Abstract. Biomass burning (BB) is a significant source of dicarboxylic acids
(diacids) and related compounds that play important roles in atmospheric
chemistry and climate change. In this study, a combustion chamber and
oxidation flow reactor were used to generate fresh and aged aerosols from
burned rice, maize and wheat straw to investigate atmospheric aging and the
stable carbon isotopic (δ13C) composition of these emissions.
Succinic acid (C4) was the most abundant species in fresh samples,
while oxalic acid (C2) became dominant after atmospheric aging. Of all
diacids, C2 had the highest aged to fresh emission ratios (A/F),
suggesting that C2 is largely produced through secondary photochemical
processes. Compared with fresh samples, the emission factors of
ketocarboxylic acids and α-dicarbonyls increased after 2 d but
decreased after 7 d aging, indicating a short residence time and further
atmospheric degradation from 2 to 7 d. The δ13C values of
C2 for aged biomass samples were higher than those of urban aerosols
but lower than marine or mountain aerosols, and the δ13C values
of C2 became isotopically heavier during aging. Relationships between
the reduction in volatile organic compounds (VOCs), such as toluene,
benzene and isoprene, and increase in diacids after 2 d aging indicate
that these VOCs led to the formation of diacids. However, no significant
correlation was found between decreases in VOCs and increases in 7 d aged
diacids. In addition, the A/F of C2 was 50.8 at 2 d and 64.5 at 7 d, indicating that the conversion of VOCs to C2 was almost completed
within 2 d. For the longer aging times, the particulate-phase compounds
may undergo further degradation in the oxidation processes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.