We used a dynamic mixed layer model to determine carbon export by the oxygen mass balance method from a time series of O2/Ar, N2/Ar and Ne measurements collected at station ALOHA near Hawaii from July 2000 to June 2001. The inert gas measurements constrain the flux of oxygen into the mixed layer from small, collapsing bubbles (injection) to be greater than or equal to the flux from larger bubbles (exchange), with mean estimates of the ratio in the range of 1–2. We also show that monthly observations of temperature and inert gases cannot constrain the rate of diapycnal mixing at this location, because of uncertainties in air-sea heat flux estimates and bubble dynamics. Organic carbon export from the mixed layer calculated from our dataset was 1.1 ± 0.5 mol C m–2 yr–1, with most of the error deriving from uncertainties in the parameterization of diffusive gas exchange with wind speed. Our estimates of carbon export from the zone beneath the mixed layer but still in the euphotic zone ranged from 0 to 0.6 mol C m–2 yr–1 as the rate of background diapycnal mixing was increased from 0.1 to 1.0 cm2 s–1. We conclude that the oxygen mass balance method has errors of about a factor of two in areas similar to the subtropical North Pacific, with the main uncertainties deriving from mixing rates and the parameterization of diffusive gas exchange.

We used a dynamic mixed layer model to determine carbon export by the oxygen mass balance method from a time series of O-2/Ar, N-2/Ar and Ne measurements collected at station ALOHA near Hawaii from July 2000 to June 2001. The inert gas measurements constrain the flux of oxygen into the mixed layer from small, collapsing bubbles (injection) to be greater than or equal to the flux from larger bubbles (exchange), with mean estimates of the ratio in the range of 1-2. We also show that monthly observations of temperature and inert gases cannot constrain the rate of diapycnal mixing at this location, because of uncertainties in air-sea heat flux estimates and bubble dynamics. Organic carbon export from the mixed layer calculated from our dataset was 1.1 +/- 0.5 mol C m(-2) yr(-1), with most of the error deriving from uncertainties in the parameterization of diffusive gas exchange with wind speed. Our estimates of carbon export from the zone beneath the mixed layer but still in the euphotic zone ranged from 0 to 0.6 mol C m(-2) yr(-1) as the rate of background diapycnal mixing was increased from 0. 1 to 1.0 cm(2) s(-1). We conclude that the oxygen mass balance method has errors of about a factor of two in areas similar to the subtropical North Pacific, with the main uncertainties deriving from mixing rates and the parameterization of diffusive gas exchange.

Large discrepancies in published neon and nitrogen solubility data limit the interpretation of oceanic measurements of these gases. We present new solubility measurements for neon, nitrogen and argon in distilled water and seawater, over a temperature range of 1-30 degreesC. Water was equilibrated with air at measured temperatures, salinities and pressures. Dissolved Ne concentrations were then determined by isotope dilution using a quadrupole mass spectrometer. Ratios of O2/N2/Ar were measured on a stable isotope ratio mass spectrometer, from which absolute N2 and Ar concentrations were calculated using published O2 solubilities. We propose new equations, fitted to the data, for the equilibrium concentrations of Ne, N2 and Ar with estimated errors of 0.30%, 0.14% and 0.13%, respectively. The Ar results matched those of most previous researchers within 0.4%. However, the Ne and N2 results were greater by 1% or more than those of Weiss (1971,1970). (C) 2004 Elsevier Ltd. All rights reserved.

We describe an analytical method with improved precision for measuring the concentration of neon dissolved in water. Measurements were calibrated by isotope dilution, with addition of a Ne-22 spike directly to the evacuated sample flask prior to water collection. The use of glass flasks for water sampling, with flushing of air from the system by CO2, greatly reduced the chance of contamination. Dissolved gases were extracted from the water sample by equilibration with a headspace and cryogenically processed to remove interferences. The Ne-22/Ne-20 ratio was then measured on a quadrupole mass spectrometer operated in static mode. Mass fractionation by the system was accounted for by frequent analyses of the Ne-22/Ne-20 ratio in air. We routinely obtained precisions of +/-0.13% based on the standard deviation of duplicate field samples. Accuracy of the method, in the form of possible systematic offsets that could skew all the data, was assessed to be +/-0.18%, excluding a possible +/-0.2% error in the estimate of the Ne concentration of air. (C) 2004 Elsevier B.V. All rights reserved.