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Chemistry of aerosols over a semi‐arid region: Evidence for acid neutralization by mineral dust
Author(s) -
Rastogi N.,
Sarin M. M.
Publication year - 2006
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl027708
Subject(s) - radiative forcing , mineral dust , chemical composition , aerosol , arid , environmental chemistry , mineral , atmospheric sciences , environmental science , acid rain , neutralization , dominance (genetics) , mineralogy , chemistry , geology , paleontology , biochemistry , organic chemistry , gene , antibody , immunology , biology
A two‐year study based on chemical characteristics of ambient aerosols, from an urban site of a semi‐arid region in western India, provides an unequivocal evidence for the quantitative neutralization of acidic constituents by mineral aerosols. The mineral dust component varied in the range 16–220 μ g m −3 (Av: 88, sd: 42); and contributed to 69 ± 5% of the TSP (range: 43–273 μ g m −3 , Av: 125, sd: 49). A characteristic feature of the in‐situ chemical reactions is well reflected by the relative dominance of Ca 2+ and HCO 3 − ions in the water‐soluble composition of aerosols and anti‐correlation among HCO 3 − /Ca 2+ and “Excess Acid”/Ca 2+ . A ubiquitous alkaline‐nature of rainfall events over this high dust region further attests to our chemical data. Such regional‐scale atmospheric transformation processes suggest the over estimation of negative radiative forcing (climate cooling) due to sulphate aerosols in the global climate models.