scholarly journals Light induced conversion of nitrogen dioxide into nitrous acid on submicron humic acid aerosol

2007 ◽  
Vol 7 (2) ◽  
pp. 4035-4064 ◽  
Author(s):  
K. Stemmler ◽  
M. Ammann ◽  
Y. Elshorbany ◽  
J. Kleffmann ◽  
M. Ndour ◽  
...  
Keyword(s):  
Humic Acid ◽  
Relative Humidity ◽  
Nitrogen Dioxide ◽  
Nitrous Acid ◽  
Ambient Pressure ◽  
Urban Environments ◽  
Atmospheric Conditions ◽  
Rural And Urban ◽  
Humic Materials ◽  
Uptake Coefficients

Abstract. The interactions of aerosols consisting of humic acids with gaseous nitrogen dioxide (NO2) were investigated under different light conditions in aerosol flow tube experiments at ambient pressure and temperature. The results show that NO2 is converted on the humic acid aerosol into nitrous acid (HONO), which is released from the aerosol and can be detected in the gas phase at the reactor exit. The formation of HONO on the humic acid aerosol is strongly activated by light: In the dark, the HONO-formation was below the detection limit, but it was increasing with the intensity of the irradiation with visible light. Under simulated atmospheric conditions with respect to the actinic flux, relative humidity and NO2-concentration, reactive uptake coefficients γrxn for the NO2→HONO conversion on the aerosol between γrxn <10−7 (in the dark) and γrxn = 6×10−6 were observed. The observed uptake coefficients decreased with increasing NO2-concentration in the range from 2.7 to 280 ppb and were dependent on the relative humidity (RH) with slightly reduced values at low humidity (<20% RH) and high humidity (>60% RH). The measured uptake coefficients for the NO2→HONO conversion are too low to explain the HONO-formation rates observed near the ground in rural and urban environments by the conversion of NO2→HONO on organic aerosol surfaces, even if one would assume that all aerosols consist of humic acid only. It is concluded that humic materials present on the Earth surface will have a much larger impact on the HONO-formation in the lowermost layer of the troposphere than humic materials potentially occurring in airborne particles.

scholarly journals Light induced conversion of nitrogen dioxide into nitrous acid on submicron humic acid aerosol

2007 ◽  
Vol 7 (16) ◽  
pp. 4237-4248 ◽  
Author(s):  
K. Stemmler ◽  
M. Ndour ◽  
Y. Elshorbany ◽  
J. Kleffmann ◽  
B. D'Anna ◽  
...  
Keyword(s):  
Humic Acid ◽  
Relative Humidity ◽  
Nitrogen Dioxide ◽  
Nitrous Acid ◽  
Ambient Pressure ◽  
Urban Environments ◽  
Atmospheric Conditions ◽  
Rural And Urban ◽  
Humic Materials ◽  
Uptake Coefficients

Abstract. The interactions of aerosols consisting of humic acids with gaseous nitrogen dioxide (NO2) were investigated under different light conditions in aerosol flow tube experiments at ambient pressure and temperature. The results show that NO2 is converted on the humic acid aerosol into nitrous acid (HONO), which is released from the aerosol and can be detected in the gas phase at the reactor exit. The formation of HONO on the humic acid aerosol is strongly activated by light: In the dark, the HONO-formation was below the detection limit, but it was increasing with the intensity of the irradiation with visible light. Under simulated atmospheric conditions with respect to the actinic flux, relative humidity and NO2-concentration, reactive uptake coefficients γrxn for the NO2→HONO conversion on the aerosol between γrxn <10−7 (in the dark) and γrxn=6×10−6 were observed. The observed uptake coefficients decreased with increasing NO2-concentration in the range from 2.7 to 280 ppb and were dependent on the relative humidity (RH) with slightly reduced values at low humidity (<20% RH) and high humidity (>60% RH). The measured uptake coefficients for the NO2→HONO conversion are too low to explain the HONO-formation rates observed near the ground in rural and urban environments by the conversion of NO2→HONO on organic aerosol surfaces, even if one would assume that all aerosols consist of humic acid only. It is concluded that the processes leading to HONO formation on the Earth surface will have a much larger impact on the HONO-formation in the lowermost layer of the troposphere than humic materials potentially occurring in airborne particles.

scholarly journals Heterogeneous conversion of NO<sub>2</sub> on secondary organic aerosol surfaces: A possible source of nitrous acid (HONO) in the atmosphere?

