exchange rates across the sediment-water and air-water interfaces have been measured in a section of south San Francisco Bay. Two independent methods have been used to determine sediment-water exchange rates, and the annual averages of these methods agree within the uncertainty of the determinations, about 20%. The annual average of benthic fluxes from shoal areas is nearly a factor of 2 greater than fluxes from the channel areas. Fluxes from the shoal and channel areas exceed those expected from simple molecular diffusion by factors of 4 and 2, respectively, apparently due to macrofaunal irrigation. Values of the gas transfer coefficient for radon exchange across the air-water interface were determined by constructing a radon mass balance for the water column and by direct measurement using floating chambers. The chamber method appears to yield results which are too high. Transfer coefficients computed using the mass balance method range from 0.4 m/day to 1.8 m/day, with a 6-year average of 1.0 m/day. Gas exchange is linearly dependent upon wind speed over a wind speed range of 3.2–6.4 m/s, but shows no dependence upon current velocity. Gas transfer coefficients predicted from an empirical relationship between gas exchange rates and wind speed observed in lakes and the oceans are within 30% of the coefficients determined from the radon mass balance and are considerably more accurate than coefficients predicted from theoretical gas exchange models.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Gas exchange rates across the sediment-water and air-water interfaces in south San Francisco Bay
Series title Journal of Geophysical Research C: Oceans
DOI 10.1029/JC089iC03p03593
Volume 89
Issue C3
Year Published 1984
Language English
Publisher AGU Publications
Contributing office(s) San Francisco Bay-Delta
Description 11 p.
First page 3593
Last page 3603
Country United States
State California
Other Geospatial San Francisco Bay
Online Only (Y/N) N
Additional Online Files (Y/N) N