Carboxylic acids and carbonyl compounds in southern California clouds and fogs

Munger, J. William; Collett, Jeff; Daube, Bruce C.; Hoffmann, Michael R.

doi:10.1111/j.1600-0889.1989.tb00303.x

Cited by 82 publications

(32 citation statements)

References 33 publications

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“…Overall, the concentrations of chloride, nitrate, and sulfate in these fog events are within the wide range observed for snow precipitation and surface snow layers in central Greenland, while those of organic acids are much higher [De Angelis and Legrand, 1995]. All are, however, much lower than concentrations observed in midlatitude fog samples [Munger et al, 1989]. The water fluxes were very similar for the three events, making chemical concentrations directly comparable without taking into account dilution effects.…”

Section: Aerosol Size Distributions: Submicron Modessupporting

confidence: 54%

Biomass burning signatures in the atmosphere of central Greenland

Jaffrezo¹,

Davidson²,

Kuhns³

et al. 1998

J. Geophys. Res.

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Abstract. Daily atmospheric concentrations of particulate oxalate measured at the Summit of the Greenland Ice Sheet are presented for the summers 1992 -1995. We believe that four episodes of elevated concentrations are due to biomass burning plumes passing over the site. In at least two cases the source regions of the fires are located in northern Canada. Further characteristics of the aerosol are examined during one of these events. A large increase of particle number concentrations in the accumulation mode can be observed, while the increase is much more limited for total particle number. The suite of chemical species enriched in the aerosol includes typical biomass burning tracers like fine K, large concentrations of ammonium, particulate formate and acetate, as well as other organic species like glycolate. The size distributions of K, oxalate, and glycolate are skewed toward the accumulation mode and exhibit the very same shape as sulfate, suggesting internal mixing of these species in the same particles. Molar ratios S/K indicate incorporation of S during transport, most probably by production of sulfate. Concentrations of these species were measured in fog samples for radiative events that occurred during the plume passage. There is a good agreement in the relative variation of concentrations between the aerosol and fog for oxalate and glycolate, while the gas phase probably dominates incorporation in the fog droplets for acetate, formate, chloride, nitrate, and sulfate (incorporated as SO2, which is further oxidized). The complexity of the transfer of the organic acids from the atmosphere to fog is underlined.

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Section: Aerosol Size Distributions: Submicron Modessupporting

confidence: 54%

Biomass burning signatures in the atmosphere of central Greenland

Jaffrezo¹,

Davidson²,

Kuhns³

et al. 1998

J. Geophys. Res.

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“…Since only relatively large cloud drops are captured by the snow crystals, it also would be useful to know how the cloudwater composition varies with drop size (26)(27)(28). Evaluating the extent of riming is, however, a tedious task producing results that are at best semiquantitative.…”

Section: Discussionmentioning

confidence: 99%

Physical factors influencing winter precipitation chemistry

Collett¹,

Prévôt²,

Staehelin³

et al. 1991

Environ. Sci. Technol.

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Two case studies of winter precipitation events highlight the roles of transport and snow crystal riming (the capture of supercooled cloud droplets by snow crystals) in determining precipitation chemistry. In one case, passage of a cold front leads to a change in the air mass producing precipitation over the monitoring site. A simultaneous decrease in precipitation ion concentrations is observed. Correlations of the ion concentrations with the pseudoequivalent potential temperature, which serves as an air mass identifier, suggest that the decrease in ion concentrations is caused by the air mass change, rather than by washout of aerosols and gases from the atmosphere. In the second case, evidence is presented indicating that an increase in precipitation ion concentrations results from significant capture of polluted cloudwater droplets by the snow crystals. Influences on precipitation chemistry from both processes, transport and riming, can be large. In order to study other processes influencing precipitation chemistry that occur on similar time scales (minutes to hours), such as aerosol and gas scavenging or aqueousphase oxidation, it is important to evaluate possible confounding effects of tranmort and riming.

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“…The possible effect of organics may be estimated from the inhibition parameters in Table 1 and typical concentrations of organics. One might expect that formate ion would be an inhibitor, since the inhibition parameter is large, and formate is a significant constituent of cloudwater [Keene et al, 1983;Munger et al, 1989]. For remote clouds, Jacob [1986] suggests that 2 x 10 -6 M formate is typical, and this would give an inhibition of less than 10%, which is not significant.…”

Section: Consequences For Atmospheric Chemistrymentioning

confidence: 99%

The iron catalyzed oxidation of sulfur(IV) in aqueous solution: Differing effects of organics at high and low pH

Martin¹,

Hill²,

Tai³

et al. 1991

J. Geophys. Res.

111

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We have studied the oxidation of sulfur dioxide by dissolved oxygen in highly dilute solutions with a new differential optical absorption technique. We measured the rate of oxidation catalyzed by iron(III) over a wide range of pH, ionic strength, and in the presence of various organic materials. The studies indicate that noncomplexing organic molecules are highly inhibiting at “high” pH values of 5 and above and are not inhibiting at “low” pH values of 3 and below. Furthermore, the order of the reaction with respect to iron is different in the two pH regimes. This suggests that the mechanism of this reaction differs in the two pH regimes and is probably a free radical chain at high pH and a nonradical mechanism at low pH. Some of the mechanisms proposed in the literature are discussed in the light of these new data. None of the proposed mechanisms give completely satisfactory agreement with the data. We propose a modified free radical chain mechanism for the high pH regime, which correctly predicts the organic inhibitions. For the low pH regime, mechanisms proposed by Conklin and Hoffmann (1988) and by Hoffmann and Jacob (1984) give fair agreement with the pH data and correctly predict the self‐inhibition, the sulfate inhibition, and the ionic strength inhibition. In view of the new data we believe that the iron(III) catalyzed reaction in tropospheric clouds can be a major contributor to the rate of sulfate formation, but there will be significant inhibition of this process by formic acid in some situations.

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Carboxylic acids and carbonyl compounds in southern California clouds and fogs

Cited by 82 publications

References 33 publications

Biomass burning signatures in the atmosphere of central Greenland

Biomass burning signatures in the atmosphere of central Greenland

Physical factors influencing winter precipitation chemistry

The iron catalyzed oxidation of sulfur(IV) in aqueous solution: Differing effects of organics at high and low pH

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