2003 ◽  
Vol 3 (3) ◽  
pp. 469-474 ◽  
Author(s):  
R. Bröske ◽  
J. Kleffmann ◽  
P. Wiesen
Keyword(s):  
Nitrous Acid ◽  
Secondary Organic Aerosols ◽  
Organic Aerosols ◽  
Oh Radicals ◽  
Atmospheric Conditions ◽  
Alpha Pinene ◽  
Upper Limits ◽  
Uptake Coefficients ◽  
Heterogeneous Formation ◽  
Organic Particles

Abstract. The heterogeneous conversion of NO2 on different secondary organic aerosols (SOA) was investigated with the focus on a possible formation of nitrous acid (HONO). In one set of experiments different organic aerosols were produced in the reactions of O3 with alpha-pinene, limonene or catechol and OH radicals with toluene or limonene, respectively. The aerosols were sampled on filters and exposed to humidified NO2  mixtures under atmospheric conditions. The estimated upper limits for the uptake coefficients of NO2  and the reactive uptake coefficients NO2  -> HONO are in the range of 10-6 and 10-7, respectively. The integrated HONO formation for 1 h reaction time was <1013 cm-2 geometrical surface and <1017 g-1 particle mass. In a second set of experiments the conversion of NO2 into HONO in the presence of organic particles was carried out in an aerosol flow tube under atmospheric conditions. In this case the aerosols were produced in the reaction of O3 with beta-pinene, limonene or catechol, respectively. The upper limits for the reactive uptake coefficients NO2 -> HONO were in the range of 7 x 10-7 - 9 x 10-6. The results from the present study show that heterogeneous formation of nitrous acid on secondary organic aerosols (SOA) is unimportant for the atmosphere.

scholarly journals Photosensitized reduction of nitrogen dioxide on humic acid as a source of nitrous acid

Nature ◽  
2006 ◽  
Vol 440 (7081) ◽  
pp. 195-198 ◽  
Author(s):  
Konrad Stemmler ◽  
Markus Ammann ◽  
Chantal Donders ◽  
Jörg Kleffmann ◽  
Christian George
Keyword(s):  
Humic Acid ◽  
Nitrogen Dioxide ◽  
Nitrous Acid

scholarly journals Phase transitions and hygroscopic growth of aerosol particles containing humic acid and mixtures of humic acid and ammonium sulphate

2005 ◽  
Vol 5 (5) ◽  
pp. 9581-9620 ◽  
Author(s):  
C. L. Badger ◽  
I. George ◽  
P. T. Griffiths ◽  
C. F. Braban ◽  
R. A. Cox ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Growth Factors ◽  
Humic Acid ◽  
Relative Humidity ◽  
Ammonium Sulphate ◽  
Water Uptake ◽  
Phase Changes ◽  
Hygroscopic Growth ◽  
Differential Mobility Analysis ◽  
Humic Materials

Abstract. The phase transitions and hygroscopic growth of two humic acid aerosols (Aldrich sodium salt and Leonardite Standard (IHSS)) and their mixtures with ammonium sulphate have been investigated using a combination of two techniques, Fourier transform infra-red (FTIR) spectroscopy and tandem differential mobility analysis (TDMA). A growth factor of 1.16 at 85% relative humdity (RH) was found for the Aldrich humic acid which can be regarded as an upper limit for growth factors of humic-like substances (HULIS) found in atmospheric aerosol and is significantly smaller than that of typical atmospheric inorganics. We find that the humic acid aerosols exhibit water uptake over all relative humidites with no apparent phase changes, suggesting that these aerosols readily form supersaturated droplets. In the mixed particles, the humic acid component decreases the deliquescence relative humidity (DRH) and increases the efflorescence relative humidity (ERH) of the ammonium sulphate component, and there is some degree of water uptake prior to ammonium sulphate deliquescence. In addition, at low RH, the FTIR spectra show that the ammonium is present in a different chemical environment in the mixed aerosols than in crystalline ammonium sulphate, perhaps existing as a complex with the humic materials. The growth factors of the mixed aerosols are intermediate between those of the single component aerosols and can be predicted assuming that the inorganic and organic fractions take up water independently.

