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Real‐time measurements of ambient aerosols in a polluted Indian city: Sources, characteristics, and processing of organic aerosols during foggy and nonfoggy periods
Author(s) -
Chakraborty Abhishek,
Bhattu Deepika,
Gupta Tarun,
Tripathi Sachchida N.,
Canagaratna Manjula R.
Publication year - 2015
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2015jd023419
Subject(s) - aerosol , environmental science , environmental chemistry , biomass burning , total organic carbon , atmospheric sciences , atmosphere (unit) , meteorology , chemistry , geology , geography
A detailed time‐resolved chemical characterization of ambient nonrefractory submicron aerosols (NR‐PM 1 ) was conducted for the first time in India. The measurements were performed during the winter (November 2011 to January 2012) in a heavily polluted city of Kanpur, which is situated in the Indo‐Gangetic Plain. Real‐time measurements provided new insights into the sources and evolution of organic aerosols (OA) that could not be obtained using previously deployed filter‐based measurements at this site. The average NR‐PM 1 loading was very high (>100 µg/m 3 ) throughout the study, with OA contributing approximately 70% of the total aerosol mass. Source apportionment of the OA using positive matrix factorization revealed large contributions from fresh and aged biomass burning OA throughout the entire study period. A back trajectory analysis showed that the polluted air masses were affected by local sources and distant source regions where the burning of paddy residues occurs annually during winter. Several fog episodes were encountered during the study, and the OA composition varied between foggy and nonfoggy periods, with higher oxygen to carbon (O/C) ratios during the foggy periods. The evolution of OA and their elemental ratios (O:C and H:C) were investigated for the possible effects of fog processing.