Surface measurements of formaldehyde and formic and acetic acids at a subtropical semiarid site in India

Khare, Puja; Satsangi, Gur Sumiran; Kumar, N.; Kumari, K. Maharaj; Srivastava, S. N.

doi:10.1029/97jd00735

Cited by 20 publications

(10 citation statements)

References 64 publications

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“…However, their relative importance is quite variable. Khare et al [1997] reported a significant diurnal variation of formic acid for a semiurban site with an increase in formic acid concentration in the afternoon during the hours of high solar irradiation, indicating the importance of secondary formation. In our measurements photochemical activity was much stronger in August than September as seen from the ozone traces.…”

Section: Resultsmentioning

confidence: 95%

Online gas and aerosol measurement of water soluble carboxylic acids in Zurich

Fisseha¹,

Dommen²,

Gaeggeler³

et al. 2006

J. Geophys. Res.

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[1] We discuss the diurnal and seasonal variability of low molecular weight organic acids in Zurich city on the basis of online quasi-continuous measurement in the gas and aerosol phase using a wet effluent diffusion denuder/aerosol collector (WEDD/AC) coupled to ion chromatography. The measurements were performed during August-September 2002 and March 2003. Acetic acid exhibited the highest concentration in the gas phase during all the measurement periods, followed by formic acid. Oxalic acid was predominantly found in the aerosol phase and often below the detection limit in the gas phase. In addition, filter samples were analyzed using ion chromatography-mass spectrometry (IC-MS) to provide more information on organic acids in the aerosol phase. From the offline IC-MS measurements, 20 monocarboxylic, dicarboxylic, and tricarboxylic acids were determined. In addition, more than 20 different masses were detected with the MS; however, identification of the organic acids was not possible. The sum of the carboxylic acids contributed on average 2% to the water soluble organic carbon (WSOC). The fraction of dicarboxylic acids to the WSOC was higher in summer compared to winter suggesting that dicarboxylic acids are mainly a result of photochemical reactions in summer whereas in winter they mainly result from primary sources.

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Section: Resultsmentioning

confidence: 95%

Online gas and aerosol measurement of water soluble carboxylic acids in Zurich

Fisseha¹,

Dommen²,

Gaeggeler³

et al. 2006

J. Geophys. Res.

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“…Concentrations of formate were analyzed by ion chromatography (DX-500, Dionex) with an anion exchange column (Ionpac AS11) using a mobile phase of NaOH(aq) with a concentration gradient ranging from 0.5 mM to 38.25 mM. (Heikes, 1992;Faust, 1994;Zhuang et al, 1992;Gunz and Hoffmann, 1990;Sakugawa et al, 1990;Lowe and Schmidt, 1983;Khare et al, 1997). We observed the formation of formate only when CH 2 (OH) 2 , HOOH and metals (metal = Fe(III) or Cu(II)) co-existed, and we also found that the formation was significantly enhanced (approximately 5 times) when the solution underwent the freezing process ( proximately 20% of the frozen sample).…”

Section: Methodsmentioning

confidence: 99%

Enhanced formation of formate by freezing in solutions of hydrated formaldehyde-metal-hydrogen peroxide

et al. 2004

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We detected the formation of formate (HCOOH/HCOO -) in solutions containing hydrated formaldehyde (CH 2 (OH) 2 ), HOOH, and Fe(III) or Cu(II). Formate formation increased significantly (ca. 5 times) when the solution underwent freezing and thawing. Although the reaction mechanisms are not clearly understood, we believe that the concentration effect of freezing enhanced the catalytic reactions between HOOH and Fe(III) or Cu(II) and the reduction of transition metals, i.e., Fe(III) to Fe(II) and Cu(II) to Cu(I). The concentration effect also enhanced reactions between Fe(II) and HOOH or Cu(I) and HOOH, which generated OH radical ("freeze-Fenton reaction"). We suspect that hydroxyl radical formed by the freeze-Fenton reaction probably oxidized CH 2 (OH) 2 and resulted in the formation of formate. Samples of identical compositions kept in the refrigerator did not form any formate except for the CH 2 (OH) 2 -Fe(III)-HOOH solution that formed a small amount of formate. Our study of the effects of pH on the CH 2 (OH) 2 -Fe(III)-HOOH solution (pHs between 1.5-5.0) showed that formate formation was the highest at pH = 4.0, indicating that the speciation of Fe(III) affected the formation of formate. Concentration-dependent experiments demonstrated that Fe is probably the limiting agent under typical environmental conditions.

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“…However, no variation was observed between the ratio of HCOOH/HCHO and the measured rainwater acidity [22]. As a consequence, the correlation between HCHO (aq) and HCOOH may indicate the common sources or different sources which have fairly constant strengths or products of the same reaction for the two species [9,23].…”

Section: Relationship Between the Hcho (Aq) And Other Speciesmentioning

confidence: 99%

The Annual Characteristics of Rainwater HCHO in Guiyang City, Southwest of China

Shao

Lee

et al. 2010

CLEAN Soil Air Water

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The Annual Characteristics of Rainwater HCHO in Guiyang City, Southwest of China HCHO is ubiquitous and important chemical constitutes in the troposphere. The concentrations of the HCHO (aq) in the rainwater were measured in the Guiyang city, southeastern of China from May 2006 to April 2007 and 153 discrete samples were collected. Rainwater (N ¼ 151) HCHO (aq) concentrations ranged from lower than method detection limit (MDL) to 40.2 mmol/L with a volume weighted mean value of 7.4 AE 8.8 mmol/L. The strong correlations between HCHO (aq) and HCOO À (r ¼ 0.69, n ¼ 137), HCHO (aq) and nss-SO 2À 4 (r ¼ 0.74, n ¼ 137), HCHO (aq) and NO À 3 (r ¼ 0.67, n ¼ 137), HCHO (aq) and NH þ 4 (r ¼ 0.74, n ¼ 133) suggest the significant influence of the anthropogenic input for the HCHO (aq) levels. The concentration levels of rainwater HCHO (aq) was inversely proportional to the amount of rainfall, indicating the belowcloud process is the most important mechanism for rainwater HCHO (aq) scavenging processes. More than 70% of the HCHO (aq) wet deposition took place during the early stage of the rainfall. According to the air mass back-trajectory analysis, the rainwater with industrial back-trajectories coming from the north had the highest levels of HCHO (aq) while the rainwater with the green-covered or marine back-trajectories from the southeast had the lowest concentrations, and this indicate the HCHO (aq) originated from urban or industrial regions served as an important source of the rainwater. The annual HCHO (aq) wet deposition flux was calculated as 6.96 mmol/m 2 per year and the total deposition flux was estimated as 24.35 mmol/m 2 per year, 71.4% of which was dominated by dry deposition.

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Surface measurements of formaldehyde and formic and acetic acids at a subtropical semiarid site in India

Cited by 20 publications

References 64 publications

Online gas and aerosol measurement of water soluble carboxylic acids in Zurich

Online gas and aerosol measurement of water soluble carboxylic acids in Zurich

Enhanced formation of formate by freezing in solutions of hydrated formaldehyde-metal-hydrogen peroxide

The Annual Characteristics of Rainwater HCHO in Guiyang City, Southwest of China

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