W. J. De Bruyn

Uptake of gas phase sulfur species methanesulfonic acid, dimethylsulfoxide, and dimethyl sulfone by aqueous surfaces

Biogenic reduced sulfur species are emitted from the oceans and then oxidized in the marine boundary layer. The gas-liquid interactions of these oxidized species must be understood in order to evaluate the relative contributions to marine boundary layer aerosol levels from anthropogenic and biogenic sources and to assess the overall impact of these aerosols on global climate. A key parameter in understanding these interactions is the mass accommodation coefficient, which is simply the probability that a gas phase molecule enters into a liquid on striking the liquid surface. The mass accommodation coefficients for dimethylsulfoxide, dimethyl sulfone, and methanesulfonic acid into water have been measured as a function of temperature (260–280 K), pH (1–14), and NaCl concentration (0–3.5 M). The experimental method employs a monodispersed train of fast droplets in a low-pressure flow reactor. The mass accommodation coefficients show a negative temperature dependence varying from ∼0.1 to ∼0.2 over the range of temperatures studied. The measured uptake is independent of pH and NaCl concentration in the ranges studied. The mass accommodation coefficients are well expressed in terms of an observed Gibbs free energy ΔGobs# = ΔHobs# - TΔSobs# as α/(1 - α) = exp (−ΔGobs#/RT). The results are discussed in terms of a previously described uptake model. In the marine boundary layer, mass transfer of these species into aerosols will be limited by mass accommodation for aerosols with diameters of less than 2 μm.

Atmospheric variability of methyl chloride during the last 300 years from an Antarctic ice core and firn air

Measurements of methyl chloride (CH3Cl) in Antarctic polar ice and firn air are used to describe the variability of atmospheric CH3Cl during the past 300 years. Firn air results from South Pole and Siple Dome suggest that the atmospheric abundance of CH3Cl increased by about 10% in the 50 years prior to 1990. Ice core measurements from Siple Dome provide evidence for a cyclic natural variability on the order of 10%, with a period of about 110 years in phase with the 20th century rise inferred from firn air. Thus, the CH3Cl increase measured in firn air may largely be a result of natural processes, which may continue to affect the atmospheric CH3Cl burden during the 21st century.

Correction to “Oceanic uptake and the global atmospheric acetone budget”

] In the paper ‘‘Oceanic uptake and the global atmo-spheric acetone budget’’ by C. A. Marandino et al. (Geo-phys. Res. Lett., 32, L15806, doi:10.1029/2005GL023285)it was recently determined that a calculation error was madeduring flux data processing. The flux data has been reproc-essed and all the values in both the text and figures havebeen recomputed. The qualitative discussion and conclu-sions remain the same. After the data was reprocessed, itwas determined that the low frequency correction could bemodified. Instead of eliminating the power at frequencieslower than 5E-3 Hz in all of the records, a low frequencydiagnostic was created to assess whether the record shouldbe retained at all. This diagnostic was the ratio between theflux at the 5E-3 Hz cutoff and the full flux (i.e. no cutoff). Ifthe ratio indicated a difference greater than 30%, the recordwas not included in the final dataset. The entire dataprocessing procedure will be published in the Journal ofGeophysical Research [Marandino et al., 2006]. A secondcalculationerrorwasfoundintheuncertaintyanalysisfortheglobal acetone sink budget. Corrected versions of Table 1and Figures 1–3 from the original paper are given. Anadditional table (Table 2) has been included listing therecomputed values of several quantities discussed in theoriginal paper.

Correction to “Eddy correlation measurements of the air/sea flux of dimethylsulfide over the North Pacific Ocean”

[1] In the paper ‘‘Eddy correlation measurements of the air/sea flux of dimethylsulfide over the North Pacific Ocean’’ by C. A. Marandino et al. (Journal of Geophysical Research, 112, D03301, doi:10.1029/2006JD007293, 2007), the Wanninkhof [1992] parameterization in Figure 13 was calculated incorrectly. The revised Figure 13 is included. The discussion and conclusions of the original paper are not impacted by this change.

Correction to "Measurements of the diffusion coefficients of CFC-11 and CFC-12 in pure water and seawater" by M. Zheng et al.

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 103, NO. C10, PAGE 21,735, SEPTEMBER Correction to Measurements of the diffusion coefficients of CFC-11 and CFC-12 in pure water and seawater by M. Zheng et al. In the paper Measurements of the diffusion coefficients of CFC- 11 and CFC- 12 in pure water and seawater by M. Zheng, W. J. De Bruyn, and E. S. Saltzman (Journal of Geophysical Research, 103(C1), 1998), Figure l a was inadvertently left out. The complete Figure 1 appears below. lO E I v , I I 1 I , I I I ,I I I ,, I I a D=0.036exp(-20.1/RT) -D=0.015exp(- 18.1/RT) •. •.• b I I I ,I I I I I,, I, I t I Temperature (C) Temperature (C) Figure 1. Diffusion coefficients of (a) CFC-11 and (b) CFC-12 in pure water as a function of temperature. Also shown are the fits to the data (solid line, this study) and the estimates from the empirical expressions proposed by Wilke and Chang [1955] (dot-dash line) and Hayduk and Laudie [1974] (dashed line). The updated Wilke Chang estimate (dotted line) is the Wilke-Chang estimate using an updated association factor for water recommended by Hayduk and Laudie Read E-6 as lif o. (Received August 14, 1998.) Copyright 1998 by the American Geophysical Union. Paper number 98JC02688. 0148-0227/98/98JC-02688509.00