scholarly journals Phase transitions and hygroscopic growth of aerosol particles containing humic acid and mixtures of humic acid and ammonium sulphate

2006 ◽  
Vol 6 (3) ◽  
pp. 755-768 ◽  
Author(s):  
C. L. Badger ◽  
I. George ◽  
P. T. Griffiths ◽  
C. F. Braban ◽  
R. A. Cox ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Growth Factors ◽  
Humic Acid ◽  
Relative Humidity ◽  
Ammonium Sulphate ◽  
Water Uptake ◽  
Phase Changes ◽  
Hygroscopic Growth ◽  
Differential Mobility Analysis ◽  
Humic Materials

Abstract. The phase transitions and hygroscopic growth of two humic acid aerosols (Aldrich sodium salt and Leonardite Standard (IHSS)) and their mixtures with ammonium sulphate have been investigated using a combination of two techniques, Fourier transform infra-red (FTIR) spectroscopy and tandem differential mobility analysis (TDMA). A growth factor of 1.16 at 85% relative humidity (RH) was found for the Aldrich humic acid which can be regarded as an upper limit for growth factors of humic-like substances (HULIS) found in atmospheric aerosol and is significantly smaller than that of typical atmospheric inorganics. We find that the humic acid aerosols exhibit water uptake over all relative humidities with no apparent phase changes, suggesting that these aerosols readily form supersaturated droplets. In the mixed particles, the humic acid component decreases the deliquescence relative humidity (DRH) and increases the efflorescence relative humidity (ERH) of the ammonium sulphate component, and there is some degree of water uptake prior to ammonium sulphate deliquescence. In addition, at low RH, the FTIR spectra show that the ammonium is present in a different chemical environment in the mixed aerosols than in crystalline ammonium sulphate, perhaps existing as a complex with the humic materials. The growth factors of the mixed aerosols are intermediate between those of the single-component aerosols and can be predicted assuming that the inorganic and organic fractions take up water independently.

Humic acid in ice: Photo-enhanced conversion of nitrogen dioxide into nitrous acid

2010 ◽  
Vol 44 (40) ◽  
pp. 5443-5450 ◽  
Author(s):  
Thorsten Bartels-Rausch ◽  
Marcello Brigante ◽  
Yasin F. Elshorbany ◽  
Markus Ammann ◽  
Barbara D'Anna ◽  
...  
Keyword(s):  
Humic Acid ◽  
Nitrogen Dioxide ◽  
Nitrous Acid

scholarly journals Heterogeneous conversion of NO<sub>2</sub> on secondary organic aerosol surfaces: A possible source of nitrous acid (HONO) in the atmosphere?

2003 ◽  
Vol 3 (1) ◽  
pp. 597-613 ◽  
Author(s):  
R. Bröske ◽  
J. Kleffmann ◽  
P. Wiesen
Keyword(s):  
Nitrous Acid ◽  
Secondary Organic Aerosols ◽  
Organic Aerosols ◽  
Oh Radicals ◽  
Atmospheric Conditions ◽  
Flow Tube ◽  
Upper Limits ◽  
Uptake Coefficients ◽  
Heterogeneous Formation ◽  
Organic Particles

Abstract. The heterogeneous conversion of NO2 on different secondary organic aerosols (SOA) was investigated with the focus on a possible formation of nitrous acid (HONO). In one set of experiments different organic aerosols were produced in the reactions of O3 with α-pinene, limonene or catechol and OH radicals with toluene or limonene, respectively. The aerosols were sampled on filters and exposed to humidified NO2 mixtures under atmospheric conditions. The estimated upper limits for the uptake coefficients of NO2 and the reactive uptake coefficients NO2 →HONO are in the range of 10−6 and 10−7, respectively. The integrated HONO formation for 1 h reaction time was <1013 cm−2 geometrical surface and <1017 g−1 particle mass. In a second set of experiments the conversion of NO2 into HONO in the presence of organic particles was carried out in an aerosol flow tube under atmospheric conditions. In this case the aerosols were produced in the reaction of O3 with β-pinene, limonene or catechol, respectively. The upper limits for the reactive uptake coefficients NO2 \\rightarrow HONO were in the range of 7×10−7 −9×10−6. The results from the present study show that heterogeneous formation of nitrous acid on secondary organic aerosols (SOA) is unimportant for the atmosphere.

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