Document Detail

Investigating the potential role of ammonia in ion chemistry of fine particulate matter formation for an urban environment.
MedLine Citation:
PMID:  20452648     Owner:  NLM     Status:  MEDLINE    
To investigate the potential role of ammonia in ion chemistry of PM(2.5) aerosol, measurements of PM(2.5) (particulate matter having aerodynamic diameter < 2.5 microm) along with its ionic speciation and gaseous pollutants (sulfur dioxide (SO2), nitrogen oxides (NO(x)), ammonia (NH3) and nitric acid (HNO3)) were undertaken in two seasons (summer and winter) of 2007-2008 at four sampling sites in Kanpur, an urban-industrial city in the Ganga basin, India. Mean concentrations of water-soluble ions were observed in the following order (i) summer: SO4(2-) (26.3 microg m(-3)) > NO3(-) (16.8) > NH4+ (15.1) > Ca2+ (4.1) > Na+ (2.4) > K+ (2.1 microg m(-3)) and (ii) winter: SO4(2-) (28.9 microg m(-3)) > NO3(-) (23.0) > NH4+ (16.4) > Ca2+ (3.4) > K+ (3.3) > Na+ (3.2 microg m(-3)). The mean molar ratio of NH4+ to SO4(2-) was 2.8+/-0.6 (mostly > 2), indicated abundance of NH3 to neutralize H2SO4. The excess of NH4+ was inferred to be associated with NO3(-) and Cl(-). Higher sulfur conversion ratio (F(s): 58%) than nitrogen conversion ratio (F(n): 39%) indicated that SO4(2-) was the preferred secondary species to NO3(-). The charge balance for the ion chemistry of PM(2.5) revealed that compounds formed from ammonia as precursor are (NH4)2SO4, NH4NO3 and NH4Cl. This study conclusively established that while there are higher contributions of NH4+, SO4(2-) to PM(2.5) in summer but for nitrates (in particulate phase), it is the winter season, which is critical because of low temperatures that drives the reaction between ammonia and HNO3 in forward direction for enhanced nitrate formation. In summary, inorganic secondary aerosol formation accounted for 30% mass of PM(2.5) and any particulate control strategy should include optimal control of primary precursor gases including ammonia.
Sailesh N Behera; Mukesh Sharma
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Publication Detail:
Type:  Journal Article     Date:  2010-05-10
Journal Detail:
Title:  The Science of the total environment     Volume:  408     ISSN:  1879-1026     ISO Abbreviation:  Sci. Total Environ.     Publication Date:  2010 Aug 
Date Detail:
Created Date:  2010-06-28     Completed Date:  2010-11-05     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0330500     Medline TA:  Sci Total Environ     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  3569-75     Citation Subset:  IM    
Copyright Information:
2010 Elsevier B.V. All rights reserved.
Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India.
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MeSH Terms
Air Pollutants / analysis,  chemistry*
Ammonia / analysis,  chemistry*
Atmosphere / chemistry
Environmental Monitoring
Ions / analysis,  chemistry
Particle Size
Particulate Matter / analysis,  chemistry*
Reg. No./Substance:
0/Air Pollutants; 0/Ions; 0/Particulate Matter; 7664-41-7/Ammonia

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